Mercury is a naturally-occurring metal, yet it gets into the air from some consumer products, incineration of wastes, and burning of coal and other fossil fuels. Mercury precipitates into even the most pristine of lakes. In the water, bacteria and other processes convert it to methylmercury, which fish absorb from food and from water passing over their gills. Synthetic oils called PCBs once appeared in electrical transformers, cutting oils, and carbonless paper. Yet because they do not decompose easily, they remain in the water and in sediments.
Fish absorb PCBs from water, suspended sediments, and food.
Toxaphene is an insecticide mixture of over 670 chemicals. Though banned in 1990, it continues to appear in some fish. Dioxin is the name for a class of chemicals which occur as a by-product of the manufacture, molding, or burning of organic chemicals and plastics that contain chlorine. Public health officials must weigh the potential of public exposure to contaminants and make recommendations. In this simulation, you will decide what fish advisories you would make.