Eight percent of newborns in Lake Superior basin show high levels of
mercury, according to a recent study by Minnesota’s Department of
In Minnesota alone, 10 percent of the newborns whose
blood was tested for overall mercury showed levels above the
Environmental Protection Agency’s reference dose.
samples taken from a pool of 1,465 infants born between 2008 and 2010 in
Wisconsin, Minnesota and Michigan were tested. The elevated levels
found in the infants most likely resulted from pregnant women’s contact
with methylmercury, a form of mercury that gets introduced into the food
chain via fish.
The presence of methylmercury in newborns is
cause for alarm, as it has been shown to have an impact on cognitive
functions ranging from memory to motor skills.
“It’s a pretty
limited study; we can’t necessarily apply the finding to the whole
Minnesota population,” said Doug Schultz of the Minnesota Department of
Health, but the results presented “evidence that there’s more work to be
Health-care providers in Minnesota have been pressed to
make their patients aware of the risks of methylmercury in fish,
especially in the spring and summer, when locals will consume greater
numbers of locally caught fish.
mercury deposition levels tend to decrease in extreme northern states
like Minnesota and Michigan’s upper peninsula, there are problematic
species along the southern shore of Lake Superior. The levels for these
northern Great Lakes states are significantly lower than areas such as
downstate Illinois and Indiana, according to David Gay, coordinator of
the National Atmospheric Deposition Program at the University of
There was a seasonal pattern in the study as well,
showing an elevated concentration in the summer, when fish consumption
by pregnant women goes up. Mercury
levels in smaller inland lakes that exceed threshold levels provided
for fish consumption and protecting human health..
avoid mercury exposure, the Minnesota Department of Health advises
limiting consumption of some fish, such as bass, catfish and small
walleye. For some species, they recommend avoiding them altogether,
especially predatory fish like lake trout and northern pike.
identifying species of fish with elevated levels of toxins, the health
department also provides a site-by-site advisory for freshwater bodies
throughout the state.