Negotiations for a legally binding global treaty to restrict mercury use could begin next year if the United Nations Environmental Programme (UNEP) Governing Council follows the advice of scientific experts concerned about the environmental and health impacts of mercury.

Some 150 scientists from UNEP’s Mercury Assessment Working Group (MAWG) met in Geneva in September and concluded that “there is sufficient evidence of significant global adverse impacts to warrant international action” on protecting against mercury pollution. UNEP’s Council hopes to reach a consensus on the proposal at its meeting in Nairobi next February. The main threat comes from consuming methylmercury, which accumulates in fish, animals, and humans. Methylmercury is a potent neurotoxin even at low doses.

“It is almost certain that the governing council will approve something,” says Jim Willis, UNEP’s chemicals director, who is not aware of any countries that oppose a mercury treaty. Treaties usually take two to four years to negotiate and another two to five years to enter into force.

The MAWG noted the dangers of mercury, including adverse neurodevelopmental effects, as well as adverse effects on the cardiovascular, immune, and reproductive systems. The group recommended several options for restricting mercury use, including a “nonbinding global program of action”. It also suggested that UNEP should encourage governments and industry to reduce or eliminate mercury’s production.

More immediately, governments could raise the awareness of the dangers of mercury among vulnerable groups, such as pregnant women. “Outside of a few wealthy countries, little has been done to inform susceptible people of the risks they face, ” says Willis.

Plans to remove mercury from commerce could be thwarted due to an excess of surplus mercury in both Europe and the United States, combined with a demand for it in developing countries. In a report published in September, the European Commission found there would be 13,000–15,000 tons of mercury left once mercury-based chlor-alkali plants, which produce chlorine and caustic soda, are phased out. The EU industry has agreed to phase out mercury-based plants by 2020. The U.S. government holds more than 5000 tons of mercury in storage, the report notes, and the United States’ chlor-alkali industry estimates it will have some 3000 tons of mercury available once it shuts down its mercury-cell plants.

The European industry favors mercury reuse, says Peter Whippy of Euro Chlor, the chlor-alkali industry federation in Western Europe. Because mining mercury produces emissions to air, reuse “helps minimize environmental pollution by leaving the equivalent amount of mercury in the ground,” he adds. Reuse projects are under way: Euro Chlor members have agreed to sell up to 1000 tons per year of mercury back to Minas de Almaden, the largest mercury mine in the world, where it will be sold for reuse. “A continuing supply of surplus mercury will keep the price low and the use of mercury will remain attractive,” according to the EC report.

However, the EC is concerned about considerable environmental damage that could be caused by surplus mercury. “Mercury is a long-range transboundary air pollutant” the EC wrote, “and further placing it on the market will lead to mercury emissions that add to the already increased local and global background levels in the environment.”

The report identifies intermediate storage as a disposal option, noting that it could be stored safely for an unknown period of time until a strategy for re-use and/or safe disposal is designed. But this option isn’t risk free: disadvantages include additional costs, because this is only an interim solution, and possibly additional emissions from handling.

The report concludes that the best solution, from an environmental standpoint, is to dispose of surplus mercury, although “appropriate methods are not yet fully developed and costs are relatively high”.

Environmental organizations are concerned about storing mercury, because it is exceptionally persistent and some leakage is inevitable, says Mathew Wilkinson of the World Wide Fund for Nature U.K. Nonetheless, the advice from UNEP’s mercury working group to the governing council “puts the issue of mercury on the radar screen of governments, so they can’t ignore it,” he adds.

The Report from the Commission to the Council Concerning Mercury from the Chlor-Alkali Industry can be found at http://europa.eu.int/eur-lex/en/com/rpt/2002/com2002_0489en01.pdf. —MARIA BURKE