Bioaccumulation of organic micropollutants in different aquatic organisms. Sublethal toxic effects on fish

Bioaccumulation of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) was investigated in plankton, crustaceans, and fish from two relatively small Amsterdam lakes, with different levels of contamination. Ratios between contaminant concentrations in organisms and sediments ranged from 0.1 to 41.7. The accumulation of pollutants could not be explained as a simple partitioning between sediment, water, and organisms. Probably, both biomagnification (PCBs and OCPs) and biotransformation (PAHs) affect the bioaccumulation in aquatic organisms. These effects were more pronounced in organisms of the higher trophic levels of the aquatic food-chain. Mixed function oxygenase (MFO) activity of liver microsomal fractions was determined in three fish species (roach, ccl, and pike) and compared with those of similar fish taken from a less contaminated lake that served as a reference. Despite the low level of contaminants present in the two lakes, an induction of both cytochrome P-450 and ethoxy-resorufin-O-deothylase (EROD) activity was observed in all three fish species involved. Pentoxyresoufin-O-depentylase (PROD) activity was induced in pike and eel only. Both the 3-methylcholan-threne-type inducible isozymes (P-450IA) and the phenobarbital-type inducible isozymes (P-450IIB) seem to be induced in the fish. These findings suggest that MFO enzyme activity in fish liver may be a suitable and sensitive indicator for the presence of trace organics in the aquatic environment. Despite the enzyme induction, no significant liver enlargement was observed in the fish species investigated, which can be interpreted as the absence of some pathological changes.