Ecological Risk Assessment of Endocrine Disruptors

Article excerpt

The European Centre for Ecotoxicology and Toxicology of Chemicals proposes a tiered approach for the ecological risk assessment of endocrine disruptors, integrating exposure and hazard (effects) characterization. Exposure assessment for endocrine disruptors should direct specific tests for wildlife species, placing hazard data into a risk assessment context. Supplementing the suite of mammalian screens now under Organization for Economic Cooperation and Development (OECD) validation, high priority should be given to developing a fish screening assay for detecting endocrine activity in oviparous species. Taking into account both exposure characterization and alerts from endocrine screening, higher tier tests are also a priority for defining adverse effects. We propose that in vivo mammalian and fish assays provide a comprehensive screening battery for diverse hormonal functions (including androgen, estrogen, and thyroid hormone), whereas Amphibia should be considered at higher tiers if there are exposure concerns. Higher tier endocrine-disruptor testing should include fish development and fish reproduction tests, whereas a full life-cycle test could be subsequently used to refine aquatic risk assessments when necessary. For avian risk assessment, the new OECD,.Japanese quail reproduction test guideline provides a valuable basis for developing a test to detecting endocrine-mediated reproductive effects; this species could be used, where necessary, for an avian life-cycle test. For aquatic and terrestrial invertebrates, data from existing developmental and reproductive tests remain of high value for ecological risk assessment. High priority should be given to research into comparative endocrine physiology of invertebrates to support data extrapolation to this diverse fauna. Key words, ecological risk assessment, endocrine disruptor, environment, hormone mimic, screening, testing. Environ Health Perspect 108:1007-1014 (2000). [Online 4 October 2000] /abstract.html

Given many reports of contaminant-associated reproductive and developmental impacts in wildlife, often considered to be caused by endocrine disruption, there is now a major global effort to develop ecotoxicity test guidelines for the hazard assessment of endocrine disruptors. The Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC) (1) and the U.S. Environmental Protection Agency's (U.S. EPA's) proposed Endocrine Disruptor Screening Program (EDSP) (2) have made key initiatives for hazard assessment per se. Critically, however, the strategy for ecological effects characterization of endocrine disruptors also needs to be integrated into the exposure characterization component of a risk-based laboratory and field approach (3,4).

The European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) established the Environmental Oestrogens Task Force to identify the best ways to evaluate potential endocrine-disrupting substances for human and ecological risk assessment. From these efforts, our ECETOC working group argues for an ecological risk assessment framework for endocrine disruptors and supports the establishment of new wildlife screening and testing protocols.

Our strategy for ecotoxicity screening and testing is discussed versus the proposed EDSP (2), based on the earlier report from the EDSTAC (1). Specifically, our critical review of the EDSTAC considers both the scientific rationale and ethical use of animals for ecotoxicity hazard assessment (5). Throughout this exercise, we support the internationally agreed definition from the 1996 Weybridge workshop, whereby an endocrine disruptor is "an exogenous substance which causes adverse effects in an organism, or its progeny, subsequent to changes in the endocrine system." (6). In vitro test systems are not addressed in our present discussion because it has been widely agreed at several international workshops that endocrine-disruptor assessments in wildlife should primarily focus on in vivo studies (7,8). …