HARWICH — The Massachusetts Department of Public Health has issued public health advisories recommending fish caught in two Harwich ponds not be eaten due to high levels of mercury.
The advisory was issued on July 3 and pinpoints a number of ponds across the commonwealth where fish have been contaminated by mercury. According to the advisory, children under 12, pregnant women, nursing mothers, and women of childbearing age who may become pregnant should not eat all species of fish caught in White Pond or largemouth bass from the Mill Pond. For all others, the advisory sets a consumption limit of two meals of fish caught in the ponds a month.
White Pond is located in North Harwich and extends into Dennis along the north side of Old Chatham Road. Mill Pond is located on the west side of Route 137 at the Brewster town line.
The mercury levels in all fish tested from White Pond was above the DPH guideline level of 0.5 parts and thus the regular consumption of the fish pose a potential concern, according to Marc A. Nascarella, director of the environmental toxicology program at the state Bureau of Environmental Health. The mercury levels in largemouth bass in Mill Pond exceeded the levels as well.
Nascarella said DPH works cooperatively with the state Department of Environmental Protection and the Division of Marine Fisheries in designing fish surveys and measuring concentrations of contamination in freshwater fish samples. When elevated levels are detected, DPH issues consumption advisories.
There were advisories issued for more than 200 lakes and ponds across the state, including 24 freshwater bodies on the Cape and Islands. Baker’s Pond on the Orleans-Brewster town line was also posted for high mercury content in yellow perch. Sheep Pond in Brewster was identified as having excessive mercury in all species of fish. Advisories were also issued for several ponds in Truro and Wellfleet. No advisories were issued for ponds in Chatham.
According to the MassDEP Mercury Information website, mercury can be found at low levels almost anywhere, but burning of coal and trash have greatly increased its levels in the environment. The environmental impacts of mercury can be local or carried across whole regions or entire continents by the wind.
In lakes, ponds, and the ocean, mercury can be transformed by natural processes into a more toxic form called methylmercury, which enters the food chain when small organisms absorb it.
“Methylmercury is extremely poisonous and can damage the brain even at low levels. People may be exposed to this type of mercury by eating contaminated fish,” according to the website. “Developing fetuses, nursing babies, and young children are affected by mercury. Small amounts can damage the brain even before birth. High levels of mercury can affect how well children learn, think, behave, and develop later in life. Children who have been exposed to mercury in the womb can experience symptoms even if their mothers do not.”
Health Department Director Meggan Eldredge said she has received the DPH advisories and was planning to post notifications at White and Mill ponds.