Mechanisms of bioaccumulation in aquatic systems.

Bioaccumulation of contaminants in aquatic organisms occur via several routes, including absorption across the cuticle and respiratory surfaces and assimilation from ingested media. For many contaminants of environmental importance, bioaccumulation can be understood as a simple partitioning process in which contaminants accumulate in living organisms in proportion to their lipophilicity. However, there are a variety of biological and physical factors that can influence bioaccumulation and result in deviations from the expected steady-state distribution of contaminants. Key variables have been identified, although their influence alone and in combination on bioaccumulation have yet to be determined. Because risk assessment depends on having an accurate evaluation of contaminant fate and effects, it is imperative to understand how bioaccumulation profiles may be modified by these variables.