How do contaminants get into fish?
Contaminants can reach rivers and lakes from local sources such as improperly stored wastes and abandoned dumps. If a local source is identified, it may be possible to clean it up and decrease the contamination of the lake or river. However, contaminants also reach remote and pristine lakes from the atmosphere. Once in a lake, mercury is converted to methylmercury by bacteria. Fish absorb methylmercury from their food. Mercury is tightly bound to proteins in all fish tissue, including muscle. There is no method of cooking or cleaning fish that will reduce the amount of mercury in a meal. Larger, older fish and fish which eat other fish accumulate more contaminants than smaller, younger fish which eat less contaminated prey. Fish absorb fat-soluble chemicals like PCBs and dioxins from water, suspended sediments, and food. PCBs and Dioxins concentrate in the fat of fish, and in fatty fish such as carp and catfish. Cleaning and cooking a fish to remove fat will lower the amount of PCBs an
