Time to contain mercury emissions

The European Union has moved aggressively to combat mercury exposure.

The harm that can be caused by consuming or breathing mercury is well known and terrible. A pregnant woman, eating too much of the wrong kind of fish, risks bearing a child with neurological damage. Adults or children exposed to mercury can experience mood swings or tremors, or sometimes even respiratory failure or death.

In January, representatives of dozens of countries will gather in Geneva to discuss combating mercury emissions, which are rising in Asia even as Europe and the United States have tightened controls. The meeting is the last of five negotiating rounds—the first took place in 2010 in Stockholm—and a legally binding treaty on mercury contamination is expected to come together next year.

The signing of that treaty is set to take place in the Japanese city of Minamata, where widespread mercury poisoning occurred in the mid-20th century after discharges from a factory contaminated the seawater. But the extent to which countries will commit to reducing mercury, and whether they will follow through on those commitments, are open questions.

“What remains to be seen is the stringency of the requirements,” said Noelle Eckley Selin, an assistant professor of engineering systems and atmospheric chemistry at the Massachusetts Institute of Technology. The negotiations “appear to be going in the direction of voluntary compliance,” said Leonard Levin, an air quality specialist with the Electric Power Research Institute, a nonprofit organisation with headquarters in Palo Alto, California.

Major conference

The negotiations in Geneva are being conducted under the auspices of the UN Environment Programme and are to be followed in the summer by a major conference on mercury in Edinburgh, where scientists and policy makers will discuss how to implement a treaty.

Roughly one-third of the world’s mercury air emissions come from human activity, like coal-fired power plants. Another third of emissions come from natural sources, like volcanoes or wildfires, and the final third are “re-emitted” after their initial release.

Within the human-generated category, Asia contributes nearly 50 percent of mercury emissions, with North America at 7 percent and Europe and North Africa at 12 percent combined, according to Jerry Lin, a professor of environmental engineering at Lamar University in Texas. In addition to coal-fired power plants, a major source of mercury emissions is small-scale gold mining.

Miners working on their own often use mercury to help extract gold and then boil it off, leaving behind dangerous contamination.

The effects of mercury contamination are not limited to the local environment. Mercury finds its way into the sea, affecting fish like bluefin tuna, and airborne emissions can travel between continents. “The mercury today will continue to circulate in the system for a long time,” Dr Selin said. “We’re talking decades to centuries.”

Meanwhile, research into the health consequences of mercury “has been finding adverse effects at lower and lower exposures,” Philippe Grandjean, chair of environmental medicine at the University of Southern Denmark, said in an e-mail. New research has found that some people may be more sensitive to the effects of mercury, he said, because of factors like genetics.

The European Union has moved aggressively to combat mercury exposure. A ban on mercury exports began in 2011, and the Union has issued rules on storing mercury and restrictions on some products containing mercury, like thermometers. It is currently considering additional rules on mercury in dental fillings and batteries.

Sweden has “been really out in front” on national mercury regulations, Dr. Selin said. The country banned mercury from dental fillings and other products several years ago.

Starting in January, the United States will ban the export of elemental mercury, whose uses include gold mining. (The ban covers the Department of Defence and the Department of Energy, which keep large stockpiles.) The new policy results from the Mercury Export Ban Act of 2008, which was signed into law by president George W Bush.

In another key mercury development, last year, the Environmental Protection Agency in the United States completed its first rule aimed at mercury emissions from coal plants. The effect on the power industry is unclear, however.

Other regulations in the United States have also affected coal plants. Controls required for pollutants like nitrogen oxide and sulfur dioxide can also reduce mercury emissions, as a “co-benefit.” For China, which is building new coal-fired power plants at a rapid rate, such ‘co-benefits’ could prove crucial, said Dr Lin of Lamar University. That is because it would be economically difficult to control only for mercury.