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Oltramare C, Zennegg M, Graille M, Lerch S, Berthet A, Vernez D. Polychlorinated dibenzo- p-dioxin and dibenzofuran contamination of free-range eggs: estimation of the laying hen's soil ingestion based on a toxicokinetic model, and human consumption recommendations. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2024:1-13. [PMID: 39133508 DOI: 10.1080/19440049.2024.2384416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 07/15/2024] [Accepted: 07/17/2024] [Indexed: 08/13/2024]
Abstract
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are ubiquitous in the environment. The main route of human exposure is through food consumption. Soil contamination can be problematic for sanitary safety depending on the usage of the soil, such as farming. In case of environmental soil contamination with PCDD/Fs, hen's eggs may be contaminated due to soil ingestion by hens. For this reason, it is important to understand the parameters that influence eggs' contamination when hens are raised in contaminated areas. After the discovery of a contaminated area in Lausanne (Switzerland), we collected hens' eggs from ten domestic-produced eggs and one farm. Based on PCDD/F measurements of eggs and soil, and a toxicokinetic model, we estimated individual hen's soil intake levels and highlighted appropriate parameters to predict the dose ingested. Recommended weekly consumption for home-produced eggs was calculated based on the tolerable weekly intake proposed by EFSA in 2018. The most important parameter to assess the soil ingestion does not seem to be the soil coverage by vegetation but rather the hen's pecking behaviour, the latter being difficult to estimate objectively. For this reason, we recommend using a realistic soil ingestion interval to assess the distribution of egg PCDD/F concentration from free-range hens reared on contaminated soil. The addition of soil contamination in the toxicokinetic model can then be used to recommend to the general population weekly consumption of eggs. The consumption by adults of free-range eggs produced on land with soil containing >90 ng toxic-equivalent (TEQ)/kg dry soil should be avoided. Even with a low level of soil contamination (1-5 ng TEQ/kg dry soil), we would recommend consuming not more than 5 eggs per week for adults and no more than 2 eggs for children below 4 years old.
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Affiliation(s)
- Christelle Oltramare
- Department of Occupational Health and Environment, Center for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges, Switzerland
| | - Markus Zennegg
- EMPA, Laboratory for Advanced Analytical Technologies, Dübendorf, Switzerland
| | - Mélanie Graille
- Department of Occupational Health and Environment, Center for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges, Switzerland
| | - Sylvain Lerch
- Ruminant Nutrition and Emissions, Agroscope, Posieux, Switzerland
| | - Aurélie Berthet
- Department of Occupational Health and Environment, Center for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges, Switzerland
| | - David Vernez
- Department of Occupational Health and Environment, Center for Primary Care and Public Health (Unisanté), University of Lausanne, Epalinges, Switzerland
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2
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Eaton DL, Simon TW, Kaminski NE, Perdew GH, Nebert DW. Species differences in specific ligand-binding affinity and activation of AHR: The biological basis for calculation of relative effective potencies and toxic equivalence factors. Regul Toxicol Pharmacol 2024; 149:105598. [PMID: 38548044 DOI: 10.1016/j.yrtph.2024.105598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/25/2024] [Accepted: 03/05/2024] [Indexed: 05/01/2024]
Abstract
In 2022 the World Health Organization (WHO) published updated 'Toxic Equivalence Factors' (TEFs) for a wide variety of chlorinated dioxins, dibenzofurans and PCBs [collectively referred to as 'dioxin-like chemicals'; DLCs) that interact with the aryl hydrocarbon receptor (AHR)]. Their update used sophisticated statistical analysis of hundreds of published studies that reported estimation of 'Relative Effective Potency' (REP) values for individual DLC congeners. The weighting scheme used in their assessment of each study favored in vivo over in vitro studies and was based largely on rodent studies. In this Commentary, we highlight the large body of published studies that demonstrate large species differences in AHR-ligand activation and provide supporting evidence for our position that the WHO 2022 TEF values intended for use in human risk assessment of DLC mixtures will provide highly misleading overestimates of 'Toxic Equivalent Quotients' (TEQs), because of well-recognized striking differences in AHR ligand affinities between rodent (rat, mouse) and human. The data reviewed in our Commentary support the position that human tissue-derived estimates of REP/TEF values for individual DLC congeners, although uncertain, will provide much better, more realistic estimates of potential activation of the human AHR, when exposure to complex DLC mixtures occurs.
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Affiliation(s)
- David L Eaton
- Department of Environmental Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA.
| | | | - Norbert E Kaminski
- Department of Pharmacology and Toxicology, Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, USA
| | - Gary H Perdew
- The Pennsylvania State University, State College, PA, USA
| | - Daniel W Nebert
- Department of Environmental and Public Health Sciences, Center for Environmental Genetics, University of Cincinnati College of Medicine, USA; Department of Pediatrics & Molecular Developmental Biology, Division of Human Genetics, Cincinnati Children's Research Foundation, Cincinnati, OH, USA
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Yang X, Chen W, Jin J, Hu J. Levels, enrichment characteristics and dietary intake risk of polychlorinated dibenzo-p-dioxin/furans in traditional smoked pork. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 328:121657. [PMID: 37075920 DOI: 10.1016/j.envpol.2023.121657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/10/2023] [Accepted: 04/15/2023] [Indexed: 05/03/2023]
Abstract
The concentrations and TEQs of polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) in traditional smoked pork were significantly higher than those in raw pork, and mainly distributed in the surface layer. The main enriched congeners during traditional smoking were 2378-TCDF, 12378-PeCDF, 23478-PeCDF, 1234678-HpCDF, OCDF, 1234678-HpCDD and OCDD. The ability of each congener to transfer from the surface to the inner part was various. According to the dietary habits of local residents, PCDD/Fs in more than half of the traditional smoked pork samples posed a potential carcinogenic risk, and the risk in the surface samples were 1.02-10.2 times that of the corresponding inner samples. Some variables might be the important factors affecting the concentration of PCDD/Fs in smoked pork, such as the duration of smoking and the kind of fuel. It is recommended to achieve lower risk by reducing the consumption of smoked pork, especially the surface layer of smoked pork, and innovating traditional smoking technologies.
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Affiliation(s)
- Xinrui Yang
- College of Life and Environmental Science, Minzu University of China, Beijing, 100081, China; Hainan Ecological Environmental Monitoring Center, 98 Baiju Avenue, Haikou, 571126, China.
| | - Wenming Chen
- College of Life and Environmental Science, Minzu University of China, Beijing, 100081, China.
| | - Jun Jin
- College of Life and Environmental Science, Minzu University of China, Beijing, 100081, China; Key Laboratory of Ecology and Environment in Minority Areas (Minzu University of China), National Ethnic Affairs Commission, Beijing, 100081, China; Beijing Engineering Research Center of Food Environment and Public Health, Minzu University of China, Beijing, 100081, China.
| | - Jicheng Hu
- College of Life and Environmental Science, Minzu University of China, Beijing, 100081, China; Key Laboratory of Ecology and Environment in Minority Areas (Minzu University of China), National Ethnic Affairs Commission, Beijing, 100081, China; Beijing Engineering Research Center of Food Environment and Public Health, Minzu University of China, Beijing, 100081, China.
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Vernez D, Oltramare C, Sauvaget B, Demougeot-Renard H, Aicher L, Roth N, Rossi I, Radaelli A, Lerch S, Marolf V, Berthet A. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) soil contamination in Lausanne, Switzerland: Combining pollution mapping and human exposure assessment for targeted risk management. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 316:120441. [PMID: 36349640 DOI: 10.1016/j.envpol.2022.120441] [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: 08/23/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
In December 2020, high soil concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were discovered across large parts of Lausanne, Switzerland. Concentrations reached up to 640 ng TEQWHO-2005/kg dry weight. The most likely source was a former municipal waste incinerator. A three-step, multidisciplinary approach to human health risk assessment was conducted to determine the potential population exposure to PCDD/Fs and identify appropriate preventive measures. First, exposure scenarios were developed based on contaminated land uses. Second, the toxicological risks of different scenarios were evaluated using a toxicokinetic model estimating increases in blood serum PCDD/F concentrations over background concentrations from the general population's food consumption. Third, a detailed geostatistical mapping of PCDD/F soil contamination was performed. Stochastic simulations with an external drift and an anisotropic model of the variogram were generated to incorporate the effects of distance from emission source, topography, and main wind directions on the spatial distribution of PCDD/Fs in topsoil. Three main scenarios were assessed: i) direct ingestion of soil by children in playgrounds; ii) consumption of vegetables from private gardens by children and adults; and iii) consumption of food from livestock and poultry raised on contaminated soil. The worst exposure scenario involved the consumption of eggs from private hen houses, resulting in PCDD/F concentrations in serum an order of magnitude higher than might normally be expected. No relevant increases in serum concentrations were calculated for direct soil ingestion and vegetable consumption, except for cucurbitaceous vegetables. Combining mapping and exposure scenario assessment resulted in targeted protective measures for land users, especially concerning food consumption. The results also raised concerns about the potential unsafe consumption of products derived from animals raised on land with PCDD/F concentrations only moderately over environmental background levels.
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Affiliation(s)
- David Vernez
- Department of Occupational and Environmental Health, Center for Primary Care and Public Health (Unisanté), University of Lausanne, CH-1066 Epalinges, Switzerland.
| | - Christelle Oltramare
- Department of Occupational and Environmental Health, Center for Primary Care and Public Health (Unisanté), University of Lausanne, CH-1066 Epalinges, Switzerland
| | | | | | - Lothar Aicher
- Swiss Centre for Applied Human Toxicology (SCAHT) and Department of Pharmaceutical Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Nicolas Roth
- Swiss Centre for Applied Human Toxicology (SCAHT) and Department of Pharmaceutical Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Isabelle Rossi
- Department of Occupational and Environmental Health, Center for Primary Care and Public Health (Unisanté), University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Arianna Radaelli
- Public Health Service, Canton of Vaud, CH-1014 Lausanne, Switzerland
| | - Sylvain Lerch
- Ruminant Research Group, Agroscope, CH-1725 Posieux, Switzerland
| | | | - Aurélie Berthet
- Department of Occupational and Environmental Health, Center for Primary Care and Public Health (Unisanté), University of Lausanne, CH-1066 Epalinges, Switzerland
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Svobodová J, Procházková J, Kabátková M, Krkoška M, Šmerdová L, Líbalová H, Topinka J, Kléma J, Kozubík A, Machala M, Vondráček J. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Disrupts Control of Cell Proliferation and Apoptosis in a Human Model of Adult Liver Progenitors. Toxicol Sci 2020; 172:368-384. [PMID: 31536130 DOI: 10.1093/toxsci/kfz202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) activation has been shown to alter proliferation, apoptosis, or differentiation of adult rat liver progenitors. Here, we investigated the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated AhR activation on a human model of bipotent liver progenitors, undifferentiated HepaRG cells. We used both intact undifferentiated HepaRG cells, and the cells with silenced Hippo pathway effectors, yes-associated protein 1 (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), which play key role(s) in tissue-specific progenitor cell self-renewal and expansion, such as in liver, cardiac, or respiratory progenitors. TCDD induced cell proliferation in confluent undifferentiated HepaRG cells; however, following YAP, and, in particular, double YAP/TAZ knockdown, TCDD promoted induction of apoptosis. These results suggested that, unlike in mature hepatocytes, or hepatocyte-like cells, activation of the AhR may sensitize undifferentiated HepaRG cells to apoptotic stimuli. Induction of apoptosis in cells with silenced YAP/TAZ was associated with upregulation of death ligand TRAIL, and seemed to involve both extrinsic and mitochondrial apoptosis pathways. Global gene expression analysis further suggested that TCDD significantly altered expression of constituents and/or transcriptional targets of signaling pathways participating in control of expansion or differentiation of liver progenitors, including EGFR, Wnt/β-catenin, or tumor growth factor-β signaling pathways. TCDD significantly upregulated cytosolic proapoptotic protein BMF (Bcl-2 modifying factor) in HepaRG cells, which could be linked with an enhanced sensitivity of TCDD-treated cells to apoptosis. Our results suggest that, in addition to promotion of cell proliferation and alteration of signaling pathways controlling expansion of human adult liver progenitors, AhR ligands may also sensitize human liver progenitor cells to apoptosis.
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Affiliation(s)
- Jana Svobodová
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno 61137, Czech Republic
| | - Jiřina Procházková
- Department of Chemistry and Toxicology, Veterinary Research Institute, Brno 62100, Czech Republic
| | - Markéta Kabátková
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Martin Krkoška
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno 61137, Czech Republic
| | - Lenka Šmerdová
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Helena Líbalová
- Department of Genetic Ecotoxicology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
| | - Jan Topinka
- Department of Genetic Ecotoxicology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
| | - Jiří Kléma
- Department of Computer Science, Czech Technical University, Prague 12135, Czech Republic
| | - Alois Kozubík
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
| | - Miroslav Machala
- Department of Chemistry and Toxicology, Veterinary Research Institute, Brno 62100, Czech Republic
| | - Jan Vondráček
- Department of Cytokinetics, Institute of Biophysics of the Czech Academy of Sciences, Brno 61265, Czech Republic
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6
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Rusin M, Dziubanek G, Marchwińska-Wyrwał E, Ćwieląg-Drabek M, Razzaghi M, Piekut A. PCDDs, PCDFs and PCBs in locally produced foods as health risk factors in Silesia Province, Poland. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 172:128-135. [PMID: 30708223 DOI: 10.1016/j.ecoenv.2019.01.052] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/08/2019] [Accepted: 01/12/2019] [Indexed: 06/09/2023]
Abstract
Dioxins (PCDDs), furans (PCDFs) and polychlorinated biphenyls (PCBs) emitted into the environment can accumulate in foods and become a significant source of dietary exposure for consumers of these compounds. This study aims to assess the dietary exposure of the residents in a rural area of the Silesia region in southern Poland to PCDDs, PCDFs and PCBs. The goal is to estimate cancer and non-cancer health risks due to the consumption of foods of animal origin. The area has relatively higher concentration of PCDDs, PCDFs and PCBs in the air in comparison to large industrialized cities of the Silesia province. Three popular foods of animal origin, namely free-range chicken meat, free-range chicken eggs, and cow milk produced in the farms were used. The control samples were the same foods from the local grocery stores. Two exposure scenarios were considered: Firstly that residents consumed free-range foods and secondly that the food items were purchased from stores in the study area. In the first scenario, exposure to concentrations of PCDDs, PCDFs, and dioxin-like PCBs (dl-PCBs) yielded evidence of elevated cancer and non-cancer risks. The hazard quotient (HQ) was 71.3 for non-cancer risk and 7.5 × 10-3 for cancer risk. The health risk from exposure to PCDDs, PCDFs and dl-PCBs in the second scenario was 6.9 × 10-4 and HQ = 0.8, respectively. Implementation of educational activities in the study area is needed to increase the resident's awareness of the risks associated with the emissions of chlorinated persistent organic pollutants to the environment, including aspects such as the main sources of the emission and how to avoid exposure to these compounds.
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Affiliation(s)
- Monika Rusin
- Department of Environmental Health Risk Factors, School of Public Health in Bytom, Medical University of Silesia in Katowice, ul. Piekarska 18, 42-902 Bytom, Poland.
| | - Grzegorz Dziubanek
- Department of Environmental Health Risk Factors, School of Public Health in Bytom, Medical University of Silesia in Katowice, ul. Piekarska 18, 42-902 Bytom, Poland.
| | - Ewa Marchwińska-Wyrwał
- Department of Environmental Health, School of Public Health in Bytom, Medical University of Silesia in Katowice, ul. Piekarska 18, 42-902 Bytom, Poland.
| | - Małgorzata Ćwieląg-Drabek
- Department of Environmental Health Risk Factors, School of Public Health in Bytom, Medical University of Silesia in Katowice, ul. Piekarska 18, 42-902 Bytom, Poland.
| | - Mehdi Razzaghi
- Department of Mathematical and Digital Sciences, Bloomsburg University, 400 E. Second St., Bloomsburg, PA 17815, USA.
| | - Agata Piekut
- Department of Environmental Health, School of Public Health in Bytom, Medical University of Silesia in Katowice, ul. Piekarska 18, 42-902 Bytom, Poland.
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7
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Dose-dependence of chemical carcinogenicity: Biological mechanisms for thresholds and implications for risk assessment. Chem Biol Interact 2019; 301:112-127. [DOI: 10.1016/j.cbi.2019.01.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/11/2019] [Accepted: 01/25/2019] [Indexed: 12/19/2022]
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Sand S, Lindqvist R, von Rosen D, Ilbäck NG. Dose-Related Severity Sequence, and Risk-Based Integration, of Chemically Induced Health Effects. Toxicol Sci 2018; 165:74-89. [PMID: 29897534 PMCID: PMC6190798 DOI: 10.1093/toxsci/kfy124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Risk assessment of chemical hazards is typically based on single critical health effects. This work aims to expand the current approach by characterizing the dose-related sequence of the development of multiple (lower- to higher-order) toxicological health effects caused by a chemical. To this end a "reference point profile" is defined as the relation between benchmark doses for considered health effects, and a standardized severity score determined for these effects. For a given dose of a chemical or mixture the probability for exceeding the reference point profile, thereby provoking lower- to higher-order effects, can be assessed. The overall impact at the same dose can also be derived by integrating contributions across all health effects following severity-weighting. In its generalized form the new impact metric relates to the probability of response for the most severe health effects. Reference points (points of departure) corresponding to defined levels of response can also be estimated. The proposed concept, which is evaluated for dioxin-like chemicals, provides an alternative for characterizing the low-dose region below the reference point for a severe effect like cancer. The shape and variability of the reference point profile add new dimensions to risk assessment, which for example extends the characterization of chemical potency, and the concept of acceptable effect sizes for individual health effects. Based on the present data the method shows high stability at low doses/responses, and is also robust to differences in severity categorization of effects. In conclusion, the novel method proposed enables risk-based integration of multiple dose-related health effects. It provides a first step towards a more comprehensive characterization of chemical toxicity, and suggests a potential for improved low-dose risk assessment.
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Affiliation(s)
- Salomon Sand
- Department of Risk-Benefit Assessment, Swedish National Food Agency, SE-75126 Uppsala, Sweden
| | - Roland Lindqvist
- Department of Risk-Benefit Assessment, Swedish National Food Agency, SE-75126 Uppsala, Sweden
| | - Dietrich von Rosen
- Department of Energy and Technology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
- Department of Mathematics, Linköping University, SE-581 83 Linköping, Sweden
| | - Nils-Gunnar Ilbäck
- Department of Risk-Benefit Assessment, Swedish National Food Agency, SE-75126 Uppsala, Sweden
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9
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Gou YY, Que DE, Chuang CY, Chao HR, Shy CG, Hsu YC, Lin CW, Chuang KP, Tsai CC, Tayo LL. Dust levels of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) in the Taiwanese elementary school classrooms: Assessment of the risk to school-age children. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 572:734-741. [PMID: 27515016 DOI: 10.1016/j.scitotenv.2016.07.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/06/2016] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
Elementary school classroom dust is an important source of exposure to polybrominated dibenzo-p-dioxins/furans and diphenyl ethers (PBDD/DF/DEs) for school-age children. Our goal is thus to investigate concentrations of PBDD/DF/DEs in elementary school classroom dust to further assess the impact on school-age children via ingestion. The dust from classrooms, including both normal (NR) and computer classrooms (CR), was collected from six urban and four rural schools. Fourteen PBDEs and twelve PBDD/Fs were measured using high-resolution gas-chromatography/high-resolution mass-spectrometry. The mean levels of Σ14PBDEs in NR and CR dust from the urban classrooms were 370 and 2510ng/g and those whose dust from the rural classrooms were 464 and 1780ng/g. The means of ΣPBDD/Fs were 0.0401ng-WHO2005-TEQ/g (concentration: 4.72ng/g) in urban NR dust, 0.0636ng-WHO2005-TEQ/g (7.51ng/g) in urban CR dust, 0.0281ng-WHO2005TEQ/g (3.60ng/g) in rural NR dust, and 0.0474ng-WHO2005TEQ/g (6.28ng/g) in rural CR dust. The PBDEs pattern in NR dust was quite different from that in CR dust, but the PBDD/Fs patterns in NR and CR dust were similar. A linearly significant correlation coefficient (n=20, r=0.862, p<0.001) was found between ΣPBDEs and ΣPBDD/Fs in NR and CR dust, indicating that the PBDEs and PBDD/Fs in the dust may be from the same sources in the elementary school classrooms. This study assessed the risks (daily intake and cancer and non-cancer risks) of PBDEs and PBDD/Fs for the children from the classroom dust, and the calculated risk values did not exceed the related thresholds. With regard to the exposure scenarios for school-age children in an indoor environment, the results suggest that they might ingest more dust PBDD/DF/DEs in their homes than in the schools. In conclusion, the exposure of Taiwanese elementary school children to PBDD/DF/DEs via indoor dust was with a safe range based on our findings.
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Affiliation(s)
- Yan-You Gou
- Emerging Compounds Research Center, Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung County 912, Taiwan
| | - Danielle E Que
- School of Chemical Engineering, Chemistry, Biological Engineering and Material Science and Engineering, Mapúa Institute of Technology, Intramuros, Manila 1002, Philippines
| | - Chun-Yu Chuang
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu City 300, Taiwan
| | - How-Ran Chao
- Emerging Compounds Research Center, Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Neipu, Pingtung County 912, Taiwan.
| | - Cherng-Gueih Shy
- Department of Radiology, Pingtung Christian Hospital, Pingtung City, Pingtung 900, Taiwan
| | - Yi-Chyun Hsu
- Department of Environmental Engineering, Kun Shan University, Yung-Kang Dist., Tainan City 71003, Taiwan
| | - Chun-Wen Lin
- Department of Child Care, National Pingtung University of Science and Technology, Pingtung County 912, Taiwan
| | - Kuo Pin Chuang
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, Neipu, Pingtung County 912, Taiwan
| | - Chih-Chung Tsai
- Graduate Institute of Science Education and Environmental Education, National Kaohsiung Normal University, Yan-Chou District, Kaohsiung City 824, Taiwan
| | - Lemmuel L Tayo
- School of Chemical Engineering, Chemistry, Biological Engineering and Material Science and Engineering, Mapúa Institute of Technology, Intramuros, Manila 1002, Philippines
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10
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Simon TW, Zhu Y, Dourson ML, Beck NB. Bayesian methods for uncertainty factor application for derivation of reference values. Regul Toxicol Pharmacol 2016; 80:9-24. [DOI: 10.1016/j.yrtph.2016.05.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/03/2016] [Accepted: 05/16/2016] [Indexed: 12/17/2022]
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11
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Sany SBT, Hashim R, Rezayi M, Rahman MA, Razavizadeh BBM, Abouzari-lotf E, Karlen DJ. Integrated ecological risk assessment of dioxin compounds. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:11193-11208. [PMID: 25953606 DOI: 10.1007/s11356-015-4511-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/07/2015] [Indexed: 06/04/2023]
Abstract
Current ecological risk assessment (ERA) schemes focus mainly on bioaccumulation and toxicity of pollutants in individual organisms. Ecological models are tools mainly used to assess ecological risks of pollutants to ecosystems, communities, and populations. Their main advantage is the relatively direct integration of the species sensitivity to organic pollutants, the fate and mechanism of action in the environment of toxicants, and life-history features of the individual organism of concern. To promote scientific consensus on ERA schemes, this review is intended to provide a guideline on short-term ERA involving dioxin chemicals and to identify key findings for exposure assessment based on policies of different agencies. It also presents possible adverse effects of dioxins on ecosystems, toxicity equivalence methodology, environmental fate and transport modeling, and development of stressor-response profiles for dioxin-like chemicals.
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12
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Becker RA, Patlewicz G, Simon TW, Rowlands JC, Budinsky RA. The adverse outcome pathway for rodent liver tumor promotion by sustained activation of the aryl hydrocarbon receptor. Regul Toxicol Pharmacol 2015; 73:172-90. [PMID: 26145830 DOI: 10.1016/j.yrtph.2015.06.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/19/2015] [Accepted: 06/22/2015] [Indexed: 12/29/2022]
Abstract
An Adverse Outcome Pathway (AOP) represents the existing knowledge of a biological pathway leading from initial molecular interactions of a toxicant and progressing through a series of key events (KEs), culminating with an apical adverse outcome (AO) that has to be of regulatory relevance. An AOP based on the mode of action (MOA) of rodent liver tumor promotion by dioxin-like compounds (DLCs) has been developed and the weight of evidence (WoE) of key event relationships (KERs) evaluated using evolved Bradford Hill considerations. Dioxins and DLCs are potent aryl hydrocarbon receptor (AHR) ligands that cause a range of species-specific adverse outcomes. The occurrence of KEs is necessary for inducing downstream biological responses and KEs may occur at the molecular, cellular, tissue and organ levels. The common convention is that an AOP begins with the toxicant interaction with a biological response element; for this AOP, this initial event is binding of a DLC ligand to the AHR. Data from mechanistic studies, lifetime bioassays and approximately thirty initiation-promotion studies have established dioxin and DLCs as rat liver tumor promoters. Such studies clearly show that sustained AHR activation, weeks or months in duration, is necessary to induce rodent liver tumor promotion--hence, sustained AHR activation is deemed the molecular initiating event (MIE). After this MIE, subsequent KEs are 1) changes in cellular growth homeostasis likely associated with expression changes in a number of genes and observed as development of hepatic foci and decreases in apoptosis within foci; 2) extensive liver toxicity observed as the constellation of effects called toxic hepatopathy; 3) cellular proliferation and hyperplasia in several hepatic cell types. This progression of KEs culminates in the AO, the development of hepatocellular adenomas and carcinomas and cholangiolar carcinomas. A rich data set provides both qualitative and quantitative knowledge of the progression of this AOP through KEs and the KERs. Thus, the WoE for this AOP is judged to be strong. Species-specific effects of dioxins and DLCs are well known--humans are less responsive than rodents and rodent species differ in sensitivity between strains. Consequently, application of this AOP to evaluate potential human health risks must take these differences into account.
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Affiliation(s)
- Richard A Becker
- Regulatory and Technical Affairs Department, American Chemistry Council (ACC), Washington, DC 20002, USA.
| | - Grace Patlewicz
- DuPont Haskell Global Centers for Health and Environmental Sciences, Newark, DE 19711, USA
| | - Ted W Simon
- Ted Simon LLC, 4184 Johnston Road, Winston, GA 30187, USA
| | - J Craig Rowlands
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
| | - Robert A Budinsky
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
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Patlewicz G, Simon TW, Rowlands JC, Budinsky RA, Becker RA. Proposing a scientific confidence framework to help support the application of adverse outcome pathways for regulatory purposes. Regul Toxicol Pharmacol 2015; 71:463-77. [PMID: 25707856 DOI: 10.1016/j.yrtph.2015.02.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 02/13/2015] [Accepted: 02/16/2015] [Indexed: 10/24/2022]
Abstract
An adverse outcome pathway (AOP) describes the causal linkage between initial molecular events and an adverse outcome at individual or population levels. Whilst there has been considerable momentum in AOP development, far less attention has been paid to how AOPs might be practically applied for different regulatory purposes. This paper proposes a scientific confidence framework (SCF) for evaluating and applying a given AOP for different regulatory purposes ranging from prioritizing chemicals for further evaluation, to hazard prediction, and ultimately, risk assessment. The framework is illustrated using three different AOPs for several typical regulatory applications. The AOPs chosen are ones that have been recently developed and/or published, namely those for estrogenic effects, skin sensitisation, and rodent liver tumor promotion. The examples confirm how critical the data-richness of an AOP is for driving its practical application. In terms of performing risk assessment, human dosimetry methods are necessary to inform meaningful comparisons with human exposures; dosimetry is applied to effect levels based on non-testing approaches and in vitro data. Such a comparison is presented in the form of an exposure:activity ratio (EAR) to interpret biological activity in the context of exposure and to provide a basis for product stewardship and regulatory decision making.
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Affiliation(s)
- Grace Patlewicz
- DuPont Haskell Global Centers for Health and Environmental Sciences, 1090 Elkton Road, Newark, DE 19711, USA.
| | - Ted W Simon
- Ted Simon LLC, 4184 Johnston Road, Winston, GA 30187, USA
| | - J Craig Rowlands
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
| | - Robert A Budinsky
- The Dow Chemical Company, Toxicology & Environmental Research & Consulting, 1803 Building Washington Street, Midland, MI 48674, USA
| | - Richard A Becker
- Regulatory and Technical Affairs Department, American Chemistry Council (ACC), Washington, DC 20002, USA
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Ruiz P, Aylward LL, Mumtaz M. Application of pharmacokinetic modelling for 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure assessment. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2014; 25:873-90. [PMID: 25397879 PMCID: PMC8204318 DOI: 10.1080/1062936x.2014.962083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and mono- and non-ortho polychlorinated biphenyls (dioxin-like PCBs) are identified as a family or group of organic compounds known as 'dioxins' or dioxin-like chemicals (DLCs). The most toxic member of this group is 2,3,7,8-tetrachlorodibenzo-(p)-dioxin (TCDD). Historically, DLCs have caused a variety of negative human health effects, but a disfiguring skin condition known as chloracne is the only health effect reported consistently. As part of translational research to make computerized models accessible to health risk assessors, the Concentration- and Age-Dependent Model (CADM) for TCDD was recoded in the Berkeley Madonna simulation language. The US Agency for Toxic Substances and Disease Registry's computational toxicology laboratory used the recoded model to predict TCDD tissue concentrations at different exposure levels. The model simulations successfully reproduced the National Health and Nutrition Examination Survey (NHANES) 2001-2002 TCDD data in age groups from 6 to 60 years and older, as well as in other human datasets. The model also enabled the estimation of lipid-normalized serum TCDD concentrations in breastfed infants. The model performed best for low background exposures over time compared with a high acute poisoning case that could due to the large dose and associated liver toxicity. Hence, this model may be useful for interpreting human biomonitoring data as a part of an overall DLC risk assessment.
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Affiliation(s)
- P. Ruiz
- Computational Toxicology and Methods Development Laboratory, Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, Atlanta, GA, USA
| | | | - M. Mumtaz
- Computational Toxicology and Methods Development Laboratory, Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, Atlanta, GA, USA
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Simon TW, Simons SS, Preston RJ, Boobis AR, Cohen SM, Doerrer NG, Fenner-Crisp PA, McMullin TS, McQueen CA, Rowlands JC. The use of mode of action information in risk assessment: Quantitative key events/dose-response framework for modeling the dose-response for key events. Crit Rev Toxicol 2014; 44 Suppl 3:17-43. [DOI: 10.3109/10408444.2014.931925] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Budinsky RA, Schrenk D, Simon T, Van den Berg M, Reichard JF, Silkworth JB, Aylward LL, Brix A, Gasiewicz T, Kaminski N, Perdew G, Starr TB, Walker NJ, Rowlands JC. Mode of action and dose–response framework analysis for receptor-mediated toxicity: The aryl hydrocarbon receptor as a case study. Crit Rev Toxicol 2013; 44:83-119. [DOI: 10.3109/10408444.2013.835787] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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AhR signalling and dioxin toxicity. Toxicol Lett 2013; 230:225-33. [PMID: 24239782 DOI: 10.1016/j.toxlet.2013.10.039] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/14/2013] [Accepted: 10/18/2013] [Indexed: 12/02/2022]
Abstract
Dioxins are a family of molecules associated to several industrial accidents such as Ludwigshafen in 1953 or Seveso in 1976, to the Agent Orange used during the war of Vietnam, and more recently to the poisoning of the former president of Ukraine, Victor Yushchenko. These persistent organic pollutants are by-products of industrial activity and bind to an intracellular receptor, AhR, with a high potency. In humans, exposure to dioxins, in particular 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces a cutaneous syndrome known as chloracne, consisting in the development of many small skin lesions (hamartoma), lasting for 2-5 years. Although TCDD has been classified by the WHO as a human carcinogen, its carcinogenic potential to humans is not clearly demonstrated. It was first believed that AhR activation accounted for most, if not all, biological properties of dioxins. However, certain AhR agonists found in vegetables do not induce chloracne, and other chemicals, in particular certain therapeutic agents, may induce a chloracne-like syndrome without activating AhR. It is time to rethink the mechanism of dioxin toxicity and analyse in more details the biological events following exposure to these compounds and other AhR agonists, some of which have a very different chemical structure than TCDD. In particular various food-containing AhR agonists are non-toxic and may on the contrary have beneficial properties to human health.
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The importance of problem formulations in risk assessment: A case study involving dioxin-contaminated soil. Regul Toxicol Pharmacol 2013; 66:208-16. [DOI: 10.1016/j.yrtph.2013.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 03/21/2013] [Accepted: 03/22/2013] [Indexed: 11/22/2022]
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Chopra M, Schrenk D. Dioxin toxicity, aryl hydrocarbon receptor signaling, and apoptosis-persistent pollutants affect programmed cell death. Crit Rev Toxicol 2011; 41:292-320. [PMID: 21323611 DOI: 10.3109/10408444.2010.524635] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Exogenous ligands of the aryl hydrocarbon receptor (AhR) such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related substances are highly toxic pollutants ubiquitously present in the environment. They cause a variety of toxic effects to different organs and tissues. Among other effects, TCDD exposure to laboratory animals leads to thymus atrophy and immunosuppression on the one hand, and to tumor formation on the other. Apoptosis appears to be involved in both these toxic effects: AhR activation by TCDD was discussed to induce apoptosis of immune cells, leading to the depletion of thymocytes and ultimately immunosuppression. This mechanism could help to explain the highly immunotoxic actions of TCDD but it is nevertheless under debate whether this is the mode of action for immunosuppression by this class of chemical substances. In other cell types, especially liver cells, TCDD inhibits apoptosis induced by genotoxic treatment. In initiation-promotion studies, TCDD was shown to be a potent liver tumor promoter. Among other theories it was hypothesized that TCDD acts as a tumor promoter by preventing initiated cells from undergoing apoptosis. The exact mechanisms of apoptosis inhibition by TCDD are not fully understood, but both in vivo and in vitro studies consistently showed an involvement of the tumor suppressor p53 in this effect. Various strings of evidence have been established linking apoptosis to the detrimental effects of exogenous activation of the AhR. Within this article, studies elucidating the effects of TCDD and related substances on apoptosis signaling, be it inducing or repressing, is to be reviewed.
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Affiliation(s)
- Martin Chopra
- Institute of Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, Germany
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Bogen KT. Generic Hockey-Stick Model for Estimating Benchmark Dose and Potency: Performance Relative to BMDS and Application to Anthraquinone. Dose Response 2010; 9:182-208. [PMID: 21731536 DOI: 10.2203/dose-response.10-018.bogen] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Benchmark Dose Model software (BMDS), developed by the U.S. Environmental Protection Agency, involves a growing suite of models and decision rules now widely applied to assess noncancer and cancer risk, yet its statistical performance has never been examined systematically. As typically applied, BMDS also ignores the possibility of reduced risk at low doses ("hormesis"). A simpler, proposed Generic Hockey-Stick (GHS) model also estimates benchmark dose and potency, and additionally characterizes and tests objectively for hormetic trend. Using 100 simulated dichotomous-data sets (5 dose groups, 50 animals/group), sampled from each of seven risk functions, GHS estimators performed about as well or better than BMDS estimators, and a surprising observation was that BMDS mis-specified all of six non-hormetic sampled risk functions most or all of the time. When applied to data on rodent tumors induced by the genotoxic chemical carcinogen anthraquinone (AQ), the GHS model yielded significantly negative estimates of net potency exhibited by the combined rodent data, suggesting that-consistent with the anti-leukemogenic properties of AQ and structurally similar quinones-environmental AQ exposures do not likely increase net cancer risk. In addition to its simplicity and flexibility, the GHS approach offers a unified, consistent approach to quantifying environmental chemical risk.
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Budinsky RA, LeCluyse EL, Ferguson SS, Rowlands JC, Simon T. Human and rat primary hepatocyte CYP1A1 and 1A2 induction with 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, and 2,3,4,7,8-pentachlorodibenzofuran. Toxicol Sci 2010; 118:224-35. [PMID: 20705892 DOI: 10.1093/toxsci/kfq238] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The concentration dose response for aryl hydrocarbon receptor (AHR)-mediated CYP1A1 and CYP1A2 messenger RNA (mRNA) induction and enzyme activity was determined in primary cultures of rat and human hepatocytes for 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,4,7,8-pentachlorodibenzofuran, and 2,3,7,8-tetrachlorodibenzofuran. Eleven different congener concentrations from 0.00001 to 100 nM were used, thus spanning seven orders of magnitude. The Hill model was used to obtain values of EC(x) and maximal response from the individual data sets. No-observed effect concentration values were derived using several statistical methods including Dunnett's test, the Welch-Aspin test, and step-down bilinear regression. Thresholds were estimated using baseline projection methods and a "hockey stick" fitting method. Human hepatocytes were less responsive and less sensitive with respect to CYP1A1 activity and mRNA induction than rats. On the other hand, the human CYP1A2 response was more robust than the response in rats but generally less sensitive. These data allow an evaluation of relative species sensitivities for developing interspecies toxicodynamic adjustment factors, for assessing AHR activation thresholds, and for evaluating relative congener potencies. Overall, these data support the position that humans are less sensitive than rats to these AHR-dependent end points and support the use of a data-derived adjustment factor of 1.0 or less for extrapolating between rats and humans.
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Abstract
The willingness to view risk as part of daily life has vanished. A risk-averse mindset among environmental regulators engenders confusion between the ethics of intention and the ethics of consequence, leading to the elevation of the precautionary principle with unintended and often unfortunate outcomes. Environmental risk assessment is conservative, but the actual level of conservatism cannot be determined. High-end exposure assumptions and current toxicity criteria from the USEPA, based on linear extrapolation for carcinogens and default uncertainty factors for systemic toxicants, obscure the degree of conservatism in risk assessments. Ideally, one could choose a percentile of the target population to include within environmental standards, but this choice is complicated by the food, pharmaceutical and advertising industries, whose activities, inadvertent or not, often promote maladaptive and unhealthy lifestyle choices. There has lately been much discussion about background exposures and disease processes and their potential to increase the risk from environmental chemicals. Should these background exposures or disease processes, especially those associated with maladaptive individual choices, be included as part of a regulatory risk evaluation? A significant ethical question is whether environmental regulation should protect those pursuing a self-destructive lifestyle that may add to or synergize with otherwise innocuous environmental exposures. Choosing a target percentile of protection would provide an increased level of transparency and the flexibility to choose a higher or lower percentile if such a choice is warranted. Transparency and flexibility will lead to more responsive environmental regulation that balances protection of public health and the stewardship of societal resources.
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Affiliation(s)
- Ted Simon
- Ted Simon LLC, Winston, GA 30187, USA.
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