Inaugural Conference - June 2002
TOXICOLOGIC PATHOLOGY OF SMALL LABORATORY FISH
Piet W. Wester, Laboratory for Pathology and Immunobiology,
National Institute of Public Health and the Environment, Bilthoven, The Netherlands
Besides
infectious disease outbreaks and habitat destruction, pollution by anthropogenic
chemicals is considered a significant potential threat to wildlife health. The
aquatic environment is particularly at risk as it is an important recipient
of waste and polluted material. Among aquatic organisms fish have a high level
development and have a high position in the food chain, and thus are targets
for bio-accumulating compounds. For a meaningful interpretation of toxic effects
in fish, knowledge of sublethal events is essential and for this reason we have
conducted a series of studies with relevant environmental pollutants and using
histopathological changes as principal endpoints. This was done, for various
practical reasons, with small laboratory fish under controlled conditions. Specific
changes with potential wildlife health relevance are the atrophy of the thymus,
an essential organ in the developing immune system, in fish exposed to the antifouling
agent TBTO, and changes consistent with estrogenic effects by b-HCH, a lindane
isomer. Such estrogenic effects (e.g. accumulation of vitellogenin, disturbance
of gonad development and function) are currently essential biomarkers in the
context of endocrine disruption in aquatic wildlife studies. A compilation of
endocrine disrupting effects in small laboratory fish is made available as a
digital histology atlas on internet (http://www.rivm.nl/milieu/rivmzfatlas/fish-
toxpat/index_nl.html).
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