Fish in Minnesota lakes and rivers accumulate mercury.
Mercury recycles between land, water, and air and enters plant and animal tissue.
Although mercury is a naturally-occurring metal, most of the mercury which enters Minnesota waters comes from household and industrial wastes released during incineration, latex paints, and other fossil fuels. Mercury is found in most fish tested from Minnesota lakes. Fish in some lakes and nearly half of the rivers which have been sampled for this advisory program contain PCBs. These synthetic oils had many uses and are found in electrical transformers, cutting oils, and carbonless paper. Although they were banned in 1976, they do not decompose easily and remain in the water and lake sediments for years.