Underscoring a growing concern about mercury poisoning, the state Department of Public Health is preparing this week to release 13 new fish consumption advisories, a sign that mercury contamination in bodies of water may be worsening across the state.
Primarily a residual effect of industrial plants in the Midwest, the mercury has tainted lakes, rivers, streams, and ponds in virtually every part of the state. Pregnant women and small children are particularly at risk of neurological damage from eating certain types of freshwater fish from these areas, say state health officials.
In areas northwest of Boston, several bodies of water already have the consumption advisories, a situation that spurred a public forum this week in Groton. Part of the discussion at the forum centered on ways area residents can help curb mercury emissions by avoiding throwing away products that contain mercury - thermometers, button cell batteries, fluorescent lights, and the like - into the trash. Instead, consumers are encouraged to refrain from buying such products or to take them to local transfer stations, where municipalities often have mercury disposal programs in place.
Todd Dresser, an environmental scientist invited to speak at the forum, said last week that local disposal of items containing mercury represents a small part of the equation in terms of mercury emissions into the environment. But every little bit helps mitigate further pollution, he said.
"There's certainly a local component to it," said Dresser. "It's a challenge because it's a global issue, and people get overwhelmed by it. The point is, mercury is a big problem, but there are local impacts we should take notice of."
When incinerated at a solid waste recycling facility, mercury from thermometers and fluorescent lights escapes into the atmosphere and enters lakes and ponds through rainfall, Dresser said. Once the mercury is in the water, plankton absorbs it, he said. "It goes right into the food chain."
But the deeper problem is smoke and smog from incinerators in the Ohio Valley area, whose residue blows east along the jet stream and into Massachusetts, he said.
That issue has led to a lawsuit by 16 states, including Massachusetts and New Hampshire, which are seeking to force the US Environmental Protection Agency to crack down more forcefully on mercury emissions, said Dresser.
Area bodies of water with existing fish consumption advisories include Massapoag Pond in Dunstable, Bare Hill Pond in Harvard, the Concord River in Carlisle, and Forge Pond in Littleton.
The warnings, available on the Department of Public Health's website, vary from town to town. The consumption of all fish is discouraged at Massapoag Pond, for example, while only largemouth bass is cited for Forge Pond.
In both cases, small children and pregnant woman are directed not to eat classified fish from these sources at all, while the rest of the population is advised against eating such fish from these ponds more than twice a month.
Generally speaking, fish higher up in the food chain, such as pickerel and bass, tend to absorb the mercury in higher doses, said Dresser. No recent deaths or illnesses have been linked to fish consumption in the last decade, but Suzanne Condon, director of the Bureau of Environmental Health at the Department of Public Health, attributes that mainly to publicity the state has brought to the issue.
Since 1994, the department has been issuing the fish advisories and forcing towns to post signs at risky locations, she said.
"Childhood development is what we worry about most," said Condon. "We've seen an incredible rise in mercury levels in fish. It's a problem that's getting worse, and that's one reason why Massachusetts was one of the states to join the lawsuit."
The new list of advisories was to be released late this week.
Sylvia Willard, conservation administrator in Carlisle, sees people fishing on the shores of the Concord River, where she used to go canoeing on weekends. Signs had been posted on the bridge abutments along the river warning of mercury risk, but Willard still worries sometimes.
"Occasionally, you see people fishing there," she said. "I've always been uncomfortable with it."
