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Large numbers of infants and toddlers have died from lead poisoning in Nigerian villages where their parents process gold ore inside their family compounds, according to a report published Tuesday by an international team of researchers.
In two Nigerian communities, 118 children under the age of 5 died in a single year – 25 percent of the children in that age group. For the first time, the researchers uncovered strong evidence that points to lead as the likely cause for nearly all of those deaths. In addition, all of the surviving children who were tested suffered from lead poisoning, too.
“To our knowledge, this is the first documentation of an outbreak of childhood lead poisoning associated with artisanal gold mining,” the team, directed by lead experts from the U.S. Centers for Disease Control and Prevention, wrote in the online edition of the journal Environmental Health Perspectives. “Extensive environmental contamination was found in both of the villages and inside individual family compounds.”
Artisanal gold mining is small-scale, subsistence mining that occurs mostly in poor, rural communities. In the Nigerian villages, people use crude, rudimentary processes to extract gold from ore, including grinding and heating the rock. In some cases, flour-grinding machines are used. These activities contaminate the air and soil with large amounts of lead and mercury, both of which cause neurological problems in children.
Sparked by a gold rush, artisanal mining occurs throughout northern Nigeria, as well as elsewhere in Africa and in South America, including Peru. From 13 to 20 million men, women and children from over 50 developing countries are involved in artisanal mining, according to an estimate by a World Bank group.
Word first spread of hundreds of children dying in Nigeria’s Zamfara state in early 2010, when the deaths were discovered during meningitis surveillance by the international humanitarian group Médecins Sans Frontières and Nigerian public health officials. The United Nations has estimated that 400 children died there last year due to lead poisoning.
Calling the outbreak unprecedented, the scientists warned that “characterizing the full extent of the outbreak remains an urgent and ongoing matter.”
Lead poisoning is common worldwide, leading to diseases and IQ reductions, but until now, deaths have rarely been reported.
At the emergency request of Nigerian officials, researchers from the CDC and the World Health Organization visited two villages in Zamfara state where higher-than-expected numbers of children died between May, 2009 and May, 2010. They tested the blood of surviving children, took soil samples from family compounds and questioned parents about their dead children’s symptoms.
All the results were extreme. Eighty-one percent of the children who died had suffered seizures, a sign of acute lead poisoning. Of the surviving children who were tested, “all blood samples indicated lead poisoning,” while 97 percent needed immediate chelation therapy to lower those levels, according to the report. Mercury levels were lower in the children, but still excessive – four to eight times higher than the average U.S. child. And 85 percent of the soil samples taken from the family compounds exceeded the U.S. Environmental Protection Agency’s health standard for lead. One water well had 90 times more lead than the EPA’s action level for drinking water.
Of the 118 households where children under the age of 5 had died, ore processing occurred inside the family compound in 84 of them. Toddlers are most vulnerable to lead poisoning because they crawl or play on the contaminated ground and they have developing nervous systems.
The outbreak of deaths could have been tied to an increase in the number of grinding machines in the villages in November of 2009, “contributing to widespread contamination,” the researchers reported.
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