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Wang S, Jin J, Ma Y, Stubbings WA, Gbadamosi MR, Abou-Elwafa Abdallah M, Harrad S. Organophosphate triesters and their diester degradation products in the atmosphere-A critical review. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123653. [PMID: 38402940 DOI: 10.1016/j.envpol.2024.123653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 02/27/2024]
Abstract
Organophosphate triesters (tri-OPEs) have found substantial use as plasticizers and flame retardants in commercial and industrial products. Despite upcoming potential restrictions on use of OPEs, widespread environmental contamination is likely for the foreseeable future. Organophosphate diesters (di-OPEs) are known biotic or abiotic degradation products of tri-OPEs. In addition, direct use of di-OPEs as commercial products also contributes to their presence in the atmosphere. We review the available data on contamination with tri-OPEs and di-OPEs in both indoor and outdoor air. Concentrations of tri-OPEs in indoor air exceed those in outdoor air. The widespread discovery of tri-OPE traces in polar regions and oceans is noteworthy and is evidence that they undergo long-range transport. There are only two studies on di-OPEs in outdoor air and no studies on di-OPEs in indoor air until now. Current research on di-OPEs in indoor and outdoor air is urgently needed, especially in countries with potentially high exposure to di-OPEs such as the UK and the US. Di-OPE concentrations are higher at e-waste dismantling areas than at surrounding area. We also summarise the methods employed for sampling and analysis of OPEs in the atmosphere and assess the relative contribution to atmospheric concentrations of di-OPEs made by environmental degradation of triesters, compared to the presence of diesters as by-products in commercial triester products. Finally, we identify shortcomings of current research and provide suggestions for future research.
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Affiliation(s)
- Shijie Wang
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - Jingxi Jin
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - Yulong Ma
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - William A Stubbings
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - Muideen Remilekun Gbadamosi
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - Mohamed Abou-Elwafa Abdallah
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom
| | - Stuart Harrad
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, West Midlands, B15 2TT, United Kingdom.
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Wang YY, Luo WK, Tang SX, Xiang J, Dang Y, Tang B, Lu QY, Cai FS, Ren MZ, Yu YJ, Zheng J. Bioaccumulation and biotransformation of 1,2-bis (2,4,6-tribromophenoxyethane) (BTBPE) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH) in zebrafish (Danio rerio). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123460. [PMID: 38290655 DOI: 10.1016/j.envpol.2024.123460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/01/2024]
Abstract
Despite the increasing production, use, and ubiquitous occurrence of novel brominated flame retardants (NBFRs), little information is available regarding their fate in aquatic organisms. In this study, the bioaccumulation and biotransformation of two typical NBFRs, i.e., 1,2-bis (2,4,6-tribromophenoxyethane) (BTBPE) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH), were investigated in tissues of zebrafish (Danio rerio) being administrated a dose of target chemicals through their diet. Linear accumulation was observed for both BTBPE and TBECH in the muscle, liver, gonads, and brain of zebrafish, and the elimination of BTBPE and TBECH in all tissues followed pseudo-first-order kinetics, with the fastest depuration rate occurring in the liver. BTBPE and TBECH showed low bioaccumulation potential in zebrafish, with biomagnification factors (BMFs) < 1 in all tissues. Individual tissues' function and lipid content are vital factors affecting the distribution of BTBPE and TBECH. Stereoselective accumulation of TBECH enantiomers was observed in zebrafish tissues, with first-eluting enantiomers, i.e. E1-α-TBECH and E1-β-TBECH, preferentially accumulated. Additionally, the transformation products (TPs) in the zebrafish liver were comprehensively screened and identified using high-resolution mass spectrometry. Twelve TPs of BTBPE and eight TPs of TBECH were identified: biotransformation pathways involving ether cleavage, debromination, hydroxylation, and methoxylation reactions for BTBPE and hydroxylation, debromination, and oxidation processes for TBECH. Biotransformation is also a vital factor affecting the bioaccumulation potential of these two NBFRs, and the environmental impacts of NBFR TPs should be further investigated in future studies. The findings of this study provide a scientific basis for an accurate assessment of the ecological and environmental risks of BTBPE and TBECH.
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Affiliation(s)
- Yu-Yu Wang
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Wei-Keng Luo
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Song-Xiong Tang
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Jun Xiang
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Yao Dang
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Bin Tang
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China.
| | - Qi-Yuan Lu
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Feng-Shan Cai
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Ming-Zhong Ren
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Yun-Jiang Yu
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
| | - Jing Zheng
- State Environmental Protection Key Laboratory of Environmental Pollution Health Risk Assessment, Research Center of Emerging Contaminants, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510530, PR China
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Yang W, Braun JM, Vuong AM, Percy Z, Xu Y, Xie C, Deka R, Calafat AM, Ospina M, Yolton K, Cecil KM, Lanphear BP, Chen A. Patterns of urinary organophosphate ester metabolite trajectories in children: the HOME Study. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2024; 34:251-259. [PMID: 37777668 PMCID: PMC10988284 DOI: 10.1038/s41370-023-00605-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 09/03/2023] [Accepted: 09/19/2023] [Indexed: 10/02/2023]
Abstract
BACKGROUND Organophosphate esters (OPEs) have replaced flame retardant polybrominated diphenyl ethers as flame retardants in consumer products, but few longitudinal studies have characterized childhood OPE exposure. OBJECTIVE We aimed to examine the exposure pattern of urinary OPE metabolites in children. METHODS We quantified three urinary OPE metabolites five times in children (1, 2, 3, 5, 8 years) from 312 mother-child pairs in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort in Cincinnati, Ohio, USA. We examined the associations of average maternal OPE metabolite concentrations with OPE metabolite concentrations in childhood, characterized childhood OPE trajectories with latent class growth analysis (LCGA), and examined factors related to trajectory membership. RESULTS Bis(2-chloroethyl) phosphate (BCEP) had the lowest median concentrations over time (0.66-0.97 mg/L) while the median concentrations of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) increased with age (1.44-3.80 mg/L). The median concentrations of diphenyl phosphate (DPHP) fluctuated between 1.96 and 2.69 mg/L. Intraclass correlation coefficients for urinary metabolites measured at five time points indicated high variability within individuals (0.13-0.24). Average maternal urinary BCEP and BDCIPP were associated with concentrations in early childhood. Maternal education, the birth year of the child, and having a carpet in the main activity room were associated with BCEP and BDCIPP trajectory while none of the factors were associated with DPHP trajectory. SIGNIFICANCE The trajectory analysis showed different patterns of urinary OPE metabolite concentrations, suggesting the need to collect multiple samples to adequately reflect OPE exposure. IMPACT STATEMENT In this well-established cohort, we evaluated the patterns of urinary OPE metabolites in children ages 1-8 years. The number of repeated measures over childhood has not been achieved in prior studies. Our results suggested the high variability of urinary OPE metabolites within individuals. Maternal metabolite concentrations during pregnancy were related to child concentrations at ages 1-3 years. BCEP, BDCIPP, and DPHP demonstrated different trajectories in children, which suggests that multiple samples may be required to capture OPE exposure patterns in childhood.
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Affiliation(s)
- Weili Yang
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - Joseph M Braun
- Department of Epidemiology, Brown University, Providence, RI, USA
| | - Ann M Vuong
- Department of Epidemiology and Biostatistics, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Zana Percy
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Yingying Xu
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Changchun Xie
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Ranjan Deka
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Antonia M Calafat
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Maria Ospina
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Kimberly Yolton
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Kim M Cecil
- Department of Environmental and Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Bruce P Lanphear
- Child and Family Research Institute, BC Children's Hospital, Vancouver, BC, Canada
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Aimin Chen
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, PA, USA
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Morel C, Paoli J, Emond C, Debaugnies F, Hardy EM, Creta M, Montagne M, Borde P, Nieuwenhuyse AV, Duca RC, Schroeder H, Grova N. Pharmacokinetic characterisation of a valproate Autism Spectrum Disorder rat model in a context of co-exposure to α-Hexabromocyclododecane. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2024; 105:104343. [PMID: 38122861 DOI: 10.1016/j.etap.2023.104343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 12/23/2023]
Abstract
Assessing the role of α-hexabromocyclododecane α-HBCDD as a factor of susceptibility for Autism Spectrum disorders by using valproic acid-exposed rat model (VPA) required characterizing VPA pharmacokinetic in the context of α-HBCDD-co-exposure in non-pregnant and pregnant rats. The animals were exposed to α-HBCDD by gavage (100 ng/kg/day) for 12 days. This was followed by a single intraperitoneal dose of VPA (500 mg/kg) or a daily oral dose of VPA (500 mg/kg) for 3 days. Exposure to α-HBCDD did not affect the pharmacokinetics of VPA in pregnant or non-pregnant rats. Surprisingly, VPA administration altered the pharmacokinetics of α-HBCDD. VPA also triggered higher foetal toxicity and lethality with the PO than IP route. α-HBCDD did not aggravate the embryotoxicity observed with VPA, regardless of the route of exposure. Based on this evidence, a single administration of 500 mg/kg IP is the most suitable VPA model to investigate α-HBCDD co-exposure.
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Affiliation(s)
- C Morel
- Calbinotox EA-7488, Faculty of Science and Technology, University of Lorraine, Campus Aiguillettes, B.P. 70239, 54506 Vandœuvre-lès-Nancy, France.
| | - J Paoli
- Calbinotox EA-7488, Faculty of Science and Technology, University of Lorraine, Campus Aiguillettes, B.P. 70239, 54506 Vandœuvre-lès-Nancy, France; UMR Inserm 1256 nGERE, Nutrition-Génétique et exposition aux risques environnementaux, Institute of Medical Research (Pôle BMS) - University of Lorraine, B.P. 184, 54511 Nancy, France.
| | - C Emond
- Calbinotox EA-7488, Faculty of Science and Technology, University of Lorraine, Campus Aiguillettes, B.P. 70239, 54506 Vandœuvre-lès-Nancy, France; PKSH Inc., Crabtree, Quebec, Canada; School of Public Health, DSEST, University of Montreal, Montreal, Quebec, Canada.
| | - F Debaugnies
- Department of Medical Biology, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg.
| | - E M Hardy
- Department of Health Protection, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg.
| | - M Creta
- Department of Health Protection, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg.
| | - M Montagne
- Department of Health Protection, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg.
| | - P Borde
- Department of Medical Biology, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg.
| | - A Van Nieuwenhuyse
- Department of Health Protection, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg; Environment and Health, Department of Public Health and Primary Care, University of Leuven (KU Leuven), Leuven, Belgium.
| | - R C Duca
- Department of Health Protection, National Health Laboratory (LNS), Dudelange, Grand Duchy of Luxembourg; Environment and Health, Department of Public Health and Primary Care, University of Leuven (KU Leuven), Leuven, Belgium.
| | - H Schroeder
- Calbinotox EA-7488, Faculty of Science and Technology, University of Lorraine, Campus Aiguillettes, B.P. 70239, 54506 Vandœuvre-lès-Nancy, France; UMR Inserm 1256 nGERE, Nutrition-Génétique et exposition aux risques environnementaux, Institute of Medical Research (Pôle BMS) - University of Lorraine, B.P. 184, 54511 Nancy, France.
| | - N Grova
- Calbinotox EA-7488, Faculty of Science and Technology, University of Lorraine, Campus Aiguillettes, B.P. 70239, 54506 Vandœuvre-lès-Nancy, France; UMR Inserm 1256 nGERE, Nutrition-Génétique et exposition aux risques environnementaux, Institute of Medical Research (Pôle BMS) - University of Lorraine, B.P. 184, 54511 Nancy, France; Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity-Luxembourg Institute of Health, 29 rue Henri Koch, L-4354, Esch-Sur-Alzette, Grand Duchy of Luxembourg.
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Collins B, Slade D, Aillon K, Stout M, Betz L, Waidyanatha S, Ryan K. Plasma concentrations of tris(1-chloro-2-propyl) phosphate and a metabolite bis(2-chloroisopropyl) 1-carboxyethyl phosphate in Sprague-Dawley rats and B6C3F1/N mice from a chronic study of tris(chloropropyl) phosphate via feed. Toxicol Rep 2022; 9:690-698. [PMID: 35433273 PMCID: PMC9010517 DOI: 10.1016/j.toxrep.2022.03.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 11/16/2022] Open
Abstract
Tris(chloropropyl) phosphate (TCPP) is an organophosphorus flame retardant and plasticizer used in manufacturing and multiple consumer products. Commercial TCPP is a ubiquitous environmental contaminant and TCPP or its metabolites have been detected in human plasma and urine. In response to the demonstrated widespread human exposure and lack of toxicity data, the Division of the National Toxicology Program is investigating the chronic toxicity of TCPP following perinatal exposure in HSD:Sprague Dawley®SD® (HSD) rats (up to 20,000 ppm) and adult exposure in B6C3F1/N mice (females, up to 10,000 ppm; males up to 5000 ppm) to TCPP via feed. Systemic exposure and bioaccumulation were assessed by measuring plasma concentrations of tris(1-chloro-2-propyl)phosphate (TCIPP), the most abundant TCPP isomer. TCIPP concentrations in TCPP-exposed rats and mice ranged from 3.43 to 1180 ng/mL and increased with exposure concentration at all time points. No sex differences were observed in rats, but male mice had higher TCIPP concentrations than females. TCIPP did not bioaccumulate in rats or mice over the course of the study. Low TCIPP concentrations were seen in some control rats and mice that were attributed to background TCPP present during sample collection, preparation and/or analysis. Bis(2-chloroisopropyl) 1-carboxyethyl phosphate (BCPCP), a TCPP metabolite, was quantified in plasma from control and selected exposed animals. Results showed increases in BCPCP concentration that were proportional to exposure concentration in rats and mice at concentrations much higher than TCIPP, indicating that BCPCP might be a more suitable biomarker of TCPP exposure. Tris(chloropropyl)phosphate (TCPP) has widespread environmental exposure. We measured plasma levels of TCPP following chronic feed exposure in rodents. The most abundant isomer of TCPP (TCIPP) increased with exposure with no accumulation. Bis(2-chloroisopropyl)1-carboxyethyl phosphate (BCPCP) levels were higher than TCIPP. Metabolite BCPCP may be a more suitable biomarker for TCPP exposure.
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Wang X, Zhu Q, Liao C, Jiang G. Human internal exposure to organophosphate esters: A short review of urinary monitoring on the basis of biological metabolism research. JOURNAL OF HAZARDOUS MATERIALS 2021; 418:126279. [PMID: 34329041 DOI: 10.1016/j.jhazmat.2021.126279] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/23/2021] [Accepted: 05/29/2021] [Indexed: 06/13/2023]
Abstract
As alternatives to traditional brominated flame retardants, organophosphate flame retardants (OPFRs), especially for organophosphate esters (OPEs) -- the most widely used and investigated OPFRs, have raised people's concern on their environmental and health-related risks over the years. Considering their extensive environmental occurrence and potential adverse effects, precise estimation on the human body burden of OPEs will be conducive to the restrictions on the usage of these compounds scientifically. Biomonitoring research can provide precise information on human exposure to OPEs as it reveals the degree of external exposure from all exposure routes. Knowledge on biotransformation and metabolism of OPEs in the biosystems is of great significance for our understanding of the internal exposure to these compounds. In this study, the biological metabolic processes of nine OPEs prevalent in the environment, involving tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tripropyl phosphate (TPrP), tri-n-butyl phosphate (TnBP), tris(2-butoxyethyl) phosphate (TBOEP), triphenyl phosphate (TPhP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP), are comprehensively reviewed. Specifically, the metabolic pathway, kinetics and mechanism of OPEs are depicted in detail. Under this context, the advances and limitations on biomonitoring of OPE metabolites in human urine are summarized. The requirements of specificity, quantitative stability, high detection frequency/concentration are needed for OPE metabolites to be considered and validated as biomarkers. Thus far, deeper elucidations on the metabolic processes and identification of biomarkers of OPEs are urgently required, given that some OPEs have no suitable biomarkers in human biomonitoring. For better assessment of the body burden of OPEs in humans, reliable and effective methodologies for urine sampling and estimation on internal exposure to OPEs need to be further developed in the future.
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Affiliation(s)
- Xin Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingqing Zhu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunyang Liao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
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Wang XS, Tan X, Zhang Y, Hu XX, Shen C, Huang YY, Fu HL, Yu RH, He CT. The enantiomer-selective metabolism of hexabromocyclododecanes (HBCDs) by human HepG2 cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 768:144430. [PMID: 33736337 DOI: 10.1016/j.scitotenv.2020.144430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
Although hepatic metabolism of hexabromocyclododecanes (HBCDs) played critical roles in the selective bioaccumulation of HBCDs in humans, the hepatic metabolism patterns of its enantiomers remained ambiguous. Aiming to elucidate the mechanism on hepatic metabolism of hexabromocyclododecanes (HBCDs) enantiomers, the enantiomers ((+)-α-HBCD, (-)-α-HBCD, (+)-γ-HBCD, and (-)-γ-HBCD), the diastereoisomers (α-, β-, and γ-HBCDs) and the mixed of α- and γ-HBCDs were incubated with human HepG2 cell under different exposure levels in the present study. The clearance percentages ranked as γ-HBCD enantiomers >β-HBCD enantiomers >α-HBCD enantiomers at the same exposure levels. The clearance percentages of (+)- and (-)-α-HBCDs increased when cells were exposed to racemic α-HBCD and the mixture of racemic α- and γ-HBCDs (p < 0.05). (-)-γ-HBCD was more resistant to human hepatic metabolism than (+)-γ-HBCD, leading to the enantiomer fractions (EFs) of γ-HBCD lower than 0.50. (-)-α-HBCD was slightly more metabolized when independently exposed to α-HBCD, while (+)-α-HBCD was more preferentially metabolized after exposure to α- and γ-HBCD mixtures. Hydroxylation and debromination HBCD metabolites were identified. In addition, the different EFs of HBCDs in cells and mediums suggested the selective transfer of chiral HBCDs and HBCD metabolites through the cell membrane. This study provided new insight into the enantiomer-selective metabolism of HBCDs.
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Affiliation(s)
- Xue-Song Wang
- School of Agriculture, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Emergency Test for Dangerous Chemicals, China National Analytical Center Guangzhou (Guangdong Institute of Analysis), Guangdong Academy of Sciences, 100 Xianlie Middle Road, Guangzhou 510070, China
| | - Xiao Tan
- School of Agriculture, Sun Yat-sen University, Guangzhou 510275, China
| | - Yan Zhang
- School of Life Science, Sun Yat-sen University, Guangzhou 510275, China
| | - Xia-Xin Hu
- School of Agriculture, Sun Yat-sen University, Guangzhou 510275, China
| | - Chuang Shen
- School of Safety and Environmental Engineering, Hunan Institute of Technology, Hengyang 421002, China
| | - Ying-Ying Huang
- School of Safety and Environmental Engineering, Hunan Institute of Technology, Hengyang 421002, China
| | - Hui-Ling Fu
- School of Safety and Environmental Engineering, Hunan Institute of Technology, Hengyang 421002, China
| | - Ruo-Han Yu
- School of Life Science, Sun Yat-sen University, Guangzhou 510275, China
| | - Chun-Tao He
- School of Agriculture, Sun Yat-sen University, Guangzhou 510275, China.
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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Wallace H, Benford D, Fürst P, Rose M, Ioannidou S, Nikolič M, Bordajandi LR, Vleminckx C. Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food. EFSA J 2021; 19:e06421. [PMID: 33732387 PMCID: PMC7938899 DOI: 10.2903/j.efsa.2021.6421] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes (HBCDDs) in food. HBCDDs, predominantly mixtures of the stereoisomers α-, β- and γ-HBCDD, were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDDs in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level (LOAEL) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health-based guidance value (HBGV) was not considered appropriate. Instead, the margin of exposure (MOE) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDDs in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDDs were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDDs across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.
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Ding J, Deng T, Ye X, Covaci A, Liu J, Yang F. Urinary metabolites of organophosphate esters and implications for exposure pathways in adolescents from Eastern China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 695:133894. [PMID: 31425989 DOI: 10.1016/j.scitotenv.2019.133894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/10/2019] [Accepted: 08/11/2019] [Indexed: 06/10/2023]
Abstract
Ten urinary biomarkers of organophosphate esters (OPEs) from six parent OPEs were analyzed in urine from adolescents students in Eastern China. Bis (1,3-dichloro-2-propyl) phosphate, urinary biomarker of tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), was detected in all urine samples with the highest residual concentration of 6.2 ng/mL (median). Bis (1-chloro-propyl) hydroxyl-2-propyl phosphate, dibutyl phosphate, biomarkers of tris (1-chloro-2-propyl) phosphate (TCIPP), tri-n-butyl phosphate (TNBP), respectively, and tris (2-chloroethyl) phosphate (TCEP), were also frequently detected with median concentrations of 1.5, 2.6 and 0.3 ng/mL, respectively. Results indicate that exposure to OPEs, in particular to TDCIPP, TNBP, TCIPP and TCEP, was highly prevalent for adolescent students. The exposure pathways of OPEs were then evaluated according to the OPE internal body burdens (IBBs). Three pathways were identified as the main pathways for adolescents exposed to OPEs including dermal absorption, oral intake of food and dust and inhalation.
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Affiliation(s)
- Jinjian Ding
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, China; Research Institute of Zhejiang University-Taizhou, Zhejiang, China
| | - Tongqing Deng
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, China
| | - Xiaoqing Ye
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, China
| | - Adrian Covaci
- Toxicological Center, University of Antwerp, Wilrijk, Belgium
| | - Jing Liu
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, China
| | - Fangxing Yang
- Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Natural Resources and Environmental Science, Zhejiang University, Hangzhou, China.
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Chen R, Hou R, Hong X, Yan S, Zha J. Organophosphate flame retardants (OPFRs) induce genotoxicity in vivo: A survey on apoptosis, DNA methylation, DNA oxidative damage, liver metabolites, and transcriptomics. ENVIRONMENT INTERNATIONAL 2019; 130:104914. [PMID: 31226563 DOI: 10.1016/j.envint.2019.104914] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/07/2019] [Accepted: 06/09/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND As potential substitutes for polybrominated diphenyl ethers (PBDEs), organophosphate flame retardants (OPFRs) have been frequently detected in the environment. However, the genotoxicity induced by these OPFRs has rarely been described, and the results reported in previous studies are conflicting and inconsistent. OBJECTIVES The present study aimed to determine how OPFRs induced genetic toxicity in vivo. METHODS Using Chinese rare minnow as a model, the toxicity of three OPFRs was screened with RNA-seq. To verify the OPFR-induced genotoxicity, alkaline comet assay, cell apoptosis analysis, HPLC-based DNA methylation assay, 8-OHdG assay, bioconcentration and biotransformation investigation were performed. RESULTS According to transcriptomic data, TDCIPP exposure substantially altered the pathways related to DNA damage, including the cell cycle, DNA replication, Fanconi anemia pathway, p53 signaling pathway, and various DNA repair pathways. Although TBOEP and TPHP did not affect DNA damage, TDCIPP induced DNA damage in a dose-dependent manner. TDCIPP also induced apoptosis, altered the activities of caspase-3 and -9, and increased the 8-OHdG levels, while a significant difference in the levels of DNA methylation induced by OPFRs was not observed. CONCLUSIONS Based on these results, TDCIPP induced DNA oxidative damage, eventually leading to genotoxicity in vivo.
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Affiliation(s)
- Rui Chen
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100085, China
| | - Rui Hou
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China
| | - Xiangsheng Hong
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100085, China
| | - Saihong Yan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100085, China
| | - Jinmiao Zha
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Beijing Key Laboratory of Industrial Wastewater Treatment and Reuse, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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11
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A Survey of Orbitrap All Ion Fragmentation Analysis Assessed by an R MetaboList Package to Study Small-Molecule Metabolites. Chromatographia 2018. [DOI: 10.1007/s10337-018-3536-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Abdallah MAE, Sharkey M, Berresheim H, Harrad S. Hexabromocyclododecane in polystyrene packaging: A downside of recycling? CHEMOSPHERE 2018; 199:612-616. [PMID: 29459351 DOI: 10.1016/j.chemosphere.2018.02.084] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 06/08/2023]
Abstract
While there are no regulatory fire safety obligations for polystyrene (PS) when used as packaging material, concerns exist that such packaging material may contain the flame retardant hexabromocyclododecane (HBCDD) as a result of uncontrolled recycling activities. To evaluate these concerns, we collected 50 samples of PS packaging materials from the UK and 20 from Ireland. HBCDD was detected in 63 (90%) of samples, with concentrations in 4 samples from Ireland exceeding the EU's low POP concentration limit (LPCL) of 0.1% above which articles may not be recycled. Moreover, 2 further samples contained HBCDD >0.01%. While our samples were obtained in the 12 month period prior to the March 2016 introduction of the EU's 0.01% concentration limit above which articles may not be placed on the market, our data suggest that continued monitoring is required to assess compliance with this limit value. Ratios of α vs. γ-HBCDD in our EPS packaging samples (average = 0.63) exceeded significantly (p = 0.025) those in EPS building insulation material samples (average = 0.24) reported previously for Ireland. This shift towards α-HBCDD in packaging EPS is consistent with the additional thermal processing experienced by recycled PS and suggests the source of HBCDD in PS packaging is recycled PS insulation foam. This is of concern owing to the higher bioavailability and lower metabolic clearance of α-HBCDD compared to the β- and γ-isomers.
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Affiliation(s)
- Mohamed Abou-Elwafa Abdallah
- School of Geography, Earth & Environmental Sciences, University of Birmingham, UK; Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt
| | - Martin Sharkey
- School of Physics, National University of Ireland Galway, Ireland
| | | | - Stuart Harrad
- School of Geography, Earth & Environmental Sciences, University of Birmingham, UK.
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13
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Nguyen KH, Abou-Elwafa Abdallah M, Moehring T, Harrad S. Biotransformation of the Flame Retardant 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) in Vitro by Human Liver Microsomes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:10511-10518. [PMID: 28846412 DOI: 10.1021/acs.est.7b02834] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The technical mixture of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH or DBE-DBCH) and the pure β-TBECH isomer were subjected to in vitro biotransformation by human liver microsomes (HLM). After 60 min of incubation, 5 potential metabolites of TBECH were identified in microsomal assays of both the TBECH mixture and β-TBECH using ultraperformance liquid chromatography-Q-Exactive Orbitrap mass spectrometry. These include mono- and dihydroxylated TBECH and mono- and dihydroxylated TriBECH as well as an α-oxidation metabolite bromo-(1,2-dibromocyclohexyl)-acetic acid. Our results indicate potential hepatic biotransformation of TBECH via cyctochrome P450-catalyzed hydroxylation, debromination, and α-oxidation. Kinetic studies revealed that the formation of monohydroxy-TBECH, dihydroxy-TBECH, and monohydroxy-TriBECH were best fitted to a Michaelis-Menten enzyme kinetic model. Respective estimated Vmax values (maximum metabolic rate) for these metabolites were 11.8 ± 4, 0.6 ± 0.1, and 10.1 ± 0.8 pmol min-1 mg protein-1 in TBECH mixture and 4992 ± 1340, 14.1 ± 4.9, and 66.1 ± 7.3 pmol min-1 mg protein-1 in β-TBECH. This indicates monohydroxy-TBECH as the major metabolite of TBECH by in vitro HLM-based assay. The estimated in vitro intrinsic clearance (Clint) of TBECH mixture was slower (P < 0.05) than that of pure β-TBECH. While the formation of monohydroxy-TBECH may reduce the bioaccumulation potential and provide a useful biomarker for monitoring TBECH exposure, further studies are required to fully understand the levels and toxicological implications of the identified metabolites.
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Affiliation(s)
- Khanh-Hoang Nguyen
- School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B5 2TT United Kingdom
| | - Mohamed Abou-Elwafa Abdallah
- School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B5 2TT United Kingdom
- Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University , 71526 Assiut, Egypt
| | - Thomas Moehring
- Thermo Fisher Scientific (GmbH) Bremen , Hanna-Kunath-Strasse 11, 28199 Bremen, Germany
| | - Stuart Harrad
- School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B5 2TT United Kingdom
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14
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Erratico C, Zheng X, van den Eede N, Tomy G, Covaci A. Stereoselective Metabolism of α-, β-, and γ-Hexabromocyclododecanes (HBCDs) by Human Liver Microsomes and CYP3A4. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:8263-8273. [PMID: 27401979 DOI: 10.1021/acs.est.6b01059] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This is the first study investigating the in vitro metabolism of α-, β-, and γ-hexabromocyclododecane (HBCD) stereoisomers in humans and providing semiquantitative metabolism data. Human liver microsomes were incubated with individual racemic mixtures and with individual stereoisomers of α-, β-, and γ-HBCDs, the hydroxylated metabolites formed were analyzed by liquid chromatography-tandem mass spectrometry, and the value of the intrinsic in vitro clearance (Clint,vitro) was calculated. Several mono- and dihydroxylated metabolites of α-, β-, and γ-HBCDs were formed, with mono-OH-HBCDs being the major metabolites. No stereoisomerization of any of the six α-, β-, and γ-HBCD isomers catalyzed by cytochrome P450 (CYP) enzymes occurred. The value of Clint,vitro of α-HBCDs was significantly lower than that of β-HBCDs, which, in turn, was significantly lower than that of γ-HBCDs (p < 0.05). Such differences were explained by the significantly lower values of Clint,vitro of each α-HBCD stereoisomer than those of the β- and γ-HBCD stereoisomers. In addition, significantly lower values of Clint,vitro of the (-) over the (+)α- and β-HBCD stereoisomers, but not γ-HBCDs, were obtained. Our data offer a possible explanation of the enrichment of α-HBCDs over β- and γ-HBCDs on the one hand and, on the other hand, of (-)α-HBCDs over (+)α-HBCDs previously reported in human samples. It also offers information about the mechanism resulting in such enrichments, the stereoisomer-selective metabolism of α-, β-, and γ-HBCDs catalyzed by CYPs with the lack of stereoisomerization.
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Affiliation(s)
- Claudio Erratico
- Toxicological Center, University of Antwerp , Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Xiaobo Zheng
- Toxicological Center, University of Antwerp , Universiteitsplein 1, 2610 Wilrijk, Belgium
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, China
| | - Nele van den Eede
- Toxicological Center, University of Antwerp , Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Gregg Tomy
- Department of Chemistry, University of Manitoba , Winnipeg R3T 2N2, Canada
| | - Adrian Covaci
- Toxicological Center, University of Antwerp , Universiteitsplein 1, 2610 Wilrijk, Belgium
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15
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Effects of primary metabolites of organophosphate flame retardants on transcriptional activity via human nuclear receptors. Toxicol Lett 2016; 245:31-9. [DOI: 10.1016/j.toxlet.2016.01.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/01/2015] [Accepted: 01/11/2016] [Indexed: 11/20/2022]
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16
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Van den Eede N, de Meester I, Maho W, Neels H, Covaci A. Biotransformation of three phosphate flame retardants and plasticizers in primary human hepatocytes: untargeted metabolite screening and quantitative assessment. J Appl Toxicol 2016; 36:1401-8. [DOI: 10.1002/jat.3293] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Revised: 12/12/2015] [Accepted: 12/22/2015] [Indexed: 01/14/2023]
Affiliation(s)
- Nele Van den Eede
- Toxicological Center, Department of Pharmaceutical Sciences; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium
| | - Ingrid de Meester
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium
| | - Walid Maho
- Toxicological Center, Department of Pharmaceutical Sciences; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium
| | - Hugo Neels
- Toxicological Center, Department of Pharmaceutical Sciences; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium
| | - Adrian Covaci
- Toxicological Center, Department of Pharmaceutical Sciences; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium
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17
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Van den Eede N, Tomy G, Tao F, Halldorson T, Harrad S, Neels H, Covaci A. Kinetics of tris (1-chloro-2-propyl) phosphate (TCIPP) metabolism in human liver microsomes and serum. CHEMOSPHERE 2016; 144:1299-1305. [PMID: 26473552 DOI: 10.1016/j.chemosphere.2015.09.049] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/08/2015] [Accepted: 09/11/2015] [Indexed: 06/05/2023]
Abstract
Tris(1-chloro-2-propyl) phosphate (TCIPP) is an emerging contaminant which is ubiquitous in the indoor and outdoor environment. Moreover, its presence in human body fluids and biota has been evidenced. Since no quantitative data exist on the biotransformation or stability of TCIPP in the human body, we performed an in vitro incubation of TCIPP with human liver microsomes (HLM) and human serum (HS). Two metabolites, namely bis(2-chloro-isopropyl) phosphate (BCIPP) and bis(1-chloro-2-propyl) 1-hydroxy-2-propyl phosphate (BCIPHIPP), were quantified in a kinetic study using HLM or HS (only BCIPP, the hydrolysis product) and LC-MS. The Michaelis-Menten model fitted best the NADPH-dependent formation of BCIPHIPP and BCIPP in HLM, with respective V(MAX) of 154 ± 4 and 1470 ± 110 pmol/min/mg protein and respective apparent K(m) of 80.2 ± 4.4 and 96.1 ± 14.5 μM. Hydrolases, which are naturally present in HLM, were also involved in the production of BCIPP. A HS paraoxonase assay could not detect any BCIPP formation above 38.6 ± 10.8 pmol/min/μL serum. Our data indicate that BCIPP is the major metabolite of TCIPP formed in the liver. To our knowledge, this is the first quantitative assessment of the stability of TCIPP in tissues of humans or any other species. Further research is needed to confirm whether these biotransformation reactions are associated with a decrease or increase in toxicity.
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Affiliation(s)
- Nele Van den Eede
- Toxicological Center, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium.
| | - Gregg Tomy
- Department of Chemistry, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Fang Tao
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Thor Halldorson
- Department of Chemistry, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Stuart Harrad
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Hugo Neels
- Toxicological Center, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium
| | - Adrian Covaci
- Toxicological Center, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium.
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18
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Zhang J, Abdallah MAE, Williams TD, Harrad S, Chipman JK, Viant MR. Gene expression and metabolic responses of HepG2/C3A cells exposed to flame retardants and dust extracts at concentrations relevant to indoor environmental exposures. CHEMOSPHERE 2016; 144:1996-2003. [PMID: 26551197 DOI: 10.1016/j.chemosphere.2015.10.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 09/28/2015] [Accepted: 10/03/2015] [Indexed: 06/05/2023]
Abstract
Humans are routinely exposed to mixtures of flame retardants (FRs) from multiple sources including indoor dust. As a model to explore the potential effects of FR exposure from indoor dust on human health, the molecular responses of human hepatoma cells (HepG2/C3A cells) to a defined mixture of FRs and to a dust extract were investigated using multiple non-targeted omics approaches. A solvent extract of an indoor dust standard reference material SRM2585 was used as the surrogate dust sample, while a mixture of four FRs (TCEP, TCIPP, TDCIPP and HBCD) was used to mimic the FR mixture in the indoor dust. Cytotoxicity tests indicated there were no significant changes to cell viability or cell integrity after a 24- or 72-h exposure of HepG2/C3A cells to the FR mixture or to the dust extract. However, transcriptomics revealed changes in gene expression associated with the metabolism of xenobiotics (e.g. CYP1A1, CYP1A2, CYP2B6) in the dust extract group but not in the FR mixture group after a 72-h exposure. Few metabolic or lipidomic changes were detected in response to either the FR mixture or to the dust extract group. Given that the dust extract contained components that elicited a biological response, in contrast to the lack of response induced by the FR mixture, our findings suggest that the most likely causes of the molecular responses to indoor dust exposure lie in components other than the four FRs investigated, e.g. caused by PAHs or PCBs.
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Affiliation(s)
- Jinkang Zhang
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Mohamed Abou-Elwafa Abdallah
- School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK; Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University, 71526, Assiut, Egypt
| | - Timothy D Williams
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Stuart Harrad
- School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - James K Chipman
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Mark R Viant
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
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19
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Human dermal absorption of chlorinated organophosphate flame retardants; implications for human exposure. Toxicol Appl Pharmacol 2016; 291:28-37. [DOI: 10.1016/j.taap.2015.12.004] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/14/2015] [Accepted: 12/15/2015] [Indexed: 11/24/2022]
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20
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Harrad S, Abdallah MAE. Concentrations of Polybrominated Diphenyl Ethers, Hexabromocyclododecanes and Tetrabromobisphenol-A in Breast Milk from United Kingdom Women Do Not Decrease over Twelve Months of Lactation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:13899-13903. [PMID: 25924207 DOI: 10.1021/acs.est.5b00539] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Conflicting evidence exists about whether concentrations of persistent organic chemicals in human milk decrease over the course of lactation. This has implications for the timing of sampling human milk for exposure assessment purposes. We examined this issue by measuring concentrations of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), the HBCD degradation products tetrabromocyclododecenes (TBCDs), and tetrabromobisphenol-A (TBBP-A) in human milk collected in 2010-2011 from 10 first-time mothers from Birmingham, UK. To evaluate whether concentrations varied significantly over the first 12 months postpartum, 12 samples were taken-one per month-from each mother, amounting to 120 samples overall. While concentrations of most of our target contaminants displayed no significant variation (p > 0.1) over the duration of our study, significant increases were detected in concentrations of ∑TBCDs (p = 0.029, average increase 1.4%/month) and BDE-153 (p = 0.058, average increase 4.2%/month). When compared to data obtained from a different set of UK mothers from a related but geographically wider catchment area sampled contemporaneously to this study, the ratio of median concentrations of BDE-153 to BDE-99 was markedly lower in the current study (0.46 compared to 1.32). This may reflect unidentified differences in exposure of the participants in the two studies.
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Affiliation(s)
- Stuart Harrad
- School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B15 2TT United Kingdom
| | - Mohamed Abou-Elwafa Abdallah
- School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B15 2TT United Kingdom
- Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University , 71526 Assiut, Egypt
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21
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Abdallah MAE, Pawar G, Harrad S. Evaluation of 3D-human skin equivalents for assessment of human dermal absorption of some brominated flame retardants. ENVIRONMENT INTERNATIONAL 2015; 84:64-70. [PMID: 26232142 DOI: 10.1016/j.envint.2015.07.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/07/2015] [Accepted: 07/14/2015] [Indexed: 06/04/2023]
Abstract
Ethical and technical difficulties inherent to studies in human tissues are impeding assessment of the dermal bioavailability of brominated flame retardants (BFRs). This is further complicated by increasing restrictions on the use of animals in toxicity testing, and the uncertainties associated with extrapolating data from animal studies to humans due to inter-species variations. To overcome these difficulties, we evaluate 3D-human skin equivalents (3D-HSE) as a novel in vitro alternative to human and animal testing for assessment of dermal absorption of BFRs. The percutaneous penetration of hexabromocyclododecanes (HBCD) and tetrabromobisphenol-A (TBBP-A) through two commercially available 3D-HSE models was studied and compared to data obtained for human ex vivo skin according to a standard protocol. No statistically significant differences were observed between the results obtained using 3D-HSE and human ex vivo skin at two exposure levels. The absorbed dose was low (less than 7%) and was significantly correlated with log Kow of the tested BFR. Permeability coefficient values showed increasing dermal resistance to the penetration of γ-HBCD>β-HBCD>α-HBCD>TBBPA. The estimated long lag times (>30 min) suggests that frequent hand washing may reduce human exposure to HBCDs and TBBPA via dermal contact.
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Affiliation(s)
- Mohamed Abou-Elwafa Abdallah
- Division of Environmental Health and Risk Management, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt.
| | - Gopal Pawar
- Division of Environmental Health and Risk Management, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Stuart Harrad
- Division of Environmental Health and Risk Management, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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22
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Zheng X, Erratico C, Abdallah MAE, Negreira N, Luo X, Mai B, Covaci A. In vitro metabolism of BDE-47, BDE-99, and α-, β-, γ-HBCD isomers by chicken liver microsomes. ENVIRONMENTAL RESEARCH 2015; 143:221-228. [PMID: 26505652 DOI: 10.1016/j.envres.2015.10.023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/04/2015] [Accepted: 10/20/2015] [Indexed: 06/05/2023]
Abstract
The in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and the individual α-, β- and γ-hexabromocyclododecane (HBCD) isomers catalyzed by cytochrome P450 (CYP) enzymes was studied using chicken liver microsomes (CLMs). Metabolites were identified using a liquid chromatography-tandem mass spectrometry method and authentic standards for the oxidative metabolites of BDE-47 and BDE-99. Six hydroxylated tetra-BDEs, namely 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42), 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47), 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), 4'-hydroxy-2,2',4,5'- tetrabromodiphenyl ether (4'-OH-BDE-49), and 2'-hydroxy-2,3',4,4'-tetrabromodiphenyl ether (2'-OH-BDE-66), were identified and quantified after incubation of BDE-47 with CLMs. 4'-OH-BDE-49 was the major metabolite formed. Three hydroxylated penta-BDEs (5'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99), 6'-hydroxy-2,2',4,4',5- pentabromodiphenyl ether (6'-OH-BDE-99), and 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether, 4'-OH-BDE-101, were formed incubating BDE-99 with CLMs. Concentrations of BDE-99 metabolites were lower than those of BDE-47. More than four mono-hydroxylated HBCD (OH-HBCD), more than four di-hydroxylated HBCD (di-OH-HBCD), more than five mono-hydroxylated pentabromocyclododecenes (OH-PBCD), and more than five di-hydroxylated pentabromocyclododecenes (di-OH-PBCD) were detected when α-, β-, or γ-HBCD were individually incubated with CLMs. Response values (the ratio between the peak areas of the target compound and its internal standard) for OH-HBCD were 1-3 orders of magnitude higher than those for OH-PBCD, di-OH-HBCD, and di-OH-PBCD, suggesting that OH-HBCD might be the major metabolites of α-, β- and γ-HBCD produced by CLMs. No diastereoisomeric or enantiomeric bioisomerisation was observed incubating α-, β- or γ-HBCD with CLMs. Collectively, our data suggest that (i) BDE-47 is metabolized at a faster rate than BDE-99 by CLMs, (ii) OH-HBCD are the major hydroxylated metabolites of α-, β- and γ-HBCD produced by CLMs and (iii) the diastereoisomeric or enantiomeric bioisomerisation of α-, β- and γ-HBCD is not mediated by chicken CYP enzymes.
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Affiliation(s)
- Xiaobo Zheng
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, People's Republic of China; Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China
| | - Claudio Erratico
- Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Mohamed Abou-Elwafa Abdallah
- Division of Environmental Health and Risk Management, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University, 71526 Assiut, Egypt
| | - Noelia Negreira
- Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Xiaojun Luo
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China
| | - Adrian Covaci
- Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
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Abdallah MAE, Pawar G, Harrad S. Effect of Bromine Substitution on Human Dermal Absorption of Polybrominated Diphenyl Ethers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10976-83. [PMID: 26301594 DOI: 10.1021/acs.est.5b03904] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Human dermal absorption of eight mono- to deca-brominated diphenyl ethers (PBDEs) was investigated for the first time using EPISKIN human skin equivalent tissue. Using a standard in vitro protocol, EPISKIN tissues mounted in specially designed diffusion cells were exposed to the target PBDEs for 24 h. Estimated steady-state flux (Jss) and permeation coefficients (Papp) across the skin increased with decreasing bromine substitution from BDE-153 (Papp = 4.0 × 10(-4) cm/h) to BDE-1 (Papp = 1.1 × 10(-2) cm/h). This was accompanied by an increase in the time required to traverse the skin tissue into the receptor fluid (lag time) from 0.25 h for BDE-1 to 1.26 h for BDE-153. Papp values for the studied PBDEs were correlated significantly (P < 0.05) with physicochemical parameters like water solubility and log KOW. While less brominated congeners achieved faster dermal penetration, higher PBDEs displayed greater accumulation within the skin tissue. The PBDEs thus accumulated represent a contaminant depot from which they may be slowly released to the systemic circulation over a prolonged period. Maximal percutaneous penetration was observed for BDE-1 (∼ 30% of the applied 500 ng/cm(2) dose). Interestingly, BDE-183 and BDE-209 showed very low dermal absorption, exemplified by a failure to reach the steady state within the 24 h exposure period that was studied.
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Affiliation(s)
- Mohamed Abou-Elwafa Abdallah
- Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham , Birmingham B15 2TT, United Kingdom
- Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University , 71526 Assiut, Egypt
| | - Gopal Pawar
- Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham , Birmingham B15 2TT, United Kingdom
| | - Stuart Harrad
- Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham , Birmingham B15 2TT, United Kingdom
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