Carcinogens in estuaries, their monitoring and possible hazard to man.

Bottom-dwelling flatfish and their skin tumors can be used as an early-warning-system for the pollution by chemical carcinogens in sub- and inter-tidal waters. A trial in British Columbia and the State of Washington showed a link between tumor prevalence and urban activity. The possible use of marine accumulator organisms (mussels) in the estimation of benzo(a)pyrene levels of harbours is considered. The combination of biological and chemical assays could provide the basis for a large-scale routine surveillance of the marine environment.