The state also cracked down on mercury in dental implants and mercury that went up the smokestacks of crematoria and was among the first to require power plants to reduce mercury emissions. The federal Environmental Protection Agency has followed suit nationwide.
Many Northland residents were jolted a year ago when the Minnesota Department of Health released a study that showed 10 percent of all babies born in the Lake Superior region of the state have levels of toxic mercury in their bloodstreams above the 5.8 micrograms per liter that the EPA considers safe. Some went as high as 211 micrograms per liter. Fetuses, infants and children are most at risk from mercury exposure because small amounts can harm the developing brain and nervous system.
Health officials said a mother eating as few as two meals per week of fish high in mercury could cause newborn blood levels to reach unacceptable levels. That includes large trout, walleye or northern from Northland lakes or yellowfin tuna, shark, mackerel or orange roughy from the ocean. The state warns women and children not to eat any walleye over 20 inches or northern pike over 30 inches.
The mercury exposure from fish could lead to lower developmental levels as children grow.
Minnesota, Wisconsin and Michigan already have posted advisories for people — especially pregnant women and children — to limit the size and number of meals they eat of fish caught from many lakes and rivers. But the study suggests that information may not be reaching enough people.
The health department, with federal funding, is conducting an intensive follow-up study in Cook County to find out how to reduce pregnant women’s exposure to mercury, which is probably coming from fish the mothers eat.
A global treaty signed by 140 nations in January sets controls and reduction targets for many industries, products and manufacturing processes that use mercury, focusing on four main areas: the global supply and trade of mercury; the use of mercury in products and industrial processes; efforts to reduce emissions from small-scale gold mining in poor nations; and measures to reduce emissions from coal-fired power plants and metals production facilities such as smelters.