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Bloch D, Diel P, Epe B, Hellwig M, Lampen A, Mally A, Marko D, Villar Fernández MA, Guth S, Roth A, Marchan R, Ghallab A, Cadenas C, Nell P, Vartak N, van Thriel C, Luch A, Schmeisser S, Herzler M, Landsiedel R, Leist M, Marx-Stoelting P, Tralau T, Hengstler JG. Basic concepts of mixture toxicity and relevance for risk evaluation and regulation. Arch Toxicol 2023; 97:3005-3017. [PMID: 37615677 PMCID: PMC10504116 DOI: 10.1007/s00204-023-03565-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/26/2023] [Indexed: 08/25/2023]
Abstract
Exposure to multiple substances is a challenge for risk evaluation. Currently, there is an ongoing debate if generic "mixture assessment/allocation factors" (MAF) should be introduced to increase public health protection. Here, we explore concepts of mixture toxicity and the potential influence of mixture regulation concepts for human health protection. Based on this analysis, we provide recommendations for research and risk assessment. One of the concepts of mixture toxicity is additivity. Substances may act additively by affecting the same molecular mechanism within a common target cell, for example, dioxin-like substances. In a second concept, an "enhancer substance" may act by increasing the target site concentration and aggravating the adverse effect of a "driver substance". For both concepts, adequate risk management of individual substances can reliably prevent adverse effects to humans. Furthermore, we discuss the hypothesis that the large number of substances to which humans are exposed at very low and individually safe doses may interact to cause adverse effects. This commentary identifies knowledge gaps, such as the lack of a comprehensive overview of substances regulated under different silos, including food, environmentally and occupationally relevant substances, the absence of reliable human exposure data and the missing accessibility of ratios of current human exposure to threshold values, which are considered safe for individual substances. Moreover, a comprehensive overview of the molecular mechanisms and most susceptible target cells is required. We conclude that, currently, there is no scientific evidence supporting the need for a generic MAF. Rather, we recommend taking more specific measures, which focus on compounds with relatively small ratios between human exposure and doses, at which adverse effects can be expected.
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Affiliation(s)
- Denise Bloch
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany.
| | - Patrick Diel
- Department of Molecular and Cellular Sports Medicine, Institute of Cardiovascular Research and Sports Medicine, German Sport University Cologne, Cologne, Germany
| | - Bernd Epe
- Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, Mainz, Germany
| | - Michael Hellwig
- Chair of Special Food Chemistry, Technical University Dresden, Dresden, Germany
| | - Alfonso Lampen
- Risk Assessment Strategies, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Angela Mally
- Department of Toxicology, University of Würzburg, Würzburg, Germany
| | - Doris Marko
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - María A Villar Fernández
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Sabine Guth
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Angelika Roth
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Rosemarie Marchan
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Ahmed Ghallab
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, South Valley University, Qena, 83523, Egypt
| | - Cristina Cadenas
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Patrick Nell
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Nachiket Vartak
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Christoph van Thriel
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
| | - Andreas Luch
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Sebastian Schmeisser
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Matthias Herzler
- Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Robert Landsiedel
- Department of Experimental Toxicology and Ecology, BASF SE, Ludwigshafen, Germany
- Pharmacy, Pharmacology and Toxicology, Free University of Berlin, Berlin, Germany
| | - Marcel Leist
- Department of In Vitro Toxicology and Biomedicine, Inaugurated by the Doerenkamp-Zbinden Foundation, University of Konstanz, Constance, Germany
| | - Philip Marx-Stoelting
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Tewes Tralau
- Department of Pesticides Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Jan G Hengstler
- Department of Toxicology, Leibniz Research Centre for Working Environment and Human Factors (IfADo), Dortmund, Germany
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Peters JM, Gonzalez FJ. Why toxic equivalency factors are not suitable for perfluoroalkyl chemicals. Chem Res Toxicol 2011; 24:1601-9. [PMID: 21913657 PMCID: PMC6624430 DOI: 10.1021/tx200316x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The pervasive nature of perfluoroalkyl chemicals in the environment has generated considerable interest for developing new strategies for risk assessment. In experimental animal models, exposure to perfluoroalkyl chemicals can cause developmental toxicity and hepatotoxicity. Peroxisome proliferator-activated receptor-α (PPARα) is required to mediate some but not all of these effects. Since PPARα has a role in mediating some of these effects, and there is some overlap in the type of toxicities elicited by perfluoroalkyl chemicals, it has been suggested that a scaling system analogous to the toxic equivalency factor (TEF) system used for polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and polychlorinated biphenyls (PCB) could be used for perfluoroalkyl chemicals. However, evidence suggests that perfluoroalkyl chemicals can activate/interfere with other receptors, and there is reason to suggest the possibility of species differences in the response mediated by different receptors as well as qualitative differences in toxicities elicited by perfluoroalkyl chemicals. These differences and other data gaps preclude the development of a TEF approach for perfluoroalkyl chemicals.
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Affiliation(s)
- Jeffrey M Peters
- Department of Veterinary and Biomedical Sciences and The Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University , University Park, PA 16802, United States.
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Warne MA, Ebbels TMD, Lindon JC, Nicholson JK. Semiempirical Molecular-Orbital Properties of Some Polycyclic Aromatic Hydrocarbons and Correlation with Environmental Toxic Equivalency Factors. Polycycl Aromat Compd 2010. [DOI: 10.1080/10406630308062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- M. A. Warne
- a Biological Chemistry, Biomedical Sciences Division , Imperial College of Science, Technology and Medicine , London , United Kingdom
| | - T. M. D. Ebbels
- a Biological Chemistry, Biomedical Sciences Division , Imperial College of Science, Technology and Medicine , London , United Kingdom
| | - J. C. Lindon
- a Biological Chemistry, Biomedical Sciences Division , Imperial College of Science, Technology and Medicine , London , United Kingdom
| | - J. K. Nicholson
- a Biological Chemistry, Biomedical Sciences Division , Imperial College of Science, Technology and Medicine , London , United Kingdom
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Bruns-Nagel D, Schmidt TC, Drzyzga O, von Löw E, Steinbach K. Identification of oxidized TNT metabolites in soil samples of a former ammunition plant. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 1999; 6:7-10. [PMID: 19005856 DOI: 10.1007/bf02987113] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/1998] [Accepted: 07/09/1998] [Indexed: 05/27/2023]
Abstract
Water extracts of soil samples of the former ammunition plant "Tanne" near Clausthal-Zellerfeld, Lower Saxony, Germany, were investigated for highly polar oxidized 2,4,6-trinitrotoluene (TNT) metabolites. 0.4 to 9.0 mg/kg dry soil 2,4,6-trinitrobenzoic acid (TNBA) and 5.8 to 544 mg/kg dry soil 2-amino-4,6-dinitrobenzoic acid (2-ADNBA) were found. In addition to the oxidized metabolites, TNT, 4- and 2-aminodinitrotoluene (4- and 2-ADNT), and 2,4-dinitrotoluene (2,4-DNT) were extractable with water. Most interestingly, in one sample, 2-ADNBA represented the main contaminant. The origin of the oxidized nitroaromatics is unknown at this time. They might be generated chemically or photochemically. Furthermore, a biological synthesis seems possible.
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Affiliation(s)
- D Bruns-Nagel
- Institute of Immunology and Environmental Hygiene, Philipps University Marburg, Pilgrimstein 2, D-35037, Marburg, Germany.
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Feron VJ, Cassee FR, Groten JP. Toxicology of chemical mixtures: international perspective. ENVIRONMENTAL HEALTH PERSPECTIVES 1998; 106 Suppl 6:1281-9. [PMID: 9860882 PMCID: PMC1533443 DOI: 10.1289/ehp.98106s61281] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
This paper reviews major activities outside the United States on human health issues related to chemical mixtures. In Europe an international study group on combination effects has been formed and has started by defining synergism and antagonism. Successful research programs in Europe include the development and application of statistically designed experiments combined with multivariate data analysis and modeling in vitro and in vivo studies on a wide variety of chemicals such as petroleum hydrocarbons, aldehydes, food contaminants, industrial solvents, and mycotoxins. Other major activities focus on the development of safety evaluation strategies for mixtures such as the use of toxic equivalence factors or alternatives such as the question-and-answer approach, fractionation followed by recombination of the mixture in combination with a mixture design, and quantitative structure-activity relationship analysis combined with lumping analysis and physiologically based pharmacokinetic/pharmacodynamic modeling for studying complex mixtures. A scheme for hazard identification and risk assessment of complex mixtures and a consistent way to generate total volatile organic compound values for indoor air have also been developed. Examples of other activities are carcinogenicity studies on complex mixtures (petroleum middle distillates, foundry fumes, pesticides, heterocyclic amines, diesel exhaust, solid particles), neurotoxicity studies of mixtures of solvents alone or in combination with exposure to physical factors, and toxicity studies of outdoor air pollutants, focusing on particulates. Outside the United States, toxicologists and regulators clearly have a growing interest in the toxicology and risk assessment of chemical mixtures.
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Affiliation(s)
- V J Feron
- TNO-Nutrition and Food Research Institute, Toxicology Division, Zeist, The Netherlands.
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Giesy JP, Kannan K. Dioxin-like and non-dioxin-like toxic effects of polychlorinated biphenyls (PCBs): implications for risk assessment. Crit Rev Toxicol 1998; 28:511-69. [PMID: 9861526 DOI: 10.1080/10408449891344263] [Citation(s) in RCA: 276] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative, and toxic contaminants in the environment. Individual PCB congeners exhibit different physicochemical properties and biological activities that result in different environmental distributions and toxicity profiles. The variable composition of PCB residues in environmental matrices and their different mechanisms of toxicity complicate the development of scientifically based regulations for the risk assessment. In this article various approaches for the assessment of risks of PCBs have been critically examined. Recent developments in the toxic equivalency factor (TEF) approach for the assessment of toxic effects due to dioxin-like PCBs have been examined. PCB exposure studies that describe non-dioxin-like toxic effects, particularly neurobehavioral effects and their effective doses in animals were compiled. A comparative assessment of effective doses for dioxin-like and non-dioxin-like effects by PCBs has been made to evaluate the relative significance of non-ortho-and ortho-substituted PCBs in risk assessment. Using mink as an example, relative merits and implications of using TEF and total PCB approaches for assessing the potential for toxic effects in wildlife was examined. There are several advantages and limitations associated with each method used for PCB risk assessment. Toxic effects due to coplanar PCBs occur at relatively smaller concentrations than those due to non-dioxin-like PCBs and therefore the TEF approach derives the risk assessment of PCBs, in the environment. The need for the refinement of TEF approach for more accurate assessment of risks is discussed.
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Affiliation(s)
- J P Giesy
- Department of Zoology, National Food Safety and Toxicology Center, Michigan State University, East Lansing 48824, USA
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