Five “hotspots” of mercury contamination posing a risk to human health have been found in the eastern states of the US and eastern provinces of Canada.
Average mercury concentrations in many of the region’s freshwater fish exceeded the US Environmental Protection Agency’s (EPA) recommended level for safe consumption by up to 20 times.
Mercury is a well known neurotoxin. The study, led by David Evers at the Biodiversity Research Institute in Maine, raises concerns that current US laws to limit mercury emissions are falling short.
The EPA safety limit for the consumption of mercury is 0.3 parts per million, yet perch in some locations contained a concentration of about 5 parts per million. The researchers found the average mercury concentration in fish across the region was between 10% and 88% above the limit, depending on the species.
Over four years, the researchers measured mercury levels in edible fish, as well as eagles, otters and mink across New England and New York in the US, and Nova Scotia in Canada. They found five hotspots where levels were particularly high, plus nine areas of concern.
These included parts of the Adirondack Mountains in New York, the Merrimack river in New Hampshire and Massachusetts, the Kennebec river in Maine and Kejimkujik National Park in Nova Scotia, Canada. (An earlier part of the research programme found high mercury levels in songbirds.)