EARTH
Nigerian families process gold ore in flour mills. PHOTO: James Durant, ATSDR environmental health scientist
Geology, economics and culture culminate in a perfect storm with deadly results
In March 2010, a team from Médecins Sans Frontières (MSF, or Doctors Without Borders), monitoring for endemic diseases such as meningitis and malaria, visited villages in northwestern Nigeria after being informed by the local community of high mortality in children under five years old. The doctors were not immediately prepared for what they would find. In two villages they discovered children’s fresh graves and a mortality rate of more than 40 percent. Children among the living showed intractable seizures and decreased levels of consciousness. The clues pointed toward a situation massively out of the ordinary, compelling MSF to immediately launch an investigation alongside Nigeria’s state and federal government, the World Health Organization and the U.S. Centers for Disease Control and Prevention (CDC).
What exactly could be causing such an epidemic puzzled the doctors. “There was no robust explanation, no communicable disease, so the team was already thinking about toxins and heavy metals and sent off samples for screening,” says Natalie Thurtle, a doctor with MSF and health advisor for heavy metal poisoning in Zamfara.
The blood sample analysis revealed the culprit: lead. MSF initially screened eight children and two adults for heavy metal poisoning and all samples showed high levels of lead in the blood — above 100 micrograms per deciliter (µg/dL). The CDC investigation team then collected blood samples from 205 children under the age of five from two villages. About 97 percent of the children in this group had lead levels above 45 µg/dL, the threshold for initiating chelation therapy, with some as high as 700 µg/dL. CDC’s “level of concern” is just 10 µg/dL.
The lead contamination, the investigators learned, was coming from the extraction of the Zamfara region’s unusually lead-rich gold ore. Such small-scale subsistence-level mining, called artisanal gold mining, uses rudimentary techniques and the gold ore is processed at home. Unfortunately, Thurtle says, “up to 400 kids died before the multi-agency emergency response was possible.”
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