1
|
Kinkade CW, Aleksunes LM, Brinker A, Buckley B, Brunner J, Wang C, Miller RK, O'Connor TG, Rivera-Núñez Z, Barrett ES. Associations between mycoestrogen exposure and sex steroid hormone concentrations in maternal serum and cord blood in the UPSIDE pregnancy cohort. Int J Hyg Environ Health 2024; 260:114405. [PMID: 38878407 DOI: 10.1016/j.ijheh.2024.114405] [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: 02/05/2024] [Revised: 05/20/2024] [Accepted: 05/29/2024] [Indexed: 06/28/2024]
Abstract
Zearalenone (ZEN) is a fungal-derived toxin found in global food supplies including cereal grains and processed foods, impacting populations worldwide through diet. Because the chemical structure of ZEN and metabolites closely resembles 17β-estradiol (E2), they interact with estrogen receptors α/β earning their designation as 'mycoestrogens'. In animal models, gestational exposure to mycoestrogens disrupts estrogen activity and impairs fetal growth. Here, our objective was to evaluate relationships between mycoestrogen exposure and sex steroid hormone concentrations in maternal circulation and cord blood for the first time in humans. In each trimester, pregnant participants in the UPSIDE study (n = 297) provided urine for mycoestrogen analysis and serum for hormone analysis. At birth, placental mycoestrogens and cord steroids were measured. We fitted longitudinal models examining log-transformed mycoestrogen concentrations in relation to log-transformed hormones, adjusting for covariates. Secondarily, multivariable linear models examined associations at each time point (1st, 2nd, 3rd trimesters, delivery). We additionally considered effect modification by fetal sex. ZEN and its metabolite, α-zearalenol (α-ZOL), were detected in >93% and >75% of urine samples; >80% of placentas had detectable mycoestrogens. Longitudinal models from the full cohort exhibited few significant associations. In sex-stratified analyses, in pregnancies with male fetuses, estrone (E1) and free testosterone (fT) were inversely associated with ZEN (E1 %Δ: -6.68 95%CI: -12.34, -0.65; fT %Δ: -3.22 95%CI: -5.68, -0.70); while α-ZOL was positively associated with E2 (%Δ: 5.61 95%CI: -1.54, 9.85) in pregnancies with female fetuses. In analysis with cord hormones, urinary mycoestrogens were inversely associated with androstenedione (%Δ: 9.15 95%CI: 14.64, -3.30) in both sexes, and placental mycoestrogens were positively associated with cord fT (%Δ: 37.13, 95%CI: 4.86, 79.34) amongst male offspring. Findings support the hypothesis that mycoestrogens act as endocrine disruptors in humans, as in animal models and livestock. Additional work is needed to understand impacts on maternal and child health.
Collapse
Affiliation(s)
- Carolyn W Kinkade
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA.
| | - Lauren M Aleksunes
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA; Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Anita Brinker
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA
| | - Brian Buckley
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA
| | - Jessica Brunner
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY, USA
| | - Christina Wang
- Clinical and Translational Science Institute, The Lundquist Institute at Harbor - UCLA Medical Center, Torrance, CA, USA
| | - Richard K Miller
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY, USA; Department of Environmental Medicine, Pediatrics and Pathology, University of Rochester, New York, NY, 14642, USA
| | - Thomas G O'Connor
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY, USA; Department of Psychiatry, University of Rochester, NY, USA; Wynne Center for Family Research, University of Rochester, USA
| | - Zorimar Rivera-Núñez
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA; Department of Biostatistics and Epidemiology, Rutgers School of Public Health, Piscataway, NJ, USA
| | - Emily S Barrett
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ, USA; Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY, USA; Department of Biostatistics and Epidemiology, Rutgers School of Public Health, Piscataway, NJ, USA
| |
Collapse
|
2
|
Pontifex T, Yang X, Tracy A, Burns K, Craig Z, Zhou C. Prenatal Exposure to Environmentally Relevant Low Dosage Dibutyl Phthalate Reduces Placental Efficiency in CD-1 Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.26.582170. [PMID: 38464211 PMCID: PMC10925143 DOI: 10.1101/2024.02.26.582170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Introduction Dibutyl phthalate (DBP), a phthalate congener, is widely utilized in consumer products and medication coatings. Women of reproductive age have a significant burden of DBP exposure through consumer products, occupational exposure, and medication. Prenatal DBP exposure is associated with adverse pregnancy/fetal outcomes and cardiovascular diseases in the offspring. However, the role of fetal sex and the general mechanisms underlying DBP exposure-associated adverse pregnancy outcomes are unclear. We hypothesize that prenatal DBP exposure at an environmentally relevant low dosage adversely affects fetal-placental development and function during pregnancy in a fetal sex-specific manner. Methods Adult female CD-1 mice (8-10wks) were orally treated with vehicle (control) or with environmentally relevant low DBP dosages at 0.1 μg/kg/day (refer as DBP0.1) daily from 30 days before pregnancy through gestational day (GD) 18.5. Dam body mass composition was measured non-invasively using the echo-magnetic resonance imaging system. Lipid disposition in fetal labyrinth and maternal decidual area of placentas was examined using Oil Red O staining. Results DBP0.1 exposure did not significantly affect the body weight and adiposity of non-pregnant adult female mice nor the maternal weight gain pattern and adiposity during pregnancy in adult female mice. DBP0.1 exposure does not affect fetal weight but significantly increased the placental weight at GD18.5 (indicative of decreased placental efficiency) in a fetal sex-specific manner. We further observed that DBP0.1 significantly decreased lipid disposition in fetal labyrinth of female, but not male placentas, while it did not affect lipid disposition in maternal decidual. Conclusions Prenatal exposure to environmentally relevant low-dosage DBP adversely impacts the fetal-placental efficiency and lipid disposition in a fetal sex-specific manner.
Collapse
Affiliation(s)
- Tasha Pontifex
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Xinran Yang
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Ayna Tracy
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Kimberlie Burns
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Zelieann Craig
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Chi Zhou
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
- Department of Obstetrics and Gynecology, The University of Arizona, Tucson, AZ, United States
| |
Collapse
|
3
|
Chen S, Shi Z, Zhang Q. A physiologically based pharmacokinetic model of diethyl phthalates in humans. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 340:122849. [PMID: 37926418 PMCID: PMC10841618 DOI: 10.1016/j.envpol.2023.122849] [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: 06/30/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
Phthalates are a family of industrial and consumer product chemicals, among which diethyl phthalate (DEP) has been widely used. DEP is metabolized into the active metabolite monoethyl phthalate (MEP) and exposure to DEP may induce male reproductive toxicity, developmental toxicity and hepatotoxicity. To better assess the toxicity of DEP and MEP, it is important to understand and predict their internal concentrations, especially in reproductive organs. Here we present a human physiologically based pharmacokinetic (PBPK) model of DEP. Implemented in R, the PBPK model consists of seven tissue compartments, including blood, gut, liver, fat, skin, gonad, and rest of body (RB). In the blood both DEP and MEP partition into free and bound forms, and tissue distribution is considered as blood flow-limited. DEP is metabolized in the gut and liver into MEP which is further glucuronidated and cleared through the urine. The chemical-specific parameters of the model were predicted in silico or estimated based on published human urinary MEP data after exposure to DEP in the air at 250 or 300 μg/m3 for 3 or 6 h through inhalation and dermal absorption. Sensitivity analysis identified important parameters including partition coefficients of DEP for fat, RB, and skin compartments, and the rate constants for glucuronidation of MEP and urinary excretion, with regard to Cmax, area under the curve (AUC), and clearance half-lives of DEP and MEP. A subset of the sensitive parameters was then included in hierarchical population Bayesian Markov chain Monte Carlo (MCMC) simulations to characterize the uncertainty and variability of these parameters. The model is consistent with the notion that dermal absorption represents a significant route of exposure to DEP in ambient air and clothing can be an effective barrier. The developed human PBPK model can be utilized upon further refinement as a quantitative tool for DEP risk assessment.
Collapse
Affiliation(s)
- Shiyu Chen
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, GA 30322, USA
| | - Zhenzhen Shi
- The Program for Experimental and Theoretical Modeling, Division of Hepatology, Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Qiang Zhang
- Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, GA 30322, USA.
| |
Collapse
|
4
|
Abdo N, Al-Khalaileh H, Alajlouni M, Hamadneh J, Alajlouni AM. Screening for phthalates biomarkers and its potential role in infertility outcomes in Jordan. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2023; 33:273-282. [PMID: 36593351 PMCID: PMC9807094 DOI: 10.1038/s41370-022-00517-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Phthalates are endocrine disrupting chemicals that are used in plastic and personal care products. Phthalate exposure has been linked to reproductive and fertility outcomes. OBJECTIVES This study aimed to assess the phthalate exposures using both urinary level of two DEHP metabolites in females and questionnaires. It also aimed to investigate the association between phthalate levels and reproductive and fertility outcomes. METHODS 325 females with and without fertility problems at gynaecology clinics filled out a questionnaire and provided a urine sample. Urine samples were analyzed for two DEHP metabolites: MEHHP, mono (2-ethyl-5-hydroxyhexyl) phthalate; MEOHP, mono (2-ethyl-5-oxohexyl) phthalate, using an HPLC/MS/MS analytical method. RESULTS We observed a significant difference between cases and controls in terms of heating plastic in the microwave and use of skin and eye make-up, sunscreen, and nail polish. Our findings showed that MEOHP exposure is significantly associated with infertility among Jordanian women (Adjusted OR = 1.66, 95% CI: 1.14, 2.40, p-value = 0.002). SIGNIFICANCE To the best of our knowledge, our study is the first of its kind done in Jordan to screen for phthalate exposure and investigate its association with infertility. Our study demonstrated high exposure of the Jordanian population to DEHP. It confirms the association between DEHP exposure and infertility. IMPACT STATEMENT We measured phthalates in infertile and fertile women, in a community unaware of phthalate sources or its impacts, and with no regulation limits set. We aimed to increase awareness to environmental exposure to phthalates, emphasize the importance of implementation of public health interventions to control and minimize the effects of phthalate exposure and provide a base for further studies and future research to aid in the formation of policies and guidelines for the manufacturing and use of phthalates.
Collapse
Affiliation(s)
- Nour Abdo
- Department of Public Health and Family Medicine, College of Medicine, Jordan University of Science and Technology, P.O. Box, 3030, Irbid, 22110, Jordan.
| | - Hana Al-Khalaileh
- Department of Public Health and Family Medicine, College of Medicine, Jordan University of Science and Technology, P.O. Box, 3030, Irbid, 22110, Jordan
| | - Marwan Alajlouni
- Department of Public Health and Family Medicine, College of Medicine, Jordan University of Science and Technology, P.O. Box, 3030, Irbid, 22110, Jordan
| | - Jehan Hamadneh
- Department of Obstetrics and Genecology, College of Medicine, Jordan University of Science and Technology, P.O. Box, 3030, Irbid, 22110, Jordan
| | | |
Collapse
|
5
|
Kruger L, Yue G, Mettu VS, Paquette A, Sathyanarayana S, Prasad B. Differential proteomics analysis of JEG-3 and JAR placental cell models and the effect of androgen treatment. J Steroid Biochem Mol Biol 2022; 222:106138. [PMID: 35690242 DOI: 10.1016/j.jsbmb.2022.106138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/29/2022] [Accepted: 06/06/2022] [Indexed: 11/16/2022]
Abstract
The placenta is a vital fetal organ that plays an important role in maintaining fetal sex hormone homeostasis. Xenobiotics can alter placental sex-steroidogenic enzymes and transporters, including enzymes such as aromatase (CYP19A1) and the hydroxysteroid dehydrogenases (HSDs) but studying how compounds disrupt in vivo placental metabolism is complex. Utilizing high-throughput in vitro models is critical to predict the disruption of placental sex-steroidogenic enzymes and transporters, particularly by drug candidates in the early stages of drug discovery. JAR and JEG-3 cells are the most common, simple, and cost-effective placental cell models that are capable of high-throughput screening, but how well they express the sex-steroidogenic enzymes and transporters is not well known. Here, we compared the proteomes of JAR and JEG-3 cells in the presence and absence of physiologically relevant concentrations of dehydroepiandrosterone (DHEA, 8 µM) and testosterone (15 nM) to aid the characterization of sex-steroidogenic enzymes and transporters in these cell models. Global proteomics analysis detected 2931 and 3449 proteins in JAR cells and JEG-3 cells, respectively. However, dramatic differences in sex-steroidogenic enzymes and transporters were observed between these cells. In particular, the basal expression of steroid sulfatase (STS), HSD17B1, and HSD17B7 were unique to JEG-3 cells. JEG-3 cells also showed significantly higher protein levels of aldo-keto reductase (AKR) 1A1 and AKR1B1, while JAR cells showed significantly higher levels of HSD17B4 and HSDB12. Aldehyde dehydrogenase (ALDH) 3A2 and HSD17B11 enzymes as well as the transporters sterol O-acyltransferase (SOAT) 1 and ATP binding cassette subfamily G2 (ABCG2) were comparable between the cell lines, whereas sulfotransferases (SULTs) were uniquely present within JAR cells. Androgen treatments significantly lowered HSD17B11, HSD17B4, HSD17B12, and ALDH3A2 levels in JAR cells. DHEA treatment significantly raised the level of HSD17B1 by 51 % in JEG-3 cells, whereas CYP19A1 was increased to significant levels in both JAR and JEG-3 cells after androgen treatments. The proteomics data were supported by a complementary targeted metabolomics analysis of culture media in the DHEA (8 µM) and testosterone (15 nM) treated groups. This study has indicated that untreated JEG-3 cells express more sex-steroidogenic enzymes and transporters. Nevertheless, JEG-3 and JAR cells are unique and their respective proteomics data can be used to select the best model depending on the hypothesis.
Collapse
Affiliation(s)
- Laken Kruger
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Guihua Yue
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Vijaya Saradhi Mettu
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Alison Paquette
- Seattle Children's Research Institute, Seattle, WA, USA; University of Washington, Seattle, WA, USA
| | - Sheela Sathyanarayana
- Seattle Children's Research Institute, Seattle, WA, USA; University of Washington, Seattle, WA, USA
| | - Bhagwat Prasad
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, USA.
| |
Collapse
|
6
|
Deierlein AL, Wu H, Just AC, Kupsco AJ, Braun JM, Oken E, Soria-Contreras DC, Cantoral A, Pizano ML, McRae N, Téllez-Rojo MM, Wright RO, Baccarelli AA. Prenatal phthalates, gestational weight gain, and long-term weight changes among Mexican women. ENVIRONMENTAL RESEARCH 2022; 209:112835. [PMID: 35101400 PMCID: PMC8976769 DOI: 10.1016/j.envres.2022.112835] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 12/18/2021] [Accepted: 01/24/2022] [Indexed: 05/03/2023]
Abstract
BACKGROUND Phthalates are endocrine disrupting chemicals that may influence weight status; however, few studies have considered weight gain during pregnancy and subsequent long-term weight changes in women. OBJECTIVE To determine associations of prenatal phthalate exposure with maternal weight during pregnancy and through up to seven years post-delivery. METHODS We analyzed 15 urinary phthalate biomarker concentrations during the 2nd and 3rd trimesters among 874 pregnant women enrolled in the Programming Research in Obesity, Growth Environment and Social Stress Study in Mexico City. We examined three time-specific maternal weight outcomes: gestational weight gain (between 2nd and 3rd trimesters), short-term weight (between 3rd trimester and 12 months post-delivery), and long-term weight (between 18 months and 6-7 years post-delivery). We used Bayesian Kernel Machine Regression (BKMR) to estimate associations for the total phthalate mixture, as well as multivariable linear mixed models for individual phthalate biomarkers. RESULTS As a mixture, 2nd trimester urinary phthalate biomarker concentrations were associated with somewhat lower gestational weight gain between the 2nd and 3rd trimesters (interquartile range, IQR, difference: -0.07 standard deviations, SD; 95% credible interval, CrI: -0.20, 0.06); multivariable regression and BKMR models indicated that this inverse association was primarily driven by mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP). Prenatal (2nd and 3rd trimesters) urinary phthalate mixture concentrations were positively associated with maternal weight change through 12 months postpartum (IQR difference: 0.11 SD; 95% CrI: 0.00, 0.23); these associations persisted from 18 months to 6-7 years follow-up (IQR difference: 0.07 SD; 95% CrI: 0.04, 0.10). Postpartum weight changes were associated with mono-3-carboxypropyl phthalate (MCPP) and MECPTP. CONCLUSIONS Prenatal phthalate exposure was inversely associated with gestational weight gain and positively associated with long-term changes in maternal weight. Further investigation is required to understand how phthalates may influence body composition and whether they contribute to the development of obesity and other cardiometabolic diseases in women.
Collapse
Affiliation(s)
- Andrea L Deierlein
- Department of Epidemiology, School of Global Public Health, New York University, New York, USA.
| | - Haotian Wu
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, USA
| | - Allan C Just
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Allison J Kupsco
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, USA
| | - Joseph M Braun
- Department of Epidemiology, School of Public Health, Brown University, Providence, RI, USA
| | - Emily Oken
- Division of Chronic Disease Research Across the Lifecourse, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA
| | - Diana C Soria-Contreras
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, Mexico
| | - Alejandra Cantoral
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, Mexico
| | - Ma Luisa Pizano
- Division of Community Interventions Research, National Institute of Perinatology, Mexico City, Mexico
| | - Nia McRae
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Martha M Téllez-Rojo
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Morelos, Mexico
| | - Robert O Wright
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, USA; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andrea A Baccarelli
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, USA
| |
Collapse
|
7
|
Zhang J, Chang X, Holland TL, Hines DE, Karmaus AL, Bell S, Lee KM. Evaluation of Inhalation Exposures and Potential Health Impacts of Ingredient Mixtures Using in vitro to in vivo Extrapolation. FRONTIERS IN TOXICOLOGY 2022; 3:787756. [PMID: 35295123 PMCID: PMC8915826 DOI: 10.3389/ftox.2021.787756] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
In vitro methods offer opportunities to provide mechanistic insight into bioactivity as well as human-relevant toxicological assessments compared to animal testing. One of the challenges for this task is putting in vitro bioactivity data in an in vivo exposure context, for which in vitro to in vivo extrapolation (IVIVE) translates in vitro bioactivity to clinically relevant exposure metrics using reverse dosimetry. This study applies an IVIVE approach to the toxicity assessment of ingredients and their mixtures in e-cigarette (EC) aerosols as a case study. Reported in vitro cytotoxicity data of EC aerosols, as well as in vitro high-throughput screening (HTS) data for individual ingredients in EC liquids (e-liquids) are used. Open-source physiologically based pharmacokinetic (PBPK) models are used to calculate the plasma concentrations of individual ingredients, followed by reverse dosimetry to estimate the human equivalent administered doses (EADs) needed to obtain these plasma concentrations for the total e-liquids. Three approaches (single actor approach, additive effect approach, and outcome-oriented ingredient integration approach) are used to predict EADs of e-liquids considering differential contributions to the bioactivity from the ingredients (humectant carriers [propylene glycol and glycerol], flavors, benzoic acid, and nicotine). The results identified critical factors for the EAD estimation, including the ingredients of the mixture considered to be bioactive, in vitro assay selection, and the data integration approach for mixtures. Further, we introduced the outcome-oriented ingredient integration approach to consider e-liquid ingredients that may lead to a common toxicity outcome (e.g., cytotoxicity), facilitating a quantitative evaluation of in vitro toxicity data in support of human risk assessment.
Collapse
Affiliation(s)
- Jingjie Zhang
- Altria Client Services, LLC, Richmond, VA, United States
- *Correspondence: Jingjie Zhang,
| | - Xiaoqing Chang
- Integrated Laboratory Systems, LLC, Morrisville, NC, United States
| | - Tessa L. Holland
- Lancaster Laboratories, c/o Altria Client Services, LLC, Regulatory Affairs, VA, Richmond, United States
| | - David E. Hines
- Integrated Laboratory Systems, LLC, Morrisville, NC, United States
| | - Agnes L. Karmaus
- Integrated Laboratory Systems, LLC, Morrisville, NC, United States
| | - Shannon Bell
- Integrated Laboratory Systems, LLC, Morrisville, NC, United States
| | - K. Monica Lee
- Altria Client Services, LLC, Richmond, VA, United States
| |
Collapse
|
8
|
Human risk assessment of di-isobutyl phthalate through the application of a developed physiologically based pharmacokinetic model of di-isobutyl phthalate and its major metabolite mono-isobutyl phthalate. Arch Toxicol 2021; 95:2385-2402. [PMID: 33907876 DOI: 10.1007/s00204-021-03057-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 04/21/2021] [Indexed: 10/21/2022]
Abstract
Di-isobutyl phthalate (DiBP) is a substance used in the production of objects frequently used in human life. Mono-isobutyl phthalate (MiBP), a major in vivo metabolite of DiBP, is a biomarker for DiBP exposure assessment. Therefore, risk assessment studies on DiBP and MiBP, which have not yet been reported in detail, are needed. The aim of this study was to develop and evaluate a physiologically based pharmacokinetic (PBPK) model for DiBP and MiBP in rats and extend this to human risk assessment based on human exposure. Pharmacokinetic studies were performed in male rats following the administration of 5-100 mg/kg DiBP, and these results were used for the development and validation of the PBPK model. In addition, the previous pharmacokinetic results in female rats following DiBP administration and the pharmacokinetic results in both males and females according to multiple exposures to DiBP were used to develop and validate the PBPK model. The metabolism of DiBP to MiBP in the body was very significant and rapid, and the biodistribution of MiBP was broad and major. Furthermore, the amount of MiBP in the body showed a correlation with DiBP exposure, and from this, a PBPK model was developed to evaluate the external exposure of DiBP from the internal exposure of MiBP. The predicted rat plasma, urine, fecal, and tissue concentrations using the developed PBPK model fitted well with the observed values. The established PBPK model for rats was extrapolated to a human PBPK model of DiBP and MiBP based on human physiological parameters and allometric scaling. The reference dose of 0.512 mg/kg/day of DiBP and external doses of 6.14-280.90 μg/kg/day DiBP for human risk assessment were estimated using Korean biomonitoring values. Valuable insight and approaches to assessing human health risks associated with DiBP exposure were provided by this study.
Collapse
|
9
|
Al-Saleh I, Elkhatib R, Alrushud N, Alnuwaysir H, Alnemer M, Aldhalaan H, Shoukri M, McWalter P, Alkhenizan A. Potential health risks of maternal phthalate exposure during the first trimester - The Saudi Early Autism and Environment Study (SEAES). ENVIRONMENTAL RESEARCH 2021; 195:110882. [PMID: 33621597 DOI: 10.1016/j.envres.2021.110882] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Phthalates are the most ubiquitous contaminants that we are exposed to daily due to their wide use as plasticizers in various consumer products. A few studies have suggested that in utero exposure to phthalates can disturb fetal growth and development in humans, because phthalates can interfere with endocrine function. We collected spot urine samples from 291 pregnant women in their first trimester (9.8 ± 2.3 gestational weeks) recruited in an ongoing prospective cohort study in Saudi Arabia. A second urine sample was collected within 1-7 d after enrollment. The aims of this study were to: (1) assess the extent of exposure to phthalates during the first trimester and (2) estimate the risk from single and cumulative exposures to phthalates. Most phthalate metabolites' urinary levels were high, several-fold higher than those reported in relevant studies from other countries. The highest median levels of monoethyl phthalate, mono-n-butyl phthalate (MnBP), mono-iso-butyl phthalate (MiBP), and mono-(2-ethylhexyl) phthalate (MEHP) in μg/l (μg/g creatinine) were 245.62 (197.23), 114.26 (99.45), 39.59 (34.02), and 23.51 (19.92), respectively. The MEHP levels were highest among three di (2-ethylhexyl) phthalate (DEHP) metabolites. %MEHP4, the ratio of MEHP to four di (2-ethylhexyl) phthalate metabolites (∑4DEHP), was 44%, indicating interindividual differences in metabolism and excretion. The hazard quotient (HQ) of individual phthalates estimated based on the reference dose (RfD) of the U.S. Environmental Protection Agency indicated that 58% (volume-based) and 37% (creatinine-based) of the women were at risk of exposure to ∑4DEHP (HQ > 1). Based on the tolerable daily intake (TDI) from the European Food Safety Authority, 35/12% (volume-/creatinine-based data) of the women were at risk of exposure to two dibutyl phthalate (∑DBP) metabolites (MiBP and MnBP). The cumulative risk was assessed using the hazard index (HI), the sum of HQs of all phthalates. The percentages of women (volume-/creatinine-based data) at health risks with an HI > 1 were 64/40% and 42/22% based on RfD and TDI, respectively. In view of these indices for assessing risk, our results for the anti-androgenic effects of exposing pregnant women to ∑4DEHP and ∑DBP early during pregnancy are alarming.
Collapse
Affiliation(s)
- Iman Al-Saleh
- Environmental Health Program, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia.
| | - Rola Elkhatib
- Environmental Health Program, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Nujud Alrushud
- Environmental Health Program, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Hissah Alnuwaysir
- Environmental Health Program, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Maha Alnemer
- Obstetrics and Gynecology Department, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Hesham Aldhalaan
- Center for Autism Research, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Mohamed Shoukri
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Patricia McWalter
- Family Medicine and Polyclinics Department, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| | - Abdullah Alkhenizan
- Family Medicine and Polyclinics Department, King Faisal Specialist Hospital and Research Centre, P.O.Box: 3354, Riyadh 11211, Saudi Arabia
| |
Collapse
|
10
|
Chou WC, Lin Z. Development of a Gestational and Lactational Physiologically Based Pharmacokinetic (PBPK) Model for Perfluorooctane Sulfonate (PFOS) in Rats and Humans and Its Implications in the Derivation of Health-Based Toxicity Values. ENVIRONMENTAL HEALTH PERSPECTIVES 2021; 129:37004. [PMID: 33730865 PMCID: PMC7969127 DOI: 10.1289/ehp7671] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 02/08/2021] [Accepted: 02/12/2021] [Indexed: 05/03/2023]
Abstract
BACKGROUND There is a great concern on potential adverse effects of exposure to perfluorooctane sulfonate (PFOS) in sensitive subpopulations, such as pregnant women, fetuses, and neonates, due to its reported transplacental and lactational transfer and reproductive and developmental toxicities in animals and humans. OBJECTIVES This study aimed to develop a gestational and lactational physiologically based pharmacokinetic (PBPK) model in rats and humans for PFOS to aid risk assessment in sensitive human subpopulations. METHODS Based upon existing PBPK models for PFOS, the present model addressed a data gap of including a physiologically based description of basolateral and apical membrane transporter-mediated renal reabsorption and excretion in kidneys during gestation and lactation. The model was calibrated with published rat toxicokinetic and human biomonitoring data and was independently evaluated with separate data. Monte Carlo simulation was used to address the interindividual variability. RESULTS Model simulations were generally within 2-fold of observed PFOS concentrations in maternal/fetal/neonatal plasma and liver in rats and humans. Estimated fifth percentile human equivalent doses (HEDs) based on selected critical toxicity studies in rats following U.S. Environmental Protection Agency (EPA) guidelines ranged from 0.08 to 0.91 μ g / kg per day . These values are lower than the HEDs estimated in U.S. EPA guidance (0.51 - 1.6 μ g / kg per day ) using an empirical toxicokinetic model in adults. CONCLUSIONS The results support the importance of renal reabsorption/excretion during pregnancy and lactation in PFOS dosimetry and suggest that the derivation of health-based toxicity values based on developmental toxicity studies should consider gestational/lactational dosimetry estimated from a life stage-appropriate PBPK model. This study provides a quantitative tool to aid risk reevaluation of PFOS, especially in sensitive human subpopulations, and it provides a basis for extrapolating to other per- and polyfluoroalkyl substances (PFAS). All model codes and detailed tutorials are provided in the Supplemental Materials to allow readers to reproduce our results and to use this model. https://doi.org/10.1289/EHP7671.
Collapse
Affiliation(s)
- Wei-Chun Chou
- Institute of Computational Comparative Medicine, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Zhoumeng Lin
- Institute of Computational Comparative Medicine, Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| |
Collapse
|
11
|
Philips EM, Jaddoe VWV, Deierlein A, Asimakopoulos AG, Kannan K, Steegers EAP, Trasande L. Exposures to phthalates and bisphenols in pregnancy and postpartum weight gain in a population-based longitudinal birth cohort. ENVIRONMENT INTERNATIONAL 2020; 144:106002. [PMID: 32745783 PMCID: PMC7572597 DOI: 10.1016/j.envint.2020.106002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/09/2020] [Accepted: 07/19/2020] [Indexed: 05/08/2023]
Abstract
BACKGROUND Experimental evidence suggests that exposures to phthalates and bisphenols may interfere with processes related to glucose and lipid metabolism, insulin sensitivity, and body weight. Few studies have considered the possible influence of chemical exposures during pregnancy on maternal weight gain or metabolic health outcomes postpartum. OBJECTIVE To examine the associations of early and mid-pregnancy bisphenol and phthalate urine concentrations with maternal weight gain 6 years postpartum. METHODS We analyzed urine samples for bisphenol, phthalate and creatinine concentrations from early and mid-pregnancy in 1192 women in a large, population-based birth cohort in Rotterdam, the Netherlands, and examined postpartum weight gain using maternal anthropometrics before pregnancy and 6 years postpartum. We have used covariate-adjusted linear regressions to evaluate associations of early and mid-pregnancy bisphenols and phthalate metabolites with weight change. Mediator and interaction models have been used to assess the role of gestational weight gain and breastfeeding, respectively. Sensitivity analysis is performed among women without subsequent pregnancies. RESULTS Among all 1192 mothers included in the analysis, each log unit increase in the average bisphenol A and all assessed phthalate groupings were associated with increased maternal weight gain. As a proxy for phthalate exposure, each log unit increase in averaged phthalic acid was associated with 734 g weight gain (95% CI 273-1196 g) between pre-pregnancy and 6 years postpartum. Mediation by gestational weight gain was not present. Breastfeeding and ethnicity did not modify the effects. Stratification revealed these associations to be strongest among overweight and obese women. Among women without subsequent pregnancies (n = 373) associations of bisphenols, HMW phthalate metabolites and di-2-ethylhexylphthalate metabolites attenuated. For phthalic acid, LMW phthalate metabolites and di-n-octylphthalate metabolites associations increased. Similarly to the whole group, stratification yielded significant results among overweight and obese women. DISCUSSION In a large population-based birth cohort, early and mid-pregnancy phthalate exposures are associated with weight gain 6 years postpartum, particularly among overweight and obese women. These data support ongoing action to replace phthalates with safer alternatives.
Collapse
Affiliation(s)
- Elise M Philips
- The Generation R Study Group, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; Department of Pediatrics, Sophia Children's Hospital, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Vincent W V Jaddoe
- The Generation R Study Group, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; Department of Pediatrics, Sophia Children's Hospital, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Andrea Deierlein
- New York University College of Global Public Health, New York City, NY, United States
| | - Alexandros G Asimakopoulos
- Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, NY 12201, United States; Department of Chemistry, The Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Kurunthachalam Kannan
- Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, NY 12201, United States; Biochemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Eric A P Steegers
- Department of Obstetrics & Gynecology, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Leonardo Trasande
- New York University College of Global Public Health, New York City, NY, United States; Department of Pediatrics, New York University School of Medicine, New York City, NY, United States; Department of Environmental Medicine, New York University School of Medicine, New York City, NY, United States; Department of Population Health, New York University School of Medicine, New York City, NY, United States; New York Wagner School of Public Service, New York City, NY, United States.
| |
Collapse
|
12
|
Campbell JL, Otter R, Anderson WA, Longnecker MP, Clewell RA, North C, Clewell HJ. Development of a physiologically based pharmacokinetic model of diisononyl phthalate (DiNP) in pregnant rat and human. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2020; 83:631-648. [PMID: 32757748 DOI: 10.1080/15287394.2020.1798831] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A physiologically based pharmacokinetic (PBPK) model for di-isononyl phthalate (DiNP) was developed by adapting the existing models for di(2-ethylhexyl) phthalate (DEHP) and di-butylphthalate (DBP). Both pregnant rat and human time-course plasma and urine data were used to address the hydrolysis of DiNP in intestinal tract, plasma, and liver as well as hepatic oxidative metabolism and conjugation of the monoester and primary oxidative metabolites. Data in both rats and humans were available to inform the uptake and disposition of mono-isononyl phthalate (MiNP) as well as the three primary oxidative metabolites including hydroxy (7-OH)-, oxo (7-OXO)-, and carboxy (7-COX)-monoisononyl phthalate in plasma and urine. The DiNP model was reliable over a wide range of exposure levels in the pregnant rat as well as the two low exposure levels in humans including capturing the nonlinear behavior in the pregnant rat after repeated 750 mg/kg/day dosing. The presented DiNP PBPK model in pregnant rat and human, based upon an extensive kinetic dataset in both species, may provide a basis for assessing human equivalent exposures based upon either rodent or in vitro points of departure.
Collapse
Affiliation(s)
| | - Rainer Otter
- Regulatory Affairs/Advocacy, Basf Se , Ludwigshafen, Germany
| | - Warwick A Anderson
- Food Safety, Fera Science Ltd., National Agri-Food Innovation Campus , York, UK
| | | | | | - Colin North
- Toxicology & Environmental Science, ExxonMobil Biomedical Sciences, Inc , Annandale, NJ, USA
| | | |
Collapse
|
13
|
Silinski MAR, Fernando RA, Robinson VG, Waidyanatha S. Development and Validation of an Analytical Method for Quantitation of Monobutylphthalate, a Metabolite of Di-n-Butylphthalate, in Rat Plasma, Amniotic Fluid, Fetuses and Pups by UPLC-MS/MS. J Anal Toxicol 2020; 44:370-377. [PMID: 31776566 DOI: 10.1093/jat/bkz090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Phthalates have been used for decades as softening agents in the production of plastics, but in recent years have been extensively investigated for their potential hazards to human health and the environment. Di-n-butyl phthalate (DBP), with widespread exposure occurring through a variety of consumer products such as cosmetics and pesticides, is a suspected carcinogen and an endocrine system disruptor in both humans and laboratory animals. Its predominant metabolite is the monoester, monobutyl phthalate (MBP), which can serve as a marker of exposure. To support toxicological studies of DBP in pregnant and lactating rats and their offspring, a novel ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for quantitation of MBP in rat plasma, amniotic fluid, fetuses and whole pup samples. Plasma samples were extracted using a simple protein precipitation with acetonitrile. Extraction and delipidation of pup homogenate was performed using acetonitrile and then submerging the vials in liquid nitrogen. Extracts were analyzed by UPLC-MS/MS in the negative ion mode. The method was successfully validated over the concentration ranges 25-5,000 ng/mL in female Sprague Dawley (SD) rat plasma and 50-5,000 ng/g in SD pup homogenate. Matrix calibration curves were linear (r ≥ 0.99), and the percent relative error (%RE) values were ≤ ±15% for standards at all levels. Absolute recoveries were > 92% in both matrices. The limits of detection (LODs) were 6.9 ng/mL in plasma and 9.4 ng/g in pup homogenate. Acceptable intra- and interday accuracy and precision were demonstrated by mean %RE ≤ ±7.5 and relative standard deviation (%RSD) ≤ 10.1%. Extract stability was demonstrated for ~6 days at various temperatures and freeze-thaw stability was demonstrated after 3 cycles over 3 days. Secondary matrix evaluation was performed for MBP in amniotic fluid and pooled fetus homogenate (mean %RE ≤ ±11.5 and %RSD ≤ 13.7). These data demonstrate that this simple method is suitable for determination of MBP in plasma, amniotic fluid, fetus and pup samples from toxicological studies of DBP.
Collapse
Affiliation(s)
- Melanie A Rehder Silinski
- Analytical Sciences, RTI International, P.O. Box 12194, 3040 Cornwallis Rd, Research Triangle Park, NC 27709, USA and
| | - Reshan A Fernando
- Analytical Sciences, RTI International, P.O. Box 12194, 3040 Cornwallis Rd, Research Triangle Park, NC 27709, USA and
| | - Veronica G Robinson
- Division of the National Toxicology Program, NIEHS, P.O. Box 12233, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Suramya Waidyanatha
- Division of the National Toxicology Program, NIEHS, P.O. Box 12233, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| |
Collapse
|
14
|
Waits A, Chen HC, Kuo PL, Wang CW, Huang HB, Chang WH, Shih SF, Huang PC. Urinary phthalate metabolites are associated with biomarkers of DNA damage and lipid peroxidation in pregnant women - Tainan Birth Cohort Study (TBCS). ENVIRONMENTAL RESEARCH 2020; 188:109863. [PMID: 32846647 DOI: 10.1016/j.envres.2020.109863] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
Phthalate exposure and oxidative stress have been linked to adverse reproductive outcomes in experimental studies, whereas no clear line has been drawn for human, especially in pregnant women. This study explored relationships between urinary phthalate metabolites and biomarkers of lipid peroxidation and oxidative and nitrosative DNA damage. Measurements from 97 Taiwanese pregnant women were taken at three different times during second and third trimesters. Five oxidative/nitrosative stress biomarkers - 8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO2Gua), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA), 8-isoprostaglandin F2α (8-isoPF2α), and malondialdehyde (MDA), and 11 phthalate metabolites were measured in urine samples. Linear regressions in each visit and linear mixed-model regressions were fitted to estimate percent changes in oxidative/nitrosative stress biomarkers resulting from inter-tertile increase of phthalate metabolite level and the cumulative concentrations of di (2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate. The highest urine concentrations of phthalate metabolites and the greatest number of significant positive associations between phthalate metabolites and oxidative/nitrosative stress biomarkers were observed in the third visit and in repeated measurements analysis, respectively. Of the biomarkers related to DNA damage, 8-OHdG (25.4% inter-tertile increase for mono-iso-butyl phthalate) was more sensitive to phthalate exposure than 8-NO2Gua. Among the biomarkers of lipid peroxidation, HNE-MA (61.2% inter-tertile increase for sum of DEHP metabolites) was more sensitive than 8-isoPF2α and MDA. Our findings support the hypothesis that pregnant phthalate exposure increases the oxidative stress biomarkers of DNA damage and lipid peroxidation. Future research may elucidate the mediating roles of oxidative/nitrosative stress biomarkers in the link between phthalate exposure and adverse reproductive outcomes.
Collapse
Affiliation(s)
- Alexander Waits
- National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan
| | - Hsin-Chang Chen
- Institute of Food Safety and Health, National Taiwan University, Taipei, Taiwan
| | - Pao-Lin Kuo
- Department of Obstetrics and Gynecology, National Cheng Kung University Hospital and College of Medicine, Tainan, Taiwan
| | - Chih-Wen Wang
- Hepatobiliary Division, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Han-Bin Huang
- School of Public Health, National Defense Medical Center, Taipei, Taiwan
| | - Wei-Hsiang Chang
- Department of Food Safety/ Hygiene and Risk Management, National Cheng Kung University, Tainan, Taiwan
| | - Shu-Fang Shih
- Department of Health Management and Policy, University of Michigan School of Public Health, USA
| | - Po-Chin Huang
- National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.
| |
Collapse
|
15
|
Feng YL, Liao X, Chen D, Takser L, Cakmak S, Chan P, Zhu J. Correlations of phthalate metabolites in urine samples from fertile and infertile men: Free-form concentration vs. conjugated-form concentration. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 263:114602. [PMID: 33618486 DOI: 10.1016/j.envpol.2020.114602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/26/2020] [Accepted: 04/13/2020] [Indexed: 06/12/2023]
Abstract
In previous studies, the total content of urinary phthalate metabolites was commonly used to evaluate human exposure to phthalates. However, phthalate metabolites are mainly present in urine in two forms, conjugated and free. These metabolite forms in urine are more relevant to the biotransformation pathways of the phthalates in humans. Therefore, the concentration of these forms is more relevant to exposure related health outcomes than total content. In this study, instead of measuring total content, the free- and conjugated-form concentrations of phthalate metabolites in the urine of fertile and infertile men were measured. The main metabolites in urine of both groups are monoethyl phthalate (MEP) and the di-(2-ethylhexyl) phthalate (DEHP) metabolites. The geometric means of their both conjugated- and free-forms in the infertile group were higher than in the fertile group, specifically, 24.3 and 43.4 μg/g creatinine vs 8.5 and 28.9 μg/g creatinine, respectively, for MEP, and 50.0 and 9.1 μg/g creatinine vs 39.1 and 8.4 μg/g creatinine, respectively for total DEHP metabolites. We investigated the correlations of free- and conjugated-form phthalate metabolite concentrations between the infertile and fertile group as well as among different phthalate metabolites. The results showed that there was a statistically significant difference between the infertile and fertile group for monobenzyl phthalate (MBzP) in both free-form and conjugated-form. However, there was only a statistically significant difference between the two groups for conjugated-form MEP and MEHP, and no statistically significant difference between the two groups for free-form MEP and MEHP. The results of the Pearson correlation test revealed that the correlations between DEHP metabolites and the correlations between mid-sized phthalate metabolites (mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP) and mono-benzyl phthalate (MBzP)) were stronger than between these two clusters of metabolites. This study is the first attempt to examine possible effects of conjugated-form concentrations of phthalate metabolites on human fertility. The results of this study suggest that conjugated-form and free-form concentrations of urinary phthalate metabolites may be appropriate biomarkers for assessing human exposure to phthalates and association with health outcomes.
Collapse
Affiliation(s)
- Yong-Lai Feng
- Environmental Health Science and Research Bureau, Health Canada, AL: 2203 B, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, K1Y 0M1, Canada.
| | - Xiangjun Liao
- Environmental Health Science and Research Bureau, Health Canada, AL: 2203 B, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, K1Y 0M1, Canada
| | - Da Chen
- School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, Guangdong, 510632, China
| | - Larissa Takser
- Département Pédiatrie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
| | - Sabit Cakmak
- Environmental Health Science and Research Bureau, Health Canada, AL: 2203 B, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, K1Y 0M1, Canada
| | - Peter Chan
- Department of Urology, Royal Victoria Hospital, McGill University Health Centre, Montreal, Quebec, Canada
| | - Jiping Zhu
- Environmental Health Science and Research Bureau, Health Canada, AL: 2203 B, 251 Sir Frederick Banting Driveway, Ottawa, Ontario, K1Y 0M1, Canada
| |
Collapse
|
16
|
Jeong SH, Jang JH, Cho HY, Lee YB. Risk assessment for humans using physiologically based pharmacokinetic model of diethyl phthalate and its major metabolite, monoethyl phthalate. Arch Toxicol 2020; 94:2377-2400. [PMID: 32303804 DOI: 10.1007/s00204-020-02748-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 04/08/2020] [Indexed: 11/24/2022]
Abstract
Diethyl phthalate (DEP) belongs to phthalates with short alkyl chains. It is a substance frequently used to make various products. Thus, humans are widely exposed to DEP from the surrounding environment such as food, soil, air, and water. As previously reported in many studies, DEP is an endocrine disruptor with reproductive toxicity. Monoethyl phthalate (MEP), a major metabolite of DEP in vivo, is a biomarker for DEP exposure assessment. It is also an endocrine disruptor with reproductive toxicity, similar to DEP. However, toxicokinetic studies on both MEP and DEP have not been reported in detail yet. Therefore, the objective of this study was to evaluate and develop physiologically based pharmacokinetic (PBPK) model for both DEP and MEP in rats and extend this to human risk assessment based on human exposure. This study was conducted in vivo after intravenous or oral administration of DEP into female (2 mg/kg dose) and male (0.1-10 mg/kg dose) rats. Biological samples consisted of urine, plasma, and 11 different tissues. These samples were analyzed using UPLC-ESI-MS/MS method. For DEP, the tissue to plasma partition coefficient was the highest in the kidney, followed by that in the liver. For MEP, the tissue to plasma partition coefficient was the highest in the liver. It was less than unity in all other tissues. Plasma, urine, and fecal samples were also obtained after IV administration of MEP (10 mg/kg dose) to male rats. All results were reflected in a model developed in this study, including in vivo conversion from DEP to MEP. Predicted concentrations of DEP and MEP in rat urine, plasma, and tissue samples using the developed PBPK model fitted well with observed values. We then extrapolated the PBPK model in rats to a human PBPK model of DEP and MEP based on human physiological parameters. Reference dose of 0.63 mg/kg/day (or 0.18 mg/kg/day) for DEP and external doses of 0.246 μg/kg/day (pregnant), 0.193 μg/kg/day (fetus), 1.005-1.253 μg/kg/day (adults), 0.356-0.376 μg/kg/day (adolescents), and 0.595-0.603 μg/kg/day (children) for DEP for human risk assessment were estimated using Korean biomonitoring values. Our study provides valuable insight into human health risk assessment regarding DEP exposure.
Collapse
Affiliation(s)
- Seung-Hyun Jeong
- College of Pharmacy, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, 61186, Republic of Korea
| | - Ji-Hun Jang
- College of Pharmacy, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, 61186, Republic of Korea
| | - Hea-Young Cho
- College of Pharmacy, CHA University, 335 Pangyo-ro, Bundang-gu, Seongnam-si, Gyeonggi-Do, 13488, Republic of Korea.
| | - Yong-Bok Lee
- College of Pharmacy, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, 61186, Republic of Korea.
| |
Collapse
|
17
|
Zhou Y, Ma T, Yan M, Meng X, Wu J, Ding J, Han X, Li D. Exposure of DBP in gestation induces inflammation of testicular Sertoli cells in progeny by activating NLRP3 inflammasomes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:136139. [PMID: 31863983 DOI: 10.1016/j.scitotenv.2019.136139] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/22/2019] [Accepted: 12/14/2019] [Indexed: 06/10/2023]
Abstract
Di-n-butyl phthalate (DBP), as one of the environmental chemicals, can cause male reproductive decline including testicular hypoplasia and impairments of spermatogenesis. Testicular inflammation is positively related to decline in male reproductive function. However, whether exposure to DBP in utero can cause testicular inflammation in progeny has not been studied. In this study, we established an animal model and observed that DBP exposure during gestation induced testicular inflammation in progeny with the increased expression of pro-inflammatory cytokines and chemokines including tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1) and CXC chemokine ligand-10 (CXCL-10), representing the activation of the nuclear factor kappa B (NF-κB). However, NF-κB was activated within 1 h in Sertoli cells (SCs) when exposed to MBP (a metabolite of DBP) in vitro. Meanwhile, we detected increased expression of inflammatory NLR family pyrin domain containing 3 (NLRP3), resulting from Pellino2-mediated NLRP3 inflammasome priming. Further, we confirmed that the activation of the NLRP3/caspase-1/IL-1β canonical inflammasome pathway induced secretion of inflammatory factors of SCs and immune response, and INF39 (an inhibitor of NLRP3) could inhibit the inflammation in vitro. Collectively, these findings indicated that NLRP3 inflammasomes played key roles in DBP-induced inflammation in testicular SCs.
Collapse
Affiliation(s)
- Yuan Zhou
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Tan Ma
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Minghao Yan
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Xiannan Meng
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Jiang Wu
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Jie Ding
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Xiaodong Han
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China.
| | - Dongmei Li
- Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, Jiangsu 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, Jiangsu 210093, China.
| |
Collapse
|
18
|
Wei W, Ramalho O, Mandin C. Modeling the bioaccessibility of inhaled semivolatile organic compounds in the human respiratory tract. Int J Hyg Environ Health 2020; 224:113436. [PMID: 31978732 DOI: 10.1016/j.ijheh.2019.113436] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/26/2019] [Accepted: 12/13/2019] [Indexed: 01/05/2023]
Abstract
The bioaccessibility of semivolatile organic compounds (SVOCs) via inhalation has rarely been studied, as indicated by the literature. There is no model to calculate the SVOC bioaccessibility following inhalation, and measurement data have focused on only a few polycyclic aromatic hydrocarbons (PAHs) in the particle phase. The present work developed a mechanistic model to address the mass transfer of inhaled SVOCs among the gas, particle and mucus phases in the human respiratory tract. The model considers (1) the SVOC partitioning between the gas and particle phases as well as between the gas and mucus phases and (2) the deposition of gas- and particle-phase SVOCs in the mucus of the respiratory tract. Based on the model, the inhalation bioaccessibility for 72 SVOCs was calculated. The SVOCs were measured in French dwellings at the nationwide scale, and their median concentrations in both the gas and particle phases were used for the bioaccessibility calculations. The results show that the inhalation bioaccessibility varies considerably from one compound to another, e.g., between 0.62 and 1.00 for phthalates, between 0.71 and 0.79 for polybrominated diphenyl ethers (PBDEs), between 0.48 and 0.56 for polychlorinated biphenyls (PCBs), between 0.48 and 1.00 for different chemical families of pesticides and between 0.48 and 0.90 for PAHs.
Collapse
Affiliation(s)
- Wenjuan Wei
- University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Marne la Vallée Cedex 2, Champs sur Marne, 77447, France.
| | - Olivier Ramalho
- University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Marne la Vallée Cedex 2, Champs sur Marne, 77447, France
| | - Corinne Mandin
- University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Marne la Vallée Cedex 2, Champs sur Marne, 77447, France
| |
Collapse
|
19
|
Codaccioni M, Bois F, Brochot C. Placental transfer of xenobiotics in pregnancy physiologically-based pharmacokinetic models: Structure and data. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.comtox.2019.100111] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
20
|
Domínguez-Romero E, Scheringer M. A review of phthalate pharmacokinetics in human and rat: what factors drive phthalate distribution and partitioning? Drug Metab Rev 2019; 51:314-329. [DOI: 10.1080/03602532.2019.1620762] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Elena Domínguez-Romero
- Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Martin Scheringer
- Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Brno, Czech Republic
| |
Collapse
|
21
|
Sarigiannis DA, Karakitsios S, Dominguez-Romero E, Papadaki K, Brochot C, Kumar V, Schuhmacher M, Sy M, Mielke H, Greiner M, Mengelers M, Scheringer M. Physiology-based toxicokinetic modelling in the frame of the European Human Biomonitoring Initiative. ENVIRONMENTAL RESEARCH 2019; 172:216-230. [PMID: 30818231 DOI: 10.1016/j.envres.2019.01.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/25/2019] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Given the opportunities provided by internal dosimetry modelling in the interpretation of human biomonitoring (HBM) data, the assessment of the links between exposure to chemicals and observed HBM data can be effectively supported by PBTK modelling. This paper gives a comprehensive review of available human PBTK models for compounds selected as a priority by the European Human Biomonitoring Initiative (HBM4EU). We highlight their advantages and deficiencies and suggest steps for advanced internal dose modelling. The review of the available PBTK models highlighted the conceptual differences between older models compared to the ones developed recently, reflecting commensurate differences in research questions. Due to the lack of coordinated strategies for deriving useful biomonitoring data for toxicokinetic properties, significant problems in model parameterisation still remain; these are further increased by the lack of human toxicokinetic data due to ethics issues. Finally, questions arise as well as to the extent they are really representative of interindividual variability. QSARs for toxicokinetic properties is a complementary approach for PBTK model parameterisation, especially for data poor chemicals. This approach could be expanded to model chemico-biological interactions such as intestinal absorption and renal clearance; this could serve the development of more complex generic PBTK models that could be applied to newly derived chemicals. Another gap identified is the framework for mixture interaction terms among compounds that could eventually interact in metabolism. From the review it was concluded that efforts should be shifted toward the development of generic multi-compartmental and multi-route models, supported by targeted biomonitoring coupled with parameterisation by both QSAR approach and experimental (in-vivo and in-vitro) data for newly developed and data poor compounds.
Collapse
Affiliation(s)
- Dimosthenis A Sarigiannis
- Aristotle University of Thessaloniki, Department of Chemical Engineering, Environmental Engineering Laboratory, University Campus, Thessaloniki 54124, Greece; HERACLES Research Center on the Exposome and Health, Center for Interdisciplinary Research and Innovation, Balkan Center, Bldg. B, 10th km Thessaloniki-Thermi Road, 57001, Greece.
| | - Spyros Karakitsios
- Aristotle University of Thessaloniki, Department of Chemical Engineering, Environmental Engineering Laboratory, University Campus, Thessaloniki 54124, Greece; HERACLES Research Center on the Exposome and Health, Center for Interdisciplinary Research and Innovation, Balkan Center, Bldg. B, 10th km Thessaloniki-Thermi Road, 57001, Greece
| | | | - Krystalia Papadaki
- Aristotle University of Thessaloniki, Department of Chemical Engineering, Environmental Engineering Laboratory, University Campus, Thessaloniki 54124, Greece
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Rodríguez-Carmona Y, Cantoral A, Trejo-Valdivia B, Téllez-Rojo MM, Svensson K, Peterson KE, Meeker JD, Schnaas L, Solano M, Watkins DJ. Phthalate exposure during pregnancy and long-term weight gain in women. ENVIRONMENTAL RESEARCH 2019; 169:26-32. [PMID: 30408750 PMCID: PMC6347540 DOI: 10.1016/j.envres.2018.10.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 10/11/2018] [Accepted: 10/13/2018] [Indexed: 05/20/2023]
Abstract
BACKGROUND Phthalates are known endocrine disruptors and peroxisome proliferator-activated receptor (PPAR) activators, potentially capable of promoting an obesogenic effect. Pregnant women are especially vulnerable to phthalate exposure due to physiological and metabolic changes during pregnancy, including those related to the metabolism of xenobiotics. Phthalate exposure during pregnancy has been associated with early gestational weight gain, however, its effect on long-term weight gain remains unclear. The aim of the present study was to evaluate the association between phthalate exposure during pregnancy and long-term changes in weight among women. METHODS Urinary phthalate concentrations, socioeconomic, anthropometry and information on diet and socioeconomic status were collected during pregnancy from 178 women from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) birth cohort. Maternal body weight and diet information was also collected up to 5 times in the first year postpartum and twice during follow-up visits 5.2-10.7 years later. A path analysis was performed to assess associations between urinary phthalate metabolite levels during pregnancy and change in weight (kg) per year after delivery, including age, education, living with/without partner, parity, daily energy intake and breastfeeding duration. RESULTS The mean age at pregnancy was 27.3 ± 5.9 years and mean body mass index during the first postpartum year was 27.07 ± 4.22 kg/m2. On average, women gained 3.48 kg (0.52 ± 0.84 kg/year). A unit increase in log-transformed mono-3-carboxypropyl phthalate (MCPP) was associated with 0.33 kg (95% CI: 0.09, 0.56) higher weight gain per year, and mono-benzyl phthalate (MBzP) with 0.21 kg (95% CI: -0.38, -0.03) lower weight gain per year. CONCLUSION Exposure to certain phthalates during pregnancy may be associated with long-term weight change in women. More studies on the effects of phthalate exposure during pregnancy on women's long-term health are required.
Collapse
Affiliation(s)
| | - Alejandra Cantoral
- CONACYT, National Institute of Public Health, Center for Nutrition and Health Research, Av Universidad 655 Col. Sta. Ma. Ahuacatitlán, Cuernavaca C.P. 62100, Morelos, Mexico.
| | - Belem Trejo-Valdivia
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Mexico
| | - Martha M Téllez-Rojo
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Mexico
| | - Katherine Svensson
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Karen E Peterson
- Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, USA
| | - John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, USA
| | - Lourdes Schnaas
- Division of Research in Community Interventions, National Institute of Perinatology, Mexico City, Mexico
| | - Maritsa Solano
- Center for Nutrition and Health Research, National Institute of Public Health, Cuernavaca, Mexico
| | - Deborah J Watkins
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, USA
| |
Collapse
|
23
|
Neal-Kluever A, Fisher J, Grylack L, Kakiuchi-Kiyota S, Halpern W. Physiology of the Neonatal Gastrointestinal System Relevant to the Disposition of Orally Administered Medications. Drug Metab Dispos 2018; 47:296-313. [DOI: 10.1124/dmd.118.084418] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 12/14/2018] [Indexed: 12/13/2022] Open
|
24
|
Lorber M, Weschler CJ, Morrison G, Bekö G, Gong M, Koch HM, Salthammer T, Schripp T, Toftum J, Clausen G. Linking a dermal permeation and an inhalation model to a simple pharmacokinetic model to study airborne exposure to di(n-butyl) phthalate. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2017; 27:601-609. [PMID: 27531370 PMCID: PMC5658674 DOI: 10.1038/jes.2016.48] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/13/2016] [Indexed: 05/05/2023]
Abstract
Six males clad only in shorts were exposed to high levels of airborne di(n-butyl) phthalate (DnBP) and diethyl phthalate (DEP) in chamber experiments conducted in 2014. In two 6 h sessions, the subjects were exposed only dermally while breathing clean air from a hood, and both dermally and via inhalation when exposed without a hood. Full urine samples were taken before, during, and for 48 h after leaving the chamber and measured for key DnBP and DEP metabolites. The data clearly demonstrated high levels of DnBP and DEP metabolite excretions while in the chamber and during the first 24 h once leaving the chamber under both conditions. The data for DnBP were used in a modeling exercise linking dose models for inhalation and transdermal permeation with a simple pharmacokinetic model that predicted timing and mass of metabolite excretions. These models were developed and calibrated independent of these experiments. Tests included modeling of the "hood-on" (transdermal penetration only), "hood-off" (both inhalation and transdermal) scenarios, and a derived "inhalation-only" scenario. Results showed that the linked model tended to duplicate the pattern of excretion with regard to timing of peaks, decline of concentrations over time, and the ratio of DnBP metabolites. However, the transdermal model tended to overpredict penetration of DnBP such that predictions of metabolite excretions were between 1.1 and 4.5 times higher than the cumulative excretion of DnBP metabolites over the 54 h of the simulation. A similar overprediction was not seen for the "inhalation-only" simulations. Possible explanations and model refinements for these overpredictions are discussed. In a demonstration of the linked model designed to characterize general population exposures to typical airborne indoor concentrations of DnBP in the United States, it was estimated that up to one-quarter of total exposures could be due to inhalation and dermal uptake.
Collapse
Affiliation(s)
- Matthew Lorber
- Office of Research and Development, US EPA, Washington, District of Columbia, USA
- Office of Research and Development, US EPA, NCEA (8623N), 1200 Pennsylvania Avenue, NW, Washington, DC 20460, USA. Tel.: 703 347-8535. Fax: 703 347-8690. E-mail:
| | - Charles J Weschler
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, New Jersey, USA
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Glenn Morrison
- Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, Missouri, USA
| | - Gabriel Bekö
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Mengyan Gong
- National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Holger M Koch
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-Universität Bochum (IPA), Bochum, Germany
| | - Tunga Salthammer
- Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI, Braunschweig, Germany
| | - Tobias Schripp
- Department of Material Analysis and Indoor Chemistry, Fraunhofer WKI, Braunschweig, Germany
| | - Jørn Toftum
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Geo Clausen
- International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark
| |
Collapse
|
25
|
Kinetics of the phthalate metabolites mono-2-ethylhexyl phthalate (MEHP) and mono-n-butyl phthalate (MnBP) in male subjects after a single oral dose. Toxicol Lett 2016; 252:22-8. [DOI: 10.1016/j.toxlet.2016.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/30/2016] [Accepted: 04/07/2016] [Indexed: 11/19/2022]
|
26
|
Lin Z, Gehring R, Mochel JP, Lavé T, Riviere JE. Mathematical modeling and simulation in animal health – Part
II
: principles, methods, applications, and value of physiologically based pharmacokinetic modeling in veterinary medicine and food safety assessment. J Vet Pharmacol Ther 2016; 39:421-38. [DOI: 10.1111/jvp.12311] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/21/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Z. Lin
- Institute of Computational Comparative Medicine (ICCM) Department of Anatomy and Physiology College of Veterinary Medicine Kansas State University Manhattan KS USA
| | - R. Gehring
- Institute of Computational Comparative Medicine (ICCM) Department of Anatomy and Physiology College of Veterinary Medicine Kansas State University Manhattan KS USA
| | - J. P. Mochel
- Roche Pharmaceutical Research and Early Development Roche Innovation Center Basel Switzerland
| | - T. Lavé
- Roche Pharmaceutical Research and Early Development Roche Innovation Center Basel Switzerland
| | - J. E. Riviere
- Institute of Computational Comparative Medicine (ICCM) Department of Anatomy and Physiology College of Veterinary Medicine Kansas State University Manhattan KS USA
| |
Collapse
|
27
|
Zhu Y, Wan Y, Li Y, Zhang B, Zhou A, Cai Z, Qian Z, Zhang C, Huo W, Huang K, Hu J, Cheng L, Chang H, Huang Z, Xu B, Xia W, Xu S. Free and total urinary phthalate metabolite concentrations among pregnant women from the Healthy Baby Cohort (HBC), China. ENVIRONMENT INTERNATIONAL 2016; 88:67-73. [PMID: 26722670 DOI: 10.1016/j.envint.2015.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 12/03/2015] [Accepted: 12/04/2015] [Indexed: 05/21/2023]
Abstract
Total urinary phthalate metabolites (the free plus glucuronidated forms) have been frequently measured in the general population. However, data are limited on the free forms which may be more bioactive, especially for sensitive population such as pregnant women. Here the data gap was addressed by measuring concentrations of free and total forms of six phthalate metabolites in 293 urine samples from pregnant women at delivery, who were randomly selected from the prospective Healthy Baby Cohort (HBC), China. We observed detectable concentrations of the total amount of phthalate metabolites in all urine samples. The geometric mean (GM) urinary concentrations of free and total mono-butyl phthalate (MBP) (5.20, 54.49ng/mL) were the highest, followed by mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) (4.52, 7.27ng/mL). For most of phthalate metabolites, urinary concentrations were significantly higher in women who were nulliparous. Significantly higher concentrations of mono-ethyl phthalate (MEP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) were found in women who had higher educational level. To our knowledge, this is the first study to report the free and total forms of phthalate metabolites among pregnant women in China. The results suggest that exposure characteristics may be related to parity and education.
Collapse
Affiliation(s)
- Yingshuang Zhu
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Yanjian Wan
- CDC of Yangtze River Administration and Navigational Affairs, General Hospital of the Yangtze River Shipping, Wuhan 430019, China
| | - Yuanyuan Li
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Bin Zhang
- Women and Children Medical and Healthcare Center of Wuhan, Wuhan, Hubei, People's Republic of China
| | - Aifen Zhou
- Women and Children Medical and Healthcare Center of Wuhan, Wuhan, Hubei, People's Republic of China
| | - Zongwei Cai
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, People's Republic of China
| | - Zhengmin Qian
- Department of Epidemiology, College for Public Health and Social Justice, Saint Louis University, St. Louis, MO, United States
| | - Chuncao Zhang
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Wenqian Huo
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Kai Huang
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Jie Hu
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Lu Cheng
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Huailong Chang
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Zheng Huang
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Bing Xu
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China
| | - Wei Xia
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
| | - Shunqing Xu
- Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
| |
Collapse
|
28
|
Male rats exposed in utero to di(n-butyl) phthalate: Age-related changes in Leydig cell smooth endoplasmic reticulum and testicular testosterone-biosynthesis enzymes/proteins. Reprod Toxicol 2015; 59:139-46. [PMID: 26706031 DOI: 10.1016/j.reprotox.2015.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 11/15/2015] [Accepted: 12/09/2015] [Indexed: 12/31/2022]
Abstract
This study investigated the age-related (i.e., weeks 5, 7, 9, 14 and 17) morphological changes of Leydig cell smooth endoplasmic reticulum (LCs-ER) and testicular testosterone biosynthesis/protein expression in rats in utero exposed to di(n-butyl) phthalate (DBP) (intragastrically; 100mg/kg/day) on days 12-21 post-conception. Ultrastructural observations revealed the LCs-ER of the DBP group were non-dilated until peri-puberty, and thereafter decreased and disappeared. RT-PCR and Western blotting analyses revealed that StAR and P450scc levels in the DBP group were significantly lower at 5 and 7 weeks compared with the vehicle group but became similar during weeks 9-17. Although 3β-HSD, P450c17, and 17β-HSD levels of mRNA and protein in the DBP group were similar to the vehicle control group at 5 and 7 weeks of age, they were significantly lower during weeks 9-17. In utero DBP exposure results in age-related LCs-ER changes corresponding to reduction of testicular testosterone biosynthesis enzymes/associated proteins.
Collapse
|
29
|
Wakui S, Shirai M, Motohashi M, Mutou T, Oyama N, Wempe MF, Takahashi H, Inomata T, Ikegami M, Endou H, Asari M. Effects of in utero exposure to di(n-butyl) phthalate for estrogen receptors α, β, and androgen receptor of Leydig cell on rats. Toxicol Pathol 2014; 42:877-87. [PMID: 24067674 DOI: 10.1177/0192623313502879] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Estrogens and androgens affect male and female reproductive systems. Recently, we reported that prenatal di(n-butyl) phthalate (DBP) exposure induced atypical Leydig cells (LCs) hyperplasia during adulthood. The present study investigated the expression of estrogen receptor α (ERα), estrogen receptor β (ERβ), and androgen receptor (AR) in LCs of 5-, 7-, 9-, 14-, and 17-week-old Sprague-Dawley (srl) rats whose dams had been administered DBP intragastrically at 100 mg/kg/day or the vehicle (corn oil) from days 12 to 21 postconception. Immunohistochemical, Western blotting, and reverse transcription polymerase chain reaction analyses revealed that the expressions of ERα, ERβ, and AR proteins and mRNAs in the DBP group were similar to those of the vehicle group at 5 and 7 weeks, but significantly higher ERα and lower ERβ and AR levels were observed in the DBP group at 9 to 17 weeks. The rats prenatally exposed to DBP had seminiferous tubule degeneration and atypical hyperplasia of LCs during adulthood, which was associated with an increase in expression of ERα and a decrease of ERβ and AR in the testis.
Collapse
Affiliation(s)
- Shin Wakui
- Department of Toxicology, Laboratory Animal Science and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| | - Masaru Shirai
- Department of Toxicology, Laboratory Animal Science and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| | - Masaya Motohashi
- Department of Toxicology, Laboratory Animal Science and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| | | | | | - Michael F Wempe
- School of Pharmacy, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Hiroyuki Takahashi
- Department of Pathology, The Jikei University School of Medicine, Tokyo, Japan
| | - Tomoo Inomata
- Department of Toxicology, Laboratory Animal Science and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| | - Masahiro Ikegami
- Department of Pathology, The Jikei University School of Medicine, Tokyo, Japan
| | | | - Masao Asari
- Department of Toxicology, Laboratory Animal Science and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| |
Collapse
|
30
|
Lin Z, Fisher JW, Wang R, Ross MK, Filipov NM. Estimation of placental and lactational transfer and tissue distribution of atrazine and its main metabolites in rodent dams, fetuses, and neonates with physiologically based pharmacokinetic modeling. Toxicol Appl Pharmacol 2013; 273:140-58. [DOI: 10.1016/j.taap.2013.08.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/07/2013] [Accepted: 08/10/2013] [Indexed: 11/27/2022]
|
31
|
Enke U, Schleussner E, Pälmke C, Seyfarth L, Koch HM. Phthalate exposure in pregnant women and newborns – The urinary metabolite excretion pattern differs distinctly. Int J Hyg Environ Health 2013; 216:735-42. [DOI: 10.1016/j.ijheh.2013.01.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 01/24/2013] [Accepted: 01/27/2013] [Indexed: 01/02/2023]
|
32
|
Balbuena P, Campbell J, Clewell HJ, Clewell RA. Evaluation of a predictive in vitro Leydig cell assay for anti-androgenicity of phthalate esters in the rat. Toxicol In Vitro 2013; 27:1711-8. [DOI: 10.1016/j.tiv.2013.03.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/26/2013] [Accepted: 03/31/2013] [Indexed: 11/28/2022]
|
33
|
Shirai M, Wakui S, Wempe MF, Mutou T, Oyama N, Motohashi M, Takahashi H, Kansaku N, Asari M, Hano H, Endou H. Male Sprague-Dawley rats exposed to in utero di(n-butyl) phthalate: dose dependent and age-related morphological changes in Leydig cell smooth endoplasmic reticulum. Toxicol Pathol 2013; 41:984-91. [PMID: 23416961 DOI: 10.1177/0192623312474725] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
When 100 mg/kg/day of di(n-butyl) phthalate (DBP) was intragastrically administered to pregnant Sprague-Dawley rats throughout gestation days 12 to 21, the male pups had similar body weights with no apparent physical differences (e.g., litter size, sex ratio) compared to that of the vehicle group. However, prominent age-related morphological alterations in the smooth endoplasmic reticulum (sER) of testicular Leydig cells (LCs) were observed once these animals reached puberty. At weeks 5 to 7, the abundant sER with non-dilated cisternae was distributed in LCs. Subsequently, although the number of LCs significantly increased, the amount of sER was significantly decreased at 9 to 14 weeks of age and had disappeared at 17 weeks. In contrast, the number of LCs and the amount of sER in LCs of the lower dose groups (10, 30, and 50 mg/kg/day) were similar to those of the vehicle group. Further, serum testosterone levels in the 100 mg/kg dose group were significantly lower during 5 to 17 weeks of age. While their luteinizing hormone (LH) level was significantly lower at 5 to 7 weeks of age, it became significantly higher during 9 to 17 weeks. The amount of sER in LCs decreased with age with the increase in LCs proliferation and serum LH levels in rat exposed in utero to DBP in a dose-dependent manner.
Collapse
Affiliation(s)
- Masaru Shirai
- 1Department of Toxicology and Veterinary Anatomy, Azabu University School of Veterinary Medicine, Kanagawa, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Plummer SM, Dan D, Quinney J, Hallmark N, Phillips RD, Millar M, Macpherson S, Elcombe CR. Identification of transcription factors and coactivators affected by dibutylphthalate interactions in fetal rat testes. Toxicol Sci 2013; 132:443-57. [PMID: 23358192 DOI: 10.1093/toxsci/kft016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Previous analysis of in utero dibutylphthalate (DBP)-exposed fetal rat testes indicated that DBP's antiandrogenic effects were mediated, in part, by indirect inhibition of steroidogenic factor 1 (SF1), suggesting that peroxisome proliferator-activated receptor alpha (PPARα) might be involved through coactivator (CREB-binding protein [CBP]) sequestration. To test this hypothesis, we have performed chromatin immunoprecipitation (ChIP) microarray analysis to assess the DNA binding of PPARα, SF1, CBP, and RNA polymerase II in DBP-induced testicular maldevelopment target genes. Pathway analysis of expression array data in fetal rat testes examined at gestational day (GD) 15, 17, or 19 indicated that lipid metabolism genes regulated by SF1 and PPARα, respectively, were overrepresented, and the time dependency of changes to PPARα-regulated lipid metabolism genes correlated with DBP-mediated repression of SF1-regulated steroidogenesis genes. ChIP microarrays were used to investigate whether DBP-mediated repression of SF1-regulated genes was associated with changes in SF1 binding to genes involved in DBP-induced testicular maldevelopment. DBP treatment caused reductions in SF1 binding in CYP11a, StAR, and CYP17a. Follicle-stimulating hormone receptor (FSHR), regulated by SF1 but unaffected by DBP-treatment, also contained SF1-binding peaks, but DBP did not change this compared with control. GD15 and GD19 fetal testes contained PPARα protein-binding peaks in CYP11a, StAR, and CYP17a regulatory regions. In contrast to its repressive effect on SF1, DBP treatment caused increases in these peaks compared with control. PPARα-binding peaks in the FSHR promoter were not detected in GD15 samples. Hence, the repressive effect of DBP on SF1-regulated steroidogenic genes correlates with inhibition of SF1-DNA binding and increased PPARα-DNA binding. The data indicate that PPARα may act as an indirect transrepressor of SF1 on steroidogenic genes in fetal rat testes in response to DBP treatment.
Collapse
|
35
|
Clewell RA, Sochaski M, Edwards K, Creasy DM, Willson G, Andersen ME. Disposition of diiosononyl phthalate and its effects on sexual development of the male fetus following repeated dosing in pregnant rats. Reprod Toxicol 2013; 35:56-69. [DOI: 10.1016/j.reprotox.2012.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 06/27/2012] [Accepted: 07/03/2012] [Indexed: 10/28/2022]
|
36
|
Heger NE, Hall SJ, Sandrof MA, McDonnell EV, Hensley JB, McDowell EN, Martin KA, Gaido KW, Johnson KJ, Boekelheide K. Human fetal testis xenografts are resistant to phthalate-induced endocrine disruption. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1137-43. [PMID: 22511013 PMCID: PMC3440087 DOI: 10.1289/ehp.1104711] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 04/17/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND In utero exposure to endocrine-disrupting chemicals may contribute to testicular dysgenesis syndrome (TDS), a proposed constellation of increasingly common male reproductive tract abnormalities (including hypospadias, cryptorchidism, hypospermatogenesis, and testicular cancer). Male rats exposed in utero to certain phthalate plasticizers exhibit multinucleated germ cell (MNG) induction and suppressed steroidogenic gene expression and testosterone production in the fetal testis, causing TDS-consistent effects of hypospadias and cryptorchidism. Mice exposed to phthalates in utero exhibit MNG induction only. This disparity in response demonstrates a species-specific sensitivity to phthalate-induced suppression of fetal Leydig cell steroidogenesis. Importantly, ex vivo phthalate exposure of the fetal testis does not recapitulate the species-specific endocrine disruption, demonstrating the need for a new bioassay to assess the human response to phthalates. OBJECTIVES In this study, we aimed to develop and validate a rat and mouse testis xenograft bioassay of phthalate exposure and examine the human fetal testis response. METHODS Fetal rat, mouse, and human testes were xenografted into immunodeficient rodent hosts, and hosts were gavaged with a range of phthalate doses over multiple days. Xenografts were harvested and assessed for histopathology and steroidogenic end points. RESULTS Consistent with the in utero response, phthalate exposure induced MNG formation in rat and mouse xenografts, but only rats exhibited suppressed steroidogenesis. Across a range of doses, human fetal testis xenografts exhibited MNG induction but were resistant to suppression of steroidogenic gene expression. CONCLUSIONS Phthalate exposure of grafted human fetal testis altered fetal germ cells but did not reduce expression of genes that regulate fetal testosterone biosynthesis.
Collapse
Affiliation(s)
- Nicholas E Heger
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Coecke S, Pelkonen O, Leite SB, Bernauer U, Bessems JG, Bois FY, Gundert-Remy U, Loizou G, Testai E, Zaldívar JM. Toxicokinetics as a key to the integrated toxicity risk assessment based primarily on non-animal approaches. Toxicol In Vitro 2012; 27:1570-7. [PMID: 22771339 DOI: 10.1016/j.tiv.2012.06.012] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 03/09/2012] [Accepted: 06/22/2012] [Indexed: 02/02/2023]
Abstract
Toxicokinetics (TK) is the endpoint that informs about the penetration into and fate within the body of a toxic substance, including the possible emergence of metabolites. Traditionally, the data needed to understand those phenomena have been obtained in vivo. Currently, with a drive towards non-animal testing approaches, TK has been identified as a key element to integrate the results from in silico, in vitro and already available in vivo studies. TK is needed to estimate the range of target organ doses that can be expected from realistic human external exposure scenarios. This information is crucial for determining the dose/concentration range that should be used for in vitro testing. Vice versa, TK is necessary to convert the in vitro results, generated at tissue/cell or sub-cellular level, into dose response or potency information relating to the entire target organism, i.e. the human body (in vitro-in vivo extrapolation, IVIVE). Physiologically based toxicokinetic modelling (PBTK) is currently regarded as the most adequate approach to simulate human TK and extrapolate between in vitro and in vivo contexts. The fact that PBTK models are mechanism-based which allows them to be 'generic' to a certain extent (various extrapolations possible) has been critical for their success so far. The need for high-quality in vitro and in silico data on absorption, distribution, metabolism as well as excretion (ADME) as input for PBTK models to predict human dose-response curves is currently a bottleneck for integrative risk assessment.
Collapse
Affiliation(s)
- Sandra Coecke
- ECVAM, Institute for Health & Consumer Protection, European Commission Joint Research Centre, 21027 Ispra (VA), Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Johnson KJ, Heger NE, Boekelheide K. Of mice and men (and rats): phthalate-induced fetal testis endocrine disruption is species-dependent. Toxicol Sci 2012; 129:235-48. [PMID: 22700540 DOI: 10.1093/toxsci/kfs206] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
For over 15 years, reproductive toxicologists have explored the physiological outcomes and mechanism of fetal phthalate exposure to determine the risk posed to human male reproductive health. This review examines the fetal male reproductive system response to phthalate exposure across species including rat, mouse, and human, with emphasis on the testis. In the rat, in utero phthalate exposure causes male reproductive tract malformations, in large part, by targeting the testis and inhibiting fetal Leydig cell hormone production. Despite mouse phthalate pharmacokinetics being similar to the rat, inhibition of fetal Leydig cell hormone synthesis is not observed in the mouse. The species-specific differences in testicular response following in utero phthalate exposure and the discordant reaction of the rodent fetal testis when exposed to phthalates ex vivo versus in vivo have made determining risk to humans difficult, yet critically important. The recent use of fetal testis xenotransplants to study phthalate toxicity suggests that the human fetal testis responds like the mouse fetal testis; it appears refractory to phthalate-induced inhibition of testosterone production. Although this result is unfulfilling from the perspective of identifying environmental contributions to human reproductive maldevelopment, it has important implications for phthalate risk assessment.
Collapse
Affiliation(s)
- Kamin J Johnson
- Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, Delaware 19803, USA.
| | | | | |
Collapse
|
39
|
Loccisano AE, Campbell JL, Butenhoff JL, Andersen ME, Clewell HJ. Evaluation of placental and lactational pharmacokinetics of PFOA and PFOS in the pregnant, lactating, fetal and neonatal rat using a physiologically based pharmacokinetic model. Reprod Toxicol 2011; 33:468-490. [PMID: 21872655 DOI: 10.1016/j.reprotox.2011.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 06/25/2011] [Accepted: 07/22/2011] [Indexed: 11/24/2022]
Abstract
Perfluoroalkyl carboxylates and sulfonates (PFAAs) have many consumer and industrial applications. Developmental toxicity studies in animals have raised concern about potential developmental effects of PFOA and PFOS in humans. We have developed PBPK models for PFAAs in the rat to help define a relationship between external dose, internal tissue concentrations, and observed adverse effects, and to understand how physiological changes that occur during gestation and lactation affect tissue distribution of PFAAs in the mother, fetus, and neonate. The models developed here expand upon a PBPK model for PFAAs in the adult female rat, and are consistent with available PK data. These models, along with the adult rat PFAA models, published in the companion paper, will help address concerns about possible health effects due to PFAA exposure in the fetus and neonate and will be useful in comparing PK across life stages.
Collapse
Affiliation(s)
- Anne E Loccisano
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, 6 Davis Drive, P.O. Box 12137, Research Triangle Park, NC 27709, United States.
| | - Jerry L Campbell
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, 6 Davis Drive, P.O. Box 12137, Research Triangle Park, NC 27709, United States
| | - John L Butenhoff
- 3M Medical Department, Corporate Toxicology, 3M Center 220-2E-02, St. Paul, MN 55144, United States
| | - Melvin E Andersen
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, 6 Davis Drive, P.O. Box 12137, Research Triangle Park, NC 27709, United States
| | - Harvey J Clewell
- Center for Human Health Assessment, The Hamner Institutes for Health Sciences, 6 Davis Drive, P.O. Box 12137, Research Triangle Park, NC 27709, United States
| |
Collapse
|
40
|
Gentry PR, Clewell HJ, Clewell R, Campbell J, Van Landingham C, Shipp AM. Challenges in the application of quantitative approaches in risk assessment: a case study with di-(2-ethylhexyl)phthalate. Crit Rev Toxicol 2011; 41 Suppl 2:1-72. [DOI: 10.3109/10408444.2011.599366] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
41
|
Aylward LL, Hays SM. Consideration of dosimetry in evaluation of ToxCast™ data. J Appl Toxicol 2011; 31:741-51. [PMID: 21381051 DOI: 10.1002/jat.1626] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/04/2010] [Accepted: 10/11/2010] [Indexed: 12/15/2022]
Abstract
The US Environmental Protection Agency (US EPA) Toxcast™ program has the stated goal of predicting hazard, characterizing toxicity pathways and prioritizing the toxicity testing of environmental chemicals through the use of in vitro high-throughput screening (HTS) assays. This analysis integrates data from biomonitoring and from in vivo toxicity and pharmacokinetic studies to examine the physiological relevance of the tested and responding in vitro concentrations for five case study chemicals: triclosan, 2,4-dichlorophenoxyacetic acid, perfluorooctanoic acid, monobutyl phthalate and mono-2(ethylhexyl)phthalate. This analysis also examines the ToxCast™ phase 1 data set for approximately 50 chemicals belonging to four 'common mechanism groups' which have been the subject of cumulative risk assessments by the US EPA for both the pattern of key responses and the relative potencies of included chemicals compared with the in vivo relative potencies. Responding concentrations in vitro were generally in the range of serum or plasma concentrations associated with no-observed to lowest-observed effect levels for the case study chemicals, while available biomonitoring data demonstrating actual exposures were generally lower. ToxCast™ assay endpoints related to acetylcholinesterase (AChE) inhibition had low sensitivity for detecting organophosphate pesticides but good sensitivity for detecting N-methyl carbamates. However, in vitro relative potencies did not correlate with in vivo potency. Both qualitative and quantitative predictive power is probably affected by the lack of comprehensive metabolic activity in most current in vitro systems explored in the ToxCast™ program, and this remains a fundamental challenge for high-throughput toxicity screening efforts.
Collapse
|
42
|
Pang KS, Durk MR. Physiologically-based pharmacokinetic modeling for absorption, transport, metabolism and excretion. J Pharmacokinet Pharmacodyn 2010; 37:591-615. [PMID: 21153869 DOI: 10.1007/s10928-010-9185-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 11/12/2010] [Indexed: 01/19/2023]
Abstract
The seminal paper on the liver physiologically-based pharmacokinetic (PBPK) model by Rowland et al. (J Pharmacokinet Biopharm 1:123-136, 1973) that described the influence of blood flow, intrinsic clearance, and binding on hepatic clearance had inspired further development of PBPK modeling of the liver, kidney and intestine as well as whole body. Shortly thereafter, a series of papers from Pang and Rowland compared the well-stirred and parallel-tube liver models and sparked further development on clearance concepts in the liver, including those described by the dispersion model. From 2005 onwards, several seminal papers by Rodgers and Rowland, in their recognition of the binding of molecules to tissue acidic and neutral phospholipids, improved the methodology in providing estimates of the tissue-to-plasma coefficient and rendering easy calculation of these hard-to-get constants. The improvement has strongly consolidated the basic premise on PBPK modeling and simulations and these basics have allowed scientists to focus on other important variables: membrane barriers, and transporter and enzyme and their heterogeneities that further impact drug disposition. In particular, the PBPK models have delved into sequential metabolism and futile cycling to illustrate how transporters and enzymes could affect the metabolism of drugs and metabolites. PBPK models that are especially pertinent to metabolite kinetics are being utilized in drug studies and risk assessment. These types of PBPK modeling reveal differences in kinetics between the formed vs. preformed metabolite, showing special considerations for membrane barriers, and the influence of competing pathways and competing organs.
Collapse
Affiliation(s)
- K Sandy Pang
- Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON, M5S 3M2, Canada.
| | | |
Collapse
|
43
|
Clewell RA, Campbell JL, Ross SM, Gaido KW, Clewell HJ, Andersen ME. Assessing the relevance of in vitro measures of phthalate inhibition of steroidogenesis for in vivo response. Toxicol In Vitro 2010; 24:327-34. [DOI: 10.1016/j.tiv.2009.08.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 08/11/2009] [Accepted: 08/13/2009] [Indexed: 10/20/2022]
|
44
|
Struve MF, Gaido KW, Hensley JB, Lehmann KP, Ross SM, Sochaski MA, Willson GA, Dorman DC. Reproductive toxicity and pharmacokinetics of di-n-butyl phthalate (DBP) following dietary exposure of pregnant rats. ACTA ACUST UNITED AC 2009; 86:345-54. [PMID: 19585553 DOI: 10.1002/bdrb.20199] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Most rodent developmental toxicity studies of dibutylphthalate (DBP) have relied on bolus gavage dosing. This study characterized the developmental toxicity of dietary DBP. Pregnant CD rats were given nominal doses of 0, 100, or 500 mg DBP/kg/day in diet (actual intake 0, 112, and 582 mg/kg/day) from gestational day (GD) 12 through the morning of GD 19. Rats were killed 4 or 24 hr thereafter. DBP dietary exposure resulted in significant dose-dependent reductions in testicular mRNA concentration of scavenger receptor class B, member 1; steroidogenic acute regulatory protein; cytochrome P450, family 11, subfamily a, polypeptide 1; and cytochrome P450 family 17, subfamily a, polypeptide 1. These effects were most pronounced 4 hr after the end of exposure. Testicular testosterone was reduced 24 hr post-exposure in both DBP dose groups and 4 hr after termination of the 500-mg DBP/kg/day exposure. Maternal exposure to 500 mg DBP/kg/day induced a significant reduction in male offspring's anogenital distance indicating in utero disruption of androgen function. Leydig cell aggregates, increased cord diameters, and multinucleated gonocytes were present in DBP-treated rats. Monobutyl phthalate, the developmentally toxic metabolite of DBP, and its glucuronide conjugate were found in maternal and fetal plasma, amniotic fluid, and maternal urine. Our results, when compared to previously conducted gavage studies, indicate that approximately equal doses of oral DBP exposure of pregnant rats, from diet or gavage, result in similar responses in male offspring.
Collapse
Affiliation(s)
- Melanie F Struve
- CIIT at The Hamner Institutes for Health Sciences, 6 Davis Drive, P.O. Box 12137, Research Triangle Park, NC 27709-2137, USA
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Aylward LL, Hays SM, Gagné M, Krishnan K. Derivation of Biomonitoring Equivalents for di-n-butyl phthalate (DBP), benzylbutyl phthalate (BzBP), and diethyl phthalate (DEP). Regul Toxicol Pharmacol 2009; 55:259-67. [PMID: 19751787 DOI: 10.1016/j.yrtph.2009.09.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 09/10/2009] [Indexed: 11/19/2022]
Abstract
Recent efforts worldwide have resulted in a growing database of measured concentrations of chemicals in blood and urine samples taken from the general population. However, few tools exist to assist in the interpretation of the measured values in a health risk context. Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline, and are derived by integrating available data on pharmacokinetics with existing chemical risk assessments. This study reviews available health-based exposure guidance values for di-n-butyl phthalate (DBP), benzylbutyl phthalate (BzBP), and diethyl phthalate (DEP) from Health Canada, the United States Environmental Protection Agency (U.S. EPA), the Agency for Toxic Substances and Disease Registry (ATSDR), and the European Food Safety Authority (EFSA). BE values corresponding to the oral reference dose (RfD), minimal risk level (MRL) or tolerable daily intake (TDI) estimates from these agencies were derived for each compound based on data on excretion fractions of key urinary metabolites. These values may be used as screening tools for evaluation of biomonitoring data for metabolites of these three phthalate compounds in the context of existing risk assessments and for prioritization of the potential need for additional risk assessment efforts for each of these compounds relative to other chemicals.
Collapse
|
46
|
Seckin E, Fromme H, Völkel W. Determination of total and free mono-n-butyl phthalate in human urine samples after medication of a di-n-butyl phthalate containing capsule. Toxicol Lett 2009; 188:33-7. [PMID: 19433267 DOI: 10.1016/j.toxlet.2009.03.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 03/03/2009] [Accepted: 03/03/2009] [Indexed: 01/28/2023]
Abstract
Phthalates like di-n-butyl phthalate (DnBP) and diisobutyl phthalate (DiBP) are commonly used as plasticisers, enteric coatings in medications and their metabolites (MnBP respectively MiBP) are suspect of adverse endocrine activities. The aim of this study was to determine kinetical data in humans after the application of a drug containing 3600 microg of DnBP and to quantify main metabolites of DnBP and DiBP with and without glucuronidase treatment. Since commonly glucuronides do not exhibit endocrine activity it is of interest to determine the potentially active metabolite like free MnBP and MiBP for a valid risk assessment. After the application of one capsule containing 3600 microg of DnBP to 17 volunteers 78% (median of 2248 microg of total MnBP) of administered DnBP was found within 24h in urine. After 24h the levels of MnBP in urine were comparable to concentrations before administration showing a fast elimination. In contrast to controls in all urine samples collected within 24h after the administration of the drug free MnBP was observed with a median of 4% of total MnBP. In controls total MnBP and MiBP were found in median concentration of 23 microg/24h and about 50 microg/24h, respectively and therefore environmental exposure to DnBP is only 1% compared to medication. Since an uptake of 3600 microg in only one capsule is already above the tolerable daily intake (TDI) for DnBP of 10 microg/kg b.w. from a preventive health protection DnBP should be replaced in medical drugs.
Collapse
Affiliation(s)
- Elcim Seckin
- Bavarian Health and Food Safety Authority, Environmental Medicine/Biomonitoring, Munich, Germany
| | | | | |
Collapse
|
47
|
Eveillard A, Mselli-Lakhal L, Mogha A, Lasserre F, Polizzi A, Pascussi JM, Guillou H, Martin PGP, Pineau T. Di-(2-ethylhexyl)-phthalate (DEHP) activates the constitutive androstane receptor (CAR): a novel signalling pathway sensitive to phthalates. Biochem Pharmacol 2009; 77:1735-46. [PMID: 19428328 DOI: 10.1016/j.bcp.2009.02.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 02/25/2009] [Accepted: 02/25/2009] [Indexed: 12/27/2022]
Abstract
Di-(2-ethylhexyl)-phthalate (DEHP), a widely used plasticizer, is detected in consumer's body fluids. Contamination occurs through environmental and food chain sources. In mouse liver, DEHP activates the peroxisome proliferator-activated receptor alpha (PPARalpha) and regulates the expression of its target genes. Several in vitro investigations support the simultaneous recruitment of additional nuclear receptor pathways. We investigated, in vivo, the hepatic impact of low doses of DEHP on PPARalpha activation, and the putative activation of additional signalling pathways. Wild-type and PPARalpha-deficient mice were exposed to different doses of DEHP. Gene expression profiling delineated the role of PPARalpha and revealed a PPARalpha-independent regulation of several prototypic constitutive androstane receptor (CAR) target genes. Thus, we developed an original hepatic cell line expressing CAR to investigate its activation by DEHP. By means of a pharmacological inhibitor or CAR-targeting shRNAs, we established that CAR is required for the effect of DEHP on Cyp2b10, a recognized CAR target gene. Moreover, DEHP dose-dependently induced CYP2B6 in human primary hepatocyte cultures. This finding demonstrates that CAR also represents a transcriptional regulator sensitive to phthalates. CAR-mediated effects of DEHP provide a new rationale for most endpoints of phthalates toxicity described previously, including endocrine disruption, hepatocarcinogenesis and the metabolic syndrome.
Collapse
Affiliation(s)
- Alexandre Eveillard
- Laboratoire de Pharmacologie et Toxicologie, Institut National de la Recherche Agronomique, INRA UR66, Toulouse, France
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Benson R. Hazard to the developing male reproductive system from cumulative exposure to phthalate esters—dibutyl phthalate, diisobutyl phthalate, butylbenzyl phthalate, diethylhexyl phthalate, dipentyl phthalate, and diisononyl phthalate. Regul Toxicol Pharmacol 2009; 53:90-101. [DOI: 10.1016/j.yrtph.2008.11.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 11/07/2008] [Accepted: 11/27/2008] [Indexed: 10/21/2022]
|
49
|
Sun H, Pang KS. Disparity in Intestine Disposition between Formed and Preformed Metabolites and Implications: A Theoretical Study. Drug Metab Dispos 2008; 37:187-202. [DOI: 10.1124/dmd.108.022483] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
|
50
|
Pang KS. Safety testing of metabolites: Expectations and outcomes. Chem Biol Interact 2008; 179:45-59. [PMID: 18926805 DOI: 10.1016/j.cbi.2008.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 09/12/2008] [Accepted: 09/15/2008] [Indexed: 12/18/2022]
Abstract
Metabolites arising from chemical entities, old or new, are often mediators of toxicity. Frequently, metabolites are investigated in test animals, with the expectation that the resultant toxicity or activity will mimic the exposure of their formed counterparts. This communication described observations that showed discrepant kinetics between formed and preformed metabolites in the liver, intestine, and kidney, major drug removal organs. Differences in the observed areas under the curve (AUCs) or the extraction ratios (Es) of formed and preformed metabolites in the liver had been attributed to zonal, enzyme heterogeneity, membrane barriers, or transporters. Preformed and formed metabolite also differed in their handling by the kidney; only the preformed and not the formed metabolite would be filtered. In the intestine, differences in the absorption of the precursor and the metabolite and the flow pattern in the intestine would bring about discrepancy in the time-courses of the formed vs. preformed metabolites. Analytical solutions of the AUCs of the metabolites and extraction ratios, based on physiological modeling of the liver, kidney, and intestine, showed that the AUC of the preformed, administered metabolite was dependent only on metabolite parameters, whereas the AUC of the formed metabolite was modulated additionally by the metabolic, secretory and intestinal absorptive intrinsic clearances of the precursor drug. Hence, administration of the synthetic metabolite would not reflect the toxicity associated with the metabolite formed via bioactivation. However, data on preformed metabolite may be used for simultaneous fitting by a combined model of drug and metabolite. Such a strategy is shown to be successful in risk assessment of environmental chemicals. Upon refinement of the resultant model with data on metabolite transport and handling by modeling and simulations, the resultant model would be more robust to provide improved predictions on metabolite toxicity pursuant to drug administration.
Collapse
|