Women along the North Shore who reduced their meals of higher-mercury fish and instead ate lower-mercury fish reduced the mercury level in their blood by an average of 40 percent, according to results of a Minnesota Department of Health study released Monday.

The study of 499 women in Cook County, including many members of the Grand Portage Band of Lake Superior Chippewa, found that 3 percent of the women tested had elevated mercury levels.

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Those 15 women with high mercury levels and another 30 women who did not have elevated mercury levels were asked to reduce the amount of large walleye and lake trout that they ate and instead choose other fish like lake herring, also called cisco.

The effort was aimed at women between the ages of 16 and 50 and is the state's response to an alarming 2011 study that found 10 percent of newborn babies tested in the Lake Superior watershed of Minnesota had dangerous levels of mercury in their blood.

Unable to track exactly where those babies came from because the original tests were anonymous, the Department of Health instead focused on areas near Lake Superior where fish consumption is high. Fish and seafood are the most likely pathway for toxic mercury to enter people.

The state coordinated outreach efforts through the Sawtooth Mountain Clinic in Grand Marais and on the Grand Portage Reservation.

"We found that we could successfully reduce mercury levels in women through education ... educating women about mercury in fish did result in them changing their fish meals away from higher-mercury fish to lower-mercury fish, so they still received the health benefits of eating fish,'' Pat McCann, fish consumption program manager for the Minnesota Department of Health, told the News Tribune.

"Fish and fishing is our history and a strong part of the culture of the communities along the North Shore," said Rita Plourde, CEO of Sawtooth Mountain Clinic. "Together with our patients, we wholeheartedly agreed to do whatever was needed to educate and ultimately reduce mercury exposure in women who are or may become pregnant, thereby reducing mercury levels in future babies."

The study results - released five days before Minnesota's fishing opener - also found that asking women several key questions about their fish consumption is a very good predictor of which ones will have higher mercury in their blood, McCann said.

The question results "tended to overstate the mercury level, so we had some false positives. But we got a pretty good indicator by asking a few key questions,'' she said, noting that should help healthcare providers statewide track down and educate potential high-mercury patients.

With the state's targeted North Shore effort now concluded, the Department of Health is focusing on a statewide and Great Lakes-wide effort to encourage women to reduce or eliminate high-mercury fish from their diet.

Exposure to mercury, even small amounts, may cause serious health problems, especially for children and developing fetuses. Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes.

Some mercury that enters the atmosphere comes from volcanic activity and weathering of rocks but most comes from human activity such as burning coal in power plants, mining gold, incinerating garbage and processing taconite iron ore. Once in the environment, especially in water, mercury can be transformed by bacteria into toxic methylmercury, an organic compound that bioaccumulates in fish. Mercury increases as it moves up the food chain, including in people and animals that eat contaminated fish.

Minnesota's fish consumption advisory warns against eating frequent meals of large predatory fish like walleyes, northern pike and lake trout, especially for women and children. Smaller fish contain less mercury. Some types of tuna and other seafood also are high in mercury.

New website launched

Based on findings from the North Shore project and other research, the state and Health Partners joined efforts to release a new brochure and website, www.ChooseYourFish.org, both launched Monday. They are aimed at making it easier for women and families to follow the state's fish consumption guidelines. ChooseYourFish.org describes how often different fish species can be eaten to provide safe yet beneficial meals. The website also features simple recipes, videos and tips for selecting and cooking fish.