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Not all that glitters: mercury poisoning in Colombia

2012; Elsevier BV; Volume: 379; Issue: 9824 Linguagem: Inglês

10.1016/s0140-6736(12)60582-0

1474-547X

Paul Webster,

Mercury impact and mitigation studies

Researchers tracking mercury poisoning from artisanal gold mining in Colombia have found that people in Antioquia have the world's highest per head mercury pollution. Paul C Webster reports. Segovia, a city of 44 000 people in Colombia's Antioquia province, offers an unsettling pair of initial impressions. First, there are the heavily armed combat troops at the outskirts of town, stationed here because Segovia is one of Colombia's busiest gold refining centres, and guerrillas and paramilitary groups raid here for easy cash. The other initiation is more insidious: it begins a few minutes after arrival with an unfamiliar, metallic taste on the tongue. Within an hour, it has crept to the back of the throat. After a couple of hours it is in the lungs. This is the taste of airborne mercury, a severe local environmental and public health problem. Like the combat troops, it, too, can be traced to Segovia's gold wealth, and the violence it attracts. The airborne mercury in Segovia emanates from scores of small gold mills, locally known as entables, where gold-flecked rocks from nearby mines are pulverised in rolling steel drums containing mercury, which forms an easily retrieved amalgam with gold. Once the mercury-gold amalgam is removed from the drums, it is heated in small furnaces that vaporise the mercury, producing semi-pure gold while disseminating a powerful airborne neurotoxin into the city's air. These health-threatening gold production practices, which were pioneered centuries ago but long-abandoned by large-scale gold companies, are used by an estimated 200 000 artisanal miners in Colombia, and as many as 13 million others in 70 nations worldwide. Unlike in other parts of the world, where highly-toxic artisanal gold production is a largely rural industry, the persistence of a low-level civil war in Antioquia has driven gold producers into crowded cities where they have military protection. The result, according to a team of researchers from the UN Industrial Development Organization (UNIDO), is a set of serious community health risks centring on neurological, lung, and kidney damage. After closely tracking artisanal practices in five cities in Antioquia over the past several years, the UNIDO investigators, who are financed by the Government of Antioquia Province as part of efforts to reform the artisanal gold industry, concluded in a recently published report that people here are exposed to the world's highest per head mercury pollution. Colombia as a whole, they believe, is the world's third largest consumer of mercury used in artisanal gold mining after China and Indonesia, and the world's highest per head polluter of mercury used in this type of industry. “The use of mercury in artisanal gold mining is a global problem that poses huge environmental and human health problems”, explains Marcello Veiga, a specialist on artisanal mining pollution from the University of British Colombia, in Vancouver, Canada, who works with UNIDO's mercury control efforts in Colombia, “but what we are seeing in cities in Antioquia is especially worrying, because it is largely an urban problem there. Mercury vapours are being released in the urban environment, intoxicating hundreds of thousands of neighbours of the gold processing centres and gold buyers.” The data supporting these warnings are stark. Using two types of mobile spectrometers to measure airborne mercury levels, a technical team led by Veiga tested air quality at hundreds of sites in Antioquia including numerous entables as well as street front shops where gold is separated from mercury in small furnaces. In many of the entables and gold shops, mercury levels were found to exceed WHO limits by up to a thousand times. Airborne mercury limits in residential areas in the five cities studied were ten times the WHO limits. In Segovia, mercury levels 40 times WHO safety limits were measured near an elementary school. “Workers' exposure at times approaches fatal levels”, the UNIDO team reported, while noting that even low levels of exposure to mercury vapour can derive “symptoms of fatigue, irritability, loss of memory, vivid dreams, and depression”. In studies of mercury poisoning in Antioquia between 2007 and 2011, UNIDO found at least 30% of almost 2000 people studied were highly intoxicated—figures roughly similar to those estimated by UNIDO in other studies undertaken in gold mining communities in Ghana, Tanzania, and Zimbabwe. 49-year-old Rauol Rios, a disabled gold worker, says he believes his health was permanently ruined by massive mercury exposure 30 years ago. After burning mercury-gold amalgam daily for several years, in 1982 he succumbed to severe trembling and was sent to the regional referral hospital in Medellin, Antioquia's provincial capital. These days, he says, he continues to be plagued with kidney and prostate problems, difficulty eating, and impotence. And, perhaps because he continues to live in an area surrounded by gold producers that ventilate mercury vapours, his blood levels of mercury remain stubbornly high. For the past 15 years, 36-year-old Bryan Hernandez has purchased gold amalgam in a shop in the centre of Segovia's bustling gold-processing district. While customers wait, he incinerates the amalgam in a small, primitively filtered propane furnace, and then weighs and buys the gold. Hernandez, who is the father of three young children, describes a set of health complaints ranging from constant chest infections to trembling hands to internal bleeding. “It could be the mercury”, he suggests. “There are 16 gold shops ventilating mercury vapours within a 100 metres from here.” The UNIDO team, Hernandez notes, is pushing gold producers to install better filtration systems based on technologies developed in Peru and Ecuador that will prevent much of the mercury from being ventilated into the community. Although Hernandez himself has not yet been willing to pay to install cleaner technologies, some others have. New data from Paul Cordy, a researcher who works with Veiga at the University of British Columbia, suggests UNIDO's efforts have reduced as much as 10% of atmospheric mercury concentrations in the past 16 months, despite a 30% increase in gold production. The UNIDO Colombia team is urging for tighter government control of mercury, removal of gold processing facilities from urban areas, and accelerated adoption of cleaner technologies. In 2009, the UN Environment Program began working on a global legally binding treaty for control of mercury—much of which is produced in Algeria, Kyrgyzstan, and China—with negotiations expected to be concluded in 2013. At Segovia's main public clinic, located in a cramped room above an electronics shop in the town's riotously busy centre, resident doctor Paula Gallo, says she is convinced mercury pollution is a menace. “I see many patients with shaking hands and tiny signatures, which are classic symptoms of mercury poisoning. And there is also a disturbingly high rate of depression and suicides here.” But getting people in Segovia to take precautions is not easy, says Gallo, who has practised here for 4 years. “There is strong local resistance to taking blood samples. Everyone here works in the gold industry. To a large degree people just don't want to know the truth. I forbid pregnant patients to work in the mines. But they continue.” At the San Juan de Dios Hospital in Segovia, general physician Martin Diaz estimates that about 10% of his patients show classic mercury-poisoning symptoms including shaking hands, fatigue, depression, and suicidal thoughts. “There are 17 doctors working here. We all frequently talk about the mercury problem on a case–by-case basis”, he explains. “But it is difficult to know how much contamination patients have. This is a primary-care facility and we don't have the capacity to do routine tests.” Aceneth Castillon, a nurse who works alongside Diaz, says she believes the mercury vapours are a “very major problem”, which she firmly associates with suicide. “Nothing is being done about it”, she fumed. In a conversation monitored by several hospital administrators who claimed lack of information because they were recently appointed following the election of a new governor in Antioquia, Castillon cited data from blood tests on 80 patients last year revealing that more than a third exceeded government health limits—some by as much as thirty times. “The problem seems to me to be getting worse”, Castillon said. At the Hospital San Vicente de Paul in Remedios, a town of 9000 about half an hour's drive from Segovia, Luis Eduardo Rojas, a 20-year veteran doctor at the hospital, also said he believes the mercury is linked to heightened levels of violence, depression, and suicide in the region. Rojas complained that the only clues about the health impacts come from foreign studies, an assertion echoed by hospital administrator Lenis Silva Novoa, who said “this community is frightened and wants action”. At the Department of Antioquia's health ministry in Medillin, Rosendo Orozco, director of toxicology, says although the Government of Antioquia suspended a health surveillance programme in 2007, the newly replaced regional government is now moving to re-establish a similar programme. “There was a large increase in new [gold mining] licences in recent years without environmental control”, Orozco said. “The affected municipalities are absolutely aware of the health risks, but they are forced to ignore them due to poverty.”