MINNEAPOLIS -- One in 10 babies along Minnesota's border with Lake Superior is born with unhealthy levels of mercury, according to a new report.
Researchers also found the Minnesota infants were more likely to have unhealthy mercury levels in their blood than their counterparts in Wisconsin and Michigan. In Minnesota, 10 percent of the blood samples had mercury levels above the healthy standard.
"We've never had hard evidence that there were exposures," said Pat McCann, the research scientist who conducted the study for the Health Department and the Environmental Protection Agency. "This provides that."
Health officials said mothers in the area likely eat more fish -- the primary source of mercury contamination -- than elsewhere. McCann told the Star Tribune that babies born in the summer months, when local fish consumption is highest, had higher levels of mercury.
Mercury is a pollutant that can cause neurological damage and is distributed around the world, primarily by coal-fired power plants. It can affect the brain and nervous system development in fetuses and babies. At high levels, it's been shown to affect memory, attention and language.
Between 2008 and 2010 the researchers randomly checked blood samples taken from 1,465 unidentified infants born around the Lake Superior Basin. The majority by far were from Minnesota, where the basin extends from Duluth to Hibbing and up along the shore to the Canadian border. In all, 8 percent of the babies had blood concentrations above the EPA health standard -- up to a thousand times higher.
Infants in that region were chosen because an international organization focused on Lake Superior contributed funding, not because the population there is at higher risk, McCann said.