Mercury built into older-model U.S. vehicles will be removed before they are melted down for scrap under an agreement announced Friday, putting a small dent in a worsening global environmental threat. Droplets of airborne mercury emitted by coal-burning plants, waste incinerators and from small-stakes gold mining operations circle the Earth for up to a year before descending in rainfall, contaminating waterways and converting to a toxic form that is dangerous to humans and wildlife.

"Mercury is a global pollutant that affects populations without regard to where they live," said James Hurley, director of an international conference on mercury pollution held this week at the University of Wisconsin in Madison. The agreement between the U.S. Environmental Protection Agency and the industry that dismantles, shreds, and melts down the hulks of old vehicles requires the removal of mercury-laden switches found in the trunks and hoods of vehicles made prior to 2003. Vehicles built since 2003 do not contain mercury, a familiar liquid metal used in consumer products from fluorescent light bulbs to thermometers.

The total amount of mercury in vehicles built over the past 30 years totals 250 tons, the group Environmental Defense said. But some 2,000 tons of mercury finds its way into the global environment each year, half of which comes from Asia -- a majority of that from China. While developed countries have sharply curbed emissions of the metal by exerting controls on garbage and medical waste incinerators, tons of mercury from scrapped products is exported to developing countries where lax environmental controls combined with increased coal burning and a gold mining boom have lifted mercury pollution.

Applying mercury to ore is an outmoded method of extracting gold, yet it is commonly used by the estimated 15 million small-scale miners attracted to rising gold prices.

Toxic Effects

Mercury s toxic effects are pronounced in the nervous systems and brains of exposed children, and can damage organs and cause seizures in adults. Research was presented at the conference showing high concentrations of mercury in the Arctic, where it tends to accumulate under the ice but also in polar bears.

Wetlands rich in the microorganisms that convert it to its organic form, methylmercury, can also be heavily contaminated. Methylmercury enters the food chain and accumulates in fish and the animals and humans that eat them. Even songbirds recorded high mercury levels, showing it is not just an aquatic pollutant.

All but six U.S. states have issued advisories warning pregnant women and young children to avoid eating fish caught in some or all of their waterways and for adults to limit consumption. But those advisories rarely get to people who catch and eat fish, University of Wisconsin researcher Maria Powell said.

"In markets in Cleveland, you can buy carp and catfish that are on the do-not-eat list for Lake Erie," she said. Despite anecdotal information that selenium found in many foods and omega-3 fatty acids in fish might protect against mercurys effects or rid the body of the mineral, studies at the conference found neither did.
(Por Andrew Stern, Environmental News Network, 14/08/2006)