Minnesota regulatory officials said Monday that the state’s coal-fired power plants have cut their mercury emissions by more than half over the past 15 years as the state tries to limit its residents’ exposure to the toxic metal.
The Minnesota Pollution Control Agency held a media event at a Twin Cities power plant to herald the effort of cutting mercury from 1,850 pounds per year in the 1990s to about 870 pounds today.
PCA Commissioner John Link Stine said the goal is to cut power-plant emissions to less than 200 pounds by 2016, and he praised Duluth-based Minnesota Power and Twin Cities-based Xcel Energy for their effort to cut back on mercury.
“One measure of their success is that the U.S. Environmental Protection Agency now looks to Minnesota as a model for how other states can reduce their own emissions of mercury from power utilities,” Stine said in a statement.
Margaret Hodnik, Minnesota Power vice president of regulatory and legislative affairs, said the utility has cut mercury by 90 percent at its coal-burning plants in the region.
Despite Minnesota’s success at reducing mercury going into the air, it hasn’t been able to stop mercury from falling out of the sky. That’s because about 10 percent of the mercury that falls in Minnesota comes from human-caused sources within the state. The rest comes from all over the Earth, including as far as Asia, as mercury floats through the atmosphere before falling in rain and snow.
That’s also why, despite Minnesota’s efforts, fish in Minnesota lakes haven’t shown a major reduction in mercury.
That mercury can transform into highly toxic methylmercury in wetlands, lakes and rivers, building up in fish and in animals, including loons and eagles — and humans — that eat fish.
Minnesota, Wisconsin and most other states have issued fish-consumption advisories, warning anglers and others to limit their meals of some fish, such as walleye and northern pike. The advisories warn children and pregnant women not to eat larger fish. The warnings are aimed at preventing accumulated toxic mercury buildup known to cause severe developmental and neurological damage, especially in fetuses and young children.
Electric utilities are the largest source of mercury emissions in Minnesota and most other states, and burning coal is the largest source in that sector. In Minnesota, the taconite-processing industry is the second-largest source, and efforts to cut mercury reductions there are under way.
Minnesota already has been taking action for more than a decade to reduce mercury from products such as batteries, thermostats, switches and light bulbs.
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.
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