Serious mercury pollution from small-scale gold mining will lead to disaster

Peter W. U. Appel is senior research scientist at the Geological Survey of Denmark and Greenland; Imelda Perez is researcher at the Ateneo School of Government. This article was published in the January 5 edition of the Business World, pages S1/4 to S1/5.

Mercury, a metal used in the process of gold extraction in small-scale gold mining, poses a serious environmental and health threat to the country. It is estimated that thousands of tons of mercury are present in fragile earth ponds containing tailings (mine wastes) in gold mining areas all over the country. A 2001 Department of Health report on mercury in mine wastes in Butuan Bay in Northern Mindanao and Davao Gulf  and a 2007 World Bank investigation of small mines in Zamboanga del Norte and Camarines Norte show that small-scale mining may be releasing as much as 145 tons of mercury per year in those areas alone. The total release of mercury from all small-scale miners may be several times higher.

The most notorious case of mercury poisoning yet occurred in Japan in the 1950s. Over a period of 35 years, a chemical factory released 27 tons of mercury into Minamata Bay in the west coast of the island of Kyushu. The mercury was contained in the factory’s waste water. The factory began operations in 1908 and by the late 1920s, its waste water discharges were being blamed for reduced fish catch in the bay. Until the late 1950s the bio-accumulation of this toxic substance in the shellfish and fish that people around the bay ate, began to show its deadly effects in humans. People intoxicated with mercury began to feel numbness in their extremities and had difficulty walking without stumbling. They complained that their vision, hearing and ability to swallow were also impaired. In 1956, 40 people were found to have had these symptoms, 14 of whom died. Later, babies were born with both mental and physical disabilities. The factory continued releasing mercury until 1968. In 2001, close to 2,300 people were officially diagnosed as having been severely poisoned with 1,800 of them subsequently dying. The affliction came to be known worldwide as the Minamata disease.

Small-scale miners use anywhere from 20 to 40 grams of mercury to extract a gram of gold. Once the gold is separated from the mercury, the chemical is washed away into the tailings ponds of these mines. These ponds are quite fragile and often leak. Heavy rains also cause them to overflow. The mercury is eventually drained to creeks and rivers that then carry the chemical to the sea where it may accumulate in mangrove swamps and in the sea floor. It is there where the mercury, now in organic form, enters the food chain. The mangrove swamps serve as hatching grounds for fish and shellfish. Over time the fish and shell fish will accumulate very high amounts of mercury in their bodies. This mercury is then transferred to humans who eat them; fish and shellfish are the main sources of protein for many poor people. Studies of some coastal areas of Mindanao have shown that the sea-floor sediments already have elevated mercury contents, and the level of mercury in fish and shell fish has started to build up.

Hospitals in Davao have diagnosed many patients with symptoms of mercury poisoning. Fortunately, no outbreak has occurred yet, but it may only be a matter of time before one does. In Japan it took many years before the mercury released into Minamata Bay started to build up in fish and shell fish. It took yet another long time before the mercury in the population reached high enough levels to impair those poisoned. No one can say when a Minamata disaster will hit the Philippines, but if nothing is done to stop further releases of mercury to the environment and to clean up the tailings ponds, a similar disaster is inevitable. Mitigating activities can be accomplished if enough people care about the situation and start to act.

Not all small gold miners use that much mercury. In Benguet, some miners use as little as 0.2 gram of mercury to extract one gram of gold while others do not use mercury at all. Instead, they use borax, a non-toxic chemical. This means that other miners can be taught to use little mercury or to switch to borax, thereby significantly minimizing or even completely eliminating mercury releases into the environment. Switching to these methods also offers efficiencies in the process as well as significant cost savings as miners no longer have to shell out money to buy the mercury. (Selling mercury is illegal so there is a high economic rent to be paid to acquire it.)

Another way is to recycle the mercury used.  This is done with the use of a simple tool called a retort. Invented in South America, the retort is widely used among many small miners there. The tool is made of a few pieces of pipe tubing and allows the collection of the mercury to be recycled for later use.

There has been no real study of the amount of mercury contained in the tailings ponds. In 2006, a team from the Maximo Kalaw Institute for Sustainable Development and the Geological Survey of Denmark and Greenland (GEUS) undertook a limited chemical analysis of these tailings, which revealed that up to 250 grams of mercury may exist per ton of tailings. The analysis also showed very high amounts of good or high quality gold in the tailings that were not extracted by the miners. A clean-up of the tailings may possibly be financed by the gold that can potentially be recovered during the activity. This would prevent further releases of the chemical from ponds.

In Tocmo, Benguet, small-scale miners use mercury to extract gold, but they use less than one gram of mercury to recover one gram of gold. Nevertheless, after hearing about the environmental and health risks caused by mercury, they have been  keen to learn alternative methods of gold extraction. They have favourably received borax method and the use of a retort.

The Federation of Small Scale Miners in Benguet has agreed to teach other small-scale miners in the province these alternative methods. The participants acknowledge that it would be counterproductive to insist on an immediate mercury ban.  Instead, they propose that information campaigns be undertaken, by the participants themselves and by members of the barangay council.

Decisions on small-scale mining are made at the level of provincial governments, by the Provincial Mining Regulatory Board (PMRB) specifically.  It is a known fact, however, that small-scale mining is generally done surreptitiously, as the required registration process is slow and tedious.   This only makes it difficult for the local government unit to monitor and regulate small-scale mining.

The Mines and Geosciences Bureau claims that mercury use is already banned, that miners have been informed of the dangers of mercury use, and that miners have been introduced to the use of the retort. It then says that its efforts have had insignificant results because miners refuse to abandon proven methods for new, untested ways of doing things.   Lack of human and financial resources has also been cited as limitation, a common excuse for government failure. The cost of a future disaster, however, will greatly exceed the current costs of changing the ways of small-scale miners.

No comments yet.