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Fujiwara N, Yamashita S, Okamoto M, Cooley MA, Ozaki K, Everett ET, Suzuki M. Perfluorooctanoic acid-induced cell death via the dual roles of ROS-MAPK/ERK signaling in ameloblast-lineage cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 260:115089. [PMID: 37271104 DOI: 10.1016/j.ecoenv.2023.115089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/27/2023] [Accepted: 05/29/2023] [Indexed: 06/06/2023]
Abstract
Perfluorooctanoic acid (PFOA) is an artificial fluorinated organic compound that has generated increased public attention due to its potential health hazards. Unsafe levels of PFOA exposure can affect reproduction, growth and development. During tooth enamel development (amelogenesis), environmental factors including fluoride can cause enamel hypoplasia. However, the effects of PFOA on ameloblasts and tooth enamel formation remain largely unknown. In the present study we demonstrate several PFOA-mediated cell death pathways (necrosis/necroptosis, and apoptosis) and assess the roles of ROS-MAPK/ERK signaling in PFOA-mediated cell death in mouse ameloblast-lineage cells (ALC). ALC cells were treated with PFOA. Cell proliferation and viability were analyzed by MTT assays and colony formation assays, respectively. PFOA suppressed cell proliferation and viability in a dose dependent manner. PFOA induced both necrosis (PI-positive cells) and apoptosis (cleaved-caspase-3, γH2AX and TUNEL-positive cells). PFOA significantly increased ROS production and up-regulated phosphor-(p)-ERK. Addition of ROS inhibitor N-acetyl cysteine (NAC) suppressed p-ERK and decreased necrosis, and increased cell viability compared to PFOA alone, whereas NAC did not change apoptosis. This suggests that PFOA-mediated necrosis was induced by ROS-MAPK/ERK signaling, but apoptosis was not associated with ROS. Addition of MAPK/ERK inhibitor PD98059 suppressed necrosis and increased cell viability compared to PFOA alone. Intriguingly, PD98059 augmented PFOA-mediated apoptosis. This suggests that p-ERK promoted necrosis but suppressed apoptosis. Addition of the necroptosis inhibitor Necrostatin-1 restored cell viability compared to PFOA alone, while pan-caspase inhibitor Z-VAD did not mitigate PFOA-mediated cell death. These results suggest that 1) PFOA-mediated cell death was mainly caused by necrosis/necroptosis by ROS-MAPK/ERK signaling rather than apoptosis, 2) MAPK/ERK signaling plays the dual roles (promoting necrosis and suppressing apoptosis) under PFOA treatment. This is the initial report to indicate that PFOA could be considered as a possible causative factor for cryptogenic enamel malformation. Further studies are required to elucidate the mechanisms of PFOA-mediated adverse effects on amelogenesis.
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Affiliation(s)
- Natsumi Fujiwara
- Department of Oral Health Promotion, Tokushima University Graduate School of Biomedical Sciences, 3-18-15 Kuramoto, Tokushima 770-8504, Japan
| | - Shohei Yamashita
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Motoki Okamoto
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Marion A Cooley
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Kazumi Ozaki
- Department of Oral Health Promotion, Tokushima University Graduate School of Biomedical Sciences, 3-18-15 Kuramoto, Tokushima 770-8504, Japan
| | - Eric T Everett
- Division of Oral and Craniofacial Health Sciences, Adams School of Dentistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Maiko Suzuki
- Department of Oral Science and Translational Research, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA.
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Xia Y, Hao L, Li Y, Li Y, Chen J, Li L, Han X, Liu Y, Wang X, Li D. Embryonic 6:2 FTOH exposure causes reproductive toxicity by disrupting the formation of the blood-testis barrier in offspring mice. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 250:114497. [PMID: 36608565 DOI: 10.1016/j.ecoenv.2023.114497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/31/2022] [Accepted: 01/01/2023] [Indexed: 06/17/2023]
Abstract
Previous studies have revealed nephrotoxicity, hepatotoxicity, subchronic developmental and reproductive toxicity in rats exposed to fluorotelomer alcohol (FTOH). However, the effects of embryonic 6:2 FTOH exposure on the reproductive system of offspring mice remain unclear. The purpose of this study is to explore the reproductive toxic effects of embryonic 6:2 FTOH exposure on offspring male mice and the related molecular mechanisms. Therefore, the pregnant mice were given corn oil or 6:2 FTOH by gavage from gestational days 12.5-21.5. The results demonstrated that embryonic 6:2 FTOH exposure resulted in disrupted testicular structure, low expression of tight junction protein between Sertoli cells (SCs), impaired blood-testis barrier (BTB) formation and maturation, reduced sperm viability and increased malformation, and induced testicular inflammation in the offspring of mice. Further in vitro studies showed that 6:2 FTOH treatment upregulated MMP-8 expression by activating AKT/NF-κB signaling pathway, which in turn enhanced occludin cleavage leading to the disruption of SCs barrier integrity. In summary, this study demonstrated that 6:2 FTOH exposure caused reproductive dysfunction in male offspring through disruption of BTB, which provided new insights into the effects of 6:2 FTOH exposure on the offspring.
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Affiliation(s)
- Yunhui Xia
- 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
| | - Lanxiang Hao
- Endocrinology Department, Yancheng First Hospital, Affiliated Hospital of Nanjing University Medical School; The First people's Hospital of Yancheng, Yancheng, Jiangsu 224001, China
| | - Yueyang Li
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, China
| | - Yifan Li
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
| | - Junhan Chen
- 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
| | - Lei Li
- Endocrinology Department, Yancheng First Hospital, Affiliated Hospital of Nanjing University Medical School; The First people's Hospital of Yancheng, Yancheng, Jiangsu 224001, 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
| | - Yanmei Liu
- Endocrinology Department, Yancheng First Hospital, Affiliated Hospital of Nanjing University Medical School; The First people's Hospital of Yancheng, Yancheng, Jiangsu 224001, China.
| | - Xiaojian Wang
- Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, 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.
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3
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Daramola O, Rand AA. Emerging investigator series: human CYP2A6 catalyzes the oxidation of 6:2 fluorotelomer alcohol. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1688-1695. [PMID: 34734218 DOI: 10.1039/d1em00307k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The biotransformation of 6:2 fluorotelomer alcohol (6:2 FTOH) results in the production of bioactive and persistent metabolites, including perfluorinated carboxylic acids (PFCAs). While the products of 6:2 FTOH metabolism have been elucidated in several animal models, the responsible cytochrome P450 (CYP) isoform(s) have not been reported. Here, we characterized the in vitro oxidation of 6:2 FTOH using human liver microsomes and recombinant human CYPs. Six major xenobiotic metabolizing CYPs were screened for their capacity to catalyze 6:2 FTOH oxidation using chemical inhibitors selective towards CYP isoforms. Of the CYP isoforms investigated, CYP2A6 was the only enzyme capable of catalyzing 6:2 FTOH in human liver microsomes, with KM and Vmax values of 4076 ng mL-1 and 69 ng mL-1 min-1, respectively. We further probed the metabolic mechanism by plotting the 6:2 FTOH kinetic profile and extrapolating data to several possible kinetic models. 6:2 FTOH oxidation followed the typical one-site Michaelis-Menten kinetic model. This study also reports that 6:2 FTOH loss is associated with active CYP2A6 by incubating microsomes with the selective CYP2A6 inhibitor tranylcypromine, which bound competitively to the enzyme as determined by an increased KM (8796 ng mL-1) but unchanged Vmax value. Collectively, these findings provide a mechanistic perspective on the potential importance of CYP2A6 in the metabolic activation and phase I elimination of 6:2 FTOH and indirect human exposure to PFCAs.
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Affiliation(s)
- Oluwadamilola Daramola
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Amy A Rand
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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Goodrum PE, Anderson JK, Luz AL, Ansell GK. Application of a Framework for Grouping and Mixtures Toxicity Assessment of PFAS: A Closer Examination of Dose-Additivity Approaches. Toxicol Sci 2021; 179:262-278. [PMID: 32735321 PMCID: PMC7846094 DOI: 10.1093/toxsci/kfaa123] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Environmental occurrence and biomonitoring data for per- and polyfluoroalkyl substances (PFAS) demonstrate that humans are exposed to mixtures of PFAS. This article presents a new and systematic analysis of available PFAS toxicity study data using a tiered mixtures risk assessment framework consistent with United States and international mixtures guidance. The lines of evidence presented herein include a critique of whole mixture toxicity studies and analysis of dose-response models based on data from subchronic oral toxicity studies in rats. Based on available data to-date, concentration addition and relative potency factor methods are found to be inappropriate due to differences among sensitive effects and target organ potencies and noncongruent dose-response curves for the same effect endpoints from studies using the same species and protocols. Perfluorooctanoic acid and perfluorooctane sulfonic acid lack a single mode of action or molecular initiating event and our evaluation herein shows they also have noncongruent dose-response curves. Dose-response curves for long-chain perfluoroalkyl sulfonic acids (PFSAs) also significantly differ in shapes of the curves from short-chain PFSAs and perfluoroalkyl carboxylic acids evaluated, and additional differences are apparent when curves are evaluated based on internal or administered dose. Following well-established guidance, the hazard index method applied to perfluoroalkyl carboxylic acids and PFSAs grouped separately is the most appropriate approach for conducting a screening level risk assessment for nonpolymeric PFAS mixtures, given the current state-of-the science. A clear presentation of assumptions, uncertainties, and data gaps is needed before dose-additivity methods, including hazard index , are used to support risk management decisions. Adverse outcome pathway(s) and mode(s) of action information for perfluorooctanoic acid and perfluorooctane sulfonic acid and for other nonpolymer PFAS are key data gaps precluding more robust mixtures methods. These findings can guide the prioritization of future studies on single chemical and whole mixture toxicity studies.
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Degradation and effect of 6:2 fluorotelomer alcohol in aerobic composting of sludge. Biodegradation 2021; 32:99-112. [PMID: 33481147 DOI: 10.1007/s10532-020-09924-9] [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: 08/26/2020] [Accepted: 12/22/2020] [Indexed: 10/22/2022]
Abstract
Perfluoroalkyl carboxylates (PFCAs) is toxic to the environment and human health. However, the degradation characteristics of fluorotelomer alcohols (FTOHs), precursors of PFACAs biodegradation, in the sludge during aerobic composting remain unclear. In this study, the degradation characteristics of 6:2 FTOH in sewage sludge by composting were researched and the influences of 6:2 FTOH on the composting process and microbial communities of the sludge were evaluated. After 52 days of composting, 6:2 FTOH retained only 0.73% of its original concentration, and its half-life was less than 1 d; 6:2 FTOH was degraded finally to perfluorohex unsaturated acid, perfluoropentanoic acid, 5:3 polyfluorinated acid (FTCA), 4:3 FTCA, and perfluorobutanoic acid through two pathways; and 6:2 FTCA and 6:2 fluorotel unsaturated acid were the intermediate products. Notably, dosing with 6:2 FTOH affected the composting process of sewage sludge. Additionally, 50 mg/kg 6:2 FTOH resulted in a decrease in the microbial richness and diversity of sludge compost. When compared with the compost without 6:2 FTOH, the proportion of Proteobacteria had increased, and the proportion of Firmicutes had decreased as the concentration of 6:2 FTOH increased. The negative effect of a dosage of 50 mg/kg 6:2 FTOH was more obvious than the effect of other treatments. This study expanded our understanding of the risk of sludge contaminated by 6:2 FTOH being used as a fertilizer after composting.
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Yang Y, Meng K, Chen M, Xie S, Chen D. Fluorotelomer Alcohols' Toxicology Correlates with Oxidative Stress and Metabolism. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 256:71-101. [PMID: 33866421 DOI: 10.1007/398_2020_57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fluorotelomer alcohols (FTOHs) are widely used as industrial raw materials due to their unique hydrophobic and oleophobic properties. However, because of accidental exposure to products containing FTOHs or with the widespread use of FTOHs, they tend to contaminate the water and the soil. There are reports demonstrating that FTOHs can cause various harmful effects in animals and humans (for example, neurotoxicity, hepatotoxicity, nephrotoxicity, immunotoxicity, endocrine-disrupting activity, and developmental and reproductive toxicities). Oxidative stress is related to a variety of toxic effects induced by FTOHs. To date, few reviews have addressed the relationship between the toxicity of FTOHs and oxidative stress. This article summarises research demonstrating that the toxicity induced by FTOHs correlates with oxidative stress and metabolism. Furthermore, during the metabolic process of FTOHs, a number of cytochrome P450 enzymes (CYP450) are involved and many metabolites are produced by these enzymes, which can induce oxidative stress. This is also reviewed.
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Affiliation(s)
- Yujuan Yang
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, Hubei, China
| | - Kuiyu Meng
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, Hubei, China
| | - Min Chen
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, Hubei, China
| | - Shuyu Xie
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, Hubei, China
| | - Dongmei Chen
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, Hubei, China.
- MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Huazhong Agricultural University, Wuhan, Hubei, China.
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7
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Anderson JK, Luz AL, Goodrum PE. Letter to the editor regarding Rice et al. (2020). Food Chem Toxicol 2020; 145:111756. [PMID: 32946933 DOI: 10.1016/j.fct.2020.111756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 09/14/2020] [Indexed: 11/24/2022]
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Rice PA, Aungst J, Cooper J, Bandele O, Kabadi SV. Comparative analysis of the toxicological databases for 6:2 fluorotelomer alcohol (6:2 FTOH) and perfluorohexanoic acid (PFHxA). Food Chem Toxicol 2020; 138:111210. [DOI: 10.1016/j.fct.2020.111210] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 12/30/2022]
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Kabadi SV, Fisher JW, Doerge DR, Mehta D, Aungst J, Rice P. Characterizing biopersistence potential of the metabolite 5:3 fluorotelomer carboxylic acid after repeated oral exposure to the 6:2 fluorotelomer alcohol. Toxicol Appl Pharmacol 2020; 388:114878. [PMID: 31923437 DOI: 10.1016/j.taap.2020.114878] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/05/2019] [Accepted: 01/04/2020] [Indexed: 01/09/2023]
Abstract
Our previous report on pharmacokinetic (PK) evaluation of 6:2 fluorotelomer alcohol (6:2 FTOH) examined the biopersistence potential of its metabolites based on data published from single inhalation and occupational 6:2 FTOH exposure studies. We calculated internal exposure estimates of three key metabolites of 6:2 FTOH, of which 5:3 fluorotelomer carboxylic acid (5:3 acid) had the highest internal exposure and the slowest clearance. No oral repeated 6:2 FTOH exposure data were available at the time to fully characterize the biopersistence potential of the metabolite 5:3 acid. We recently received additional data on 6:2 FTOH and 5:3 acid, which included a 90-day toxicokinetic study report on repeated oral 6:2 FTOH exposure to rats. We reviewed the study and analyzed the reported 5:3 acid concentrations in plasma, liver, and fat using one-compartment PK modeling and calculated elimination rate constants (kel), elimination half-lives (t1/2) and times to steady state (tss) of 5:3 acid at three 6:2 FTOH doses. Our results showed that tss of 5:3 acid in plasma and evaluated tissues were approximately close to 1 year, such that the majority of highest values were observed at the lowest 6:2 FTOH dose, indicating its association with the biopersistence of 6:2 FTOH. The results of our PK analysis are the first to characterize biopersistence potential of the 5:3 acid after repeated oral exposure to the parent compound 6:2 FTOH based on steady state PK parameters, and therefore, may have an impact on future study designs when conducting toxicity assays for such compounds.
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Affiliation(s)
- Shruti V Kabadi
- FDA/CFSAN/OFAS/DFCS, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States of America.
| | - Jeffrey W Fisher
- FDA/NCTR/DBT, 3900 NCTR Road, Jefferson, AR 72079, United States of America
| | - Daniel R Doerge
- FDA/NCTR/DBT, 3900 NCTR Road, Jefferson, AR 72079, United States of America
| | - Darshan Mehta
- FDA/NCTR/DBT, 3900 NCTR Road, Jefferson, AR 72079, United States of America
| | - Jason Aungst
- FDA/CFSAN/OFAS/DFCS, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States of America
| | - Penelope Rice
- FDA/CFSAN/OFAS/DFCS, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States of America
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Annunziato KM, Jantzen CE, Gronske MC, Cooper KR. Subtle morphometric, behavioral and gene expression effects in larval zebrafish exposed to PFHxA, PFHxS and 6:2 FTOH. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 208:126-137. [PMID: 30669116 PMCID: PMC6396680 DOI: 10.1016/j.aquatox.2019.01.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/11/2019] [Accepted: 01/11/2019] [Indexed: 05/06/2023]
Abstract
Recent studies of perfluoroalkylated substances (PFASs) have focused on the toxicity of long chain PFASs, such as PFOS or PFOA, which have been demonstrated to cause an array of developmental and behavioral effects. However, less is known about low molecular weight PFASs and alternatives. This study examined the morphometric and behavioral effects in zebrafish following developmental exposures of C6 PFASs: perfluorohexanoic acid, PFHxA, perfluorohexane sulfonate, PFHxS, and 6:2 fluorotelomer alcohol, 6:2 FTOH. Embryos were exposed to 0.02-20 μM concentrations of these compounds from the high stage (˜3 h post fertilization, hpf) until 120 hpf. Morphometric and gene expression endpoints were examined at 120 hpf. Genes selected for analysis were previously shown to be altered in zebrafish developmentally exposed to PFOS and PFOA. Additionally, exposed larvae were transferred to clean water and reared until 14 days post fertilization, dpf, when behavioral assays were completed and morphometric endpoints examined. While PFHxA was found to be the most acutely toxic at 120 hpf, few morphometric effects were observed. Gene expression was the most sensitive endpoint with significant increased tgfb1a, bdnf, and ap1s1 expression observed with PFHxA exposure. PFHxS exposure produced morphometric effects in the larvae, specifically increased length and yolk sac area at 2 and 20 μM. This phenotype persisted to the 14 dpf time point, where these larvae additionally displayed decreased distance traveled and crosses through the center of the arena of the behavioral assay. Exposure to 6:2 FTOH caused no morphometric effects at 120 hpf, and this compound was the least acutely toxic. However, expression of both tgfb1a and bdnf were increased by greater than 2 fold change at this time point. Effects also persisted to 14 dpf where a significant increase in distance traveled and velocity were observed in the behavioral assay. This study demonstrates effects on behavioral, morphometric and gene expression endpoints with developmental PFHxA, PFHxS, and 6:2 FTOH exposures in zebrafish.
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Affiliation(s)
- Kate M Annunziato
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.
| | - Carrie E Jantzen
- Department of Environmental Science, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Melissa C Gronske
- Department of Animal Science, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Keith R Cooper
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA; Department of Environmental Science, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA; Department of Animal Science, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.
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11
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Stanifer JW, Stapleton HM, Souma T, Wittmer A, Zhao X, Boulware LE. Perfluorinated Chemicals as Emerging Environmental Threats to Kidney Health: A Scoping Review. Clin J Am Soc Nephrol 2018; 13:1479-1492. [PMID: 30213782 PMCID: PMC6218824 DOI: 10.2215/cjn.04670418] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/27/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND OBJECTIVES Per- and polyfluoroalkyl substances (PFASs) are a large group of manufactured nonbiodegradable compounds. Despite increasing awareness as global pollutants, the impact of PFAS exposure on human health is not well understood, and there are growing concerns for adverse effects on kidney function. Therefore, we conducted a scoping review to summarize and identify gaps in the understanding between PFAS exposure and kidney health. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We systematically searched PubMed, EMBASE, EBSCO Global Health, World Health Organization Global Index, and Web of Science for studies published from 1990 to 2018. We included studies on the epidemiology, pharmacokinetics, or toxicology of PFAS exposure and kidney-related health, including clinical, histologic, molecular, and metabolic outcomes related to kidney disease, or outcomes related to the pharmacokinetic role of the kidneys. RESULTS We identified 74 studies, including 21 epidemiologic, 13 pharmacokinetic, and 40 toxicological studies. Three population-based epidemiologic studies demonstrated associations between PFAS exposure and lower kidney function. Along with toxicology studies (n=10) showing tubular histologic and cellular changes from PFAS exposure, pharmacokinetic studies (n=5) demonstrated the kidneys were major routes of elimination, with active proximal tubule transport. In several studies (n=17), PFAS exposure altered several pathways linked to kidney disease, including oxidative stress pathways, peroxisome proliferators-activated receptor pathways, NF-E2-related factor 2 pathways, partial epithelial mesenchymal transition, and enhanced endothelial permeability through actin filament modeling. CONCLUSIONS A growing body of evidence portends PFASs are emerging environmental threats to kidney health; yet several important gaps in our understanding still exist.
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Affiliation(s)
- John W. Stanifer
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, North Carolina; and
- Duke Global Health Institute
| | | | - Tomokazu Souma
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, North Carolina; and
| | | | | | - L. Ebony Boulware
- Division of General Internal Medicine, Department of Medicine, Duke University, Durham, North Carolina
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12
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Fathollahipour S, Patil PS, Leipzig ND. Oxygen Regulation in Development: Lessons from Embryogenesis towards Tissue Engineering. Cells Tissues Organs 2018; 205:350-371. [PMID: 30273927 DOI: 10.1159/000493162] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2018] [Indexed: 12/19/2022] Open
Abstract
Oxygen is a vital source of energy necessary to sustain and complete embryonic development. Not only is oxygen the driving force for many cellular functions and metabolism, but it is also involved in regulating stem cell fate, morphogenesis, and organogenesis. Low oxygen levels are the naturally preferred microenvironment for most processes during early development and mainly drive proliferation. Later on, more oxygen and also nutrients are needed for organogenesis and morphogenesis. Therefore, it is critical to maintain oxygen levels within a narrow range as required during development. Modulating oxygen tensions is performed via oxygen homeostasis mainly through the function of hypoxia-inducible factors. Through the function of these factors, oxygen levels are sensed and regulated in different tissues, starting from their embryonic state to adult development. To be able to mimic this process in a tissue engineering setting, it is important to understand the role and levels of oxygen in each developmental stage, from embryonic stem cell differentiation to organogenesis and morphogenesis. Taking lessons from native tissue microenvironments, researchers have explored approaches to control oxygen tensions such as hemoglobin-based, perfluorocarbon-based, and oxygen-generating biomaterials, within synthetic tissue engineering scaffolds and organoids, with the aim of overcoming insufficient or nonuniform oxygen levels and nutrient supply.
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Affiliation(s)
| | - Pritam S Patil
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio, USA
| | - Nic D Leipzig
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio,
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13
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Kabadi SV, Fisher J, Aungst J, Rice P. Internal exposure-based pharmacokinetic evaluation of potential for biopersistence of 6:2 fluorotelomer alcohol (FTOH) and its metabolites. Food Chem Toxicol 2018; 112:375-382. [PMID: 29331735 DOI: 10.1016/j.fct.2018.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/05/2018] [Accepted: 01/08/2018] [Indexed: 11/26/2022]
Abstract
Polyfluorinated compounds (PFCs) are authorized for use as greaseproofing agents in food contact paper. As C8-PFCs (8-carbons) are known to accumulate in tissues, shorter-chain C6-PFCs (6-carbons) have replaced C8-PFCs in many food contact applications. However, the potential of C6-PFCs for human biopersistence has not been fully evaluated. For the first time, we provide internal exposure estimates to key metabolites of 6:2 fluorotelomer alcohol (6:2 FTOH), a monomeric component of C6-PFCs, to extend our understanding of exposure beyond estimates of external exposure. Pharmacokinetic data from published rat and human studies on 6:2 FTOH were used to estimate clearance and area under the curve (AUC) for its metabolites: 5:3 fluorotelomer carboxylic acid (5:3 A), perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA). Internal exposure to 5:3 A was the highest of evaluated metabolites across species and it had the slowest clearance. Additionally, 5:3 A clearance decreased with increasing 6:2 FTOH exposure. Our analysis provides insight into association of increased internal 5:3 A exposure with high biopersistence potential of 6:2 FTOH. Our results identify 5:3 A as an important biomarker of internal 6:2 FTOH exposure for use in biomonitoring studies, and are potentially useful for toxicological assessment of chronic dietary 6:2 FTOH exposure.
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Affiliation(s)
- Shruti V Kabadi
- FDA/CFSAN/OFAS/DFCN, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States.
| | - Jeffrey Fisher
- FDA/NCTR, 3900 NCTR Road, Jefferson, AR 72079, United States
| | - Jason Aungst
- FDA/CFSAN/OFAS/DFCN, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States
| | - Penelope Rice
- FDA/CFSAN/OFAS/DFCN, 5001 Campus Drive, HFS 275, College Park, MD 20740, United States
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Zhang S, Merino N, Wang N, Ruan T, Lu X. Impact of 6:2 fluorotelomer alcohol aerobic biotransformation on a sediment microbial community. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 575:1361-1368. [PMID: 27756549 DOI: 10.1016/j.scitotenv.2016.09.214] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 09/26/2016] [Accepted: 09/27/2016] [Indexed: 06/06/2023]
Abstract
Sediment microbial communities are responsible for many chemical biotransformation processes in the aquatic environment and play a critical role in various ecosystems and biogeochemical cycling. However, the impact of polyfluoroalkyl substances on sediment microbial communities remains unclear. These substances are increasingly being used in consumer and industrial products to replace environmentally persistent perfluoroalkyl substances. In this study, we investigated the effects of low (5mg/L) and high (15mg/L) doses of 6:2 fluorotelomer alcohol [6:2 FTOH, F(CF2)6CH2CH2OH] on the structure of a sediment microbial community. 6:2 FTOH biotransformation was rapid in the sediment mixture with a half-life <3days, regardless of the initial doses. After 28days, major products produced in the high dose condition included 28mol% 5:2 sFTOH [F(CF2)5CH(OH)CH3], 9.6mol% 5:3 Acid [F(CF2)5CH2CH2COOH] and 11mol% PFHxA [F(CF2)5COOH], while 73mol% 5:2 sFTOH, 23mol% 5:3 Acid and 26mol% PFHxA were observed in the low dose condition. In the original (control) sediment without 6:2 FTOH dosing, Proteobacteria was the predominant microorganism (18%), followed by Chloroflexi (14%), Verrucomicrobia (13%), Firmicutes (3.4%), Bacterioidetes (2.4%), Actinobacteria (1.7%) and Planctomycetes (1.3%). The presence of 6:2 FTOH and the accumulation of transient transformation products in the sediment exerted selection pressure on the microbial taxonomic distribution and diversity. Our observations indicate that potential 6:2 FTOH degraders and tolerant strains, such as Dokdonella spp., Thauera spp., Albidovulum spp. and Caldanaerovirga spp., existed in the sediment mixture and began to dominate over time. This suggests that these genera might have higher tolerance towards elevated 6:2 FTOH and its transformation products. These findings on the characterization of sediment microbial community stability and dynamics will help predict changes in response to perfluoroalkyl and polyfluoroalkyl substances and also help identify robust microbial strains to degrade polyfluoroalkyl substances in the environment.
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Affiliation(s)
- Shu Zhang
- Laboratory for Earth Surface Processes, Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Nancy Merino
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Ning Wang
- 132 Shrewsbury Dr., Wilmington, DE 19810, USA.
| | - Ting Ruan
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Xiaoxia Lu
- Laboratory for Earth Surface Processes, Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
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Is there a human health risk associated with indirect exposure to perfluoroalkyl carboxylates (PFCAs)? Toxicology 2017; 375:28-36. [DOI: 10.1016/j.tox.2016.11.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/07/2016] [Accepted: 11/14/2016] [Indexed: 11/19/2022]
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16
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Fromme H, Dreyer A, Dietrich S, Fembacher L, Lahrz T, Völkel W. Neutral polyfluorinated compounds in indoor air in Germany--the LUPE 4 study. CHEMOSPHERE 2015; 139:572-578. [PMID: 26340371 DOI: 10.1016/j.chemosphere.2015.07.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/26/2015] [Accepted: 07/07/2015] [Indexed: 06/05/2023]
Abstract
Perfluoroalkyl- and polyfluoroalkyl-substances (PFAS) have been detected in many types of environmental media and biota including humans. We determined volatile PFAS, including fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTACs), perfluorooctane sulfonamides (FOSAs), and perfluorooctane sulfonamidoethanols (FOSEs), in indoor air of residences and schools in Germany. FTOHs, FTACs, FOSEs, and FOSAs were quantified with median levels in schools (in residences) of 11,783pg/m(3) (13,198pg/m(3)), 737pg/m(3) (450pg/m(3)), 130pg/m(3) (278pg/m(3)), and 243pg/m(3) (110pg/m(3)), respectively. Using our data and previously published results in a simplified model based on the medians and 95th percentiles, the "typical" and "high" daily non-dietary exposures were calculated to be 4.2ng/kg body weight (9.9ng/kgb.w.) for Σ-FTOHs and 0.1ng/kgb.w. (0.8ng/kgb.w.) for Σ-FOSEs/FOSAs in children. Inhalation was the dominant intake pathway for FTOHs; however, dust ingestion contributed significantly to the total intake of FOSEs/FOSAs. In organisms, 8:2 FTOH is degraded to perfluorooctanoate (PFOA). Assuming that 1% of 8:2 FTOH is converted to PFOA, 8:2 FTOH exposure in Germany has a negligible contribution to the total daily PFOA exposure, which is mainly driven by dietary intake.
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Affiliation(s)
- Hermann Fromme
- Bavarian Health and Food Safety Authority, Department of Chemical Safety and Toxicology, Pfarrstrasse 3, D-80538 Munich, Germany; Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Ziemssenstrasse 1, D-80336 Munich, Germany.
| | | | - Silvio Dietrich
- Bavarian Health and Food Safety Authority, Department of Chemical Safety and Toxicology, Pfarrstrasse 3, D-80538 Munich, Germany
| | - Ludwig Fembacher
- Bavarian Health and Food Safety Authority, Department of Chemical Safety and Toxicology, Pfarrstrasse 3, D-80538 Munich, Germany
| | - Thomas Lahrz
- Berlin-Brandenburg State Laboratory, Department of Environmental Health Protection, Invalidenstr. 60, D-10557 Berlin, Germany
| | - Wolfgang Völkel
- Bavarian Health and Food Safety Authority, Department of Chemical Safety and Toxicology, Pfarrstrasse 3, D-80538 Munich, Germany
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Russell MH, Himmelstein MW, Buck RC. Inhalation and oral toxicokinetics of 6:2 FTOH and its metabolites in mammals. CHEMOSPHERE 2015; 120:328-35. [PMID: 25180935 DOI: 10.1016/j.chemosphere.2014.07.092] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/28/2014] [Accepted: 07/31/2014] [Indexed: 05/21/2023]
Abstract
The toxicokinetics of 6:2 fluorotelomer alcohol (6:2 FTOH) and its terminal perfluorinated and polyfluorinated metabolites (PFBA, PFHxA, PFHpA and 5:3 Acid) have been calculated from laboratory studies of rats and from a biomonitoring study of humans. In vitro studies with mouse, rat and human hepatocytes indicate qualitatively similar metabolic pathways of 6:2 FTOH. In a one-day inhalation study of 6:2 FTOH in rats, PFBA, PFHxA, PFHpA and 5:3 Acid were determined to be the major metabolites in plasma with calculated elimination half-lives of 1.3-15.4h and metabolic yields up to 2.7 mol%. In five-day and 23-day inhalation studies and a 90-day oral study of 6:2 FTOH, the plasma or serum concentration profile of 5:3 Acid was several-fold higher than concentrations observed in the single day study, resulting in an estimated elimination half-life of 20-30 d. In contrast, the concentrations of PFBA, PFHxA and PFHpA showed little or no concentration increase with repeated exposure. Elimination half-lives of PFHxA, PFHpA and 5:3 Acid in humans were estimated from a study of professional ski wax technicians who were occupationally exposed to aerosolized and volatilized components of fluorinated glide wax. The resulting human elimination half-life values of PFHxA, PFHpA and 5:3 Acid were 32, 70 and 43 d, respectively. Based on a one compartment toxicokinetic model, current environmental air concentrations of 6:2 FTOH are estimated to result in plasma concentrations of PFHxA, PFHpA and 5:3 Acid that are less than or equal to typical LOQ values, in agreement with extant biomonitoring results.
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Affiliation(s)
- Mark H Russell
- DuPont Haskell Centers for Health and Environmental Sciences, E. I. duPont de Nemours and Company, Inc., 1090 Elkton Road, Newark, DE 19711-3507, USA.
| | - Matthew W Himmelstein
- DuPont Haskell Centers for Health and Environmental Sciences, E. I. duPont de Nemours and Company, Inc., 1090 Elkton Road, Newark, DE 19711-3507, USA
| | - Robert C Buck
- E. I. duPont de Nemours and Company, Inc., Chemicals and Fluoroproducts, 974 Centre Road, Wilmington, DE 19805, USA
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18
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C6-Perfluorinated Compounds: The New Greaseproofing Agents in Food Packaging. Curr Environ Health Rep 2015; 2:33-40. [DOI: 10.1007/s40572-014-0039-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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20
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Toxicology Data for Alternative “Short-Chain” Fluorinated Substances. TOXICOLOGICAL EFFECTS OF PERFLUOROALKYL AND POLYFLUOROALKYL SUBSTANCES 2015. [DOI: 10.1007/978-3-319-15518-0_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Mukerji P, Rae JC, Buck RC, O'Connor JC. Oral repeated-dose systemic and reproductive toxicity of 6:2 fluorotelomer alcohol in mice. Toxicol Rep 2014; 2:130-143. [PMID: 28962345 PMCID: PMC5598097 DOI: 10.1016/j.toxrep.2014.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/01/2014] [Accepted: 12/01/2014] [Indexed: 01/28/2023] Open
Abstract
6:2 fluorotelomer alcohol (6:2 FTOH) was evaluated for potential systemic repeated-dose and reproductive toxicity in mice. 6:2 FTOH was administered by oral gavage to CD-1 mice as a suspension in 0.5% aqueous methylcellulose with 0.1% Tween-80 at dosages of 1, 5, 25, or 100 mg/kg/day. The no-observed-adverse-effect level (NOAEL) for systemic toxicity was 25 mg/kg/day (males) and 5 mg/kg/day (females), based on effects at higher doses on mortality, clinical observations, body weight, nutritional parameters, hematology (red and white blood cell), clinical chemistry (liver-related), liver weights, and histopathology (liver, teeth, reproductive tract, and mammary gland). However, 6:2 FTOH was not a selective reproductive toxicant. The NOAEL for reproductive toxicity was >100 mg/kg/day; no effects on reproductive outcome were observed at any dosage. The NOAEL for viability and growth of the offspring was 25 mg/kg/day, based on clinical signs of delayed maturation in pups, and reductions in pup survival and pup body weight during lactation at 100 mg/kg/day. While the severity of the effects was generally greater in mice than previously reported in CD rats, the overall NOAELs were identical in both species, 5 mg/kg/day for systemic toxicity and 25 mg/kg/day for offspring viability/growth. 6:2 FTOH was not a selective reproductive toxicant in either species; no effects on reproductive outcome occurred at any dose level, and any effects observed in offspring occurred at dose levels that induced mortality and severe toxicity in maternal animals.
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Affiliation(s)
- Pushkor Mukerji
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
| | - Jessica Caverly Rae
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
| | - Robert C Buck
- E I. duPont de Nemours and Company, Inc., Chemicals and Fluoroproducts, Wilmington, DE 19805, United States
| | - John C O'Connor
- E I. duPont de Nemours and Company, Inc., Haskell Global Centers for Health & Environmental Sciences, P.O. Box 30, Newark, DE 19714, United States
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