LANSING — The Department of Community Health (DCH) is having difficulty creating health advisories for imported and locally caught fish because it’s difficult to determine where the fish is caught.

Take, for example, whitefish caught in the Great Lakes. The Lake Superior whitefish is one of cleanest to eat, measuring less than .005 parts per million (ppm) of mercury. 

But for Lake Huron whitefish over 22 inches long it’s recommended that pregnant women and children eat only one meal per month, and that men consume less than one per week.

The warning is due to high polychlorinated biphenyls and mercury levels, which are harmful to humans in a variety of ways, such as damage to children’s nervous system and brain. In adults, it can cause vomiting, intestinal bleeding and possibly kidney failure. 

“One of the biggest problems is determining where the fish come from to give an advisory. But we can’t do that because the fish are sent to distribution centers in Chicago and other areas, and we can’t tell if the whitefish is Lake Michigan or Huron whitefish,” said Corey Groetsch, a DCH toxicologist. “Most of the fish that are brought to these distribution centers are from all the United States and Canada, and this is usually when the sampling is done.”

Federal Drug Administration toxicologist Michael Bolger said, “The Great Lakes are not tested that often. That would be done more at a local level. We take samples from fish that have few samples.”

The problem doesn’t stop there. Canadian fish imported into Michigan are not tested on a regular basis.

Sea Grant, a Marquette-based, federally funded program through University of Michigan and Michigan State University (MSU) runs programs with the commercial fishing industry. It works with local fisheries, testing mercury and methylmercury levels in lakes and rivers.

District Extension Sea Grant agent Ron Kinnunen said that more testing needs to be done on imported Canadian fish because most of their whitefish are caught in inland lakes.

“The few studies done on Canadian fish show higher levels of mercury, but because of the processing centers it’s difficult to determine where and how much mercury is in the fish,” said Kinnunen.

“If you took all the Michigan whitefish caught on the Great Lakes, the Canadian whitefish caught only on the inland lakes would still be greater in number than the whitefish caught on the Great Lakes.”

Inland lakes usually have higher amounts of mercury because of soil and pollution.

Cement factories release mercury into the air through smokestacks. The mercury gets into the air, settling into lakes and raising mercury levels.

“My in-laws just bought a cottage in Alpena,” said Jason Dinsmore, a Michigan United Conservation Clubs representative. “They are afraid they won’t be able to enjoy it because of pollution from a cement factory.”

Alpena’s Lafarge North American cement plant pumps out about 580 pounds of mercury a year. The plant recently won a lawsuit against the Environmental Protection Agency, which will allow them to pump out more than 500 pounds of mercury per year, the Associated Press reported.

The plant will voluntarily try reducing its emission to 390 pounds by 2010.

Recent studies including one by Brenda Holzman, an MSU epidemiologist, examined pregnant women, and found the amounts of mercury in their body.

The study found that women, with elevated mercury levels, were more likely to have premature deliveries. The study also found that canned fish – tuna, salmon and mackerel – contained more mercury than farm-raised or fresh fish.