Cytochemical responses in the digestive tissue of Mytilus edulis complex fed a microencapsulated mixture of PAHs (composed of phenanthrene, fluoranthene and benzo[a]pyrene) or PCBs (Aroclor 1254) were evaluated. Lysosomal membrane labilization period and lipofuscin content of digestive tissue were significantly decreased and increased, respectively, after 30 days of exposure to PAHs but not PCBs. NADPH-ferrihemoprotein reductase activity in the digestive tissue was significantly increased after 30 days exposure to both PAHs and PCBs, whereas catalase activity was significantly increased only after exposure to PCBs. Neutral lipid content and gamma-glutamyl transpeptidase activity of digestive tissue of mussels were significantly increased and decreased, respectively, after 30 days exposure to both PAHs and PCBs when compared to untreated mussels, but were not significantly different when compared to mussels treated with com oil representing the vehicle control. Exposure to PAHs induced peroxisome proliferation in the digestive tissue of M. edulis complex. The observed cytochemical responses in the digestive tissue of M. edulis complex exposed to PAHs and PCBs in the laboratory are comparable to the cytochemical responses observed in the digestive tissue of mussels collected in the field from sites contaminated with predominantly PAHs and PCBs
