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(566) Biomarkers of Contaminant Exposure.
Birkholz, Detlef*,1, 1 Enviro-Test Laboratories, Edmonton, Alberta, Canada
ABSTRACT- Environmental effects studies including ecological risk assessment (ERA) usually involve the collection of fish downstream of point source discharges and from appropriate reference sites to determine if adverse health effects occur in fish exposed to industrial effluents. The difficulty with these types of studies is that interpretation of results may be compromised without also conducting a proper exposure assessment. Furthermore, many aquatic systems may have multiple point source discharges comprising a variety of contaminants making it difficult to interpret results without proper knowledge and assessment of the exposure history of the target organisms. Typically, exposure is assessed by conducting tissue analyses for priority pollutants associated with specific industrial discharges. Such an assessment generally ignores the fact that xenobiotics are distributed, metabolized, excreted and/or stored in specific tissues and organs. Effective exposure assessment tools that have been used to assess exposure of fish to contaminants, such as petroleum, pulp and paper, and mining effluent, include: measurement of metals and chlorinated organic compounds in tissues; extractable organic chlorine, resin acids, fluorescent aromatic compounds, and xenobiotic-metabolites in fish bile; induction of the mixed function oxygenases; metallothionein induction; and circulating hormones in fish plasma. Even though certain biomarkers can provide definitive evidence of exposure to specific types of contaminants, they cannot in themselves be considered bioindicators of effects until they are causally related to more biologically or ecologically-relevant endpoints. A proper mix of both biomarkers of exposure and bioindicators of effects should be used in ERA-based studies to evaluate the effects of environmental contaminants on fish health.
Key words: exposure, assessment, fish, biomarkers
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