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HISTOPATHOLOGICAL BIOMARKERS AS INTEGRATORS OF CHEMICAL CONTAMINANT EXPOSURE AND EFFECTS IN FISH
Citation:
Myers, M. S. AND J W. Fournie. HISTOPATHOLOGICAL BIOMARKERS AS INTEGRATORS OF CHEMICAL CONTAMINANT EXPOSURE AND EFFECTS IN FISH. Presented at SETAC Meeting, Salt Lake City, UT, Nov 17-20, 2002.
Description:
Histopathology can be an extremely useful tool for assessing effects of chemical exposure in fish at the level of the individual. Although somewhat qualitative, the histopathological approach is especially valuable because observed lesions represent an integration of cumulative effects of biochemical and physiological changes, allowing identification of specific cells, tissues, and organs affected, and represent actual injury to the individual. Certain lesions in various tissues and organs may at some point become reliable biomarkers of specific chemical stressors, but these require further validation by epizootiological and laboratory studies. Examples include lesions of the excretory and hemopoietic kidney, gonad, gills, central nervous system, and neurosensory organs. In our opinion, there are only a small number of histopathological biomarkers that have been shown via rigorous epizootiological methods and experimental validation to be reliable and useful indicators of exposure to various chemical stressors in wild fish. These include liver lesions (especially those involved in the histogenesis of neoplasia), splenic macrophage aggregates, some skin and oral neoplasms, and certain musculoskeletal abnormalities. These lesions range from relatively specific to nonspecific in their etiology, and all require accounting for seasonal, physiological, age and sex-related variation. For example, an epizootic of liver neoplasms and other lesions involved in the stepwise histogenesis of liver neoplasia in a population of fish indicates that they have been exposed to hepatotoxic and hepatocarcinogenic contaminants. Increased frequency of splenic macrophage aggregates is a far less specific biomarker, but still indicates that affected fish probably have been exposed to contaminated sediments, low dissolved oxygen, or some other stressor; it is therefore useful as a screening tool. Overall, in order to do an environmental assessment of the health status of a body of water, it is necessary to evaluate the health of the organisms inhabiting that particular body of water, which requires a histopathological examination of representative tissues and organs from those organisms.