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Andres KL, Olsen GW, Krisko RM, Nunnally MC, Boeding RR, Leniek KL, Taiwo OA. An investigation of 3M Cordova, IL production worker's per- and polyfluoroalkyl substances biomonitoring results and mortality experience. Int J Hyg Environ Health 2024; 256:114321. [PMID: 38244249 DOI: 10.1016/j.ijheh.2024.114321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 01/22/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a wide-ranging group of chemicals that have been used in a variety of polymer and surfactant applications. While 3M Cordova, Illinois was not one of 3M's primary manufacturing facilities for the legacy long-chain PFAS (PFOS, PFOA, PFHxS), it has been a major manufacturing site for short-chain PFAS (compounds that are or may degrade to PFBS or PFBA). The purpose of this research focused on: 1) an analysis of biomonitoring data of employees and retirees, and 2) an analysis of the cohort mortality of workers from 1970 to 2018. Employees had higher PFBS and PFBA serum concentrations than the retirees, while retirees had higher concentrations for PFOS, PFOA, and PFHxS. Compared to the 2017-2018 NHANES data, employees' PFOS and PFHxS concentrations in 2022 were two-fold higher, with PFOA levels comparable. These NHANES data did not include serum PFBS or PFBA. Cross-sectional trends of PFOS and PFOA levels from 1997 to 2022 showed PFOS declined from 151 ng/mL to 10.4 ng/mL. Similarly, PFOA decreased from 100 ng/mL to 1.5 ng/mL. A longitudinal analysis of 48 participants with measurements in both 2006 and 2022 showed concentrations decreased by 74% for PFOS and 90% for PFOA. In the mortality study, 1707 employees who worked 1 day or longer were followed for an average of 25.6 years and had 143 (8%) deaths. There were no significantly elevated risks for any specific cause of death, regardless of latency period (0 or 15 years). While no specific PFAS exposures were examined, worker mortality experience (1970-2018) was analyzed by major departments representing primary work areas. Employees and retirees at the Cordova facility continue to have elevated PFOS and PFHxS serum concentrations compared to the general population, however, their legacy PFAS concentrations have declined over time, consistent with the estimated serum elimination half-lives of these PFAS in humans assuming nominal ambient exposures. For PFBS and PFBA, the results indicated no long-term accumulation in the blood likely due to their short serum elimination half-lives. After nearly 50 years of follow-up, this Cordova workforce showed no increased risk of mortality from cancer or any other specific cause of death.
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Affiliation(s)
- Kara L Andres
- 3M Company, Corporate Occupational Medicine, St. Paul, MN, 55144, United States.
| | - Geary W Olsen
- 3M Company, Corporate Occupational Medicine, St. Paul, MN, 55144, United States.
| | - Ryan M Krisko
- 3M Company, Environment, Health, Safety and Product Stewardship, St. Paul, MN, 55144, United States.
| | - Matthew C Nunnally
- 3M Cordova, Environment, Health & Safety Area Chemical Operations, Cordova, IL, 61242, United States.
| | - Rebecca R Boeding
- 3M Cordova, Corporate Occupational Medicine, Cordova, IL, 61242, United States.
| | - Karyn L Leniek
- 3M Company, Corporate Occupational Medicine, St. Paul, MN, 55144, United States.
| | - Oyebode A Taiwo
- 3M Company, Corporate Occupational Medicine, St. Paul, MN, 55144, United States.
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Yao J, Dong Z, Jiang L, Pan Y, Zhao M, Bai X, Dai J. Emerging and Legacy Perfluoroalkyl Substances in Breastfed Chinese Infants: Renal Clearance, Body Burden, and Implications. ENVIRONMENTAL HEALTH PERSPECTIVES 2023; 131:37003. [PMID: 36862174 PMCID: PMC9980344 DOI: 10.1289/ehp11403] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 12/12/2022] [Accepted: 01/18/2023] [Indexed: 05/19/2023]
Abstract
BACKGROUND Human breast milk is a primary route of exposure to perfluoroalkyl substances (PFAS) in infants. To understand the associated risks, the occurrence of PFAS in human milk and the toxicokinetics of PFAS in infants need to be addressed. OBJECTIVES We determined levels of emerging and legacy PFAS in human milk and urine samples from Chinese breastfed infants, estimated renal clearance, and predicted infant serum PFAS levels. METHODS In total, human milk samples were collected from 1,151 lactating mothers in 21 cities in China. In addition, 80 paired infant cord blood and urine samples were obtained from two cities. Nine emerging PFAS and 13 legacy PFAS were analyzed in the samples using ultra high-performance liquid chromatography tandem mass spectrometry. Renal clearance rates (CLrenals) of PFAS were estimated in the paired samples. PFAS serum concentrations in infants (<1 year of age) were predicted using a first-order pharmacokinetic model. RESULTS All nine emerging PFAS were detected in human milk, with the detection rates of 6:2 Cl-PFESA, PFMOAA, and PFO5DoDA all exceeding 70%. The level of 6:2 Cl-PFESA in human milk (median concentration=13.6 ng/L) ranked third after PFOA (336 ng/L) and PFOS (49.7 ng/L). The estimated daily intake (EDI) values of PFOA and PFOS exceeded the reference dose (RfD) of 20 ng/kg BW per day recommended by the U.S. Environmental Protection Agency in 78% and 17% of breastfed infant samples, respectively. 6:2 Cl-PFESA had the lowest infant CLrenal (0.009mL/kg BW per day), corresponding to the longest estimated half-life of 49 y. The average half-lives of PFMOAA, PFO2HxA, and PFO3OA were 0.221, 0.075, and 0.304 y, respectively. The CLrenals of PFOA, PFNA, and PFDA were slower in infants than in adults. CONCLUSIONS Our results demonstrate the widespread occurrence of emerging PFAS in human milk in China. The relatively high EDIs and half-lives of emerging PFAS suggest potential health risks of postnatal exposure in newborns. https://doi.org/10.1289/EHP11403.
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Affiliation(s)
- Jingzhi Yao
- State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Zhaomin Dong
- School of Space and Environment and Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University, Beijing, China
| | - Lulin Jiang
- State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yitao Pan
- State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Meirong Zhao
- College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Xiaoxia Bai
- Department of Obstetrics, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jiayin Dai
- State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
- State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
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Chou WC, Lin Z. Machine learning and artificial intelligence in physiologically based pharmacokinetic modeling. Toxicol Sci 2023; 191:1-14. [PMID: 36156156 PMCID: PMC9887681 DOI: 10.1093/toxsci/kfac101] [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] [Indexed: 02/03/2023] Open
Abstract
Physiologically based pharmacokinetic (PBPK) models are useful tools in drug development and risk assessment of environmental chemicals. PBPK model development requires the collection of species-specific physiological, and chemical-specific absorption, distribution, metabolism, and excretion (ADME) parameters, which can be a time-consuming and expensive process. This raises a need to create computational models capable of predicting input parameter values for PBPK models, especially for new compounds. In this review, we summarize an emerging paradigm for integrating PBPK modeling with machine learning (ML) or artificial intelligence (AI)-based computational methods. This paradigm includes 3 steps (1) obtain time-concentration PK data and/or ADME parameters from publicly available databases, (2) develop ML/AI-based approaches to predict ADME parameters, and (3) incorporate the ML/AI models into PBPK models to predict PK summary statistics (eg, area under the curve and maximum plasma concentration). We also discuss a neural network architecture "neural ordinary differential equation (Neural-ODE)" that is capable of providing better predictive capabilities than other ML methods when used to directly predict time-series PK profiles. In order to support applications of ML/AI methods for PBPK model development, several challenges should be addressed (1) as more data become available, it is important to expand the training set by including the structural diversity of compounds to improve the prediction accuracy of ML/AI models; (2) due to the black box nature of many ML models, lack of sufficient interpretability is a limitation; (3) Neural-ODE has great potential to be used to generate time-series PK profiles for new compounds with limited ADME information, but its application remains to be explored. Despite existing challenges, ML/AI approaches will continue to facilitate the efficient development of robust PBPK models for a large number of chemicals.
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Affiliation(s)
- Wei-Chun Chou
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL 32610, USA
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32608, USA
| | - Zhoumeng Lin
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL 32610, USA
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32608, USA
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Moriceau MA, Cano-Sancho G, Kim M, Coumoul X, Emond C, Arrebola JP, Antignac JP, Audouze K, Rousselle C. Partitioning of Persistent Organic Pollutants between Adipose Tissue and Serum in Human Studies. TOXICS 2022; 11:toxics11010041. [PMID: 36668767 PMCID: PMC9866963 DOI: 10.3390/toxics11010041] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/23/2022] [Accepted: 12/27/2022] [Indexed: 06/01/2023]
Abstract
Blood is the most widely used matrix for biomonitoring of persistent organic pollutants (POPs). It is assumed that POPs are homogenously distributed within body lipids at steady state; however, the variability underlying the partitioning of POPs between fat compartments is poorly understood. Hence, the objective of this study was to review the state of the science about the relationships of POPs between adipose tissue and serum in humans. We conducted a narrative literature review of human observational studies reporting concentrations of POPs in paired samples of adipose tissue with other lipid-based compartments (e.g., serum lipids). The searches were conducted in SCOPUS and PUBMED. A meta-regression was performed to identify factors responsible for variability. All included studies reported high variability in the partition coefficients of POPs, mainly between adipose tissue and serum. The number of halogen atoms was the physicochemical variable most strongly and positively associated with the partition ratios, whereas body mass index was the main biological factor positively and significantly associated. To conclude, although this study provides a better understanding of partitioning of POPs to refine physiologically based pharmacokinetic and epidemiological models, further research is still needed to determine other key factors involved in the partitioning of POPs.
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Affiliation(s)
| | | | - MinJi Kim
- INSERM UMR-S 1124, Université Paris Sorbonne Nord, 93017 Bobigny, France
| | - Xavier Coumoul
- INSERM UMR-S 1124, Université Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France
| | - Claude Emond
- School of Public Health, Department of Environmental and Occupational Health, University of Montreal, Montreal, QC H3C 3J7, Canada
| | - Juan-Pedro Arrebola
- Department of Preventive Medicine and Public Health, Universidad de Granada, Campus de Cartuja s/n, 18071 Granada, Spain
- Instituto de Investigación Biosanitaria (ibs.GRANADA), Avda. de Madrid, 15. Pabellón de Consultas Externas 2, 2a Planta, 18012 Granada, Spain
- Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | | | - Karine Audouze
- INSERM UMR-S 1124, Université Paris Cité, 45 rue des Saints-Pères, 75006 Paris, France
| | - Christophe Rousselle
- ANSES, European and International Affairs Department, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort, France
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Preston EV, Hivert MF, Fleisch AF, Calafat AM, Sagiv SK, Perng W, Rifas-Shiman SL, Chavarro JE, Oken E, Zota AR, James-Todd T. Early-pregnancy plasma per- and polyfluoroalkyl substance (PFAS) concentrations and hypertensive disorders of pregnancy in the Project Viva cohort. ENVIRONMENT INTERNATIONAL 2022; 165:107335. [PMID: 35696844 PMCID: PMC9348856 DOI: 10.1016/j.envint.2022.107335] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/25/2022] [Accepted: 06/01/2022] [Indexed: 05/22/2023]
Abstract
BACKGROUND Hypertensive disorders of pregnancy (HDP), defined here as hypertensive disorders with onset in pregnancy (i.e., gestational hypertension, preeclampsia, and preeclampsia superimposed on chronic hypertension), affect up to 10% of pregnancies in the United States and are associated with substantial maternal and neonatal morbidity and mortality. Per- and polyfluoroalkyl substances (PFAS) are associated with adverse cardiometabolic outcomes during pregnancy, but associations between PFAS and HDP are inconsistent and joint effects of PFAS mixtures have not been evaluated. METHODS We studied 1,558 pregnant individuals from the Project Viva cohort, recruited during 1999-2002. We quantified concentrations of eight PFAS in plasma samples (median 9.7 weeks of gestation). Using clinical records, we calculated trimester-specific mean systolic (SBP) and diastolic (DBP) blood pressure and categorized HDP status [no HDP (normotensive & chronic hypertension), gestational hypertension, preeclampsia]. We estimated associations of individual PFAS with HDP using multinomial logistic regression and estimated associations with blood pressure using linear regression. We used Bayesian kernel machine regression (BKMR) and quantile g-computation to assess joint effects of the PFAS mixture on HDP and blood pressure measures. RESULTS Four percent of participants developed preeclampsia and 7% developed gestational hypertension. We observed higher odds of gestational hypertension, but not preeclampsia, per doubling of perfluorooctanoate (PFOA) [OR = 1.51 (95% confidence interval: 1.12, 2.03)], perfluorooctane sulfonate (PFOS) [OR = 1.38 (1.04, 1.82)], and perfluorohexane sulfonate [OR = 1.28 (1.06, 1.54)] concentrations. We observed higher mean DBP per doubling of PFOA [2nd trimester (T2): 0.39 mmHg (-0.01, 0.78); 3rd trimester (T3): 0.56 mmHg (0.14, 0.98)] and PFOS [T2: 0.46 mmHg (0.11, 0.82); T3: 0.43 mmHg (0.05, 0.80)]. The PFAS mixture was positively associated with odds of gestational hypertension [75th vs. 50th percentile: OR = 1.14 (95% credible interval:1.03, 1.25), BKMR] and mean DBP [T2 = 0.17 mmHg (-0.06, 0.40); T3 = 0.22 mmHg (-0.03, 0.48), BKMR]. CONCLUSIONS These findings suggest that exposure to certain PFAS may increase the odds of gestational hypertension during pregnancy, with potential implications for subsequent maternal and child health outcomes.
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Affiliation(s)
- Emma V Preston
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, United States.
| | - Marie-France Hivert
- Division of Chronic Disease Research Across the Lifecourse, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, United States; Diabetes Unit, Massachusetts General Hospital, Boston, MA, United States.
| | - Abby F Fleisch
- Center for Outcomes Research and Evaluation, Maine Medical Center Research Institute, Portland, ME, United States; Pediatric Endocrinology and Diabetes, Maine Medical Center, Portland, ME, United States.
| | - Antonia M Calafat
- National Center for Environmental Health, U.S. Centers for Disease Control and Prevention, Atlanta, GA, United States.
| | - Sharon K Sagiv
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California at Berkeley, Berkeley, CA, United States.
| | - Wei Perng
- Department of Epidemiology and the Lifecourse Epidemiology of Adiposity and Diabetes (LEAD) Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
| | - Sheryl L Rifas-Shiman
- Division of Chronic Disease Research Across the Lifecourse, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, United States.
| | - Jorge E Chavarro
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, United States; Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, United States; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States.
| | - 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, United States.
| | - Ami R Zota
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, United States.
| | - Tamarra James-Todd
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA, United States; Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, United States.
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Ducatman A, LaPier J, Fuoco R, DeWitt JC. Official health communications are failing PFAS-contaminated communities. Environ Health 2022; 21:51. [PMID: 35538533 PMCID: PMC9092686 DOI: 10.1186/s12940-022-00857-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/12/2022] [Indexed: 01/09/2023]
Abstract
BACKGROUND Environmental health agencies are critical sources of information for communities affected by chemical contamination. Impacted residents and their healthcare providers often turn to federal and state agency webpages, fact sheets, and other documents to weigh exposure risks and interventions. MAIN BODY This commentary briefly reviews scientific evidence concerning per- and polyfluoroalkyl substances (PFAS) for health outcomes that concern members of affected communities and that have compelling or substantial yet differing degree of scientific evidence. It then features official documents in their own language to illustrate communication gaps, as well as divergence from scientific evidence and from best health communication practice. We found official health communications mostly do not distinguish between the needs of heavily contaminated communities characterized by high body burdens and the larger population with ubiquitous but substantially smaller exposures. Most health communications do not distinguish levels of evidence for health outcomes and overemphasize uncertainty, dismissing legitimate reasons for concern in affected communities. Critically, few emphasize helpful approaches to interventions. We also provide examples that can be templates for improvement. CONCLUSIONS Immediate action should be undertaken to review and improve official health communications intended to inform the public and health providers about the risks of PFAS exposure and guide community and medical decisions.
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Affiliation(s)
- Alan Ducatman
- School of Public Health, West Virginia University, Morgantown, WV, USA.
| | - Jonas LaPier
- Green Science Policy Institute, Berkeley, CA, USA
| | | | - Jamie C DeWitt
- Brody School of Medicine, East Carolina University, Greenville, NC, USA
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Physiologically based pharmacokinetic (PBPK) modeling of perfluorohexane sulfonate (PFHxS) in humans. Regul Toxicol Pharmacol 2021; 129:105099. [PMID: 34933042 DOI: 10.1016/j.yrtph.2021.105099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/11/2021] [Accepted: 12/15/2021] [Indexed: 01/09/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent, man-made compounds prevalent in the environment and consistently identified in human biomonitoring samples. In particular, perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) have been identified at U.S. Air Force installations. The study of human toxicokinetics and physiologically based pharmacokinetic (PBPK) modeling of PFHxS has been less robust and has been limited in scope and application as compared to PFOS and PFOA. The primary goal of the current effort was to develop a PBPK model describing PFHxS disposition in humans that can be applied to retrospective, current, and future human health risk assessment of PFHxS. An existing model developed for PFOS and PFOA was modified and key parameter values for exposure and toxicokinetics were calibrated for PFHxS prediction based on human biomonitoring data, particularly general population serum levels from the U.S. Centers for Disease Prevention and Control (CDC) National Health and Nutrition Examination Survey (NHANES). Agreement between the model and the calibration and evaluation data was excellent and recapitulated observed trends across sex, age, and calendar years. Confidence in the model is greatest for application to adults in the 2000-2018 time frame and for shorter-term future projections.
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Borgert CJ, Fuentes C, Burgoon LD. Principles of dose-setting in toxicology studies: the importance of kinetics for ensuring human safety. Arch Toxicol 2021; 95:3651-3664. [PMID: 34623454 PMCID: PMC8536606 DOI: 10.1007/s00204-021-03155-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 09/02/2021] [Indexed: 01/11/2023]
Abstract
Regulatory toxicology seeks to ensure that exposures to chemicals encountered in the environment, in the workplace, or in products pose no significant hazards and produce no harm to humans or other organisms, i.e., that chemicals are used safely. The most practical and direct means of ensuring that hazards and harms are avoided is to identify the doses and conditions under which chemical toxicity does not occur so that chemical concentrations and exposures can be appropriately limited. Modern advancements in pharmacology and toxicology have revealed that the rates and mechanisms by which organisms absorb, distribute, metabolize and eliminate chemicals-i.e., the field of kinetics-often determine the doses and conditions under which hazard, and harm, are absent, i.e., the safe dose range. Since kinetics, like chemical hazard and toxicity, are extensive properties that depend on the amount of the chemical encountered, it is possible to identify the maximum dose under which organisms can efficiently metabolize and eliminate the chemicals to which they are exposed, a dose that has been referred to as the kinetic maximum dose, or KMD. This review explains the rationale that compels regulatory toxicology to embrace the advancements made possible by kinetics, why understanding the kinetic relationship between the blood level produced and the administered dose of a chemical is essential for identifying the safe dose range, and why dose-setting in regulatory toxicology studies should be informed by estimates of the KMD rather than rely on the flawed concept of maximum-tolerated toxic dose, or MTD.
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Affiliation(s)
- C J Borgert
- Applied Pharmacology and Toxicology, Inc., Gainesville, FL, USA.
- Center for Environmental and Human Toxicology (CEHT), Department of Physiological Sciences, University of Florida College of Veterinary Medicine, Gainesville, FL, USA.
| | - C Fuentes
- Department of Statistics, Oregon State University, Corvallis, OR, USA
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