Hazard and risk assessment of chemical mixtures using the toxic equivalency factor approach.
- 1 August 1998
- journal article
- Published by Environmental Health Perspectives in Environmental Health Perspectives
- Vol. 106 (suppl 4), 1051-1058
- https://doi.org/10.1289/ehp.98106s41051
Abstract
There is considerable public, regulatory, and scientific concern regarding human exposure to endocrine-disrupting chemicals, which include compounds that directly modulate steroid hormone receptor pathways (estrogens, antiestrogens, androgens, antiandrogens) and aryl hydrocarbon receptor (AhR) agonists, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. Based on quantitative structure-activity relationships for both AhR and estrogen receptor (ER) agonists, the relative potency (RP) of individual compounds relative to a standard (e.g. TCDD and 17-beta-estradiol) have been determined for several receptor-mediated responses. Therefore, the TCDD or estrogenic equivalent (TEQ or EQ, respectively) of a mixture is defined as TEQ = sigma[T(i)]xRP(i)or EQ=sigma[E(i)]xRP(i), where T(i) and E(i) are concentrations of individual AhR or ER agonists in any mixture. This approach for risk assessment of endocrine-disrupting mixtures assumes that for each endocrine response pathway, the effects of individual compounds are essentially additive. This paper will critically examine the utility of the TEQ/EQ approach for risk assessment, the validity of the assumptions used for this approach, and the problems associated with comparing low dose exposures to xeno and natural (dietary) endocrine disruptors.Keywords
This publication has 94 references indexed in Scilit:
- Inhibition of 3,3′,4,4′,5-Pentachlorobiphenyl-Induced Chicken Embryotoxicity by 2,2′,4,4′,5,5′-HexachlorobiphenylFundamental and Applied Toxicology, 1997
- Cloning of a novel receptor expressed in rat prostate and ovary.Proceedings of the National Academy of Sciences of the United States of America, 1996
- Covalent Binding of Polycyclic Aromatic Hydrocarbon Components of Manufactured Gas Plant Residue to Mouse Lung and Forestomach DNAChemical Research in Toxicology, 1995
- Induction of Cyp1a-1 and Cyp1a-2 gene expression by a reconstituted mixture of polynuclear aromatic hydrocarbons in B6C3F1 miceChemico-Biological Interactions, 1995
- Global contamination by persistent organochlorines and their ecotoxicological impact on marine mammalsScience of The Total Environment, 1994
- Synergistic activity of polynuclear aromatic hydrocarbon mixtures as aryl hydrocarbon (Ah) receptor agonistsChemico-Biological Interactions, 1993
- Comparative toxicity of four chlorinated dibenzo-p-dioxins (CDDs) and their mixtureArchives of Toxicology, 1992
- Development and Validation of in Vitro Induction Assays for Toxic Halogenated Aromatic Mixtures: A ReviewToxicology and Industrial Health, 1989
- Potentially Hazardous Residues of Non-Ortho Chlorine Substituted Coplanar PCBs in Human Adipose TissueArchives of environmental health, 1988
- Relationship between the carbon skeleton length of ketonic solvents and potentiation of chloroform-induced hepatotoxicity in ratsToxicology Letters, 1983