Study: 1 in 10 babies in Lake Superior region are born with high levels of mercuryOne of every 10 babies born in the Lake Superior region of Minnesota has unsafe levels of toxic mercury in his or her bloodstream, according to a Minnesota Department of Health study released Thursday.
By: John Myers, Duluth News Tribune
One of every 10 babies born in the Lake Superior region of Minnesota has unsafe levels of toxic mercury in his or her bloodstream, according to a Minnesota Department of Health study released Thursday.
Researchers looked at blood samples from 1,465 newborns in the Lake Superior area of Minnesota, Wisconsin and Michigan from 2008-10 for the study that was funded by the federal Environmental Protection Agency and the Minnesota Department of Health.
The results showed the highest levels of babies affected in Minnesota, at 10 percent, with 3 percent in Wisconsin and none in Michigan.
Across the three-state region, 8 percent of babies tested had levels 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 even small amounts can harm the developing brain and nervous system.
“This means that some pregnant women in the Lake Superior region have mercury exposures that need to be reduced,” the study concluded.
It’s been known for decades that too much mercury can cause severe developmental problems in children and fetuses and neurological damage in adults. Many studies have looked at the amount of mercury in fish, and some studies have looked at adult blood samples.
But health officials said this was the first study of its kind to measure and report mercury in newborn blood spot samples.
“There’s nothing to compare it to directly; there just isn’t other data out there,” said Pat McCann, research scientist for the Minnesota Department of Health. “The high levels we found in some cases were quite high. … But the percentages are in line with some of the national studies that looked at mercury levels in women.”
The report says the mercury exposure probably came close to the time of birth, and probably from the mothers eating fish or shellfish contaminated with methyl mercury. Other sources could be dental fillings or broken thermometers.
There was no difference in mercury levels between male and female babies, but babies born in the summer had higher levels of mercury.
“This seasonal effect suggests that increased consumption of locally caught fish during the warm months is an important source of pregnant women’s mercury exposure in this region,” the study concludes.
McCann 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 walleyes or northerns 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 could lead to lower developmental levels as children grow.
“There are studies that show their ability to learn and process information is impacted,” McCann said of children who had high exposure to mercury.
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.
Women “need more information on how to select fish low in mercury,” the report concludes.
“The message isn’t to scare people away from eating fish. We want women to eat fish; it’s a healthy food,” McCann said. “The message is to choose fish that will be low in mercury. … What we need to do now is get the word out to more women, before they get pregnant, on which fish are safe to eat.”
When in doubt, think smaller fish. Some of the best choices from Northland waters, McCann said, are smaller game fish, panfish, stream trout and salmon.
Mercury goes into the air when coal and other fossil fuels are burned — and from volcanoes and some other natural sources — and then falls back to Earth. In the U.S., about half of all mercury emissions come from coal-fired power plants. In Minnesota, taconite plants also are a large source. Both industries are moving to cut their mercury emissions.
Mercury that falls back to Earth can come from local and regional sources, but also from as far away as China, state pollution control officials note. That mercury can become toxic — called methylation — as it moves through the environment, and it can build up in small creatures, fish and animals that eat fish, including loons, eagles and people.
For more than a decade, Minnesota has moved to remove mercury from air emissions, consumer products and even crematoriums and dental offices. And the federal government moved just last month to cut mercury emissions from power plants nationwide.
John Doberstein, a Duluth Sierra Club activist and an angler, said education on which fish to avoid is good but that the goal should be getting more mercury out of the air and water.
“The solution is fish that aren’t contaminated that we can all eat safely,” Doberstein said. He and his wife have a 2-year-old and are expecting a second child this summer. “This is scary news for any parent. We hear companies complaining that they are over-regulated. But when our children are being poisoned, it’s clear we need to go even farther than we have to cut mercury pollution.”
To learn more
For more information on mercury in fish, including guidelines on which fish to eat, which fish to avoid and how often it’s safe to eat fish, go to www.health.state.mn.us/fish.