Today, mercury is found in electrical fixtures, switches, medical equipment, and amalgam fillings; the metal is also used in battery, chemical, and paper production, and, in many countries, gold extraction (Gilbert 2004). In Washington, mercury is emitted by the coal-burning power plant in Centralia, and by manufacturers, oil refineries, medical waste disposal facilities, dental offices, and cremation facilities (Ecology 2003). The largest amount of Washington’s environmental mercury from in-state sources likely comes from the combustion of diesel, jet fuel, and heating oil. Mercury from these sources often circulates in the atmosphere and deposits on land and water, where it increases in concentration as it moves up the food chain.

Bacteria in water convert mercury to toxic organic mercury, which builds up in fish. When we eat fish—particularly long-lived fish that have accumulated mercury from a lifetime of eating other fish—the mercury tags along and settles in our bodies. The Washington State Department of Health has issued warnings about eating fish from Lake Whatcom, Lake Roosevelt, Sinclair Inlet, the Duwamish River, and Eagle Harbor because of mercury contamination (WDOH 2006). The department has also warned women of childbearing age and children under six not to eat any shark, swordfish, tilefish, king mackerel, or tuna steaks (WDOH 2001).