Clues from wildlife to create an assay for thyroid system disruption.
In 1996 the U.S. Congress charged the U.S. Environmental Protection Agency to develop a screening program to test chemicals for their possible estrogenic and other endocrine effects. Shortly thereafter, the Chemical Guidelines Program of the Organisation for Economic Co-operation and Development's (OECD) Environmental Directorate organized a Task Force on Endocrine Disruption Testing and Assessment to coordinate development of internationally harmonized screening and testing protocols. Most of the research devoted to this effort has focused on detecting impaired estrogenicity, androgenicity, and/or steroidogenesis, with little progress toward developing assays to detect chemicals that might interfere with thyroid function. Despite the fact that wildlife biologists have been reporting abnormal thyroid gland development and unusual thyroid hormone (TH) and retinoid ratios in fish and birds since the early 1960s, few studies have demonstrated an association between an environmental contaminant and a particular health end point other than reduced reproductive success at the population level. This article is a review of the literature that specifically examines THs and their role in normal behavior and development in wildlife. It presents several studies that associated changes in the thyroid gland, TH concentrations, and behavior with contaminant exposure. The goal of this article is to provide fodder for the creation of simple screens to detect possible thyroid system agonists and antagonists.
Colborn
Theo
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Wildlife and Contaminants Program, World Wildlife Fund, 1250 24th Street NW, Washington, DC 20037-9736, USA. colborn@wwfus.org
D000663:Amphibians; D000818:Animals; D000835:Animals, Wild; D001681:Biological Assay; D001717:Birds; D004353:Drug Evaluation, Preclinical; D004703:Endocrine System / Q000187:drug effects* / Q000502:physiology; D004784:Environmental Monitoring / Q000379:methods; D005399:Fishes; D007306:Insecticides / Q000009:adverse effects*; D008322:Mammals; D012176:Retinoids / Q000494:pharmacology; D013961:Thyroid Gland / Q000187:drug effects* / Q000502:physiology; D013963:Thyroid Hormones / Q000494:pharmacology*; D015262:Xenobiotics / Q000009:adverse effects*
D007306:Insecticides; D012176:Retinoids; D013963:Thyroid Hormones; D015262:Xenobiotics