French Guiana: Mercury, the Global Threat

Illegal mining of gold contributes to the violent climate of French Guiana, but individuals also suffer due to unhealthy contact with mercury during the extraction process.

The day I arrived in French Guiana, gold was selling for $1,127 an ounce. The high price meant more conflict, but often far from where the metal was bought and traded on the world market. In 2006, soldiers dispatched to Venezuela's Caura River basin reportedly shot and killed six miners. In Ghana, two miners were shot during fights with police in 2008 and five more died while working illegally in the closed mineshafts owned by mulitnational AngloGold Ashanti. Over 75 illegal miners suffocated to death after a disused mine shaft in South Africa owned by Harmony Gold caught fire in 2009. This February, gold mining in Peru's Madre de Dios region had decimated so much jungle that the government passed an emergency decree to ban illegal mining in the region. Five people were killed when police clashed with 6,000 garimpeiros who had blocked the Pan-American Highway in protest. In Nigeria this summer, more than 160 died of lead poisoning resulting from small-scale gold mining--a tragedy the U.S. Centers for Disease Control and Prevention called "unprecedented."

Aside from violent conflict, the most significant threat from clandestine mining is the use of mercury. The chemical is cheap and prized for being lethally efficient. Using a dollop of mercury to amalgamate gold from sediment takes minutes and produces precise results; using an old-school manual method like panning takes hours and often fails to capture a significant portion of the metal. But mercury is also highly toxic and small-scale gold miners usually dump the chemical into rivers and streams. It then bioacculumates in fish, which are later consumed by local populations downriver. In 1997, France's National Public Health Network studied four Wayana Amerindian villages along the Maroni River in French Guiana and found that 57 percent of the population had mercury levels above the World Health Organization safety limit. Garimperios themselves also suffer adverse health effects from breathing mercury vapor, ranging from reduced cognitive function to respiratory failure and death.

At some point--either in the jungle or at gold-buying shops--mercury is burned off of the amalgamated gold and this has dangerous, far-reaching effects. A tiny amount seared off a gold nugget in French Guiana can travel thousands of miles through the air and then disperse via rain or snow in the U.S. or Europe. Once deposited in a lake or river, the chemical will then often transform into the highly toxic methylmercury, which builds up at higher concentrations as it moves up the aquatic food chain. This is the reason pregnant women are advised not to eat top-level predators such as shark and swordfish: Methylmercury exposure in the womb affects a baby's growing brain and nervous system. High levels of exposure can cause blindness, seizures, and mental retardation. The chemical is also an insidiously adept traveler. Methylmercury deposited in one place can change back to its elemental form, re-emit into the atmosphere, and continue traveling ever further from the original source in a series of similar hops, a phenomenon called the grasshopper effect.

In December 2008, French President Nicolas Sarkozy traveled to Rio de Janeiro and, while his wife Carla Bruni visited a human breast milk bank, met with Brazilian President President Luiz Inacio Lula da Silva. The leaders signed accords on several fronts, including an agreement to combat illegal gold mining and criminalize the use of blackmarket mercury. To date, however, neither country's legislature had ratified the agreement. Mercury is banned in French Guiana, but UNEP estimates that small-scale gold mining releases some 30 tons of the chemical into the environment in that region each year. In February 2009, environmental ministers from over 140 countries met at the United Nations Environment Programme's (UNEP) governing council and agreed to finish a treaty to control global mercury pollution by 2013. The European Union has passed legislation to ban mercury exports by 2011. In 2008, President Bush signed into law a bill drafted by then Senator Barack Obama to prohibit all U.S. mercury exports by 2013. Overall, illegal mining, which produces about 20 percent of the world's gold, is responsible for releasing an average of 1,000 tons of mercury into the environment each year—more than any other source except coal burning.