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SCREENING AND TESTING FOR ENDOCRINE DISRUPTION IN FISH - BIOMARKERS AS "SIGNPOSTS," NOT "TRAFFIC LIGHTS," IN RISK ASSESSMENT
Citation:
Hutchinson, T. H., G T. Ankley, H. Segner, AND C. Tyler. SCREENING AND TESTING FOR ENDOCRINE DISRUPTION IN FISH - BIOMARKERS AS "SIGNPOSTS," NOT "TRAFFIC LIGHTS," IN RISK ASSESSMENT. ENVIRONMENTAL HEALTH PERSPECTIVES 114(Supplement 1):106-114, (2006).
Impact/Purpose:
To make plausible linkages across levels of organization such that adverse outcomes might be associated with biomarker responses
Description:
Biomarkers provide important tools for addressing the impacts of endocrine disrupting chemicals (EDCs) in fish. Presently, biomarkers are best used as mechanistic "signposts" rather than as "red traffic lights" in the environmental risk assessment of EDCs. In field studies, biomarkers of exposure (e.g. vitellogenin [VTG] induction in male fish) are powerful diagnostic tools for tracking single substances and mixtures of concern. Biomarkers also provide linkage between field and laboratory data, playing an important role in directing the need for, and design of, fish chronic tests for EDCs. It is the adverse effect endpoints (e.g. altered development, growth and/or reproduction) from such tests that are most valuable for calculating the adverse NOEC (No-Observed Effect Concentration) or adverse EC10 (concentration giving a 10% effect), and subsequently deriving Predicted No-Effect Concentrations (PNECs). With current uncertainties, biomarkerNOEC or biomarkerEC10 data should not be used in isolation to derive PNECs. In the future, however, there may be scope to increasingly use biomarker data in environmental decision-making, if plausible linkages can be made across levels of organization such that adverse outcomes might be envisaged relative to biomarker responses...or biomarkerECx data; neither from which calculate if plausible linkages can be made across levels of organization such that adverse outcomes might be envisaged relative to biomarker responses. In terms of both field and laboratory applications, for biomarkers (or any other biological endpoints) to fulfil their potential in guiding the environmental assessment of EDCs, they should be have to be mechanistically relevant and reproducible (as measured by inter-laboratory comparisons of the same protocol). VTG is a good example of such a biomarker in that it provides an insight to the mode of action (estrogenicity) that is vital to fish reproductive health. Inter-laboratory reproducibility data for VTG are also encouraging; recent comparisons (using the same immunoassay protocol) have provided coefficients of variation (CVs) of 38 - 55% (comparable to published CVs of 19 - 58% for fish survival and growth and reproduction endpoints used in regegulatory test guidelines). Inter-laboratory comparisons may be further improved by expressing biomarkerNOEC (and biomarkerLOEC or biomarkerECx) data in terms of both absolute values and as a relative response to the controls...