PUERTO MALDONADO, Peru -- On a busy, dusty street beside a huge open-air market, signs reading “oro” mark shops that trade in gold. The customers, mostly men in work clothes and rubber boots, have just arrived from the mining camps to sell their gold and wire money home.
Inside, shopkeepers heat the miners’ clumps of gold ore, releasing mercury vapors that waft into the shop, and then outside, into the streets crowded with townspeople.
Experts have long known Peru’s miners are exposed to extremely high levels of mercury. But now new research shows that the toxic threat has spread to towns in the Amazon and Andes Mountains where gold is sold.
In Puerto Maldonado, a jungle town in Madre de Dios, one of Latin America’s most productive gold mining areas, researcher Luis Fernández in 2009 detected mercury levels at a gold shop that were more than 20 times higher than an international worker safety standard. This February, his follow-up testing found mercury levels inside one shop that were so extreme his monitor couldn’t measure them.
Then, a week later, in a town high in the Andes, Fernández became truly alarmed when he measured mercury in the air outside the gold shops, and detected levels that exceeded the amounts considered safe.
“It seems clear that these workers are under extraordinary risk for acute mercury poisoning,” he said, adding that people outside the shops are highly exposed, too.
In the first study of its kind in Peru, Fernández and a team of researchers funded by the U.S. Environmental Protection Agency are measuring mercury pollution from gold shops in Puerto Maldonado, in the Amazonian lowlands, and La Rinconada, 15,000 feet above sea level in the Andes Mountains.
Their initial findings – coupled with new tests by Peru’s National Institute of Health that measured mercury in people’s urine – point to a public health risk in towns near informal mining camps, which have flourished with skyrocketing international gold prices.
Elemental mercury – the type released into the air and inhaled at the shops – can damage the nervous system, causing tremors, memory loss, muscle weakness and twitching, irritability, insomnia, headaches and reduced mental abilities. It also has been linked to immune system disorders in Brazilian miners. Extremely high levels can be deadly.
Peruvian officials estimate that there are 100,000 small-scale miners working in virtually every region of Peru, so gold-shop emissions are a widespread problem.
If La Rinconada and parts of Madre de Dios were in the United States, they “would most likely be Superfund sites,” said Fernández, a field lab research associate at the Carnegie Institution for Science’s Department of Global Ecology, located at Stanford University.
Gold mining is a dirty, dangerous business. Most of Madre de Dios’ 20,000 miners are “informal,” working without contracts, under hazardous conditions and with no safety equipment. Officially, the region produces about 20 tons of gold a year, although the real amount is probably higher because most of the mining is unregulated.
Working in far-flung camps along rivers or in the rain forest, laborers mix sediment with mercury – often using their hands and feet – to amalgamate the gold. But health experts say the greatest hazard comes from inhaling the vapor during reheating of the amalgam in the field or in shops with a flame or torch. Fernández estimates that between 2 and 5 percent of the weight of those lumps is mercury.
Dr. Carlos Manrique, who heads the Madre de Dios regional health department’s epidemiology office, said he saw miners with tremors, headaches and gastrointestinal problems – all possible symptoms of mercury poisoning – when he worked at the health clinic in Huepetuhe, a mining town about 100 miles from Puerto Maldonado. The river there is so silted from mining that trucks now drive on it.