Environmental Impacts

Once mercury enters the environment, it is persistent--that is, it never breaks down or goes away.

Mercury is deposited into water bodies from the air and enters the aquatic food chain in small fish and crayfish. It concentrates in the fish, birds and mammals that eat those fish. This is known as bioaccumulation. Predators of fish-eating animals (e.g., eagles that eat mink that eat fish) may be highly exposed.

At high levels of exposure, methylmercury's harmful effects on these animals include reduced reproduction, slower growth and development, abnormal behavior, and death.

Studies have documented elevated mercury concentrations in the following fish-eating animals: large-mouth and small-mouth bass, tuna, swordfish, tilefish, Chinook salmon, bald eagles, osprey, Kingfishers, common merganser, common loon, otter, mink and seals.