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Tuesday, March 3, 2009

Tackling the dangers of mercury


SINGAPORE — Fear sparked by global recession, strains on banks and volatile paper currencies has brought the glitter back to gold. Its value has been rising rapidly in recent months, as investors seek a safe haven from the economic and financial storm.

But gold's resurgence has strengthened demand for its ugly longtime associate, mercury, a toxic heavy metal widely used in Asia, Africa and Latin America by millions of small-scale gold miners.

The United Nations Environment Program (UNEP) estimates that about 6,000 tons of mercury are released each year into the air, land, rivers, lakes and seas, creating a global pollution problem. The liquid metal damages the human nervous system and impairs the functioning of the liver and thyroid glands. It also causes memory loss and disturbed vision.

Japan is a strong supporter of moves to curb mercury use. The terrible long-term effects on the population around Minamata Bay from mercury poisoning helped alert the world to the danger. In 1956, researchers identified the condition caused by eating contaminated fish and shellfish. It was characterized by trouble with walking, difficulty speaking and convulsions. A generation later, in the 1970s, the effects persisted, as mothers poisoned in their youth gave birth to children with severe afflictions, including gnarled limbs, mental retardation, deafness and blindness.

Of the 6,000 tons of annual mercury releases worldwide, approximately one-third comes from burning coal to generate electricity, power industries and heat homes. Increased coal use in Asia, especially in populous China, India and Indonesia, means that mercury emissions are rising in the region. Gold mining is the second-biggest source of mercury releases.

When mercury is belched into the air from power plants, smelters and incinerators, it returns to Earth via rain, then bacteria and other natural processes convert it to methylmercury in lakes, rivers and oceans. Released into river systems that flow into the sea, the poison is dispersed through the world's oceans.

Scientists say that as global warming melts the Arctic, mercury trapped in ice and sediments is being re-released back into the oceans. It builds up in the food chain as bigger creatures consume smaller ones. Flesh of the biggest fish, among them tuna, swordfish, mackerel and sharks, contain the highest mercury concentrations.

In the United States, just under 5 million women, or one in 12 of the female population, have mercury in their bodies above the level considered safe by the U.S. Environmental Protection Agency. The U.S. and other governments have advised pregnant women, children and other groups considered vulnerable to mercury poisoning to limit fish consumption.

The global spread of mercury even to "clean and green" countries is illustrated in Sweden. Around 50,000 of the country's famed lakes have pike fish with mercury levels exceeding international health limits. Most mercury in Sweden is thought to have come from elsewhere. Swedish women of childbearing age are advised not to eat pike, perch, turbot and eel at all; the rest of the population, only once a week.

To tackle the mercury scourge, more than 140 nations meeting at UNEP headquarters in Nairobi agreed Feb. 20 to negotiate a binding global treaty to tighten controls on its use. The accord, backed by China, India and many Asian countries, came after the Obama administration announced it had reversed the U.S. stance and was now favored a ban on mercury. The European Union has called for the ban to start by 2011.

However, reaching agreement on the details of the treaty and then implementing it effectively will be difficult and take years. It will involve finding cost-effective substitutes for mercury in products like thermometers, high-intensity lamps and liquid crystal displays, and in processes such as paper-making and plastics production.

It will also involve tighter controls on mining, storage, export and import of mercury. Most mercury mines are now closed, and China only supplies its own market. So mercury comes from the leftover stockpiles of shuttered mines or the dozens of companies in Europe and the U.S. that recycle the metal from old light bulbs, batteries or industrial waste, according to the U.N. and the Zero Mercury Working Group, a coalition of 40 organizations that campaigns to reduce mercury use.

International trade in mercury, which is easy to transport, is poorly regulated. Mercury supplied for legal purposes is often diverted to gold mining, where it fetches a much higher price. In Indonesia, for example, use of mercury in gold mining is illegal. However, the price of gold has more than tripled since 2001 and mercury is the easiest way to separate gold from ore.

Tens of thousands of remote mining sites have mushroomed, mostly in Asia, Latin America and Africa as poor people try to make money from the gold boom. Small-scale gold mining uses as much as 1,000 tons of mercury each year.

UNEP estimates that 10 million miners and their families in countries such as Indonesia, India, Papua New Guinea, Brazil and Zimbabwe may suffer from mercury poisoning or exposure. It says that on Mindanao, in the southern Philippines, 70 percent of gold miners may have chronic mercury intoxication.

Transitioning to a low-mercury world is a laudable and essential goal. But it will take much international cooperation and government action to achieve.

While the terms of a new mercury treaty are negotiated, steps will be taken to raise awareness of the risks in using the poison in small-scale mining. The U.N. has already spent $7 million in six developing countries, including Indonesia, to educate miners and local suppliers about mercury.

Miners like the liquid metal because it is relatively cheap, works fast, and leaves the gold cleaner than traditional panning. The only readily available alternative is cyanide — also a poison that can ravage human and health and the environment.

Michael Richardson is a visiting senior research fellow at the Institute of Southeast Asian Studies in Singapore.


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