Study Connects Mercury-Reducing Emission Regulations to Drop in Fish Contamination

By ecoRI News staff

A recent study ties a significant drop in toxic mercury levels in two types of freshwater game fish with Massachusetts’ ongoing efforts to reduce mercury emissions from waste incinerators, power plants and other sources.

“Mercury pollution takes a significant toll on our natural resources and the health of our citizens, and is one of the most potent toxins to children,” said Energy and Environmental Affairs Secretary Rick Sullivan. “This great news demonstrates that comprehensive, long-term efforts to address serious environmental problems can make a difference.”

The data show that in a mercury “hot spot” near several solid waste incinerators, levels of mercury in largemouth bass and yellow perch dropped by more than 40 percent after localized mercury emissions were cut by 98 percent. The data also show a 13 percent statewide mercury reduction in largemouth bass and a 19 percent reduction in yellow perch between 1999 and 2011.

The study, published by the Massachusetts Department of Environmental Protection (DEP), demonstrates that the drop in mercury levels in fish is tied to the state’s efforts to reduce sources of mercury pollution, eliminate unnecessary mercury uses and enhance recycling of mercury-containing products, according to officials.

Through the Massachusetts Zero Mercury Strategy and the regional Mercury Action Plan, Massachusetts has reduced its mercury emissions by more than 90 percent since the late 1990s, according to DEP. Efforts have included improved pollution controls on coal-fired power plants, municipal solid waste combustors and medical-waste incinerators, and in the dental sector. Legislation prohibiting many unnecessary uses of mercury in consumer products and enhanced recycling of mercury products have also been adopted.

Despite these improvements, however, the study also reveals that fish from many Massachusetts lakes and ponds remain unsafe to eat. Massachusetts and the other five New England states lead the nation in mercury reduction efforts, but mercury pollution is carried by the wind across borders, according to DEP.

“The drop in fish mercury levels seen in this study is very impressive and confirms that environmental regulations can and do work. But more can be done,” DEP Commissioner Kenneth Kimmell said. “We will continue to work with our regional and national partners to ensure that our lakes and ponds can again support a healthy freshwater ecosystem.”

Once released into the environment, mercury pollution from coal-fired power plants, incineration of wastes containing mercury and other sources can be transformed into methyl-mercury. Toxic methyl-mercury then concentrates as it moves up the aquatic food chain and can reach unsafe levels in certain types of fish. Depending on the level of exposure, it has the potential to harm brain development in the fetus and children, as well as neurological and immune systems in adults.

For more than a decade, DEP scientists sampled largemouth bass and yellow perch in 23 lakes and ponds across the state. The fish were analyzed for mercury concentrations. Mercury reductions were observed over the second half of the sampling period following significant mercury emission reductions.