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N-Acetyl-L-cysteine and aminooxyacetic acid differentially modulate trichloroethylene reproductive toxicity via metabolism in Wistar rats. Arch Toxicol 2021; 95:1303-1321. [PMID: 33599830 DOI: 10.1007/s00204-021-02991-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 01/21/2021] [Indexed: 10/22/2022]
Abstract
Exposure to the industrial solvent trichloroethylene (TCE) has been associated with adverse pregnancy outcomes in humans and decreased fetal weight in rats. TCE kidney toxicity can occur through formation of reactive metabolites via its glutathione (GSH) conjugation metabolic pathway, largely unstudied in the context of pregnancy. To investigate the contribution of the GSH conjugation pathway and oxidative stress to TCE toxicity during pregnancy, we exposed rats orally to 480 mg TCE/kg/day from gestational day (GD) 6 to GD 16 with and without N-acetyl-L-cysteine (NAC) at 200 mg/kg/day or aminooxyacetic acid (AOAA) at 20 mg/kg/day as pre/co-treatments from GD 5-16. NAC is a reactive oxygen species scavenger that modifies the GSH conjugation pathway, and AOAA is an inhibitor of cysteine conjugate β-lyase (CCBL) in the GSH conjugation pathway. TCE decreased fetal weight, and this was prevented by AOAA but not NAC pre/co-treatment to TCE. Although AOAA inhibited CCBL activity in maternal kidney, it did not inhibit CCBL activity in maternal liver and placenta, suggesting that AOAA prevention of TCE-induced decreased fetal weight was due to CCBL activity inhibition in the kidneys but not liver or placenta. Unexpectedly, NAC pre/co-treatment with TCE, relative to TCE treatment alone, altered placental morphology consistent with delayed developmental phenotype. Immunohistochemical staining revealed that the decidua basale, relative to basal and labyrinth zones, expressed the highest abundance of CCBL1, flavin-containing monooxygenase 3, and cleaved caspase-3. Together, the findings show the differential effects of NAC and AOAA on TCE-induced pregnancy outcomes are likely attributable to TCE metabolism modulation.
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Urban JD, Wikoff DS, Chappell GA, Harris C, Haws LC. Systematic evaluation of mechanistic data in assessing in utero exposures to trichloroethylene and development of congenital heart defects. Toxicology 2020; 436:152427. [PMID: 32145346 DOI: 10.1016/j.tox.2020.152427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 02/18/2020] [Accepted: 03/02/2020] [Indexed: 01/23/2023]
Abstract
The hypothesis that in utero exposures to low levels of trichloroethylene (TCE) may increase the risk of congenital heart defects (CHDs) in offspring remains a subject of substantial controversy within the scientific community due primarily to the reliance on an inconsistent and unreproducible experimental study in rats. To build on previous assessments that have primarily focused on epidemiological and experimental animal studies in developing conclusions, the objective of the current study is to conduct a systematic evaluation of mechanistic data related to in utero exposures to TCE and the development of CHDs. The evidence base was heterogeneous; 79 mechanistic datasets were identified, characterizing endpoints which ranged from molecular to organismal responses in seven species, involving both in vivo and in vitro study designs in mammalian and non-mammalian models. Of these, 24 datasets were considered reliable following critical appraisal using a study quality tool that employs metrics specific to the study type. Subsequent synthesis and integration demonstrated that the available mechanistic data: 1) did not support the potential for CHD hazard in humans, 2) did not support the biological plausibility of a response in humans based on organization via a putative adverse outcome pathway for valvulo-septal cardiac defects, and 3) were not suitable for serving as candidate studies in risk assessment. Findings supportive of an association were generally limited to in ovo chicken studies, in which TCE was administered in high concentration solutions via direct injection. Results of these in ovo studies were difficult to interpret for human health risk assessment given the lack of generalizability of the study models (including dose relevance, species-specific biological differences, variations in the construct of the study design, etc.). When the mechanistic data are integrated with findings from previous evaluations of human and animal evidence streams, the totality of evidence does not support CHDs as a critical effect in TCE human health risk assessment.
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Affiliation(s)
- Jonathan D Urban
- ToxStrategies, Inc., 9390 Research Blvd, Ste. 100, Austin, TX, 78759, USA.
| | - Daniele S Wikoff
- ToxStrategies, Inc., 31 College Place, Ste. B118, Asheville, NC, 28801, USA
| | - Grace A Chappell
- ToxStrategies, Inc., 31 College Place, Ste. B118, Asheville, NC, 28801, USA
| | - Craig Harris
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Laurie C Haws
- ToxStrategies, Inc., 9390 Research Blvd, Ste. 100, Austin, TX, 78759, USA
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Aschengrau A, Winter MR, Gallagher LG, Vieira VM, Butler LJ, Fabian MP, Carwile JL, Wesselink AK, Mahalingaiah S, Janulewicz PA, Weinberg JM, Webster TF, Ozonoff DM. Reproductive and developmental health effects of prenatal exposure to tetrachloroethylene-contaminated drinking water. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:555-566. [PMID: 32051987 PMCID: PMC7937243 DOI: 10.1039/c9em00590k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Tetrachloroethylene (PCE) is a common contaminant in both occupational and community settings. High exposure levels in the workplace have been shown to have adverse impacts on reproduction and development but few epidemiological studies have examined these effects at the lower levels commonly seen in community settings. We were presented with a unique opportunity to examine the reproductive and developmental effects of prenatal exposure to PCE-contaminated drinking water resulting from the installation of vinyl-lined water pipes in Massachusetts and Rhode Island from the late 1960s through 1980. This review describes the methods and findings of two community-based epidemiological studies, places their results in the context of the existing literature, and describes the strengths and challenges of conducting epidemiological research on a historical pollution episode. Our studies found that prenatal exposure to PCE-contaminated drinking water is associated with delayed time-to-pregnancy, and increased risks of placental abruption, stillbirths stemming from placental dysfunction, and certain birth defects. No associations were observed with pregnancy loss, birth weight, and gestational duration. Important strengths of this research included the availability of historical data on the affected water systems, a relatively high exposure prevalence and wide range of exposure levels, and little opportunity for recall bias and confounding. Challenges arose mainly from the retrospective nature of the exposure assessments. This research highlights the importance of considering pregnant women and their developing fetuses when monitoring, regulating, and remediating drinking water contaminants.
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Affiliation(s)
- Ann Aschengrau
- Department of Epidemiology, Boston University School of Public Health, 710 Albany Street, Boston, MA 02118, USA.
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Associations Between Disinfection By-Product Exposures and Craniofacial Birth Defects. J Occup Environ Med 2019; 60:109-119. [PMID: 29023340 DOI: 10.1097/jom.0000000000001191] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to examine associations between craniofacial birth defects (CFDs) and disinfection by-product (DBP) exposures, including the sum of four trihalomethanes (THM4) and five haloacetic acids (HAA5) (ie, DBP9). METHODS We calculated first trimester adjusted odds ratios (aORs) for different DBPs in a matched case-control study of 366 CFD cases in Massachusetts towns with complete 1999 to 2004 THM and HAA data. RESULTS We detected elevated aORs for cleft palate with DBP9 (highest quintile aOR = 3.52; 95% CI: 1.07, 11.60), HAA5, trichloroacetic acid (TCAA), and dichloroacetic acid. We detected elevated aORs for eye defects with TCAA and chloroform. CONCLUSION This is the first epidemiological study of DBPs to examine eye and ear defects, as well as HAAs and CFDs. The associations for cleft palate and eye defects highlight the importance of examining specific defects and DBPs beyond THM4.
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Aschengrau A, Gallagher LG, Winter M, Butler L, Patricia Fabian M, Vieira VM. Modeled exposure to tetrachloroethylene-contaminated drinking water and the occurrence of birth defects: a case-control study from Massachusetts and Rhode Island. Environ Health 2018; 17:75. [PMID: 30400949 PMCID: PMC6219161 DOI: 10.1186/s12940-018-0419-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/24/2018] [Indexed: 05/31/2023]
Abstract
BACKGROUND Residents of Massachusetts and Rhode Island were exposed to tetrachloroethylene-contaminated drinking water from 1968 through the early 1990s when it leached from the vinyl lining of asbestos cement water distribution pipes. While occupational exposure to solvents during pregnancy has consistently been linked to an increased risk of certain birth defects, mixed results have been observed for environmental sources of exposure, including contaminated drinking water. The present case-control study was undertaken to examine further the association between prenatal exposure to tetrachloroethylene-contaminated drinking water and the risk of central nervous system defects, oral clefts and hypospadias. METHODS Cases were comprised of live- and stillborn infants delivered between 1968 and 1995 to mothers who resided in 28 Massachusetts and Rhode Island cities and towns with some PCE-contaminated water supplies. Infants with central nervous system defects (N = 268), oral clefts (N = 112) and hypospadias (N = 94) were included. Controls were randomly selected live-born, non-malformed infants who were delivered during the same period and geographic area as cases (N = 771). Vital records and self-administered questionnaires were used to gather identifying information, birth defect diagnoses, and other relevant data. PCE exposure during the first trimester was estimated using water distribution system modeling software that incorporated a leaching and transport model. Prenatal PCE exposure was dichotomized as "high" or "low" exposure at the level corresponding to an estimated average concentration of 40 μg/L, the criterion for remediation when PCE contamination was discovered in 1980. RESULTS Mothers with "high" levels of exposure to PCE-contaminated drinking water during the first trimester (> 40 μg/L) had increased odds of having a child with spina bifida (OR: 2.0, 95% CI: 0.8-5.4), cleft lip with or without cleft palate (OR: 3.8, 95% CI: 1.2-12.3) and hypospadias (OR: 2.1, 95% CI:0.5-8.3). No increases in the odds of other defects were observed in relation to "high" exposure levels. CONCLUSIONS The results of the present study suggest that mothers with "high" PCE exposure levels during the first trimester have increased odds of having a child with spina bifida, cleft lip with or without cleft palate, and hypospadias. These findings support several prior studies that observed an increased risk of selected birth defects following prenatal exposure to solvents in occupational and environmental settings. Even though PCE contamination from vinyl lined pipes was remediated many years ago, it remains a widespread contaminant across the U.S and so environmental regulations must be guided by a precautionary perspective that safeguards pregnant women and their offspring.
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Affiliation(s)
- Ann Aschengrau
- Department of Epidemiology, Boston University School of Public Health, 715 Albany Street, Talbot 3 East, Boston, MA 02118 USA
| | - Lisa G. Gallagher
- Department of Epidemiology, Boston University School of Public Health, 715 Albany Street, Talbot 3 East, Boston, MA 02118 USA
| | - Michael Winter
- Biostatistics and Epidemiology Data Analytics Center, Boston University School of Public Health, 715 Albany Street, Fuller-9, Boston, MA 02118 USA
| | - Lindsey Butler
- Department of Environmental Health, Boston University School of Public Health, 715 Albany Street, Talbot 4 West, Boston, MA 02118 USA
| | - M. Patricia Fabian
- Department of Environmental Health, Boston University School of Public Health, 715 Albany Street, Talbot 4 West, Boston, MA 02118 USA
| | - Veronica M. Vieira
- University of California, Irvine, Program in Public Health, 653 East Peltason Drive, Irvine, CA 92697 USA
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Wikoff D, Urban JD, Harvey S, Haws LC. Role of Risk of Bias in Systematic Review for Chemical Risk Assessment: A Case Study in Understanding the Relationship Between Congenital Heart Defects and Exposures to Trichloroethylene. Int J Toxicol 2018; 37:125-143. [PMID: 29357719 PMCID: PMC5888777 DOI: 10.1177/1091581818754330] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The National Academy of Science has recommended that a risk of bias (RoB; credibility of the link between exposure and outcome) assessment be conducted on studies that are used as primary data sources for hazard identification and dose-response assessment. Few applications of such have been conducted. Using trichloroethylene and congenital heart defects (CHDs) as a case study, we explore the role of RoB in chemical risk assessment using the National Toxicology Program's Office of Health Assessment and Translation RoB tool. Selected questions were tailored to evaluation of CHD and then applied to 12 experimental animal studies and 9 epidemiological studies. Results demonstrated that the inconsistent findings of a single animal study were likely explained by the limitations in study design assessed via RoB (eg, lack of concurrent controls, unvalidated method for assessing outcome, unreliable statistical methods, etc). Such limitations considered in the context of the body of evidence render the study not sufficiently reliable for the development of toxicity reference values. The case study highlights the utility of RoB as part of a robust risk assessment process and specifically demonstrates the role RoB can play in objectively selecting candidate data sets to develop toxicity values.
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Makris SL, Scott CS, Fox J, Knudsen TB, Hotchkiss AK, Arzuaga X, Euling SY, Powers CM, Jinot J, Hogan KA, Abbott BD, Hunter ES, Narotsky MG. A systematic evaluation of the potential effects of trichloroethylene exposure on cardiac development. Reprod Toxicol 2016; 65:321-358. [PMID: 27575429 PMCID: PMC9113522 DOI: 10.1016/j.reprotox.2016.08.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 07/27/2016] [Accepted: 08/25/2016] [Indexed: 11/26/2022]
Abstract
The 2011 EPA trichloroethylene (TCE) IRIS assessment, used developmental cardiac defects from a controversial drinking water study in rats (Johnson et al. [51]), along with several other studies/endpoints to derive reference values. An updated literature search of TCE-related developmental cardiac defects was conducted. Study quality, strengths, and limitations were assessed. A putative adverse outcome pathway (AOP) construct was developed to explore key events for the most commonly observed cardiac dysmorphologies, particularly those involved with epithelial-mesenchymal transition (EMT) of endothelial origin (EndMT); several candidate pathways were identified. A hypothesis-driven weight-of-evidence analysis of epidemiological, toxicological, in vitro, in ovo, and mechanistic/AOP data concluded that TCE has the potential to cause cardiac defects in humans when exposure occurs at sufficient doses during a sensitive window of fetal development. The study by Johnson et al. [51] was reaffirmed as suitable for hazard characterization and reference value derivation, though acknowledging study limitations and uncertainties.
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Ileka-Priouzeau S, Campagna C, Legay C, Deonandan R, Rodriguez MJ, Levallois P. Women exposure during pregnancy to haloacetaldehydes and haloacetonitriles in drinking water and risk of small-for-gestational-age neonate. ENVIRONMENTAL RESEARCH 2015; 137:338-348. [PMID: 25601737 DOI: 10.1016/j.envres.2015.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/05/2015] [Accepted: 01/08/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Past studies have examined the effects of maternal exposure to water chlorination disinfection by-products (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs) during pregnancy. However, no human-based study has yet evaluated the effect of emerging DBPs, such as haloacetaldehydes (HAs) and haloacetonitriles (HANs) on small-for-gestational-age (SGA) status in newborns. OBJECTIVE This study aims to assess the association between maternal multiroute exposure to HAs and HANs during the third trimester of pregnancy and SGA status at birth, among neonates delivered by women residing in the Quebec City area (Province of Quebec, Canada). We also evaluated the interaction between exposure to these emerging unregulated by-products and regulated DBPs also found in drinking water (THMs and HAAs), for which a positive association with adverse reproductive outcomes has been suggested in previous studies. METHODS We conducted a population-based case-control study in the Quebec City area. SGA newborns (n=330) were compared to 1100 controls, with matching based on calendar week of birth. HA and HAN concentrations in drinking water at participant's tap were estimated using spatio-temporal strategy based on bimonthly measurements carried out at several locations in the participant's distribution system. A computer-assisted telephone interview was completed to collect information on individual habits of water consumption and water related activities in order to determine individual multiroute exposure. This enabled us to estimate the dose of HAs and HANs absorbed daily by each participant. Associations between total HA, HAN concentrations in drinking water and SGA were analyzed. Associations between the daily-absorbed doses of these emerging DBPs and SGA were also analyzed. Odds ratios (ORs) comparing the 4th quartile of exposure to the reference group (the first three quartiles) were obtained by means of conditional logistic regression, and controlling for potential confounders. RESULTS Globally, no evidence of increased risk of SGA was found with total HA and HAN concentrations in tap water when participants in the 4th quartile of exposure were compared to the first three quartiles (OR=1.0; 95% CI [0.7-1.5] and OR=0.8; 95% CI [0.6-1.2], respectively). Similarly, no association was found with the daily-absorbed doses of total HAs or HANs (OR=0.9; 95% CI [0.6-1.3] and OR=1.1; 95% CI [0.7-1.6], respectively). However, a small non statistically significant association was found between the dose of brominated HA and SGA (OR=1.4; 95% CI [0.9-2.1]). Also, in spite of the lack of interaction between other DBP classes, an unexpected negative interaction was observed between concentration of chloral hydrate (CH) (which represents the main HA species), and regulated DBPs (P=0.006). CONCLUSION In this population, exposure to low levels of HAs and HANs during the third trimester of pregnancy through drinking water was not associated to SGA status in newborns. Nonetheless, more research is needed to clarify possible effect of brominated compounds and interaction between different DBPs.
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Affiliation(s)
- Samuel Ileka-Priouzeau
- Département de médecine sociale et préventive, Faculté de médecine, Université Laval, 1050 Avenue de la Médecine, Québec Québec, Canada G1V 0A6; Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, 2705 Boulevard Laurier, Québec Québec, Canada G1V 2L9
| | - Céline Campagna
- Direction de la santé environnementale et de la toxicologie, Institut national de santé publique du Québec, 945 Avenue Wolfe, Québec Québec, Canada G1V 5B3
| | - Christelle Legay
- Chaire de recherche en eau potable, École supérieure d'aménagement du territoire et de développement régional, Université Laval, Pavillon Félix-Antoine-Savard, 2325 rue des Bibliothèques, Québec Québec, Canada G1V 0A6
| | - Raywat Deonandan
- Interdisciplinary School of Public Health, University of Ottawa, Thompson Hall, 25 University Private, Ottawa Ontario, Canada K1N 6X1
| | - Manuel J Rodriguez
- Chaire de recherche en eau potable, École supérieure d'aménagement du territoire et de développement régional, Université Laval, Pavillon Félix-Antoine-Savard, 2325 rue des Bibliothèques, Québec Québec, Canada G1V 0A6
| | - Patrick Levallois
- Département de médecine sociale et préventive, Faculté de médecine, Université Laval, 1050 Avenue de la Médecine, Québec Québec, Canada G1V 0A6; Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, 2705 Boulevard Laurier, Québec Québec, Canada G1V 2L9; Direction de la santé environnementale et de la toxicologie, Institut national de santé publique du Québec, 945 Avenue Wolfe, Québec Québec, Canada G1V 5B3.
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Exposure During Pregnancy to Glycol Ethers and Chlorinated Solvents and the Risk of Congenital Malformations. Epidemiology 2012; 23:806-12. [DOI: 10.1097/ede.0b013e31826c2bd8] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Costet N, Garlantézec R, Monfort C, Rouget F, Gagnière B, Chevrier C, Cordier S. Environmental and urinary markers of prenatal exposure to drinking water disinfection by-products, fetal growth, and duration of gestation in the PELAGIE birth cohort (Brittany, France, 2002-2006). Am J Epidemiol 2012; 175:263-75. [PMID: 22156019 DOI: 10.1093/aje/kwr419] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although prenatal exposure to water disinfection by-products does not appear to affect the duration of gestation, its impact on fetal growth remains an open question. The authors studied the associations between prenatal exposure to disinfection by-products and fetal growth restriction (FGR) and preterm birth in the PELAGIE cohort, a French birth cohort comprising 3,421 pregnant women recruited between 2002 and 2006. Exposure was assessed by estimating levels of trihalomethanes (THMs) in tap water during pregnancy and maternal water use and by measuring maternal urinary levels of trichloroacetic acid (TCAA) during early pregnancy in a nested case-control design that compared 174 FGR cases, 114 preterm births, and 399 controls. Higher uptake of THMs (especially brominated THMs) was associated with a higher risk of FGR. Women with TCAA detected in their urine (>0.01 mg/L) had a higher risk of FGR than those with TCAA levels below the detection limit (adjusted odds ratio = 1.8, 95% confidence interval: 0.9, 3.7) and had an odds ratio for preterm birth below 1 (adjusted odds ratio = 0.8, 95% confidence interval: 0.3, 2.6). Results from this prospective study, the first to use a biomarker of disinfection by-product exposure, suggest that prenatal exposure affects fetal growth, but the causal agent or agents remain to be identified.
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Affiliation(s)
- Nathalie Costet
- INSERM U, Institut de Recherches sur la Santé, l’Environnement et le Travail, University of Rennes, Institut Fédératif de Recherches, France.
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Louisse J, Verwei M, Woutersen RA, Blaauboer BJ, Rietjens IMCM. Towardin vitrobiomarkers for developmental toxicity and their extrapolation to thein vivosituation. Expert Opin Drug Metab Toxicol 2011; 8:11-27. [DOI: 10.1517/17425255.2012.639762] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Colman J, Rice GE, Wright JM, Hunter ES, Teuschler LK, Lipscomb JC, Hertzberg RC, Simmons JE, Fransen M, Osier M, Narotsky MG. Identification of developmentally toxic drinking water disinfection byproducts and evaluation of data relevant to mode of action. Toxicol Appl Pharmacol 2011; 254:100-26. [DOI: 10.1016/j.taap.2011.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 04/22/2010] [Accepted: 04/22/2010] [Indexed: 12/26/2022]
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Brown Dzubow R, Makris S, Siegel Scott C, Barone S. Early lifestage exposure and potential developmental susceptibility to tetrachloroethylene. ACTA ACUST UNITED AC 2010; 89:50-65. [PMID: 20041493 DOI: 10.1002/bdrb.20222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Tetrachloroethylene, also known as perchloroethylene or "perc", is a highly volatile and lipophilic solvent widely used in dry cleaning, textile processing, and metal-cleaning operations. The limited epidemiological and toxicological data available for exposure to perc during developmental lifestages, as well as the evidence for critical windows of exposure, highlight early life as a period of potential susceptibility. METHODS A literature search was performed to identify all peer-reviewed epidemiological and toxicologial studies examining outcomes from early lifestage exposure to perc, and reviewed by developmental stage for both exposure and outcome. RESULTS Exposure scenarios to perc unique to early lifestages include transplacental and breast milk intake, along with inhalation, ingestion, or dermal exposure. Toxicokinetics factors that may influence early lifestage susceptibility to perc, along with existing physiologically based pharmacokinetic (PBPK) models, are described. Adverse outcomes examined include: reproductive outcomes examined prior to conception including reduced fertility, adverse effects on sperm, or altered reproductive hormones; prenatal outcomes examined after exposure prior to conception or prenatally including fetal death, birth defects, and decreased birth weight; postnatal outcomes examined after exposure prior to conception, prenatally, or during childhood including neurotoxicity, immunotoxicity, cancer, hepatotoxicity, congential anomalies and mortality; and adult schizophrenia examined after exposure prior to conception. CONCLUSIONS The limited evidence on early lifestage exposure to perc does not provide sufficient evidence of this sensitive period as being more or less important than exposure at a later lifestage, such as during adulthood. However, there are a number of adverse health effects observed uniquely in early lifestages, and increased sensitivity to visual system deficits is suggested in children. Other outcomes observed in adults may not have been adequately assessed in children to directly compare sensitivity.
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Affiliation(s)
- Rebecca Brown Dzubow
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Mailcode 8623-P, Washington, DC 20460, USA.
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Aschengrau A, Weinberg JM, Janulewicz PA, Gallagher LG, Winter MR, Vieira VM, Webster TF, Ozonoff DM. Prenatal exposure to tetrachloroethylene-contaminated drinking water and the risk of congenital anomalies: a retrospective cohort study. Environ Health 2009; 8:44. [PMID: 19778411 PMCID: PMC2761868 DOI: 10.1186/1476-069x-8-44] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 09/24/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND Prior animal and human studies of prenatal exposure to solvents including tetrachloroethylene (PCE) have shown increases in the risk of certain congenital anomalies among exposed offspring. OBJECTIVES This retrospective cohort study examined whether PCE contamination of public drinking water supplies in Massachusetts influenced the occurrence of congenital anomalies among children whose mothers were exposed around the time of conception. METHODS The study included 1,658 children whose mothers were exposed to PCE-contaminated drinking water and a comparable group of 2,999 children of unexposed mothers. Mothers completed a self-administered questionnaire to gather information on all of their prior births, including the presence of anomalies, residential histories and confounding variables. PCE exposure was estimated using EPANET water distribution system modeling software that incorporated a fate and transport model. RESULTS Children whose mothers had high exposure levels around the time of conception had an increased risk of congenital anomalies. The adjusted odds ratio of all anomalies combined among children with prenatal exposure in the uppermost quartile was 1.5 (95% CI: 0.9, 2.5). No meaningful increases in the risk were seen for lower exposure levels. Increases were also observed in the risk of neural tube defects (OR: 3.5, 95% CI: 0.8, 14.0) and oral clefts (OR 3.2, 95% CI: 0.7, 15.0) among offspring with any prenatal exposure. CONCLUSION The results of this study suggest that the risk of certain congenital anomalies is increased among the offspring of women who were exposed to PCE-contaminated drinking water around the time of conception. Because these results are limited by the small number of children with congenital anomalies that were based on maternal reports, a follow-up investigation should be conducted with a larger number of affected children who are identified by independent records.
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Affiliation(s)
- Ann Aschengrau
- Department of Epidemiology, Boston University School of Public Health, Talbot 3E, 715 Albany Street, Boston, MA 02118, USA
| | - Janice M Weinberg
- Department of Biostatistics, Boston University School of Public Health, Crosstown, 715 Albany Street, Boston, MA 02118, USA
| | - Patricia A Janulewicz
- Department of Epidemiology, Boston University School of Public Health, Talbot 3E, 715 Albany Street, Boston, MA 02118, USA
| | - Lisa G Gallagher
- Department of Environmental Health, Boston University School of Public Health, Talbot 4W, 715 Albany Street, Boston, MA 02118, USA
| | - Michael R Winter
- Data Coordinating Center, Boston University School of Public Health, Crosstown, 715 Albany Street, Boston MA 02118, USA
| | - Veronica M Vieira
- Department of Environmental Health, Boston University School of Public Health, Talbot 4W, 715 Albany Street, Boston, MA 02118, USA
| | - Thomas F Webster
- Department of Environmental Health, Boston University School of Public Health, Talbot 4W, 715 Albany Street, Boston, MA 02118, USA
| | - David M Ozonoff
- Department of Environmental Health, Boston University School of Public Health, Talbot 4W, 715 Albany Street, Boston, MA 02118, USA
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Aschengrau A, Weinberg J, Rogers S, Gallagher L, Winter M, Vieira V, Webster T, Ozonoff D. Prenatal exposure to tetrachloroethylene-contaminated drinking water and the risk of adverse birth outcomes. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:814-20. [PMID: 18560539 PMCID: PMC2430239 DOI: 10.1289/ehp.10414] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 02/04/2008] [Indexed: 05/22/2023]
Abstract
BACKGROUND Prior studies of prenatal exposure to tetrachloroethylene (PCE) have shown mixed results regarding its effect on birth weight and gestational age. OBJECTIVES In this retrospective cohort study we examined whether PCE contamination of public drinking-water supplies in Massachusetts influenced the birth weight and gestational duration of children whose mothers were exposed before the child's delivery. METHODS The study included 1,353 children whose mothers were exposed to PCE-contaminated drinking water and a comparable group of 772 children of unexposed mothers. Birth records were used to identify subjects and provide information on the outcomes. Mothers completed a questionnaire to gather information on residential histories and confounding variables. PCE exposure was estimated using EPANET water distribution system modeling software that incorporated a fate and transport model. RESULTS We found no meaningful associations between PCE exposure and birth weight or gestational duration. Compared with children whose mothers were unexposed during the year of the last menstrual period (LMP), adjusted mean differences in birth weight were 20.9, 6.2, 30.1, and 15.2 g for children whose mothers' average monthly exposure during the LMP year ranged from the lowest to highest quartile. Similarly, compared with unexposed children, adjusted mean differences in gestational age were -0.2, 0.1, -0.1, and -0.2 weeks for children whose mothers' average monthly exposure ranged from the lowest to highest quartile. Similar results were observed for two other measures of prenatal exposure. CONCLUSIONS These results suggest that prenatal PCE exposure does not have an adverse effect on these birth outcomes at the exposure levels experienced by this population.
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Affiliation(s)
- Ann Aschengrau
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts 02118, USA.
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Hardin BD, Kelman BJ, Brent RL. Trichloroethylene and dichloroethylene: a critical review of teratogenicity. ACTA ACUST UNITED AC 2006; 73:931-55. [PMID: 16342278 DOI: 10.1002/bdra.20192] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Trichloroethylene (TCE) and dichloroethylene (DCE) are high-volume industrial chemicals frequently found as contaminants in public drinking water supplies. The developmental toxicity of both chemicals has been evaluated in laboratory and epidemiologic studies. It has been suggested that TCE and DCE are specific cardiac teratogens and that drinking water contaminated with them increases the risk of congenital heart defects in exposed human populations. In contrast, other laboratory and epidemiologic studies do not find an increase in developmental effects, either in general or specifically affecting the heart. This laboratory and epidemiologic base was reviewed to evaluate the strengths and weaknesses of the conflicting published reports. We conclude that the weight of experimental and epidemiologic evidence does not support the hypothesis that TCE or DCE is a selective developmental toxicant in general or a cardiac teratogen specifically.
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Mishima N, Hoffman S, Hill EG, Krug EL. Chick embryos exposed to trichloroethylene in an ex ovo culture model show selective defects in early endocardial cushion tissue formation. ACTA ACUST UNITED AC 2006; 76:517-27. [PMID: 16933305 DOI: 10.1002/bdra.20283] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Formation of the primitive heart is a critical step for establishing a competent circulatory system necessary for continued morphogenesis, and as such has significant potential as a target for environmental insult. The goal of this study was to identify the initial cellular events that precede more superficially observable abnormalities resulting from exposing early chick embryos to trichloroethylene (TCE). METHODS A whole embryo culture method was used to assess the susceptibility of endocardial epithelial-mesenchymal transformation in the early chick heart to TCE. This method has the benefits of maintaining the anatomical relationships of developing tissues and organs, instantaneously exposing precisely staged embryos to quantifiable levels of TCE in a protein-free medium, and the ability to directly monitor developmental morphology. RESULTS A minority of embryos (Hamburger and Hamilton [HH] stage 13-14) exposed to TCE (10-80 ppm) were not viable after 24 hr in culture and exhibited a variety of gross malformations in a dose-dependent fashion. However, the majority of treated embryos remained viable and developed into HH stage 17 embryos that were superficially indistinguishable from vehicle-treated controls. Further analysis of the hearts of these superficially normal embryos by whole-mount confocal microscopy revealed selective reduction in the number of atrioventricular canal mesenchymal cells. Additionally, those mesenchymal cells that did develop migrated abnormally as long thin cords of adherent cells. CONCLUSIONS The regional selectivity of these effects in the chick heart suggests a critical window of susceptibility to TCE in the epithelial-mesenchymal transformation of atrioventricular canal endocardium.
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Affiliation(s)
- Noboru Mishima
- Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Andrews JE, Nichols HP, Schmid JE, Mole LM, Hunter ES, Klinefelter GR. Developmental toxicity of mixtures: the water disinfection by-products dichloro-, dibromo- and bromochloro acetic acid in rat embryo culture. Reprod Toxicol 2005; 19:111-6. [PMID: 15336719 DOI: 10.1016/j.reprotox.2004.06.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Revised: 05/10/2004] [Accepted: 06/04/2004] [Indexed: 11/25/2022]
Abstract
The chlorination of drinking water results in production of numerous disinfection by-products (DBPs). One of the important classes of DBPs is the haloacetic acids. We have previously shown that the haloacetic acids (HAs), dichloro (DCA), dibromo (DBA) and bromochloro (BCA) acetic acid are developmentally toxic in mouse whole embryo culture. Human exposure to these contaminants in drinking water would involve simultaneous exposure to all three HAs. This study explores the question of developmental toxicity interactions between these compounds. Gestational day (GD) 9.5 rat embryos were exposed to various concentrations of the three HAs (singly or in combination) for 48 h and then evaluated for dysmorphology. The embryonic effects from exposure to the single compounds and mixtures were evaluated using developmental score (DEVSC) as the parameter of comparison. Concentrations of individual compounds and mixtures were chosen (based on a dose-additivity model) which were predicted to produce scores 10 or 20% lower than control levels. Evaluations were performed on all possible combinations of the three HAs. The HAs were dysmorphogenic and resulted in primarily rotation and heart defects and to a lesser extent prosencephalic, visceral arch, and eye defects. The percent anomalies in the rat were comparable to those previously published for the mouse at comparable toxicant concentration. There was a low incidence of neural tube defects in the rat following exposure to the HAs. The rat neural tube appeared less sensitive to the HAs than did the mouse resulting in a higher rate of neural tube dysmorphology in the mouse. Following exposures to BCA and DBA, alone and in combination, there was a significant incidence of delayed embryonic caudal development with apparent normal development anterior to the second visceral arch. The developmental scores for embryos exposed to combinations of the three compounds, when compared to scores for embryos exposed to the single compounds, indicated that the dose-additivity model adequately predicted the observed toxicity and that the developmental toxicity of these water disinfection by-products appears to be additive in whole embryo culture (WEC).
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Affiliation(s)
- J E Andrews
- National Health and Environmental Effects Research Laboratory, Reproductive Toxicology Division, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Banks HT, Potter LK. Probabilistic methods for addressing uncertainty and variability in biological models: application to a toxicokinetic model. Math Biosci 2004; 192:193-225. [PMID: 15627493 DOI: 10.1016/j.mbs.2004.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Population variability and uncertainty are important features of biological systems that must be considered when developing mathematical models for these systems. In this paper we present probability-based parameter estimation methods that account for such variability and uncertainty. Theoretical results that establish well-posedness and stability for these methods are discussed. A probabilistic parameter estimation technique is then applied to a toxicokinetic model for trichloroethylene using several types of simulated data. Comparison with results obtained using a standard, deterministic parameter estimation method suggests that the probabilistic methods are better able to capture population variability and uncertainty in model parameters.
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Affiliation(s)
- H T Banks
- Center for Research in Scientific Computation, North Carolina State University, Raleigh, NC 27695-8205, USA.
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Beliles RP. Concordance across species in the reproductive and developmental toxicity of tetrachloroethylene. Toxicol Ind Health 2002; 18:91-106. [PMID: 12868798 DOI: 10.1191/0748233702th137oa] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Reproductive and developmental toxicities resulting from exposure to tetrachloroethylene include delayed or impaired conception, sperm quality, death during development, developmental neurotoxicity, and growth retardation. In most cases there was concordance between rodents and humans. The risk assessments indicated that neurotoxicity was the most sensitive endpoint for inhalation, whereas growth retardation was the most sensitive endpoint when exposure was by the oral route. The reference concentration (RfC) of 0.01 ppm was based on neurotoxicity among human subjects. The reference dose (RfD) of 0.0006 mg/kg per day was based on small for gestation age infants. In both cases, studies in rodents supported the credibility of these assessments. For the RfD, similar findings for other trihalomethanes have been reported. The latter part of pregnancy and early life may constitute a susceptible period for alterations leading to behavioral deficits. During this period, the capacity to metabolize tetrachloroethylene is reduced and may further contribute to the sensitivity during this phase of development. Studies suggest that an effect on dopamine metabolism is a plausible mode of action for some types of neurotoxicity. In addition, it has been suggested that this alteration may affect reproductive integrity by influencing prolactin levels.
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Wang JL, Chen WL, Tsai SY, Sung PY, Huang RN. An in vitro model for evaluation of vaporous toxicity of trichloroethylene and tetrachloroethylene to CHO-K1 cells. Chem Biol Interact 2001; 137:139-54. [PMID: 11551530 DOI: 10.1016/s0009-2797(01)00226-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Toxicokinetics of trichloroethylene (TCE) and tetrachloroethylene (PER) in culture medium and their toxicity to CHO-K1 cells were investigated by employing an in vitro vapor exposure system. Cells were cultured in a 60 mm petri dish with a 25 mm glass dish glued in the central area. TCE or PER was added to the central glass dish so that it would evaporate and dissolve in the surrounding medium in which cells were growing. The results showed that the concentration of TCE or PER in medium increased significantly within 20 min and then decreased very rapidly with time. After a 24 h incubation, the residual of TCE or PER in the medium was very low, but was displayed in a dose-dependent manner. Treatment of cells with either TCE or PER resulted in a dose- and time-dependent inhibition of cell growth. A significantly increase in the frequency of micronuclei (MN) was also observed with either TCE or PER treatment. Low doses of TCE (5-20 microl) or PER (1-5 microl) significantly enhanced the intracellular glutathione (GSH) level. However, the level of GSH rapidly decreased with higher doses of TCE (40-80 microl) or PER (10-20 microl). Depletion of cellular GSH showed no effect on the sensitivity of cells to TCE or PER treatment. GSH-conjugation has been proposed as an activation mechanism to account for the nephrotoxicity of TCE and PER, however the toxicity of TCE and PER to CHO-K1 cells is probably mediated through a distinct mechanism.
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Affiliation(s)
- J L Wang
- Department of Chemistry, National Central University, Chung-li, 32054, Taoyuan, Taiwan, ROC
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Claudio L, Bearer CF, Wallinga D. Assessment of the U.S. Environmental Protection Agency methods for identification of hazards to developing organisms, Part II: The developmental toxicity testing guideline. Am J Ind Med 1999; 35:554-63. [PMID: 10332508 DOI: 10.1002/(sici)1097-0274(199906)35:6<554::aid-ajim2>3.0.co;2-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The effects of toxins on developing animals depend not only on the nature of the chemical but also on the timing of exposure and assessment of outcomes. This complicates the task of regulatory agencies such as the U.S. Environmental Protection Agency (EPA), which must comply with the 1996 Food Quality Protection Act to ensure that their standards and policies protect infants and children from environmental toxins. For this task, the Agency relies heavily on scientific data obtained by manufacturers of industrial chemicals and pesticides following protocols collected under EPA's Health Effects Test Guidelines. METHODS AND RESULTS This article reviews the protocols included in the EPA guidelines to assess developmental toxicity, which are required for food-use pesticides under the core testing battery. We reviewed these protocols on the basis of their adequacy for identifying hazards to infants and children. Our analysis found limitations in the protocols that hinder their potential for identifying developmental hazards. CONCLUSIONS Methods that the EPA currently depends upon to identify developmental toxicity of chemicals have limitations that impede obtaining complete and reliable data on which to base regulatory decisions that protect children. Other methodological approaches need to be explored as alternatives or supplements to the current protocols. Until more accurate testing protocols become available, it may well be necessary under existing laws to employ safety factors that are more protective of the health of children at all stages of development.
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Affiliation(s)
- L Claudio
- Division of Environmental and Occupational Medicine, Mount Sinai Medical Center, New York, NY 10029-6574, USA.
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Yan Z, Henderson GN, James MO, Stacpoole PW. Determination of chloral hydrate metabolites in human plasma by gas chromatography-mass spectrometry. J Pharm Biomed Anal 1999; 19:309-18. [PMID: 10704096 DOI: 10.1016/s0731-7085(98)00123-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chloral hydrate (CH) is a widely used sedative. Its pharmacological and toxicological effects are directly related to its metabolism. Prior investigations of CH metabolism have been limited by the lack of analytical techniques sufficiently sensitive to identify and quantify metabolites of CH in biological fluids. In this study a gas chromatography mass spectrometry (GC/MS) method was developed and validated for determining CH and its metabolites, monochloroacetate (MCA), dichloroacetate (DCA), trichloroacetate (TCA) and total trichloroethanol (free and glucuronidated form, TCE and TCE-Glu) in human plasma. Of these, DCA and MCA are newly identified metabolites in humans. The drug, its plasma metabolites and an internal standard, 4-chlorobutyric acid (CBA), were derivatized to their methyl esters by reacting with 12% boron trifluoride-methanol complex (12% BF3-MeOH). The reaction mixture was extracted with methylene chloride and analyzed by GC/MS, using a selected ion monitoring (SIM) mode. The quantitation limits of MCA, DCA, TCA, and TCE were between 0.12 and 7.83 microM. The coefficients of variation were between 0.58 and 14.58% and the bias values ranged between -10.03 and 14.37%. The coefficients of linear regression were between 0.9970 and 0.9996.
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Affiliation(s)
- Z Yan
- Department of Medicine, University of Florida, Gainesville 32610, USA
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Abstract
OBJECTIVES The hypothesis of this study was that metabolites of trichloroethylene (TCE), dichloroethylene (DCE) and related compounds were responsible for fetal cardiac teratogenic effects seen when TCE or DCE is consumed by pregnant rats during organogenesis. Identification of teratogenic metabolites would allow more accurate assessment of environmental contaminants and public health risks from contaminated water or possibly municipal water supplies which, when chlorinated, may produce these potentially dangerous chemicals. BACKGROUND Human epidemiologic studies and previous teratogenic studies using chick embryos and fetal rats have shown an increased incidence of congenital cardiac lesions in animals exposed to TCE and DCE. METHODS Metabolites and compounds studied in drinking water exposure included: trichloroacetic acid (TCAA), monochloroacetic acid (MCAA), trichloroethanol (TCEth), carboxy methylcystine (CMC), trichloroacetaldehyde (TCAld), dichloroacetaldehyde (DCAld), and dichlorovinyl cystine (DCVC). Compounds were administered to pregnant rats during fetal heart development. RESULTS Fetuses of rats receiving 2,730 ppm TCAA in drinking water were the only group that demonstrated a significant increase in cardiac defects (10.53%) compared with controls (2.15%) on a per fetus basis (p = 0.0001, Fischer's exact test), and a per litter basis (p = 0.0004, Wilcoxon and p = 0.0015, exact permutation tests). Trichloroacetic acid also demonstrated an increased number of implantation and resorption sites (p < 0.05) over controls. Other maternal and fetal variables showed no statistically significant differences between treated and untreated groups. CONCLUSIONS Of the metabolites tested, only TCAA appeared to be a specific cardiac teratogen in the fetus when imbibed by the maternal rat.
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Affiliation(s)
- P D Johnson
- Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona, Tucson, USA.
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