By Richard Black
BBC environment correspondent
World governments have concluded an agreement on reducing production and use of the toxic heavy metal mercury.
Coal fires are a major source of mercury in the environment
It came at the biennial meeting of the United Nations Environment Programme (Unep) Governing Council in Nairobi.
The agreement stops short of setting up a legally binding global treaty, as the European Union had advocated.
Instead, it calls on member countries to establish "voluntary partnerships" to reduce the damaging impacts of mercury pollution.
It also mandates Unep to pursue various avenues of further research, including a project to document mercury use in much greater detail than has been done before.
Mercury is a naturally occurring metal released into the environment from rocks and soils, and in volcanic eruptions. But human activities, including mining, industry and power generation, are continually adding more.
About 70% of mercury emissions of human origin come from the burning of coal and the incineration of waste materials.
And once in the environment, this pollution can travel long distances.
The discussions in the Kenyan capital brought together two opposing views on how to tackle mercury.
One bloc, led by Norway and Switzerland and supported by member states of the EU, argued that a binding treaty would be the most effective way to reduce production and use.
This was opposed by the United States and its allies, which advocated instead the "voluntary partnerships" approach - although the precise nature of these partnerships between as yet undefined groups of governments, international organisations such as Unep or the World Bank, and industry has yet to be worked out.
The meeting's final document makes it clear that the US vision had won; the concept of a global treaty is there, but only in the context of an option which might possibly be considered in the future.
"We were able to convince the EU, Norway and Switzerland that we need immediate action," the leader of the US delegation, deputy assistant-secretary for Environment, Claudia McMurray, told BBC News.
"We can get started on this quickly, whereas agreeing a treaty could take years; but we do have other language saying we will look at this again after a period of time."
For environmental groups, this is not the only reason why the US opposed a global treaty.
"The US government is due to finalise new regulations on its own power stations next month," Felice Stadler, a director of the US-based Mercury Policy Project told BBC News.
Coal-fired power stations are the biggest source of mercury within the United States, accounting for around 40% of US production.
"They are basically re-writing sections of the Clean Air Act," claimed Ms Stadler.
Much higher levels of mercury are now found in beluga whales in parts of Canada and Greenland
This interpretation was backed up by a source within the US government's Environmental Protection Agency (EPA).
This source told BBC News that the agency's leaders wanted to avoid a binding international set of regulations because it would restrict their room to regulate US mercury emissions.
The EPA published a draft set of regulations, the Clean Air Mercury Rule, in January 2004; a mandatory 60-day public consultation period followed, during which the agency received more than 680,000 responses - the most it has ever received on any issue.
Most criticised the draft regulations for being too lenient, according to the BBC's source.
Claudia McMurray, speaking to BBC News from the Nairobi meeting, dismissed the idea that US domestic issues were dictating its international stance.
"The US is making history; the US has never regulated mercury emissions from power plants before, and neither has any other developed nation," she said.
European support for a global treaty is an extension of the position it has recently adopted on its own mercury production.
At the end of January, the European Commission launched a "Mercury Strategy" aimed at reducing use and production of the metal.
Its components include:
- elimination of mercury exports from the EU by 2011
- banning the marketing of measuring devices containing mercury - such as thermometers - with certain exceptions
- eliminating mercury use in the chlor-alkali industry (the plants that convert salt and water into chlorine and caustic soda, staple ingredients for the chemical industry).
Explaining the reasoning behind the strategy, the commission says that "mercury and its compounds are highly toxic to humans and the environment.
"Although most people in Europe appear to be within internationally accepted safe levels for exposure, there is evidence that some people are around or above these levels, especially in coastal areas of Mediterranean countries and the Arctic."
Mercury bio-accumulates - that is, it builds up in the tissues of animals.
Predatory fish are exposed to mercury themselves, and they eat other marine creatures which may also contain the metal; high levels can accumulate in their bodies, which is why pregnant women are advised to regulate their consumption of such fish, protecting their unborn children from exposure.
In fact, there is already one international agreement regulating mercury, the United Nations Protocol on Heavy Metals, which entered into force in December 2003.
It commits signatory countries to stabilise production, but not to reduce it.
This is the gap which the European Union, along with its allies, was hoping to plug at the Nairobi meeting.
"The US just has an aversion to all international treaties," Linda Greer, director of the Environment and Health Programme at the US-based campaign group the Natural Resources Defence Council, told BBC News from the Kenyan capital.
"It really seems a shame that [the EU] came to the table with such a strong proposal - and in addition you had the developing countries, the G-77, feeling that all the mercury in the world is flowing towards them.
"So we had all the ingredients for a meaningful agreement; but the United States was very obstructive to every idea except their partnership proposal."