The potential environmental impact of wastewater from a chemical-pharmaceutical plant was evaluated by two different characterization strategies. The aim of the first strategy was to characterize the complex ef fluent before and after degradation by activated sludge. Chemical analyses (AOX, EOX, DOC, TOC, BOD, COD(Cr), N-total, N-NH4, N-NO2, N-NO3, P-total, and P-PO4) were performed on the undegraded and the degraded sample. Ecotoxicological tests were performed on the undegraded sample (acute toxicity, Microtox(R), inhibition of respiration of activated sludge, inhibition of nitrification of activated sludge) and on the degraded sample (acute toxicity, Microtox). Moreover, the concentration of potentially bioaccumulating substances was determined in the degraded sample. The tests were done according to the STORK Project (characterization of persistent organic compounds in industrial effluents) initiated by the Swedish Environmental Protection Agency. The second characterization strategy was concentrated on single substances in the effluent. The amount of all discharged chemicals was estimated using mass-balance calculations or by chemical analysis of the water phase. Ecotoxicological data for several of the substances were drawn from the reference literature. For those without any ecotoxicological information, a limited set of tests was performed (Microtox, octanol/water partition coefficient, biodegradation). All substances were classified on the basis of environmental effects using acute toxicity, biodegradation, and bioaccumulation criteria.The two different characterization strategies were useful when predicting environmental effects of wastewater from a chemical-pharmaceutical plant. From a practical and economical point of view, a stepwise approach including elements from both of the above strategies is recommended. A chemical-oriented strategy (discharged amount and ecotoxicological data for each compound) may be useful as a primary step for sorting out hazardous water phases from harmless ones. For less defined water phases, an extensive characterization program, including chemical analyses, acute toxicity testing, and ecotoxicological parameters, may give valuable information about environmental risks.

In 1974, abnormally high mortality was recorded among yolk-sac fry of Baltic salmon (Salmo salar) originating from feral females manually stripped and fertilized with milt from feral males. The cause of this mortality, designated M74, is unknown. Our hypothesis is that xenobiotic compounds responsible for reproduction failure in higher vertebrates in the Baltic Sea also interfere with reproduction in Baltic salmon. The significance of M74 should not be underestimated, because the syndrome has caused up to 75% yearly mortality of developing Baltic salmon yolk-sac larvae in a fish hatchery dedicated to production of smolt during the last two decades. We cannot exclude the possibility that only a relatively low number of naturally spawned eggs develop normally because of M74. No individual pollutant has been shown to be responsible for the development of M74 syndrome. However, a higher total body burden of organochlorine substances may be responsible for the M74 syndrome. The presence of induced hepatic cytochrome P450 enzymes in both yolk-sac fry suffering from M74 and adult feral females producing offspring affected by M74 supports this hypothesis. In addition, the P450 enzyme activity in offspring from feral fish is higher than the activity in yolk-sac fry from hatchery-raised fish, suggesting that feral Baltic salmon are influenced by organic xenobiotics.