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Leuthner TC, Zhang S, Kohrn BF, Stapleton HM, Baugh LR. Structure-specific variation in per- and polyfluoroalkyl substances toxicity among genetically diverse Caenorhabditis elegans strains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596269. [PMID: 38854041 PMCID: PMC11160736 DOI: 10.1101/2024.05.29.596269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Background There are >14,500 structurally diverse per- and polyfluoroalkyl substances (PFAS). Despite knowledge that these "forever chemicals" are in 99% of humans, mechanisms of toxicity and adverse health effects are incompletely known. Furthermore, the contribution of genetic variation to PFAS susceptibility and health consequences is unknown. Objectives We determined the toxicity of a structurally distinct set of PFAS in twelve genetically diverse strains of the genetic model system Caenorhabditis elegans. Methods Dose-response curves for four perfluoroalkyl carboxylic acids (PFNA, PFOA, PFPeA, and PFBA), two perfluoroalkyl sulfonic acids (PFOS and PFBS), two perfluoroalkyl sulfonamides (PFOSA and PFBSA), two fluoroether carboxylic acids (GenX and PFMOAA), one fluoroether sulfonic acid (PFEESA), and two fluorotelomers (6:2 FCA and 6:2 FTS) were determined in the C. elegans laboratory reference strain, N2, and eleven genetically diverse wild strains. Body length was quantified by image analysis at each dose after 48 hr of developmental exposure of L1 arrest-synchronized larvae to estimate effective concentration values (EC50). Results There was a significant range in toxicity among PFAS: PFOSA > PFBSA ≈ PFOS ≈ PFNA > PFOA > GenX ≈ PFEESA > PFBS ≈ PFPeA ≈ PFBA. Long-chain PFAS had greater toxicity than short-chain, and fluorosulfonamides were more toxic than carboxylic and sulfonic acids. Genetic variation explained variation in susceptibility to PFBSA, PFOS, PFBA, PFOA, GenX, PFEESA, PFPeA, and PFBA. There was significant variation in toxicity among C. elegans strains due to chain length, functional group, and between legacy and emerging PFAS. Conclusion C. elegans respond to legacy and emerging PFAS of diverse structures, and this depends on specific structures and genetic variation. Harnessing the natural genetic diversity of C. elegans and the structural complexity of PFAS is a powerful New Approach Methodology (NAM) to investigate structure-activity relationships and mechanisms of toxicity which may inform regulation of other PFAS to improve human and environmental health.
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Affiliation(s)
- Tess C. Leuthner
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Sharon Zhang
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Brendan F Kohrn
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Heather M. Stapleton
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - L. Ryan Baugh
- Department of Biology, Duke University, Durham, North Carolina, USA
- Center for Genomic and Computational Biology, Duke University, North Carolina, USA
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2
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Aurisano N, Fantke P, Chiu WA, Judson R, Jang S, Unnikrishnan A, Jolliet O. Probabilistic Reference and 10% Effect Concentrations for Characterizing Inhalation Non-cancer and Developmental/Reproductive Effects for 2,160 Substances. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:8278-8288. [PMID: 38697947 PMCID: PMC11097392 DOI: 10.1021/acs.est.4c00207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/05/2024]
Abstract
Chemicals assessment and management frameworks rely on regulatory toxicity values, which are based on points of departure (POD) identified following rigorous dose-response assessments. Yet, regulatory PODs and toxicity values for inhalation exposure (i.e., reference concentrations [RfCs]) are available for only ∼200 chemicals. To address this gap, we applied a workflow to determine surrogate inhalation route PODs and corresponding toxicity values, where regulatory assessments are lacking. We curated and selected inhalation in vivo data from the U.S. EPA's ToxValDB and adjusted reported effect values to chronic human equivalent benchmark concentrations (BMCh) following the WHO/IPCS framework. Using ToxValDB chemicals with existing PODs associated with regulatory toxicity values, we found that the 25th %-ile of a chemical's BMCh distribution (POD p 25 BMC h ) could serve as a suitable surrogate for regulatory PODs (Q2 ≥ 0.76, RSE ≤ 0.82 log10 units). We applied this approach to derive POD p 25 BMC h for 2,095 substances with general non-cancer toxicity effects and 638 substances with reproductive/developmental toxicity effects, yielding a total coverage of 2,160 substances. From these POD p 25 BMC h , we derived probabilistic RfCs and human population effect concentrations. With this work, we have expanded the number of chemicals with toxicity values available, thereby enabling a much broader coverage for inhalation risk and impact assessment.
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Affiliation(s)
- Nicolò Aurisano
- Quantitative
Sustainability Assessment, Department of Environmental and Resource
Engineering, Technical University of Denmark, Bygningstorvet 115, Kgs., Lyngby 2800, Denmark
| | - Peter Fantke
- Quantitative
Sustainability Assessment, Department of Environmental and Resource
Engineering, Technical University of Denmark, Bygningstorvet 115, Kgs., Lyngby 2800, Denmark
| | - Weihsueh A. Chiu
- Department
of Veterinary Integrative Biosciences, College of Veterinary Medicine
and Biomedical Sciences, Texas A&M University, College Station, Texas 77843, United
States
| | - Richard Judson
- National
Center for Computational Toxicology, U.S.
Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27711, United States
| | - Suji Jang
- Department
of Veterinary Integrative Biosciences, College of Veterinary Medicine
and Biomedical Sciences, Texas A&M University, College Station, Texas 77843, United
States
| | - Aswani Unnikrishnan
- National
Center for Computational Toxicology, U.S.
Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27711, United States
| | - Olivier Jolliet
- Quantitative
Sustainability Assessment, Department of Environmental and Resource
Engineering, Technical University of Denmark, Bygningstorvet 115, Kgs., Lyngby 2800, Denmark
- Department
of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan 48109, United States
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3
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Chiu WA. Invited Perspective: Uneven Progress Addressing Population Variability in Human Health Risk Assessment. ENVIRONMENTAL HEALTH PERSPECTIVES 2024; 132:31305. [PMID: 38498339 PMCID: PMC10947099 DOI: 10.1289/ehp13461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/03/2023] [Accepted: 02/06/2024] [Indexed: 03/20/2024]
Affiliation(s)
- Weihsueh A. Chiu
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas, USA
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas, USA
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4
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Ford LC, Lin HC, Tsai HHD, Zhou YH, Wright FA, Sedykh A, Shah RR, Chiu WA, Rusyn I. Hazard and risk characterization of 56 structurally diverse PFAS using a targeted battery of broad coverage assays using six human cell types. Toxicology 2024; 503:153763. [PMID: 38423244 PMCID: PMC11214689 DOI: 10.1016/j.tox.2024.153763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/13/2024] [Accepted: 02/23/2024] [Indexed: 03/02/2024]
Abstract
Per- and poly-fluoroalkyl substances (PFAS) are extensively used in commerce leading to their prevalence in the environment. Due to their chemical stability, PFAS are considered to be persistent and bioaccumulative; they are frequently detected in both the environment and humans. Because of this, PFAS as a class (composed of hundreds to thousands of chemicals) are contaminants of very high concern. Little information is available for the vast majority of PFAS, and regulatory agencies lack safety data to determine whether exposure limits or restrictions are needed. Cell-based assays are a pragmatic approach to inform decision-makers on potential health hazards; therefore, we hypothesized that a targeted battery of human in vitro assays can be used to determine whether there are structure-bioactivity relationships for PFAS, and to characterize potential risks by comparing bioactivity (points of departure) to exposure estimates. We tested 56 PFAS from 8 structure-based subclasses in concentration response (0.1-100 μM) using six human cell types selected from target organs with suggested adverse effects of PFAS - human induced pluripotent stem cell (iPSC)-derived hepatocytes, neurons, and cardiomyocytes, primary human hepatocytes, endothelial and HepG2 cells. While many compounds were without effect; certain PFAS demonstrated cell-specific activity highlighting the necessity of using a compendium of in vitro models to identify potential hazards. No class-specific groupings were evident except for some chain length- and structure-related trends. In addition, margins of exposure (MOE) were derived using empirical and predicted exposure data. Conservative MOE calculations showed that most tested PFAS had a MOE in the 1-100 range; ∼20% of PFAS had MOE<1, providing tiered priorities for further studies. Overall, we show that a compendium of human cell-based models can be used to derive bioactivity estimates for a range of PFAS, enabling comparisons with human biomonitoring data. Furthermore, we emphasize that establishing structure-bioactivity relationships may be challenging for the tested PFAS.
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Affiliation(s)
- Lucie C Ford
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Hsing-Chieh Lin
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Han-Hsuan D Tsai
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Yi-Hui Zhou
- Department of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA
| | - Fred A Wright
- Department of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA
| | | | | | - Weihsueh A Chiu
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Ivan Rusyn
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA.
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5
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To KT, Kleinstreuer N, Vasiliou V, Hogberg HT. New approach methodologies to address population variability and susceptibility. Hum Genomics 2023; 17:56. [PMID: 37381067 DOI: 10.1186/s40246-023-00502-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 06/30/2023] Open
Affiliation(s)
| | - Nicole Kleinstreuer
- NIH/NIEHS/DTT/NICEATM, RTP, Morrisville, NC, 27709, USA
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, 06520, USA
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, 06520, USA
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6
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Zhang J, Liao H, Chen Y, Li X, Chen R, Han S, Liu S, Yin S. Concentrations and homologue patterns of SCCPs and MCCPs in the serum of the general population of adults in Hangzhou, China. CHEMOSPHERE 2023:139131. [PMID: 37285971 DOI: 10.1016/j.chemosphere.2023.139131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/12/2023] [Accepted: 06/03/2023] [Indexed: 06/09/2023]
Abstract
Due to their ubiquitous presence in the environment and humans, chlorinated paraffins (CPs) are a major environmental and public health concern. CPs are known to persist, bioaccumulate and potentially threaten human health, but reports on their internal exposure in the adult general population are still scarce. In this study, serum samples collected from adults living in Hangzhou, China, were quantified for SCCPs and MCCPs using GC-NCI-MS methods. A total of 150 samples were collected and subjected to analysis. ∑SCCPs were detected in 98% of the samples with a median concentration of 721 ng/g lw. MCCPs were found in all serum samples with a median concentration of 2210 ng/g lw, indicating that MCCPs were the dominant homologous group. For SCCPs and MCCPs, ∑C10 and ∑C14 were found to be the dominant carbon chain length homologues. Our results showed that age, BMI and lifestyle were not found to be significantly associated with internal exposure to CPs for the samples in this study. Based on PCA analysis, an age-specific distribution of CP homologues was observed. This suggests that internal exposure to CPs in the general population is related to exposure scenarios and history. The results of this study may contribute to a better understanding of the internal exposure to CPs in the general population and may provide a direction for the investigation of the source of exposure to CPs in the environment and daily life.
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Affiliation(s)
- Jianyun Zhang
- Department of Nutrition and Toxicology, School of Public Health, Hangzhou Normal University, Hangzhou, 311121, China
| | - Hanyu Liao
- Department of Nutrition and Toxicology, School of Public Health, Hangzhou Normal University, Hangzhou, 311121, China
| | - Yanhong Chen
- Division of Health Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Xue Li
- Department of Nutrition and Toxicology, School of Public Health, Hangzhou Normal University, Hangzhou, 311121, China
| | - Rong Chen
- Department of Nutrition and Toxicology, School of Public Health, Hangzhou Normal University, Hangzhou, 311121, China
| | - Shufen Han
- Department of Nutrition and Toxicology, School of Public Health, Hangzhou Normal University, Hangzhou, 311121, China
| | - Shuren Liu
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China
| | - Shanshan Yin
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy (IRA), Zhejiang Shuren University, Hangzhou, 310015, China; Toxicological Centre, Universiteit Antwerpen, Wilrijk, 2610, Belgium.
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7
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Busquet F, Laperrouze J, Jankovic K, Krsmanovic T, Ignasiak T, Leoni B, Apic G, Asole G, Guigó R, Marangio P, Palumbo E, Perez-Lluch S, Wucher V, Vlot AH, Anholt R, Mackay T, Escher BI, Grasse N, Huchthausen J, Massei R, Reemtsma T, Scholz S, Schüürmann G, Bondesson M, Cherbas P, Freedman JH, Glaholt S, Holsopple J, Jacobson SC, Kaufman T, Popodi E, Shaw JJ, Smoot S, Tennessen JM, Churchill G, von Clausbruch CC, Dickmeis T, Hayot G, Pace G, Peravali R, Weiss C, Cistjakova N, Liu X, Slaitas A, Brown JB, Ayerbe R, Cabellos J, Cerro-Gálvez E, Diez-Ortiz M, González V, Martínez R, Vives PS, Barnett R, Lawson T, Lee RG, Sostare E, Viant M, Grafström R, Hongisto V, Kohonen P, Patyra K, Bhaskar PK, Garmendia-Cedillos M, Farooq I, Oliver B, Pohida T, Salem G, Jacobson D, Andrews E, Barnard M, Čavoški A, Chaturvedi A, Colbourne JK, Epps DJT, Holden L, Jones MR, Li X, Müller F, Ormanin-Lewandowska A, Orsini L, Roberts R, Weber RJM, Zhou J, Chung ME, Sanchez JCG, Diwan GD, Singh G, Strähle U, Russell RB, Batista D, Sansone SA, Rocca-Serra P, Du Pasquier D, Lemkine G, Robin-Duchesne B, Tindall A. The Precision Toxicology Initiative. Toxicol Lett 2023:S0378-4274(23)00180-7. [PMID: 37211341 DOI: 10.1016/j.toxlet.2023.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/01/2023] [Accepted: 05/09/2023] [Indexed: 05/23/2023]
Abstract
The goal of PrecisionTox is to overcome conceptual barriers to replacing traditional mammalian chemical safety testing by accelerating the discovery of evolutionarily conserved toxicity pathways that are shared by descent among humans and more distantly related animals. An international consortium is systematically testing the toxicological effects of a diverse set of chemicals on a suite of five model species comprising fruit flies, nematodes, water fleas, and embryos of clawed frogs and zebrafish along with human cell lines. Multiple forms of omics and comparative toxicology data are integrated to map the evolutionary origins of biomolecular interactions, which are predictive of adverse health effects, to major branches of the animal phylogeny. These conserved elements of adverse outcome pathways (AOPs) and their biomarkers are expect to provide mechanistic insight useful for regulating groups of chemicals based on their shared modes of action. PrecisionTox also aims to quantify risk variation within populations by recognizing susceptibility as a heritable trait that varies with genetic diversity. This initiative incorporates legal experts and collaborates with risk managers to address specific needs within European chemicals legislation, including the uptake of new approach methodologies (NAMs) for setting precise regulatory limits on toxic chemicals.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Nico Grasse
- Helmholtz Centre for Environmental Research, DE
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8
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Jang S, Shao K, Chiu WA. Beyond the cancer slope factor: Broad application of Bayesian and probabilistic approaches for cancer dose-response assessment. ENVIRONMENT INTERNATIONAL 2023; 175:107959. [PMID: 37182419 PMCID: PMC10918611 DOI: 10.1016/j.envint.2023.107959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/26/2023] [Accepted: 05/03/2023] [Indexed: 05/16/2023]
Abstract
Traditional cancer slope factors derived from linear low-dose extrapolation give little consideration to uncertainties in dose-response model choice, interspecies extrapolation, and human variability. As noted previously by the National Academies, probabilistic methods can address these limitations, but have only been demonstrated in a few case studies. Here, we applied probabilistic approaches for Bayesian Model Averaging (BMA), interspecies extrapolation, and human variability distributions to 255 animal cancer bioassay datasets previously used by governmental agencies. We then derived predictions for both population cancer incidence and individual cancer risk. For model uncertainty, we found that lower confidence limits from BMA and from U.S. Environmental Protection Agency (EPA)'s Benchmark Dose Software (BMDS) correlated highly, with 86% differing by <10-fold. Incorporating other uncertainties and human variability, the lower confidence limits of the probabilistic risk-specific dose (RSD) at 10-6 population incidence were typically 3- to 30-fold lower than traditional slope factors. However, in a small (<7%) number of cases of highly non-linear experimental dose-response, the probabilistic RSDs were >10-fold less stringent. Probabilistic RSDs were also protective of individual risks of 10-4 in >99% of the population. We conclude that implementing Bayesian and probabilistic methods provides a more scientifically rigorous basis for cancer dose-response assessment and thereby improves overall cancer risk characterization.
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Affiliation(s)
- Suji Jang
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Kan Shao
- Department of Environmental and Occupational Health, School of Public Health, Indiana University, Bloomington, IN, USA
| | - Weihsueh A Chiu
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA.
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9
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Dairkee SH, Moore DH, Luciani MG, Anderle N, Gerona R, Ky K, Torres SM, Marshall PV, Goodson Iii WH. Reduction of daily-use parabens and phthalates reverses accumulation of cancer-associated phenotypes within disease-free breast tissue of study subjects. CHEMOSPHERE 2023; 322:138014. [PMID: 36746253 DOI: 10.1016/j.chemosphere.2023.138014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/12/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
Estrogenic overstimulation is carcinogenic to the human breast. Personal care products (PCPs) commonly contain xenoestrogens (XE), such as parabens and phthalates. Here, we identified the adverse effects of persistent exposure to such PCPs directly within human estrogen responsive breast tissue of subjects enrolled in a regimen of reduced XE use (REDUXE). Pre- and post-intervention fine needle aspirates (FNAs) of the breast were collected from healthy volunteers who discontinued the use of paraben and phthalate containing PCPs over a 28 d period. Based on high-dimensional gene expression data of matched FNA pairs of study subjects, we demonstrate a striking reversal of cancer-associated phenotypes, including the PI3K-AKT/mTOR pathway, autophagy, and apoptotic signaling networks within breast cells of REDUXE compliant subjects. These, and other altered phenotypes were detected together with a significant reduction in urinary parabens and phthalate metabolites. Moreover, in vitro treatment of paired FNAs with 17β-estradiol (E2), displayed a 'normalizing' impact of REDUXE on gene expression within known E2-modulated pathways, and on functional endpoints, including estrogen receptor alpha: beta ratio, and S-phase fraction of the cell cycle. In a paradigm shifting approach facilitated by community-based participatory research, REDUXE reveals unfavorable consequences from exposure to XEs from daily-use PCPs. Our findings illustrate the potential for REDUXE to suppress pro-carcinogenic phenotypes at the cellular level towards the goal of breast cancer prevention.
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Affiliation(s)
- Shanaz H Dairkee
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA.
| | - Dan H Moore
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA
| | - M Gloria Luciani
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA
| | - Nicole Anderle
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA
| | - Roy Gerona
- Department of OB/Gyn and Reproductive Sciences, University of California, San Francisco, CA, 94115, USA
| | - Karina Ky
- Department of OB/Gyn and Reproductive Sciences, University of California, San Francisco, CA, 94115, USA
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Aurisano N, Jolliet O, Chiu WA, Judson R, Jang S, Unnikrishnan A, Kosnik MB, Fantke P. Probabilistic Points of Departure and Reference Doses for Characterizing Human Noncancer and Developmental/Reproductive Effects for 10,145 Chemicals. ENVIRONMENTAL HEALTH PERSPECTIVES 2023; 131:37016. [PMID: 36989077 PMCID: PMC10056221 DOI: 10.1289/ehp11524] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 02/06/2023] [Accepted: 03/03/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Regulatory toxicity values used to assess and manage chemical risks rely on the determination of the point of departure (POD) for a critical effect, which results from a comprehensive and systematic assessment of available toxicity studies. However, regulatory assessments are only available for a small fraction of chemicals. OBJECTIVES Using in vivo experimental animal data from the U.S. Environmental Protection Agency's Toxicity Value Database, we developed a semiautomated approach to determine surrogate oral route PODs, and corresponding toxicity values where regulatory assessments are unavailable. METHODS We developed a curated data set restricted to effect levels, exposure routes, study designs, and species relevant for deriving toxicity values. Effect levels were adjusted to chronic human equivalent benchmark doses (BMDh). We hypothesized that a quantile of the BMDh distribution could serve as a surrogate POD and determined the appropriate quantile by calibration to regulatory PODs. Finally, we characterized uncertainties around the surrogate PODs from intra- and interstudy variability and derived probabilistic toxicity values using a standardized workflow. RESULTS The BMDh distribution for each chemical was adequately fit by a lognormal distribution, and the 25th percentile best predicted the available regulatory PODs [R2≥0.78, residual standard error (RSE)≤0.53 log10 units]. We derived surrogate PODs for 10,145 chemicals from the curated data set, differentiating between general noncancer and reproductive/developmental effects, with typical uncertainties (at 95% confidence) of a factor of 10 and 12, respectively. From these PODs, probabilistic reference doses (1% incidence at 95% confidence), as well as human population effect doses (10% incidence), were derived. DISCUSSION In providing surrogate PODs calibrated to regulatory values and deriving corresponding toxicity values, we have substantially expanded the coverage of chemicals from 744 to 8,023 for general noncancer effects, and from 41 to 6,697 for reproductive/developmental effects. These results can be used across various risk assessment and risk management contexts, from hazardous site and life cycle impact assessments to chemical prioritization and substitution. https://doi.org/10.1289/EHP11524.
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Affiliation(s)
- Nicolò Aurisano
- Quantitative Sustainability Assessment, Department of Environmental and Resource Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Olivier Jolliet
- Quantitative Sustainability Assessment, Department of Environmental and Resource Engineering, Technical University of Denmark, Lyngby, Denmark
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Richard Judson
- National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Suji Jang
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Aswani Unnikrishnan
- National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Marissa B. Kosnik
- Quantitative Sustainability Assessment, Department of Environmental and Resource Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Peter Fantke
- Quantitative Sustainability Assessment, Department of Environmental and Resource Engineering, Technical University of Denmark, Lyngby, Denmark
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11
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Hagiwara S, Paoli GM, Price PS, Gwinn MR, Guiseppi-Elie A, Farrell PJ, Hubbell BJ, Krewski D, Thomas RS. A value of information framework for assessing the trade-offs associated with uncertainty, duration, and cost of chemical toxicity testing. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2023; 43:498-515. [PMID: 35460101 PMCID: PMC10515440 DOI: 10.1111/risa.13931] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A number of investigators have explored the use of value of information (VOI) analysis to evaluate alternative information collection procedures in diverse decision-making contexts. This paper presents an analytic framework for determining the value of toxicity information used in risk-based decision making. The framework is specifically designed to explore the trade-offs between cost, timeliness, and uncertainty reduction associated with different toxicity-testing methodologies. The use of the proposed framework is demonstrated by two illustrative applications which, although based on simplified assumptions, show the insights that can be obtained through the use of VOI analysis. Specifically, these results suggest that timeliness of information collection has a significant impact on estimates of the VOI of chemical toxicity tests, even in the presence of smaller reductions in uncertainty. The framework introduces the concept of the expected value of delayed sample information, as an extension to the usual expected value of sample information, to accommodate the reductions in value resulting from delayed decision making. Our analysis also suggests that lower cost and higher throughput testing also may be beneficial in terms of public health benefits by increasing the number of substances that can be evaluated within a given budget. When the relative value is expressed in terms of return-on-investment per testing strategy, the differences can be substantial.
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Affiliation(s)
- Shintaro Hagiwara
- Risk Sciences International, Ottawa, Canada
- School of Mathematics and Statistics, Carleton University, Ottawa, Canada
| | | | - Paul S. Price
- Center for Compuational Toxicology and Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Maureen R. Gwinn
- Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Annette Guiseppi-Elie
- Center for Compuational Toxicology and Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Patrick J. Farrell
- School of Mathematics and Statistics, Carleton University, Ottawa, Canada
| | - Bryan J. Hubbell
- Air, Climate, and Energy Research Program, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Daniel Krewski
- Risk Sciences International, Ottawa, Canada
- McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada
| | - Russell S. Thomas
- Center for Compuational Toxicology and Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
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12
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Niu S, Chen X, Chen R, Zou Y, Zhang Z, Li L, Hageman KJ, Ng C, Dong L. Understanding inter-individual variability in short-chain chlorinated paraffin concentrations in human blood. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130235. [PMID: 36368064 DOI: 10.1016/j.jhazmat.2022.130235] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/14/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Chlorinated paraffins (CPs), particularly short-chain CPs (SCCPs), have been reported in human blood with high detection frequency and often high variation among individuals. However, factors associated with and their contributions to inter-individual variability in SCCP concentrations in human blood have not been assessed. In this study, we first measured SCCP concentrations in 57 human blood samples collected from individuals living in the same vicinity in China. We then used the PROduction-To-Exposure model to investigate the impacts of variations in sociodemographic data, biotransformation rates, dietary patterns, and indoor contamination on inter-individual variability in SCCP concentrations in human blood. Measured ∑SCCP concentrations varied by a factor of 10 among individuals with values ranging from 122 to 1230 ng/g, wet weight. Model results show that age, sex, body weight, and dietary composition played a minor role in causing variability in ∑SCCP concentrations in human blood given that modeled ∑SCCP concentrations ranged over a factor of 2 - 3 correlated to the variations of these factors. In contrast, variations in the modeled ΣSCCP concentrations increased to factors of 6 and 8 when variability in biotransformation rates and indoor contamination were considered, respectively, indicating these two factors could be the most influential on inter-individual variability in SCCP concentrations in human blood.
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Affiliation(s)
- Shan Niu
- Department of Civil & Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA; National Research Center for Environmental Analysis and Measurement, Beijing, Beijing, China.
| | - Xi Chen
- National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ruiwen Chen
- Department of Civil & Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yun Zou
- Organic Biological Analytical Chemistry Group, Department of Chemistry, University of Liège, Liège, Belgium
| | - ZhiZhen Zhang
- School of Public Health, University of Nevada, Reno, NV, USA
| | - Li Li
- School of Public Health, University of Nevada, Reno, NV, USA
| | - Kimberly J Hageman
- Department of Chemistry & Biochemistry, Utah State University, Logan, UT, USA
| | - Carla Ng
- Department of Civil & Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, USA; Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Liang Dong
- National Research Center for Environmental Analysis and Measurement, Beijing, Beijing, China
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13
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Hubal R, Cohen Hubal EA. Simulating patterns of life: More representative time-activity patterns that account for context. ENVIRONMENT INTERNATIONAL 2023; 172:107753. [PMID: 36682205 PMCID: PMC11057331 DOI: 10.1016/j.envint.2023.107753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
BACKGROUND Complex contributions of environment to health are intimately connected to human behavior. Modeling of human behaviors and their influences helps inform important policy decisions related to critical environmental and public health challenges. A typical approach to human behavior modeling involves generating daily schedules based on time-activity patterns of individual humans, simulating 'agents' with these schedules, and interpreting patterns of life that emerge from the simulation to inform a research question. Current behavior modeling, however, rarely incorporates the context that surrounds individuals' truly broad scope of activities and influences on those activities. OBJECTIVES We describe in detail a range of elements involved in generating time-activity patterns and connect work in the social science field of behavior modeling with applications in exposure science and environmental health. We propose a framework for behavior modeling that takes a systems approach and considers the broad scope of activities and influences required to simulate more representative patterns of life and thus improve modeling that underlies understanding of environmental contributions to health and associated decisions to promote and protect public health. METHODS We describe an agent-based modeling approach reliant on generating a population's schedules, filtering the schedules, simulating behavior using the schedules, analyzing the emergent patterns, and interrogating results that leverages general empirical information in a systems context to inform fit-for-purpose action. DISCUSSION We propose a centralized and standardized program to codify behavior information and generate population schedules that researchers can select from to simulate human behavior and holistically characterize human-environment interactions for a variety of public health applications.
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14
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Varshavsky JR, Rayasam SDG, Sass JB, Axelrad DA, Cranor CF, Hattis D, Hauser R, Koman PD, Marquez EC, Morello-Frosch R, Oksas C, Patton S, Robinson JF, Sathyanarayana S, Shepard PM, Woodruff TJ. Current practice and recommendations for advancing how human variability and susceptibility are considered in chemical risk assessment. Environ Health 2023; 21:133. [PMID: 36635753 PMCID: PMC9835253 DOI: 10.1186/s12940-022-00940-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A key element of risk assessment is accounting for the full range of variability in response to environmental exposures. Default dose-response methods typically assume a 10-fold difference in response to chemical exposures between average (healthy) and susceptible humans, despite evidence of wider variability. Experts and authoritative bodies support using advanced techniques to better account for human variability due to factors such as in utero or early life exposure and exposure to multiple environmental, social, and economic stressors.This review describes: 1) sources of human variability and susceptibility in dose-response assessment, 2) existing US frameworks for addressing response variability in risk assessment; 3) key scientific inadequacies necessitating updated methods; 4) improved approaches and opportunities for better use of science; and 5) specific and quantitative recommendations to address evidence and policy needs.Current default adjustment factors do not sufficiently capture human variability in dose-response and thus are inadequate to protect the entire population. Susceptible groups are not appropriately protected under current regulatory guidelines. Emerging tools and data sources that better account for human variability and susceptibility include probabilistic methods, genetically diverse in vivo and in vitro models, and the use of human data to capture underlying risk and/or assess combined effects from chemical and non-chemical stressors.We recommend using updated methods and data to improve consideration of human variability and susceptibility in risk assessment, including the use of increased default human variability factors and separate adjustment factors for capturing age/life stage of development and exposure to multiple chemical and non-chemical stressors. Updated methods would result in greater transparency and protection for susceptible groups, including children, infants, people who are pregnant or nursing, people with disabilities, and those burdened by additional environmental exposures and/or social factors such as poverty and racism.
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Affiliation(s)
- Julia R Varshavsky
- Department of Health Sciences and Department of Civil and Environmental Engineering Northeastern University, Boston, MA, 02115, USA.
| | - Swati D G Rayasam
- Department of Obstetrics, Program on Reproductive Health and the Environment, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Carl F Cranor
- Department of Philosophy, University of California, Riverside, Riverside, CA, USA
- Environmental Toxicology Graduate Program, College of Natural and Agricultural Sciences, University of California, Riverside, Riverside, CA, USA
| | - Dale Hattis
- The George Perkins Marsh Institute, Clark University, Worcester, MA, USA
| | - Russ Hauser
- Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Patricia D Koman
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | | | - Rachel Morello-Frosch
- School of Public Health, University of California, Berkeley, Berkeley, CA, USA
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA
| | - Catherine Oksas
- University of California, San Francisco School of Medicine, San Francisco, CA, USA
| | | | - Joshua F Robinson
- Department of Obstetrics, Program on Reproductive Health and the Environment, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, USA
- Center for Reproductive Sciences and Department of Obstetrics, Gynecology & Reproductive Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Sheela Sathyanarayana
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Seattle Children's Research Institute, Seattle, WA, USA
| | | | - Tracey J Woodruff
- Department of Obstetrics, Program on Reproductive Health and the Environment, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, USA
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15
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Karyakina NA, Shilnikova N, Farhat N, Ramoju S, Cline B, Momoli F, Mattison D, Jensen N, Terrell R, Krewski D. Biomarkers for occupational manganese exposure. Crit Rev Toxicol 2022; 52:636-663. [PMID: 36705643 DOI: 10.1080/10408444.2022.2128718] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Long-term inhalation exposure to manganese (Mn) metal or its inorganic compounds can result in manganism or subclinical neurofunctional deficits. Studies have described affected workers in Mn dioxide mining, Mn-containing ore crushing and milling facilities, manufacturing of dry-cell batteries, Mn steel and alloy production plants, and in welders. The objective of this study was to critically review existing evidence on the reliability of potential biomarkers of Mn exposure, specifically the relationship between inhalation exposure to Mn particulates in different occupational settings and Mn concentrations in blood and other biological fluids and tissues, with a particular focus on whole blood as a potentially useful medium for measuring internal tissue dose. We also examined available evidence on the relationship between Mn levels in blood and adverse clinical and subclinical neurotoxic outcomes. Three bibliographic databases were searched for relevant studies and identified references were screened by two independent reviewers. Of the 6338 unique references identified, 76 articles were retained for data abstraction. Findings indicate that the relationships between Mn in blood and both external Mn exposure indices and neurofunctional impairments are limited and inconsistent. Different sources of exposure to Mn compounds, heterogeneity in the methodological approaches, and inadequate reporting of essential information limited direct comparison of the reported findings. Among the Mn-exposure biomarkers considered in this review - including biomarkers in blood, plasma, serum, erythrocytes, urine, bone, toenails, fingernails, hair, saliva - biomarkers in whole blood may provide to be most useful in Mn biomonitoring and risk assessment.
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Affiliation(s)
- Nataliya A Karyakina
- Risk Sciences International, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada
| | - Natalia Shilnikova
- Risk Sciences International, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada
| | - Nawal Farhat
- Risk Sciences International, Ottawa, Canada.,School of Mathematics and Statistics, Carleton University, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | | | | | - Franco Momoli
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - Donald Mattison
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada.,Arnold School of Public Health, University of South Carolina, Columbia, SC, USA
| | - N Jensen
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - R Terrell
- Risk Sciences International, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
| | - Daniel Krewski
- Risk Sciences International, Ottawa, Canada.,McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Canada.,School of Mathematics and Statistics, Carleton University, Ottawa, Canada.,School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
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16
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Widmayer SJ, Crombie TA, Nyaanga JN, Evans KS, Andersen EC. C. elegans toxicant responses vary among genetically diverse individuals. Toxicology 2022; 479:153292. [PMID: 35995124 PMCID: PMC9573778 DOI: 10.1016/j.tox.2022.153292] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/15/2022] [Accepted: 08/17/2022] [Indexed: 11/25/2022]
Abstract
The genetic variability of toxicant responses among indisviduals in humans and mammalian models requires practically untenable sample sizes to create comprehensive chemical hazard risk evaluations. To address this need, tractable model systems enable reproducible and efficient experimental workflows to collect high-replication measurements of exposure cohorts. Caenorhabditis elegans is a premier toxicology model that has revolutionized our understanding of cellular responses to environmental pollutants and boasts robust genomic resources and high levels of genetic variation across the species. In this study, we performed dose-response analysis across 23 environmental toxicants using eight C. elegans strains representative of species-wide genetic diversity. We observed substantial variation in EC10 estimates and slope parameter estimates of dose-response curves of different strains, demonstrating that genetic background is a significant driver of differential toxicant susceptibility. We also showed that, across all toxicants, at least one C. elegans strain exhibited a significantly different EC10 or slope estimate compared to the reference strain, N2 (PD1074), indicating that population-wide differences among strains are necessary to understand responses to toxicants. Moreover, we quantified the heritability of responses (phenotypic variance attributable to genetic differences between individuals) to each toxicant exposure and observed a correlation between the exposure closest to the species-agnostic EC10 estimate and the exposure that exhibited the most heritable response. At least 20% of the variance in susceptibility to at least one exposure level of each compound was explained by genetic differences among the eight C. elegans strains. Taken together, these results provide robust evidence that heritable genetic variation explains differential susceptibility across an array of environmental pollutants and that genetically diverse C. elegans strains should be deployed to aid high-throughput toxicological screening efforts.
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Affiliation(s)
- Samuel J Widmayer
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Timothy A Crombie
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Joy N Nyaanga
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Kathryn S Evans
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
| | - Erik C Andersen
- Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
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17
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Ford LC, Jang S, Chen Z, Zhou YH, Gallins PJ, Wright FA, Chiu WA, Rusyn I. A Population-Based Human In Vitro Approach to Quantify Inter-Individual Variability in Responses to Chemical Mixtures. TOXICS 2022; 10:toxics10080441. [PMID: 36006120 PMCID: PMC9413237 DOI: 10.3390/toxics10080441] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 02/01/2023]
Abstract
Human cell-based population-wide in vitro models have been proposed as a strategy to derive chemical-specific estimates of inter-individual variability; however, the utility of this approach has not yet been tested for cumulative exposures in mixtures. This study aimed to test defined mixtures and their individual components and determine whether adverse effects of the mixtures were likely to be more variable in a population than those of the individual chemicals. The in vitro model comprised 146 human lymphoblastoid cell lines from four diverse subpopulations of European and African descent. Cells were exposed, in concentration−response, to 42 chemicals from diverse classes of environmental pollutants; in addition, eight defined mixtures were prepared from these chemicals using several exposure- or hazard-based scenarios. Points of departure for cytotoxicity were derived using Bayesian concentration−response modeling and population variability was quantified in the form of a toxicodynamic variability factor (TDVF). We found that 28 chemicals and all mixtures exhibited concentration−response cytotoxicity, enabling calculation of the TDVF. The median TDVF across test substances, for both individual chemicals or defined mixtures, ranged from a default assumption (101/2) of toxicodynamic variability in human population to >10. The data also provide a proof of principle for single-variant genome-wide association mapping for toxicity of the chemicals and mixtures, although replication would be necessary due to statistical power limitations with the current sample size. This study demonstrates the feasibility of using a set of human lymphoblastoid cell lines as an in vitro model to quantify the extent of inter-individual variability in hazardous properties of both individual chemicals and mixtures. The data show that population variability of the mixtures is unlikely to exceed that of the most variable component, and that similarity in genome-wide associations among components may be used to accrue additional evidence for grouping of constituents in a mixture for cumulative assessments.
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Affiliation(s)
- Lucie C. Ford
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA; (L.C.F.); (S.J.); (Z.C.); (W.A.C.)
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Suji Jang
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA; (L.C.F.); (S.J.); (Z.C.); (W.A.C.)
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Zunwei Chen
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA; (L.C.F.); (S.J.); (Z.C.); (W.A.C.)
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Yi-Hui Zhou
- Departments of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; (Y.-H.Z.); (F.A.W.)
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA;
| | - Paul J. Gallins
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA;
| | - Fred A. Wright
- Departments of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; (Y.-H.Z.); (F.A.W.)
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA;
| | - Weihsueh A. Chiu
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA; (L.C.F.); (S.J.); (Z.C.); (W.A.C.)
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA; (L.C.F.); (S.J.); (Z.C.); (W.A.C.)
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
- Correspondence: ; Tel.: +979-458-9866
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18
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Model systems and organisms for addressing inter- and intra-species variability in risk assessment. Regul Toxicol Pharmacol 2022; 132:105197. [DOI: 10.1016/j.yrtph.2022.105197] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/20/2022] [Accepted: 05/25/2022] [Indexed: 12/12/2022]
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19
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Crofton KM, Bassan A, Behl M, Chushak YG, Fritsche E, Gearhart JM, Marty MS, Mumtaz M, Pavan M, Ruiz P, Sachana M, Selvam R, Shafer TJ, Stavitskaya L, Szabo DT, Szabo ST, Tice RR, Wilson D, Woolley D, Myatt GJ. Current status and future directions for a neurotoxicity hazard assessment framework that integrates in silico approaches. COMPUTATIONAL TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 22:100223. [PMID: 35844258 PMCID: PMC9281386 DOI: 10.1016/j.comtox.2022.100223] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Neurotoxicology is the study of adverse effects on the structure or function of the developing or mature adult nervous system following exposure to chemical, biological, or physical agents. The development of more informative alternative methods to assess developmental (DNT) and adult (NT) neurotoxicity induced by xenobiotics is critically needed. The use of such alternative methods including in silico approaches that predict DNT or NT from chemical structure (e.g., statistical-based and expert rule-based systems) is ideally based on a comprehensive understanding of the relevant biological mechanisms. This paper discusses known mechanisms alongside the current state of the art in DNT/NT testing. In silico approaches available today that support the assessment of neurotoxicity based on knowledge of chemical structure are reviewed, and a conceptual framework for the integration of in silico methods with experimental information is presented. Establishing this framework is essential for the development of protocols, namely standardized approaches, to ensure that assessments of NT and DNT based on chemical structures are generated in a transparent, consistent, and defendable manner.
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Affiliation(s)
| | - Arianna Bassan
- Innovatune srl, Via Giulio Zanon 130/D, 35129 Padova,
Italy
| | - Mamta Behl
- Division of the National Toxicology Program, National
Institutes of Environmental Health Sciences, Durham, NC 27709, USA
| | - Yaroslav G. Chushak
- Henry M Jackson Foundation for the Advancement of Military
Medicine, Wright-Patterson AFB, OH 45433, USA
| | - Ellen Fritsche
- IUF – Leibniz Research Institute for Environmental
Medicine & Medical Faculty Heinrich-Heine-University, Düsseldorf,
Germany
| | - Jeffery M. Gearhart
- Henry M Jackson Foundation for the Advancement of Military
Medicine, Wright-Patterson AFB, OH 45433, USA
| | | | - Moiz Mumtaz
- Agency for Toxic Substances and Disease Registry, US
Department of Health and Human Services, Atlanta, GA, USA
| | - Manuela Pavan
- Innovatune srl, Via Giulio Zanon 130/D, 35129 Padova,
Italy
| | - Patricia Ruiz
- Agency for Toxic Substances and Disease Registry, US
Department of Health and Human Services, Atlanta, GA, USA
| | - Magdalini Sachana
- Environment Health and Safety Division, Environment
Directorate, Organisation for Economic Co-Operation and Development (OECD), 75775
Paris Cedex 16, France
| | - Rajamani Selvam
- Office of Clinical Pharmacology, Office of Translational
Sciences, Center for Drug Evaluation and Research (CDER), U.S. Food and Drug
Administration (FDA), Silver Spring, MD 20993, USA
| | - Timothy J. Shafer
- Biomolecular and Computational Toxicology Division, Center
for Computational Toxicology and Exposure, US EPA, Research Triangle Park, NC,
USA
| | - Lidiya Stavitskaya
- Office of Clinical Pharmacology, Office of Translational
Sciences, Center for Drug Evaluation and Research (CDER), U.S. Food and Drug
Administration (FDA), Silver Spring, MD 20993, USA
| | | | | | | | - Dan Wilson
- The Dow Chemical Company, Midland, MI 48667, USA
| | | | - Glenn J. Myatt
- Instem, Columbus, OH 43215, USA
- Corresponding author.
(G.J. Myatt)
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20
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Boysen G, Rusyn I, Chiu WA, Wright FA. Characterization of population variability of 1,3-butadiene derived protein adducts in humans and mice. Regul Toxicol Pharmacol 2022; 132:105171. [DOI: 10.1016/j.yrtph.2022.105171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/17/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
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21
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McPartland J, Shaffer RM, Fox MA, Nachman KE, Burke TA, Denison RA. Charting a Path Forward: Assessing the Science of Chemical Risk Evaluations under the Toxic Substances Control Act in the Context of Recent National Academies Recommendations. ENVIRONMENTAL HEALTH PERSPECTIVES 2022; 130:25003. [PMID: 35195451 PMCID: PMC8865089 DOI: 10.1289/ehp9649] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND In 2016, Congress enacted the Frank R. Lautenberg Chemical Safety for the 21st Century Act ("the Lautenberg Act"), which made major revisions to the main U.S. chemical safety law, the 1976 Toxic Substances Control Act (TSCA). Among other reforms, the Lautenberg Act mandates that the U.S. Environmental Protection Agency (U.S. EPA) conduct comprehensive risk evaluations of chemicals in commerce. The U.S. EPA recently finalized the first set of such chemical risk evaluations. OBJECTIVES We examine the first 10 TSCA risk evaluations in relation to risk science recommendations from the National Academies to determine consistency with these recommendations and to identify opportunities to improve future TSCA risk evaluations by further implementing these key approaches and methods. DISCUSSION Our review of the first set of TSCA risk evaluations identified substantial deviations from best practices in risk assessment, including overly narrow problem formulations and scopes; insufficient characterization of uncertainty in the evidence; inadequate consideration of population variability; lack of consideration of background exposures, combined exposures, and cumulative risk; divergent approaches to dose-response assessment for carcinogens and noncarcinogens; and a flawed approach to systematic review. We believe these deviations result in underestimation of population exposures and health risks. We are hopeful that the agency can use these insights and have provided suggestions to produce chemical risk evaluations aligned with the intent and requirements of the Lautenberg Act and the best available science to better protect health and the environment-including the health of those most vulnerable to chemical exposures. https://doi.org/10.1289/EHP9649.
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Affiliation(s)
| | - Rachel M. Shaffer
- Department of Environmental and Occupational Health Sciences, University of Washington School of Public Health, Seattle, Washington, USA
| | - Mary A. Fox
- Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Johns Hopkins Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Keeve E. Nachman
- Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Johns Hopkins Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Thomas A. Burke
- Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Johns Hopkins Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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22
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Burnett SD, Karmakar M, Murphy WJ, Chiu WA, Rusyn I. A new approach method for characterizing inter-species toxicodynamic variability. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2021; 84:1020-1039. [PMID: 34427174 PMCID: PMC8530970 DOI: 10.1080/15287394.2021.1966861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Inter-species differences in toxicodynamics are often a critical source of uncertainty in safety evaluations and typically dealt with using default adjustment factors. In vitro studies that use cells from different species demonstrated some success for estimating the relationships between life span and/or body weight and sensitivity to cytotoxicity; however, no apparent investigation evaluated the utility of these models for risk assessment. It was hypothesized that an in vitro model using dermal fibroblasts derived from diverse species and individuals might be utilized to inform the extent of inter-species and inter-individual variability in toxicodynamics. To test this hypothesis and characterize both inter-species and inter-individual variability in cytotoxicity, concentration-response cytotoxicity screening of 40 chemicals in primary dermal fibroblasts from 68 individuals of 54 diverse species was conducted. Chemicals examined included drugs, environmental pollutants, and food/flavor/fragrance agents; most of these were previously assessed either in vivo or in vitro for inter-species or inter-individual variation. Species included humans, the typical preclinical species and representatives from other orders of mammals and birds. Data demonstrated that both inter-species and inter-individual components of variability contribute to the observed differences in sensitivity to cell death. Further, it was found that the magnitude of the observed inter-species and inter-individual differences was chemical-dependent. This study contributes to the paradigm shift in risk assessment from reliance on in vivo toxicity testing to higher-throughput in vitro or alternative approaches, extending the strategy to replace use of default adjustment factors with experimental characterization of toxicodynamic inter-individual variability and to also address toxicodynamic inter-species variability.
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Affiliation(s)
- Sarah D. Burnett
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Moumita Karmakar
- Department of Statistics, Texas A&M University, College Station, TX 77843-4458, USA
| | - William J. Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
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Erber L, Goodman S, Wright FA, Chiu WA, Tretyakova NY, Rusyn I. Intra- and Inter-Species Variability in Urinary N7-(1-Hydroxy-3-buten-2-yl)guanine Adducts Following Inhalation Exposure to 1,3-Butadiene. Chem Res Toxicol 2021; 34:2375-2383. [PMID: 34726909 PMCID: PMC8715497 DOI: 10.1021/acs.chemrestox.1c00291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
1,3-Butadiene is a known carcinogen primarily targeting lymphoid tissues, lung, and liver. Cytochrome P450 activates butadiene to epoxides which form covalent DNA adducts that are thought to be a key mechanistic event in cancer. Previous studies suggested that inter-species, -tissue, and -individual susceptibility to adverse health effects of butadiene exposure may be due to differences in metabolism and other mechanisms. In this study, we aimed to examine the extent of inter-individual and inter-species variability in the urinary N7-(1-hydroxy-3-buten-2-yl)guanine (EB-GII) DNA adduct, a well-known biomarker of exposure to butadiene. For a population variability study in mice, we used the collaborative cross model. Female and male mice from five strains were exposed to filtered air or butadiene (590 ppm, 6 h/day, 5 days/week for 2 weeks) by inhalation. Urine samples were collected, and the metabolic activation of butadiene by DNA-reactive species was quantified as urinary EB-GII adducts. We quantified the degree of EB-GII variation across mouse strains and sexes; then, we compared this variation with the data from rats (exposed to 62.5 or 200 ppm butadiene) and humans (0.004-2.2 ppm butadiene). We show that sex and strain are significant contributors to the variability in urinary EB-GII levels in mice. In addition, we find that the degree of variability in urinary EB-GII in collaborative cross mice, when expressed as an uncertainty factor for the inter-individual variability (UFH), is relatively modest (≤threefold) possibly due to metabolic saturation. By contrast, the variability in urinary EB-GII (adjusted for exposure) observed in humans, while larger than the default value of 10-fold, is largely consistent with UFH estimates for other chemicals based on human data for non-cancer endpoints. Overall, these data demonstrate that urinary EB-GII levels, particularly from human studies, may be useful for quantitative characterization of human variability in cancer risks to butadiene.
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Affiliation(s)
- Luke Erber
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Samantha Goodman
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Fred A. Wright
- Bioinformatics Research Center and Departments of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Natalia Y. Tretyakova
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA,Corresponding authors: Natalia Tretyakova, Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, 2-147 CCRB, Minneapolis, MN 55455, USA; phone: (612) 626-3432; ; Ivan Rusyn, Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA; phone: (979) 458-9866;
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA,Corresponding authors: Natalia Tretyakova, Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, 2-147 CCRB, Minneapolis, MN 55455, USA; phone: (612) 626-3432; ; Ivan Rusyn, Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA; phone: (979) 458-9866;
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Chatterjee N, Zhang X. CRISPR approach in environmental chemical screening focusing on population variability. J Toxicol Sci 2021; 46:499-507. [PMID: 34719552 DOI: 10.2131/jts.46.499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A significant barrier to include population variability in risk assessment is our incomplete understanding of inter-individual variability and the differential susceptibility to environmental exposures induced adverse outcomes. By combining genome editing tools with the population diversity model, this article intended to highlight a potential strategy to identify and characterize the inter-individual variability factors, the determinant gene anchoring to a particular phenotype. The goal could be achieved by integrating the perturbed CRISPR-based unbiased functional genomics screening, genome-wide or a focused subset of genes, in a population-based in vitro model system (such as the lymphoblastoid cell lines, LCL, available from HapMap and 1000 Genomes project). Then data can be translated to genetic variability and individual (or subpopulation) susceptibility by incorporating ethnicity and corresponding genome-wide association studies (GWAS) with functional genomics screening results. This approach can provide complementary data for next-generation risk assessment, in particular, for environmental stressors. The current paper outlined the previous work conducted with a population-based in vitro model system, perturbed CRISPR-based functional toxicogenomic screening of environmental chemicals, and finally, the potential strategies to combine these two platforms with their opportunities and challenges to achieve a mechanistic understanding of population variability.
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Affiliation(s)
- Nivedita Chatterjee
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, China.,INL-International Iberian Nanotechnology Laboratory, Portugal
| | - Xiaowei Zhang
- State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, China
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Dalaijamts C, Cichocki JA, Luo YS, Rusyn I, Chiu WA. Quantitative Characterization of Population-Wide Tissue- and Metabolite-Specific Variability in Perchloroethylene Toxicokinetics in Male Mice. Toxicol Sci 2021; 182:168-182. [PMID: 33988684 DOI: 10.1093/toxsci/kfab057] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Quantification of interindividual variability is a continuing challenge in risk assessment, particularly for compounds with complex metabolism and multi-organ toxicity. Toxicokinetic variability for perchloroethylene (perc) was previously characterized across 3 mouse strains and in 1 mouse strain with various degrees of liver steatosis. To further characterize the role of genetic variability in toxicokinetics of perc, we applied Bayesian population physiologically based pharmacokinetic (PBPK) modeling to the data on perc and metabolites in blood/plasma and tissues of male mice from 45 inbred strains from the Collaborative Cross (CC) mouse population. After identifying the most influential PBPK parameters based on global sensitivity analysis, we fit the model with a hierarchical Bayesian population analysis using Markov chain Monte Carlo simulation. We found that the data from 3 commonly used strains were not representative of the full range of variability in perc and metabolite blood/plasma and tissue concentrations across the CC population. Using interstrain variability as a surrogate for human interindividual variability, we calculated dose-dependent, chemical-, and tissue-specific toxicokinetic variability factors (TKVFs) as candidate science-based replacements for the default uncertainty factor for human toxicokinetic variability of 100.5. We found that toxicokinetic variability factors for glutathione conjugation metabolites of perc showed the greatest variability, often exceeding the default, whereas those for oxidative metabolites and perc itself were generally less than the default. Overall, we demonstrate how a combination of a population-based mouse model such as the CC with Bayesian population PBPK modeling can reduce uncertainty in human toxicokinetic variability and increase accuracy and precision in quantitative risk assessment.
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Affiliation(s)
- Chimeddulam Dalaijamts
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Joseph A Cichocki
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Yu-Syuan Luo
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
| | - Weihsueh A Chiu
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, Texas 77843-4458, USA.,Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA
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Blanchette AD, Burnett SD, Grimm FA, Rusyn I, Chiu WA. A Bayesian Method for Population-wide Cardiotoxicity Hazard and Risk Characterization Using an In Vitro Human Model. Toxicol Sci 2021; 178:391-403. [PMID: 33078833 DOI: 10.1093/toxsci/kfaa151] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes are an established model for testing potential chemical hazards. Interindividual variability in toxicodynamic sensitivity has also been demonstrated in vitro; however, quantitative characterization of the population-wide variability has not been fully explored. We sought to develop a method to address this gap by combining a population-based iPSC-derived cardiomyocyte model with Bayesian concentration-response modeling. A total of 136 compounds, including 54 pharmaceuticals and 82 environmental chemicals, were tested in iPSC-derived cardiomyocytes from 43 nondiseased humans. Hierarchical Bayesian population concentration-response modeling was conducted for 5 phenotypes reflecting cardiomyocyte function or viability. Toxicodynamic variability was quantified through the derivation of chemical- and phenotype-specific variability factors. Toxicokinetic modeling was used for probabilistic in vitro-to-in vivo extrapolation to derive population-wide margins of safety for pharmaceuticals and margins of exposure for environmental chemicals. Pharmaceuticals were found to be active across all phenotypes. Over half of tested environmental chemicals showed activity in at least one phenotype, most commonly positive chronotropy. Toxicodynamic variability factor estimates for the functional phenotypes were greater than those for cell viability, usually exceeding the generally assumed default of approximately 3. Population variability-based margins of safety for pharmaceuticals were correctly predicted to be relatively narrow, including some below 10; however, margins of exposure for environmental chemicals, based on population exposure estimates, generally exceeded 1000, suggesting they pose little risk at current general population exposures even to sensitive subpopulations. Overall, this study demonstrates how a high-throughput, human population-based, in vitro-in silico model can be used to characterize toxicodynamic population variability in cardiotoxic risk.
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Affiliation(s)
- Alexander D Blanchette
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458
| | - Sarah D Burnett
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458
| | - Fabian A Grimm
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458
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Fantke P, Chiu WA, Aylward L, Judson R, Huang L, Jang S, Gouin T, Rhomberg L, Aurisano N, McKone T, Jolliet O. Exposure and Toxicity Characterization of Chemical Emissions and Chemicals in Products: Global Recommendations and Implementation in USEtox. THE INTERNATIONAL JOURNAL OF LIFE CYCLE ASSESSMENT 2021; 26:899-915. [PMID: 34140756 PMCID: PMC8208704 DOI: 10.1007/s11367-021-01889-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 03/11/2021] [Indexed: 05/24/2023]
Abstract
PURPOSE Reducing chemical pressure on human and environmental health is an integral part of the global sustainability agenda. Guidelines for deriving globally applicable, life cycle based indicators are required to consistently quantify toxicity impacts from chemical emissions as well as from chemicals in consumer products. In response, we elaborate the methodological framework and present recommendations for advancing near-field/far-field exposure and toxicity characterization, and for implementing these recommendations in the scientific consensus model USEtox. METHODS An expert taskforce was convened by the Life Cycle Initiative hosted by UN Environment to expand existing guidance for evaluating human toxicity impacts from exposure to chemical substances. This taskforce evaluated advances since the original release of USEtox. Based on these advances, the taskforce identified two major aspects that required refinement, namely integrating near-field and far-field exposure and improving human dose-response modeling. Dedicated efforts have led to a set of recommendations to address these aspects in an update of USEtox, while ensuring consistency with the boundary conditions for characterizing life cycle toxicity impacts and being aligned with recommendations from agencies that regulate chemical exposure. The proposed framework was finally tested in an illustrative rice production and consumption case study. RESULTS AND DISCUSSION On the exposure side, a matrix system is proposed and recommended to integrate far-field exposure from environmental emissions with near-field exposure from chemicals in various consumer product types. Consumer exposure is addressed via submodels for each product type to account for product characteristics and exposure settings. Case study results illustrate that product-use related exposure dominates overall life cycle exposure. On the effect side, a probabilistic dose-response approach combined with a decision tree for identifying reliable points of departure is proposed for non-cancer effects, following recent guidance from the World Health Organization. This approach allows for explicitly considering both uncertainty and human variability in effect factors. Factors reflecting disease severity are proposed to distinguish cancer from non-cancer effects, and within the latter discriminate reproductive/developmental and other non-cancer effects. All proposed aspects have been consistently implemented into the original USEtox framework. CONCLUSIONS The recommended methodological advancements address several key limitations in earlier approaches. Next steps are to test the new characterization framework in additional case studies and to close remaining research gaps. Our framework is applicable for evaluating chemical emissions and product-related exposure in life cycle assessment, chemical alternatives assessment and chemical substitution, consumer exposure and risk screening, and high-throughput chemical prioritization.
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Affiliation(s)
- Peter Fantke
- Quantitative Sustainability Assessment, Department of Technology, Management and Economics, Technical University of Denmark, Produktionstorvet 424, 2800 Kgs. Lyngby, Denmark
| | - Weihsueh A. Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Lesa Aylward
- Queensland Alliance for Environmental Health Sciences, University of Queensland, Brisbane, Australia
| | - Richard Judson
- National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Lei Huang
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Suji Jang
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Todd Gouin
- TG Environmental Research, Sharnbrook, MK44 1PL, UK
| | | | - Nicolò Aurisano
- Quantitative Sustainability Assessment, Department of Technology, Management and Economics, Technical University of Denmark, Produktionstorvet 424, 2800 Kgs. Lyngby, Denmark
| | - Thomas McKone
- School of Public Health, University of California, Berkeley, California 94720, USA
| | - Olivier Jolliet
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan 48109, USA
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Chiu WA, Paoli G. Recent Advances in Probabilistic Dose-Response Assessment to Inform Risk-Based Decision Making. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2021; 41:596-609. [PMID: 32966629 PMCID: PMC8310576 DOI: 10.1111/risa.13595] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 07/08/2020] [Accepted: 08/25/2020] [Indexed: 05/16/2023]
Abstract
Paradoxically, risk assessments for the majority of chemicals lack any quantitative characterization as to the likelihood, incidence, or severity of the risks involved. The relatively few cases where "risk" is truly quantified are based on either epidemiologic data or extrapolation of experimental animal cancer bioassay data. The paucity of chemicals and health endpoints for which such data are available severely limits the ability of decisionmakers to account for the impacts of chemical exposures on human health. The development by the World Health Organization International Programme on Chemical Safety (WHO/IPCS) in 2014 of a comprehensive framework for probabilistic dose-response assessment has opened the door to a myriad of potential advances to better support decision making. Building on the pioneering work of Evans, Hattis, and Slob from the 1990s, the WHO/IPCS framework provides both a firm conceptual foundation as well as practical implementation tools to simultaneously assess uncertainty, variability, and severity of effect as a function of exposure. Moreover, such approaches do not depend on the availability of epidemiologic data, nor are they limited to cancer endpoints. Recent work has demonstrated the broad feasibility of such approaches in order to estimate the functional relationship between exposure level and the incidence or severity of health effects. While challenges remain, such as better characterization of the relationship between endpoints observed in experimental animal or in vitro studies and human health effects, the WHO/IPCS framework provides a strong basis for expanding the breadth of risk management decision contexts supported by chemical risk assessment.
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Affiliation(s)
- Weihsueh A. Chiu
- Texas A&M University, College Station, TX, USA
- Address correspondence to Weihsueh A. Chiu, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, TAMU 4458, Texas A&M University, College Station, TX, USA, 77843-4458; tel: +1 (979) 845-4106;
| | - Greg Paoli
- Risk Sciences International, Ottawa, ON, Canada
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Chen Z, Liu Y, Wright FA, Chiu WA, Rusyn I. Rapid hazard characterization of environmental chemicals using a compendium of human cell lines from different organs. ALTEX 2020; 37:623-638. [PMID: 32521033 PMCID: PMC7941183 DOI: 10.14573/altex.2002291] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023]
Abstract
The lack of adequate toxicity data for the vast majority of chemicals in the environment has spurred the development of new approach methodologies (NAMs). This study aimed to develop a practical high-throughput in vitro model for rapidly evaluating potential hazards of chemicals using a small number of human cells. Forty-two compounds were tested using human induced pluripotent stem cell (iPSC)-derived cells (hepatocytes, neurons, cardiomyocytes and endothelial cells), and a primary endothelial cell line. Both functional and cytotoxicity endpoints were evaluated using high-content imaging. Concentration-response was used to derive points-of-departure (POD). PODs were integrated with ToxPi and used as surrogate NAM-based PODs for risk characterization. We found chemical class-specific similarity among the chemicals tested; metal salts exhibited the highest overall bioactivity. We also observed cell type-specific patterns among classes of chemicals, indicating the ability of the proposed in vitro model to recognize effects on different cell types. Compared to available NAM datasets, such as ToxCast/Tox21 and chemical structure-based descriptors, we found that the data from the five-cell-type model was as good or even better in assigning compounds to chemical classes. Additionally, the PODs from this model performed well as a conservative surrogate for regulatory in vivo PODs and were less likely to underestimate in vivo potency and potential risk compared to other NAM-based PODs. In summary, we demonstrate the potential of this in vitro screening model to inform rapid risk-based decision-making through ranking, clustering, and assessment of both hazard and risks of diverse environmental chemicals.
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Affiliation(s)
- Zunwei Chen
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Yizhong Liu
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Fred A. Wright
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
- Departments of Statistics and Biological Sciences, North Carolina State University, Raleigh, NC, USA
| | - Weihsueh A. Chiu
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
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Dalaijamts C, Cichocki JA, Luo YS, Rusyn I, Chiu WA. PBPK modeling of impact of nonalcoholic fatty liver disease on toxicokinetics of perchloroethylene in mice. Toxicol Appl Pharmacol 2020; 400:115069. [PMID: 32445755 DOI: 10.1016/j.taap.2020.115069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/13/2020] [Accepted: 05/19/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Nonalcoholic fatty liver disease (NAFLD), a major cause of chronic liver disease in the Western countries with increasing prevalence worldwide, may substantially affect chemical toxicokinetics and thereby modulate chemical toxicity. OBJECTIVES This study aims to use physiologically-based pharmacokinetic (PBPK) modeling to characterize the impact of NAFLD on toxicokinetics of perchloroethylene (perc). METHODS Quantitative measures of physiological and biochemical changes associated with the presence of NAFLD induced by high-fat or methionine/choline-deficient diets in C57B1/6 J mice are incorporated into a previously developed PBPK model for perc and its oxidative and conjugative metabolites. Impacts on liver fat and volume, as well as blood:air and liver:air partition coefficients, are incorporated into the model. Hierarchical Bayesian population analysis using Markov chain Monte Carlo simulation is conducted to characterize uncertainty, as well as disease-induced variability in toxicokinetics. RESULTS NAFLD has a major effect on toxicokinetics of perc, with greater oxidative and lower conjugative metabolism as compared to healthy mice. The NAFLD-updated PBPK model accurately predicts in vivo metabolism of perc through oxidative and conjugative pathways in all tissues across disease states and strains, but underestimated parent compound concentrations in blood and liver of NAFLD mice. CONCLUSIONS We demonstrate the application of PBPK modeling to predict the effects of pre-existing disease conditions as a variability factor in perc metabolism. These results suggest that non-genetic factors such as diet and pre-existing disease can be as influential as genetic factors in altering toxicokinetics of perc, and thus are likely contribute substantially to population variation in its adverse effects.
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Affiliation(s)
- Chimeddulam Dalaijamts
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX, USA; Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Joseph A Cichocki
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX, USA; Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Yu-Syuan Luo
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX, USA; Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX, USA; Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Weihsueh A Chiu
- Interdisciplinary Faculty of Toxicology, Texas A&M University, College Station, TX, USA; Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
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Cichocki JA, Luo YS, Furuya S, Venkatratnam A, Konganti K, Chiu WA, Threadgill DW, Pogribny IP, Rusyn I. Modulation of Tetrachloroethylene-Associated Kidney Effects by Nonalcoholic Fatty Liver or Steatohepatitis in Male C57BL/6J Mice. Toxicol Sci 2019; 167:126-137. [PMID: 30202895 DOI: 10.1093/toxsci/kfy223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Accounting for genetic and other (eg, underlying disease states) factors that may lead to inter-individual variability in susceptibility to xenobiotic-induced injury is a challenge in human health assessments. A previous study demonstrated that nonalcoholic fatty liver disease (NAFLD), one of the common underlying disease states, enhances tetrachloroethylene (PERC)-associated hepatotoxicity in mice. Interestingly, NAFLD resulted in a decrease in metabolism of PERC to nephrotoxic glutathione conjugates; we therefore hypothesized that NAFLD would protect against PERC-associated nephrotoxicity. Male C57BL/6J mice were fed a low-fat (LFD), high-fat (31% fat, HFD), or high-fat methionine/choline/folate-deficient (31% fat, MCD) diets. After 8 weeks mice were administered either a single dose of PERC (300 mg/kg i.g.) and euthanized at 1-36 h post dose, or five daily doses of PERC (300 mg/kg/d i.g.) and euthanized 4 h after last dose. Relative to LFD-fed mice, HFD- or MCD-fed mice exhibited decreased PERC concentrations and increased trichloroacetate (TCA) in kidneys. S-(1,2,2-trichlorovinyl)glutathione (TCVG), S-(1,2,2-trichlorovinyl)-l-cysteine (TCVC), and N-acetyl-S-(1,2,2,-trichlorovinyl)-l-cysteine (NAcTCVC) were also significantly lower in kidney and urine of HFD- or MCD-fed mice compared with LFD-fed mice. Despite differences in levels of nephrotoxic PERC metabolites in kidney, LFD- and MCD-fed mice demonstrated similar degree of nephrotoxicity. However, HFD-fed mice were less sensitive to PERC-induced nephrotoxicity. Thus, whereas both MCD- and HFD-induced fatty liver reduced the delivered dose of nephrotoxic PERC metabolites to the kidney, only HFD was protective against PERC-induced nephrotoxicity, possibly due to greater toxicodynamic sensitivity induced by methyl and choline deficiency. These results therefore demonstrate that pre-existing disease conditions can lead to a complex interplay of toxicokinetic and toxicodynamic changes that modulate susceptibility to the toxicity of xenobiotics.
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Affiliation(s)
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences
| | | | | | | | | | - David W Threadgill
- Texas A&M Institute for Genome Sciences and Society.,Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Igor P Pogribny
- National Center for Toxicological Research, US FDA, Jefferson, Arkansas 72079
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences
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Krewski D, Andersen ME, Tyshenko MG, Krishnan K, Hartung T, Boekelheide K, Wambaugh JF, Jones D, Whelan M, Thomas R, Yauk C, Barton-Maclaren T, Cote I. Toxicity testing in the 21st century: progress in the past decade and future perspectives. Arch Toxicol 2019; 94:1-58. [DOI: 10.1007/s00204-019-02613-4] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 11/05/2019] [Indexed: 12/19/2022]
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Wambaugh JF, Wetmore BA, Ring CL, Nicolas CI, Pearce R, Honda G, Dinallo R, Angus D, Gilbert J, Sierra T, Badrinarayanan A, Snodgrass B, Brockman A, Strock C, Setzer W, Thomas RS. Assessing Toxicokinetic Uncertainty and Variability in Risk Prioritization. Toxicol Sci 2019; 172:235-251. [PMID: 31532498 PMCID: PMC8136471 DOI: 10.1093/toxsci/kfz205] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
High(er) throughput toxicokinetics (HTTK) encompasses in vitro measures of key determinants of chemical toxicokinetics and reverse dosimetry approaches for in vitro-in vivo extrapolation (IVIVE). With HTTK, the bioactivity identified by any in vitro assay can be converted to human equivalent doses and compared with chemical intake estimates. Biological variability in HTTK has been previously considered, but the relative impact of measurement uncertainty has not. Bayesian methods were developed to provide chemical-specific uncertainty estimates for 2 in vitro toxicokinetic parameters: unbound fraction in plasma (fup) and intrinsic hepatic clearance (Clint). New experimental measurements of fup and Clint are reported for 418 and 467 chemicals, respectively. These data raise the HTTK chemical coverage of the ToxCast Phase I and II libraries to 57%. Although the standard protocol for Clint was followed, a revised protocol for fup measured unbound chemical at 10%, 30%, and 100% of physiologic plasma protein concentrations, allowing estimation of protein binding affinity. This protocol reduced the occurrence of chemicals with fup too low to measure from 44% to 9.1%. Uncertainty in fup was also reduced, with the median coefficient of variation dropping from 0.4 to 0.1. Monte Carlo simulation was used to propagate both measurement uncertainty and biological variability into IVIVE. The uncertainty propagation techniques used here also allow incorporation of other sources of uncertainty such as in silico predictors of HTTK parameters. These methods have the potential to inform risk-based prioritization based on the relationship between in vitro bioactivities and exposures.
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Affiliation(s)
- John F. Wambaugh
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
| | - Barbara A. Wetmore
- National Exposure Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
| | - Caroline L. Ring
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831
| | - Chantel I. Nicolas
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831
- Office of Pollution Prevention and Toxics, U.S. EPA, Washington, D.C. 20460
| | - Robert Pearce
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831
| | - Gregory Honda
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831
| | | | | | | | | | | | | | | | | | - Woodrow Setzer
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
| | - Russell S. Thomas
- National Center for Computational Toxicology, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711
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Axelrad DA, Setzer RW, Bateson TF, DeVito M, Dzubow RC, Fitzpatrick JW, Frame AM, Hogan KA, Houck K, Stewart M. Methods for evaluating variability in human health dose-response characterization. HUMAN AND ECOLOGICAL RISK ASSESSMENT : HERA 2019; 25:1-24. [PMID: 31404325 PMCID: PMC6688638 DOI: 10.1080/10807039.2019.1615828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/03/2019] [Indexed: 05/21/2023]
Abstract
The Reference Dose (RfD) and Reference Concentration (RfC) are human health reference values (RfVs) representing exposure concentrations at or below which there is presumed to be little risk of adverse effects in the general human population. The 2009 National Research Council report Science and Decisions recommended redefining RfVs as "a risk-specific dose (for example, the dose associated with a 1 in 100,000 risk of a particular end point)." Distributions representing variability in human response to environmental contaminant exposures are critical for deriving risk-specific doses. Existing distributions estimating the extent of human toxicokinetic and toxicodynamic variability are based largely on controlled human exposure studies of pharmaceuticals. New data and methods have been developed that are designed to improve estimation of the quantitative variability in human response to environmental chemical exposures. Categories of research with potential to provide new database useful for developing updated human variability distributions include controlled human experiments, human epidemiology, animal models of genetic variability, in vitro estimates of toxicodynamic variability, and in vitro-based models of toxicokinetic variability. In vitro approaches, with further development including studies of different cell types and endpoints, and approaches to incorporate non-genetic sources of variability, appear to provide the greatest opportunity for substantial near-term advances.
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Affiliation(s)
- Daniel A. Axelrad
- Office of Policy, U.S. Environmental Protection Agency, Washington, DC, USA
| | - R. Woodrow Setzer
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Thomas F. Bateson
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA
| | - Michael DeVito
- National Institute of Environmental Health Sciences, National Toxicology Program, Research Triangle Park, NC, USA
| | - Rebecca C. Dzubow
- Office of Children’s Health Protection, U.S. Environmental Protection Agency, Washington, DC, USA
| | - Julie W. Fitzpatrick
- Office of the Science Advisor, U.S. Environmental Protection Agency, Washington, DC, USA
| | - Alicia M. Frame
- Office of Land and Emergency Management, U.S. Environmental Protection Agency, Washington, DC, USA
| | - Karen A. Hogan
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA
| | - Keith Houck
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Michael Stewart
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
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Il'yasova D, Kinev AV. Editorial: Using Cells in Epidemiological Studies to Characterize Individual Response to Environmental Hazards. Front Public Health 2019; 7:284. [PMID: 31632944 PMCID: PMC6783490 DOI: 10.3389/fpubh.2019.00284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/18/2019] [Indexed: 11/15/2022] Open
Affiliation(s)
- Dora Il'yasova
- Department of Population Health Sciences, School of Public Health, Georgia State University, Atlanta, GA, United States
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Burnett SD, Blanchette AD, Grimm FA, House JS, Reif DM, Wright FA, Chiu WA, Rusyn I. Population-based toxicity screening in human induced pluripotent stem cell-derived cardiomyocytes. Toxicol Appl Pharmacol 2019; 381:114711. [PMID: 31425687 PMCID: PMC6745256 DOI: 10.1016/j.taap.2019.114711] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/06/2019] [Accepted: 08/14/2019] [Indexed: 11/23/2022]
Abstract
The potential for cardiotoxicity is carefully evaluated for pharmaceuticals, as it is a major safety liability. However, environmental chemicals are seldom tested for their cardiotoxic potential. Moreover, there is a large variability in both baseline and drug-induced cardiovascular risk in humans, but data are lacking on the degree to which susceptibility to chemically-induced cardiotoxicity may also vary. Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes have become an important in vitro model for drug screening. Thus, we hypothesized that a population-based model of iPSC-derived cardiomyocytes from a diverse set of individuals can be used to assess potential hazard and inter-individual variability in chemical effects on these cells. We conducted concentration-response screening of 134 chemicals (pharmaceuticals, industrial and environmental chemicals and food constituents) in iPSC-derived cardiomyocytes from 43 individuals, comprising both sexes and diverse ancestry. We measured kinetic calcium flux and conducted high-content imaging following chemical exposure, and utilized a panel of functional and cytotoxicity parameters in concentration-response for each chemical and donor. We show reproducible inter-individual variability in both baseline and chemical-induced effects on iPSC-derived cardiomyocytes. Further, chemical-specific variability in potency and degree of population variability were quantified. This study shows the feasibility of using an organotypic population-based human in vitro model to quantitatively assess chemicals for which little cardiotoxicity information is available. Ultimately, these results advance in vitro toxicity testing methodologies by providing an innovative tool for population-based cardiotoxicity screening, contributing to the paradigm shift from traditional animal models of toxicity to in vitro toxicity testing methods.
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Affiliation(s)
- Sarah D Burnett
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
| | - Alexander D Blanchette
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
| | - Fabian A Grimm
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
| | - John S House
- Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA.
| | - David M Reif
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA; Department of Statistics, North Carolina State University, Raleigh, NC 27695, USA
| | - Fred A Wright
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA; Department of Statistics, North Carolina State University, Raleigh, NC 27695, USA.
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
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Feutz AC, De Geyter C. Accuracy, discriminative properties and reliability of a human ESC-based in vitro toxicity assay to distinguish teratogens responsible for neural tube defects. Arch Toxicol 2019; 93:2375-2384. [PMID: 31401662 DOI: 10.1007/s00204-019-02512-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/04/2019] [Indexed: 12/15/2022]
Abstract
The poor correlation of developmental toxicity studies in animals with human outcome data has emphasized the need for complementary assays based on human cells and tissues. As neural tube defects represent an important proportion of congenital malformations, we evaluated here the accuracy of a human embryonic stem cell (hESC)-based assay to predict chemically induced disruption of neural tube formation. As teratogenic compounds, we used cyclopamine (CPA), valproic acid (VPA), ochratoxin A (OTA) and mycophenolic acid (MMF), all suspected or known inducers of human neural tube defects, as well as theophylline and saccharin as negative control compounds. We analyzed their effects on the ability of hES cells to give rise to neural precursors (expressing specific marker Nestin), to form neural tube-like structures (rosettes), and to express specific markers (Sox1, Otx2, Lix1, EvI1, Rspo3) during rosette formation. The results showed that various effects of the selected compounds on early neural development could be specifically revealed in vitro through related alterations of neurogenic differentiation of hESC. Furthermore, it was possible to discriminate toxicants acting at different time points during embryonic development and, therefore, responsible for distinct adverse effects on neural tube formation. By comparing four different hESC lines, we observed a significant (up to fivefold) variability of the line-dependent response to toxicants. We highlight at least two sources of variability: one related to the heterogeneity of hESC lines in culture (stemness/commitment profiles); the second to possible genetically determined differences in individual sensitivity to teratogens.
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Affiliation(s)
- Anne-Catherine Feutz
- Reproductive Medicine and Gynaecological Endocrinology (RME), University Hospital, University of Basel, Vogesenstrasse 134, 4031, Basel, Switzerland.,Department of Biomedicine (DBM), University Hospital, University of Basel, Hebelstrasse 20, 4031, Basel, Switzerland.,SCAHT-Swiss Centre for Applied Human Toxicology, University of Basel, Missionsstrasse 64, 4055, Basel, Switzerland
| | - Christian De Geyter
- Reproductive Medicine and Gynaecological Endocrinology (RME), University Hospital, University of Basel, Vogesenstrasse 134, 4031, Basel, Switzerland. .,SCAHT-Swiss Centre for Applied Human Toxicology, University of Basel, Missionsstrasse 64, 4055, Basel, Switzerland.
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38
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Farsipour B, Faghihi-Zarandi A, Mozaffari A, Karami-Mohajeri S. Immune response and oxidative stress in workers of a copper concentration factory. INTERNATIONAL JOURNAL OF WORKPLACE HEALTH MANAGEMENT 2019. [DOI: 10.1108/ijwhm-05-2018-0062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PurposeThe main occupational safety measure in factories is monitoring workers exposed to various types of contaminations. The main environmental concern of governments about copper industries is emission of dust, metals, metal compounds and volatile organic compounds in air. The purpose of this paper is to evaluate the immune system status of workers in a copper concentration factory in Iran by placing the emphasis on oxidative stress biomarkers.Design/methodology/approachA comparative cross-sectional study was performed on 40 workers of the copper concentration factory and 40 unexposed individuals. White blood cell count, plasma interleukin 2 and 4, oxidative burst of neutrophils, oxidative damages of DNA and RNA, lipid and protein, total antioxidant capacity of plasma, and antioxidant enzymes activities were measured.FindingsA significant decrease in the white blood cell count and interleukin 2 and an increase in the interleukin 4 were observed in the workers and these changes represented the possibility of inflammation and weakening of the immune system. The elevation of oxidative damages, total antioxidant capacity and the activity of antioxidant enzymes are indicative of the change in oxidative stress status.Originality/valueThe oxidative stress induction and immune system changes might be useful biomarkers in screening and surveillance for occupational hazard. More studies are needed to find out the type and the concentration of pollutants and to evaluate the protective effects of natural antioxidants.
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Perry A, Lynch RM, Rusyn I, Threadgill DW. Long-Term Combinatorial Exposure to Trichloroethylene and Inorganic Arsenic in Genetically Heterogeneous Mice Results in Renal Tubular Damage and Cancer-Associated Molecular Changes. G3 (BETHESDA, MD.) 2019; 9:1729-1737. [PMID: 30898898 PMCID: PMC6505147 DOI: 10.1534/g3.119.400161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/20/2019] [Indexed: 11/23/2022]
Abstract
Trichloroethylene (TCE) and inorganic arsenic (iAs) are environmental contaminants that can target the kidney. Chronic exposure to TCE is associated with increased incidence of renal cell carcinoma, while co-exposure to TCE and iAs likely occurs in exposed human populations, such as those near Superfund sites. In order to better understand the kidney health consequences of TCE and/or iAs exposure, a genetically heterogeneous mouse population derived from FVB/NJ and CAST/EiJ mouse strains and deficient for multidrug resistance genes (Abcb1atm1Bor , Abcb1btm1Bor ) was chronically exposed for 52-weeks to varying concentrations of TCE and iAs. Although no exposure group resulted in primary renal cell tumors, kidneys from exposed mice did have significant increases in histologic and biochemical evidence of renal tubular disease with each toxicant alone and with combined exposure, with males having significantly higher levels of damage. Although no added increase in tubular disease was observed with combination exposure compared to single toxicants, molecular changes in kidneys from mice that had the combined exposure were similar to those previous observed in an embryonic stem cell assay for the P81S TCE-induced renal cell carcinoma mutation in the Von Hippel-Lindau syndrome (VHL) gene. While this model more accurately reflects human exposure conditions, development of primary renal tumors observed in humans following chronic TCE exposure was not reproduced even after inclusion of genetic heterogeneity and co-carcinogenic iAs.
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Affiliation(s)
- Amie Perry
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843
| | - Rachel M Lynch
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843
| | - Ivan Rusyn
- Department of Veterinary Integrative Bioscience, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843
| | - David W Threadgill
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843
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40
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Lewis L, Borowa-Mazgaj B, de Conti A, Chappell GA, Luo YS, Bodnar W, Konganti K, Wright FA, Threadgill DW, Chiu WA, Pogribny IP, Rusyn I. Population-Based Analysis of DNA Damage and Epigenetic Effects of 1,3-Butadiene in the Mouse. Chem Res Toxicol 2019; 32:887-898. [PMID: 30990016 DOI: 10.1021/acs.chemrestox.9b00035] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metabolism of 1,3-butadiene, a known human and rodent carcinogen, results in formation of reactive epoxides, a key event in its carcinogenicity. Although mice exposed to 1,3-butadiene present DNA adducts in all tested tissues, carcinogenicity is limited to liver, lung, and lymphoid tissues. Previous studies demonstrated that strain- and tissue-specific epigenetic effects in response to 1,3-butadiene exposure may influence susceptibly to DNA damage and serve as a potential mechanism of tissue-specific carcinogenicity. This study aimed to investigate interindividual variability in the effects of 1,3-butadiene using a population-based mouse model. Male mice from 20 Collaborative Cross strains were exposed to 0 or 635 ppm 1,3-butadiene by inhalation (6 h/day, 5 days/week) for 2 weeks. We evaluated DNA damage and epigenetic effects in target (lung and liver) and nontarget (kidney) tissues of 1,3-butadiene-induced carcinogenesis. DNA damage was assessed by measuring N-7-(2,3,4-trihydroxybut-1-yl)-guanine (THB-Gua) adducts. To investigate global histone modification alterations, we evaluated the trimethylation and acetylation of histones H3 and H4 across tissues. Changes in global cytosine DNA methylation were evaluated from the levels of methylation of LINE-1 and SINE B1 retrotransposons. We quantified the degree of variation across strains, deriving a chemical-specific human variability factor to address population variability in carcinogenic risk, which is largely ignored in current cancer risk assessment practice. Quantitative trait locus mapping identified four candidate genes related to chromatin remodeling whose variation was associated with interstrain susceptibility. Overall, this study uses 1,3-butadiene to demonstrate how the Collaborative Cross mouse population can be used to identify the mechanisms for and quantify the degree of interindividual variability in tissue-specific effects that are relevant to chemically induced carcinogenesis.
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Affiliation(s)
- Lauren Lewis
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences , Texas A&M University , College Station , Texas 77843 , United States
| | - Barbara Borowa-Mazgaj
- Division of Biochemical Toxicology, National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas 72079 , United States
| | - Aline de Conti
- Division of Biochemical Toxicology, National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas 72079 , United States
| | - Grace A Chappell
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences , Texas A&M University , College Station , Texas 77843 , United States
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences , Texas A&M University , College Station , Texas 77843 , United States
| | - Wanda Bodnar
- Department of Environmental Sciences and Engineering , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27516 , United States
| | - Kranti Konganti
- Department of Molecular and Cellular Medicine, College of Medicine , Texas A&M University , College Station , Texas 77843-1114 , United States
| | - Fred A Wright
- Bioinformatics Research Center , North Carolina State University , Raleigh , North Carolina 27695-7566 , United States
| | - David W Threadgill
- Department of Molecular and Cellular Medicine, College of Medicine , Texas A&M University , College Station , Texas 77843-1114 , United States
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences , Texas A&M University , College Station , Texas 77843 , United States
| | - Igor P Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas 72079 , United States
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences , Texas A&M University , College Station , Texas 77843 , United States
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Il'yasova D, Kinev A, Grégoire R, Beeson CC. A Cell-Based Approach to Study the Associations Between Mitochondrial Health, Early Life Exposures, and Consequent Health Outcomes. Front Public Health 2019; 7:36. [PMID: 30918888 PMCID: PMC6424859 DOI: 10.3389/fpubh.2019.00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/12/2019] [Indexed: 11/13/2022] Open
Affiliation(s)
- Dora Il'yasova
- Department of Population Health Science, School of Public Health, Georgia State University, Atlanta, GA, United States
| | | | - Rose Grégoire
- Department of Population Health Science, School of Public Health, Georgia State University, Atlanta, GA, United States
| | - Craig C Beeson
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC, United States
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Khan F, Momtaz S, Abdollahi M. The relationship between mercury exposure and epigenetic alterations regarding human health, risk assessment and diagnostic strategies. J Trace Elem Med Biol 2019; 52:37-47. [PMID: 30732897 DOI: 10.1016/j.jtemb.2018.11.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 11/08/2018] [Accepted: 11/11/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Exposure to the environmental toxicants poses a serious threat to human health. The extent of exposure and the development of diseases are interrelated with each other. Chronic exposure to mercury (Hg) increases the risk of developing serious human disorders from embryo to adulthood. OBJECTIVES The purpose of this review is to highlight the most common human disorders induced by Hg exposure on the basis of epigenetic mechanisms. A growing body of evidence shows that Hg exposure leads to alterations in the epigenetic markers. METHODS We performed an organized search of the available literature using PubMed, Google Scholar, Medline, Reaxys, EMBASE and Scopus databases. All the relevant citations, including research and review articles in English were evaluated. The search terms included mercury, Hg, epigenetics, epigenetic alterations, DNA methylation, histone modifications, microRNAs (miRNAs), and risk assessment. RESULTS Data on human toxicity due to Hg exposure shows broad variations in terms of chemical nature, doses, and the rate of exposure. Hg consumption either via foods or environmental sources may create deleterious health effects on various physiological systems at least partially through an epigenetic mechanism. CONCLUSION Hg exposure could trigger epigenetic alterations, hence leading to various human disorders including reduced newborn cerebellum size, adverse behavioral outcomes, atherosclerosis and myocardial infarction. Similarly, in adults, occupational Hg exposure has been associated with an increased risk of autoimmunity. It has been revealed that miRNAs in the woman's cervix are a novel responder to maternal Hg exposure during pregnancy. Hg-induced epigenetic alterations analysis of kidney tissues showed a significant interruption in renal function. DNA methylation and histone post-translation modifications are predominant types of Hg epigenetic alterations.
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Affiliation(s)
- Fazlullah Khan
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran; Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Saeideh Momtaz
- Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran; Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Mohammad Abdollahi
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran; Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
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Rusyn I, Greene N. The Impact of Novel Assessment Methodologies in Toxicology on Green Chemistry and Chemical Alternatives. Toxicol Sci 2019; 161:276-284. [PMID: 29378069 DOI: 10.1093/toxsci/kfx196] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The field of experimental toxicology is rapidly advancing by incorporating novel techniques and methods that provide a much more granular view into the mechanisms of potential adverse effects of chemical exposures on human health. The data from various in vitro assays and computational models are useful not only for increasing confidence in hazard and risk decisions, but also are enabling better, faster and cheaper assessment of a greater number of compounds, mixtures, and complex products. This is of special value to the field of green chemistry where design of new materials or alternative uses of existing ones is driven, at least in part, by considerations of safety. This article reviews the state of the science and decision-making in scenarios when little to no data may be available to draw conclusions about which choice in green chemistry is "safer." It is clear that there is no "one size fits all" solution and multiple data streams need to be weighed in making a decision. Moreover, the overall level of familiarity of the decision-makers and scientists alike with new assessment methodologies, their validity, value and limitations is evolving. Thus, while the "impact" of the new developments in toxicology on the field of green chemistry is great already, it is premature to conclude that the data from new assessment methodologies have been widely accepted yet.
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Affiliation(s)
- Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Nigel Greene
- Predictive Compound Safety and ADME, AstraZeneca Pharmaceuticals LP, Waltham, Massachusetts 02451
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Savita, Sharma A. Fungi as Biological Control Agents. BIOFERTILIZERS FOR SUSTAINABLE AGRICULTURE AND ENVIRONMENT 2019. [DOI: 10.1007/978-3-030-18933-4_18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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45
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Filonov D, Tice R, Luo R, Grotegut C, Van Kanegan MJ, Ludlow JW, Il'yasova D, Kinev A. Initial Assessment of Variability of Responses to Toxicants in Donor-Specific Endothelial Colony Forming Cells. Front Public Health 2018; 6:369. [PMID: 30622937 PMCID: PMC6308159 DOI: 10.3389/fpubh.2018.00369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/03/2018] [Indexed: 12/14/2022] Open
Abstract
There is increased interest in using high throughput in vitro assays to characterize human population variability in response to toxicants and drugs. Utilizing primary human endothelial colony-forming cells (ECFCs) isolated from blood would be highly useful for this purpose because these cells are involved in neonatal and adult vasculogenesis. We characterized the cytotoxicity of four known toxic chemicals (NaAsO2, CdCl2, tributyltin [TBT], and menadione) and their four relatively nontoxic counterparts (Na2HAsO4, ZnCl2, SnCl2, and phytonadione, respectively) in eight ECFC clones representing four neonatal donors (2 male and 2 female donors, 2 clones per donor). ECFCs were exposed to 9 concentrations of each chemical in duplicate; cell viability was evaluated 48 h later using the fluorescent vital dye fluorescent dye 5-Carboxyfluorescein Diacetate (CFDA), yielding concentration-effect curves from each experiment. Technical (day-to-day) variability of the assay, assessed from three independent experiments, was low: p-values for the differences of results were 0.74 and 0.64 for the comparison of day 2 vs. day 1 and day 3 vs. day 1, respectively. The statistical analysis used to compare the entire concentration-effect curves has revealed significant differences in levels of cytotoxicity induced by the toxic and relatively nontoxic chemical counterparts, demonstrating that donor-specific ECFCs can clearly differentiate between these two groups of chemicals. Partitioning of the total variance in the nested design assessed the contributions of between-clone and between-donor variability for different levels of cytotoxicity. Individual ECFC clones demonstrated highly reproducible responses to the chemicals. The most toxic chemical was TBT, followed by NaAsO2, CdCl2, and Menadione. Nontoxic counterparts exhibited low cytotoxicity at the higher end of concentration ranges tested. Low variability was observed between ECFC clones obtained from the same donor or different donors for CdCl2, NaAsO2, and TBT, but for menadione, the between-donor variability was much greater than the between-clone variability. The low between-clone variability indicates that an ECFC clone may represent an individual donor in cell-based assays, although this finding must be confirmed using a larger number of donors. Such confirmation would demonstrate that an in vitro ECFC-based testing platform can be used to characterize the inter-individual variability of neonatal ECFCs exposed to drugs and/or environmental toxicants.
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Affiliation(s)
| | - Raymond Tice
- Creative Scientist, Inc.Durham, NC, United States
| | - Ruiyan Luo
- School of Public Health, Georgia State University, Atlanta, GA, United States
| | - Chad Grotegut
- Duke University Medical Center, Durham, NC, United States
| | | | | | - Dora Il'yasova
- School of Public Health, Georgia State University, Atlanta, GA, United States
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46
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Fantke P, Aylward L, Bare J, Chiu WA, Dodson R, Dwyer R, Ernstoff A, Howard B, Jantunen M, Jolliet O, Judson R, Kirchhübel N, Li D, Miller A, Paoli G, Price P, Rhomberg L, Shen B, Shin HM, Teeguarden J, Vallero D, Wambaugh J, Wetmore BA, Zaleski R, McKone TE. Advancements in Life Cycle Human Exposure and Toxicity Characterization. ENVIRONMENTAL HEALTH PERSPECTIVES 2018; 126:125001. [PMID: 30540492 PMCID: PMC6371687 DOI: 10.1289/ehp3871] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 11/06/2018] [Accepted: 11/15/2018] [Indexed: 05/06/2023]
Abstract
BACKGROUND The Life Cycle Initiative, hosted at the United Nations Environment Programme, selected human toxicity impacts from exposure to chemical substances as an impact category that requires global guidance to overcome current assessment challenges. The initiative leadership established the Human Toxicity Task Force to develop guidance on assessing human exposure and toxicity impacts. Based on input gathered at three workshops addressing the main current scientific challenges and questions, the task force built a roadmap for advancing human toxicity characterization, primarily for use in life cycle impact assessment (LCIA). OBJECTIVES The present paper aims at reporting on the outcomes of the task force workshops along with interpretation of how these outcomes will impact the practice and reliability of toxicity characterization. The task force thereby focuses on two major issues that emerged from the workshops, namely considering near-field exposures and improving dose–response modeling. DISCUSSION The task force recommended approaches to improve the assessment of human exposure, including capturing missing exposure settings and human receptor pathways by coupling additional fate and exposure processes in consumer and occupational environments (near field) with existing processes in outdoor environments (far field). To quantify overall aggregate exposure, the task force suggested that environments be coupled using a consistent set of quantified chemical mass fractions transferred among environmental compartments. With respect to dose–response, the task force was concerned about the way LCIA currently characterizes human toxicity effects, and discussed several potential solutions. A specific concern is the use of a (linear) dose–response extrapolation to zero. Another concern addresses the challenge of identifying a metric for human toxicity impacts that is aligned with the spatiotemporal resolution of present LCIA methodology, yet is adequate to indicate health impact potential. CONCLUSIONS Further research efforts are required based on our proposed set of recommendations for improving the characterization of human exposure and toxicity impacts in LCIA and other comparative assessment frameworks. https://doi.org/10.1289/EHP3871.
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Affiliation(s)
- Peter Fantke
- Quantitative Sustainability Assessment Division, Department of Management Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lesa Aylward
- National Centre for Environmental Toxicology, University of Queensland, Brisbane, Australia
| | - Jane Bare
- U.S. EPA (Environmental Protection Agency), Cincinnati, Ohio, USA
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Robin Dodson
- Silent Spring Institute, Newton, Massachusetts, USA
| | - Robert Dwyer
- International Copper Association, New York, New York, USA
| | | | | | - Matti Jantunen
- Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland
| | - Olivier Jolliet
- School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Nienke Kirchhübel
- Quantitative Sustainability Assessment Division, Department of Management Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Dingsheng Li
- School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
| | - Aubrey Miller
- National Institute of Environmental Health Sciences, Bethesda, Maryland, USA
| | - Greg Paoli
- Risk Sciences International, Ottawa, Ontario, Canada
| | - Paul Price
- U.S. EPA, Research Triangle Park, North Carolina, USA
| | | | - Beverly Shen
- School of Public Health, University of California, Berkeley, California, USA
| | | | - Justin Teeguarden
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, Washington, USA
| | | | - John Wambaugh
- U.S. EPA, Research Triangle Park, North Carolina, USA
| | | | - Rosemary Zaleski
- ExxonMobil Biomedical Sciences, Inc., Annandale, New Jersey, USA
| | - Thomas E McKone
- School of Public Health, University of California, Berkeley, California, USA
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47
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Zhang Q, Li J, Middleton A, Bhattacharya S, Conolly RB. Bridging the Data Gap From in vitro Toxicity Testing to Chemical Safety Assessment Through Computational Modeling. Front Public Health 2018; 6:261. [PMID: 30255008 PMCID: PMC6141783 DOI: 10.3389/fpubh.2018.00261] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/21/2018] [Indexed: 12/18/2022] Open
Abstract
Chemical toxicity testing is moving steadily toward a human cell and organoid-based in vitro approach for reasons including scientific relevancy, efficiency, cost, and ethical rightfulness. Inferring human health risk from chemical exposure based on in vitro testing data is a challenging task, facing various data gaps along the way. This review identifies these gaps and makes a case for the in silico approach of computational dose-response and extrapolation modeling to address many of the challenges. Mathematical models that can mechanistically describe chemical toxicokinetics (TK) and toxicodynamics (TD), for both in vitro and in vivo conditions, are the founding pieces in this regard. Identifying toxicity pathways and in vitro point of departure (PoD) associated with adverse health outcomes requires an understanding of the molecular key events in the interacting transcriptome, proteome, and metabolome. Such an understanding will in turn help determine the sets of sensitive biomarkers to be measured in vitro and the scope of toxicity pathways to be modeled in silico. In vitro data reporting both pathway perturbation and chemical biokinetics in the culture medium serve to calibrate the toxicity pathway and virtual tissue models, which can then help predict PoDs in response to chemical dosimetry experienced by cells in vivo. Two types of in vitro to in vivo extrapolation (IVIVE) are needed. (1) For toxic effects involving systemic regulations, such as endocrine disruption, organism-level adverse outcome pathway (AOP) models are needed to extrapolate in vitro toxicity pathway perturbation to in vivo PoD. (2) Physiologically-based toxicokinetic (PBTK) modeling is needed to extrapolate in vitro PoD dose metrics into external doses for expected exposure scenarios. Linked PBTK and TD models can explore the parameter space to recapitulate human population variability in response to chemical insults. While challenges remain for applying these modeling tools to support in vitro toxicity testing, they open the door toward population-stratified and personalized risk assessment.
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Affiliation(s)
- Qiang Zhang
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States
| | - Jin Li
- Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, United Kingdom
| | - Alistair Middleton
- Unilever, Safety and Environmental Assurance Centre, Colworth Science Park, Sharnbrook, United Kingdom
| | - Sudin Bhattacharya
- Biomedical Engineering, Michigan State University, East Lansing, MI, United States
| | - Rory B Conolly
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Durham, NC, United States
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Parajuli RP, Goodrich JM, Chan LHM, Ayotte P, Lemire M, Hegele RA, Basu N. Genetic polymorphisms are associated with exposure biomarkers for metals and persistent organic pollutants among Inuit from the Inuvialuit Settlement Region, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:569-578. [PMID: 29635199 DOI: 10.1016/j.scitotenv.2018.03.331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/12/2018] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Inuit are exposed to some of the highest levels of contaminants worldwide. Studies suggest that several genes that mediate the metabolism of these contaminants are polymorphic. We hypothesize that single nucleotide polymorphisms (SNPs) in such genes may underline differences in biomarker concentrations and/or modify exposure-biomarker associations. METHODS Members from the Inuvialuit Settlement Region (Canada) were recruited. Blood concentrations of mercury (Hg), cadmium (Cd), lead (Pb), dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyl (PCB-153) were measured. SNPs from pathways such as glutathione, metallothionein, oxidative stress, and xenobiotic transport were genotyped in 281 participants, and data from 112 SNPs were included in the analyses. Surveys were administered to obtain information on demographics, and key sources of Hg (diet) and Cd (smoking) exposure. ANOVA and linear regressions were used for data analyses. RESULTS Geometric mean concentrations of metals were 4.6μg/L for Hg, 1.3μg/L for Cd, and 32.2μg/L for Pb. Concentrations of organic pollutants were 2.0μg/L for DDE and 0.6μg/L for PCB-153. Biomarker levels for Hg, Cd, Pb, DDE, and PCB-153 differed (p<0.05) by genotype for 4, 3, 4, 3, and 3 SNPs, respectively. In multivariable analyses (for Pb, DDE, PCB-153) adjusting age, sex and body mass index (BMI), only 2 associations (one for Pb and one for DDE) remained significant. In multivariable analyses accounting for sources of Hg or Cd exposure, 24 SNPs (9 for Hg, 15 for Cd with 4 overlapping) had significant (p<0.05) main effects on biomarker levels and/or modified exposure-biomarker associations. CONCLUSION The findings suggest that polymorphisms in key environmentally responsive genes can influence biomarker levels and/or modify exposure-biomarker associations for contaminants of concern to Arctic populations. Consideration of such gene-environment results may help improve the ability to conduct exposure (and ultimately risk) assessments of country foods and Inuit health.
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Affiliation(s)
- Rajendra Prasad Parajuli
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec H9X 3V9, Canada
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | | | - Pierre Ayotte
- Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, Université Laval, QC, Canada; Centre de toxicologie du Québec, Institut national de santé publique du Québec, QC, Canada
| | - Melanie Lemire
- Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, Université Laval, QC, Canada
| | | | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec H9X 3V9, Canada; Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
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49
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Dalaijamts C, Cichocki JA, Luo YS, Rusyn I, Chiu WA. Incorporation of the glutathione conjugation pathway in an updated physiologically-based pharmacokinetic model for perchloroethylene in mice. Toxicol Appl Pharmacol 2018; 352:142-152. [PMID: 29857080 PMCID: PMC6051410 DOI: 10.1016/j.taap.2018.05.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/16/2018] [Accepted: 05/25/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Perchloroethylene (perc) induced target organ toxicity has been associated with tissue-specific metabolic pathways. Previous physiologically-based pharmacokinetic (PBPK) modeling of perc accurately predicted oxidative metabolites but suggested the need to better characterize glutathione (GSH) conjugation as well as toxicokinetic uncertainty and variability. OBJECTIVES We updated the previously published "harmonized" perc PBPK model in mice to better characterize GSH conjugation metabolism as well as the uncertainty and variability of perc toxicokinetics. METHODS The updated PBPK model includes expanded models for perc and its oxidative metabolite trichloroacetic acid (TCA), and physiologically-based sub-models for conjugative metabolites. Previously compiled mouse kinetic data in B6C3F1 and Swiss-Webster mice were augmented to include data from a recent study in male C57BL/6J mice that measured perc and metabolites in serum and multiple tissues. Hierarchical Bayesian population analysis using Markov chain Monte Carlo was conducted to characterize uncertainty and inter-strain variability in perc metabolism. RESULTS The updated model fit the data as well or better than the previously published "harmonized" PBPK model. Tissue dosimetry for both oxidative and conjugative metabolites was successfully predicted across the three strains of mice, with estimated residuals errors of 2-fold for majority of data. Inter-strain variability across three strains was evident for oxidative metabolism; GSH conjugation data were only available for one strain. CONCLUSIONS This updated PBPK model fills a critical data gap in quantitative risk assessment by predicting the internal dosimetry of perc and its oxidative and GSH conjugation metabolites and lays the groundwork for future studies to better characterize toxicokinetic variability.
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Affiliation(s)
- Chimeddulam Dalaijamts
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Joseph A Cichocki
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Yu-Syuan Luo
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
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50
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Venkatratnam A, Furuya S, Kosyk O, Gold A, Bodnar W, Konganti K, Threadgill DW, Gillespie KM, Aylor DL, Wright FA, Chiu WA, Rusyn I. Editor's Highlight: Collaborative Cross Mouse Population Enables Refinements to Characterization of the Variability in Toxicokinetics of Trichloroethylene and Provides Genetic Evidence for the Role of PPAR Pathway in Its Oxidative Metabolism. Toxicol Sci 2018; 158:48-62. [PMID: 28369613 DOI: 10.1093/toxsci/kfx065] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Background Trichloroethylene (TCE) is a known carcinogen in humans and rodents. Previous studies of inter-strain variability in TCE metabolism were conducted in multi-strain panels of classical inbred mice with limited genetic diversity to identify gene-environment interactions associated with chemical exposure. Objectives To evaluate inter-strain variability in TCE metabolism and identify genetic determinants that are associated with TCE metabolism and effects using Collaborative Cross (CC), a large panel of genetically diverse strains of mice. Methods We administered a single oral dose of 0, 24, 80, 240, or 800 mg/kg of TCE to mice from 50 CC strains, and collected organs 24 h post-dosing. Levels of trichloroacetic acid (TCA), a major oxidative metabolite of TCE were measured in multiple tissues. Protein expression and activity levels of TCE-metabolizing enzymes were evaluated in the liver. Liver transcript levels of known genes perturbed by TCE exposure were also quantified. Genetic association mapping was performed on the acquired phenotypes. Results TCA levels varied in a dose- and strain-dependent manner in liver, kidney, and serum. The variability in TCA levels among strains did not correlate with expression or activity of a number of enzymes known to be involved in TCE oxidation. Peroxisome proliferator-activated receptor alpha (PPARα)-responsive genes were found to be associated with strain-specific differences in TCE metabolism. Conclusions This study shows that CC mouse population is a valuable tool to quantitatively evaluate inter-individual variability in chemical metabolism and to identify genes and pathways that may underpin population differences.
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Affiliation(s)
- Abhishek Venkatratnam
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843.,Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Shinji Furuya
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Oksana Kosyk
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Avram Gold
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Wanda Bodnar
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Kranti Konganti
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - David W Threadgill
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843
| | - Kevin M Gillespie
- Bioinformatics Research Center and Departments of Statistics and Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - David L Aylor
- Bioinformatics Research Center and Departments of Statistics and Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - Fred A Wright
- Bioinformatics Research Center and Departments of Statistics and Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - Weihsueh A Chiu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
| | - Ivan Rusyn
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843
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