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Treaty Sought To Limit Damaging Effects Of Mercury

Fishmongers inspect large bluefin tuna before auction at Tokyo's Tsukiji fish market. Mercury levels abound in top predators like tuna after they work their way up the food chain.
Delegates from more than 130 countries and dozens of nongovernmental organizations are attending a weeklong conference to forge a global, legally binding treaty aimed at limiting the damaging effects of mercury on health and the environment.

The UN Environment Program (UNEP) is overseeing this fifth and final round of treaty talks.

UNEP reports that the global threat to human and environmental health from mercury is growing. A new report finds that worldwide, nearly 2,000 tons of mercury is emitted into the air from human activities every year. Much of this toxic substance is subsequently deposited on vegetation, in the soil, and in oceans, lakes, and rivers.

The deputy head of UNEP's Chemical Branch, David Piper, tells VOA that much human exposure to mercury is through the consumption of contaminated fish.

He says mercury may be converted by organisms into toxic organic forms, which work their way up the food chain.

"Microorganisms are eaten by small fish, the small fish are eaten by big fish, the big fish are eaten by us," Piper says. "If we have a fish-based diet, we can end up with a significant load of mercury in our bodies and, therefore, being at great risk from mercury poisoning."

Mercury affects the brain and nervous system and can cause physical and mental development problems in children. Pregnant women who ingest mercury can pass the toxic effects to their unborn children.

The UNEP finds the global demand for mercury is decreasing somewhat, with many developed countries taking measures to reduce mercury use. But it notes mercury use is increasing in developing countries.

It says small-scale gold mining and coal burning are the major sources of mercury emissions into the air. It says Asia contributes almost half of these global emissions because of increasing industrialization.

The report says annual emissions from small-scale gold mining are estimated at 727 tons, or 35 percent of the global total. Piper says this poses a direct threat to the health of millions of people in Africa, Asia, and South America.

"At the moment, artisanal and small-scale gold mining is a feature of probably around 70 countries with 10-15 million miners. I think that is probably an underestimate these days. It is very often driven by the gold price and by poverty. This is poor people looking for a source of livelihood."

Piper says the best way of reducing the risk of mercury to human health and the environment is to stop using it as soon as possible. This is unlikely to happen. So he says delegates are drafting a legally binding treaty that aims to control emissions of mercury into the atmosphere.

He says the draft treaty stresses the need for industries to work on pollution control and to avoid the spread of products containing mercury. The treaty calls on rich countries to provide financial support to poor countries and outlines a series of mechanisms to ensure compliance and implementation of the measures.

The treaty is scheduled to be adopted toward the end of the year in Japan.