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Researchers reveal strategies for mercury reduction in time for negotiations

MIT, Harvard professors map future trends, reveal ways to reduce mercury levels on eve of final international meeting for mercury control.
The fraction of present-day atmospheric mercury deposition in Europe from European anthropogenic sources, based on the GEOS-Chem global chemical transport model.
The fraction of present-day atmospheric mercury deposition in Europe from European anthropogenic sources, based on the GEOS-Chem global chemical transport model.
Graphic: E. Sunderland and N. Selin/<i>Environmental Health</i>

International negotiators will come together next week in Geneva, Switzerland for the fifth and final meeting to address global controls on mercury. Ahead of the negotiations, researchers from MIT and Harvard University are calling for aggressive emissions reductions and clear public health advice to reduce the risks of mercury.

The researchers’ commentary, published this week in the journal Environmental Health, is in response to a study on the costs associated with mercury pollution in Europe. That study showed that as many as two million children in European Union nations are born each year with long-term IQ deficits due to unsafe levels of mercury exposure. These lower IQs can have spiraling effects on the earning potential of those impacted down the road, resulting in as much as 9,000 million euros in lost revenue a year.

But the authors of the commentary, Elsie Sunderland of Harvard and Noelle Selin of MIT, say mercury’s impact — and that of its toxic form methylmercury — extends far beyond the EU.

“Mitigating the harm caused by methylmercury requires global-scale cooperation on policies and source reductions,” Sunderland says.

Fish and other species, such as polar bears, can be harmed by mercury exposure. Once entered into the food chain, this exposure harms humans. In the near term, the public health community can advise changes in seafood consumption to control the risks, the researchers say. The critical action, however, comes in making significant progress in reducing mercury emissions to prevent an even greater increase in cycling “legacy” emissions.

“Most analyses forecasting mercury levels underestimate the severity of the situation because they don’t take the entire picture into account when looking at future mercury levels,” says Selin, an assistant professor of engineering systems and atmospheric chemistry.

Selin and Sunderland explain in their commentary that most mercury exposure comes from eating fish. Coal-fired power plants and other sources such as industrial activities emit mercury to the atmosphere. This mercury eventually rains down to the land and sea. In the ocean, mercury can convert to toxic methylmercury, and accumulate in the marine food chain. Mercury pollution settles deep within the ocean and circulates for decades and even centuries, continuously posing dangers to humans and the environment.

When considering future emissions, these “legacy” emissions are often not taken into account, but should be, the researchers say, because they make up a substantial amount of future emissions and could make already-dangerous levels of mercury even more threatening.

For example, mercury in the North Pacific Ocean — a large player in the global seafood market — is expected to double by 2050, from 1995 levels, due to new emissions. With the substantial “legacy” emissions that will circle back into the atmosphere, that amount is much greater. This increase in mercury could have dire impacts on fish from the Pacific Ocean.

“Not only will we see these ‘legacy’ emissions circle back up,” Selin says. “But with energy demands growing worldwide, we’ll see more new mercury entering the atmosphere, unless we act now to control this mercury at its source — and that’s largely coal-fired power plants.”

Sunderland and Selin say the United Nations Environment Program’s negotiations represent a sure step in the right direction. The question is: Will the talks produce real results?

In an interview with MIT News just prior to the first negotiating session in 2010, Selin said U.S. domestic politics would likely be a challenge to international cooperation on mercury. But last year, the U.S. Environmental Protection Agency finalized Mercury and Air Toxics Standards that require coal-fired power plants to install scrubbing technology that will cut 90 percent of their mercury emissions by 2015. With these standards — now the most stringent mercury standards of their kind in the world — Selin says the country has proven its leadership and provided some hope.

“These standards show that the U.S. is taking leadership at home to address a widespread and substantial global problem,” Selin says.

Selin, along with ten MIT graduate students, will present recent scientific results to negotiators in Geneva next week.

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