Receiving water environmental effects associated with discharges from Ontario pulp mills

White sucker collected mean chlorinated bleached kraft mills exhibited the highest induction of liver detoxitication enzymes (measured as ethoxyresonilin-o-deethylase activity EROD) and the highest measured levels of chlorinated dioxins and turans. However, elevated enzyme activity was observed in fish from sites which did not use chlorine. Furthermore, decreased circulating levels of sex steroids, decreased gonadal size and increased liver size were observed in fish collected at sites with and without chlorine bleaching and at sites with secondary treatment of effluent.