Mercury enters lakes and other waters in rain, snow and runoff, and reacts with bacteria that converts it to a toxic form that s easily absorbed by insects and other small organisms. In this way, mercury levels accumulate up the food chain so that large predator fish such as walleye contain the highest amounts. When people eat these fish, they accumulate mercury as well. People who frequently eat fish high in mercury can accumulate levels that may harm their health. That s why the Wisconsin Department of Natural Resources and Division of Public Health advise people about the number of meals and species they can safely eat.
Fish is the main source of mercury in human diets.
Ingesting too much mercury can harm your health. At low doses, mercury can harm the developing nervous system in a fetus or may affect cardiovascular and immune systems in adults. At high doses, mercury can affect your central nervous system, triggering such health problems as memory loss, slurred speech, hearing loss, lack of coordination, loss of sensation in fingers and toes, reproductive problems, coma, and possibly death. Fetuses and babies are most at risk because their developing nervous systems are much more sensitive to mercury than adults nervous systems. An estimated 60,000 children born each year in the United States are at risk of suffering neurological and learning problems because their mothers eat large amounts of mercury-contaminated fish and seafood during their pregnancy.