Determination of the environmental fate and toxic effects of organic contaminants in the aquatic environment, especially in the fate and toxic effects of halogenated aromatic hydrocarbonons, polynuclear aromatic hydrocarbons, alkylphenol ethoxylate surfactants and prescription and non-prescription drugs in the aquatic environment. Research on endocrine disruption in fish as well as international research experience through work in Mexico, Argentina, Ecuador and Indonesia.