Several bioindicators were used to evaluate the biological and genotoxic effects of marine pollutants near large coastal cities in the northwestern part of the Mediterranean Sea. Three target species of teleosts were selected: red mullet Mullus barbatus and 2 types of comber (Serranus hepatus and S. cabrilla). Induction of ethoxyresorufin-O-deethylase (EROD) activity specific for polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) was measured in the livers of the fish, and inhibition of acetylcholinesterase (AChE) by organophosphorus insecticides and carbamates was measured in their muscle tissues. Maximal EROD activities (16.8 +/- 2.7 to 19.4 +/- 4.2 pmol min(-1) mg protein(-1)) recorded in red muller near Barcelona (Spain), Milazzo (Sicily) and Ostia (Italy) indicated exposure to high pollutant concentrations. Inhibitions of AChE activity were low in areas remote from agricultural and industrial activity. The highest inhibitions were measured at sites of heavy industrial and domestic waste, such as Genoa and Naples (Italy), Rio Ter (Spain), Barcelona, and Cortiou (France). Inhibition of AChE activity was higher at a given station for younger individuals 120 to 140 mm in length than for those 160 to 180 mm long. Antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase and DT-diaphorase) were measured in red mullet livers at 5 stations along the French and Spanish coasts. Catalase activity was highest al Cortiou, consistent with higher levels of pollution, and lower at Mallorca (Balearic Islands). Varying responses were obtained for the other antioxidant enzymes. Glutathione S-transferase (GST), a detoxification enzyme, was also measured in the livers of red mullet fish and found to be significantly higher at Cortiou than at the other locations studied. Chemical measurement of PAH in surface sediment indicated the pyrolytic origin of this contaminant for all stations except Milazzo (petroleum origin). Detection of DNA adducts as a bioindicator of exposure to carcinogenic substances was tested according to 2 complementary assay techniques: enzyme-linked immunosorbent assay (ELISA) and P-32-postlabeling. ELISA revealed maximal quantities of PAH-DNA at Barcelona (15 adducts per 10(8) nucleotides), Cap Finale (Corsica) (20.8) and Milazzo (15.5). The richest adduct profiles were detected by the P-32 method at Antibes (France), Santa Ponza (Balearic Islands), Milazzo and Cap Finale, with a maximum of 6.2 adducts per 10(8) nucleotides at Milazzo. This multimarker approach showed that pollutant exposure levels varied according to site. With a sedimentary PAH profile apparently resulting from petroleum pollution, the Milazzo station had the greatest quantity of DNA adducts and the highest inductions of EROD activity and AChE inhibitions in M. barbalus and S. hepatus.