How a Gold Rush Sickened 50K in Peru

Gold miners hoping to strike it rich in Peru appear to have inflicted the miserable side effect of mercury poisoning on an estimated 48,000 people. Peru's government declared a 60-day health emergency last month after Duke researchers analyzed hair from a sample of 3,000 Madre de Dios residents and found that 40% showed mercury levels above the maximum recommended by the WHO, reports Nature. The area has been booming, with gold production in March up 28% from a year previously. But to extract the gold, miners use a method involving mercury that results in about 40 tons of the latter being dumped into waterways annually. The Duke study suggests those with mercury poisoning—which can cause brain or kidney damage in severe cases—likely ate contaminated fish.

"We now know with certainty what the source of the exposure is," says Peru's deputy health minister. "We are not going to solve this in two months, or even in a year, but the Health Ministry has to start." Under the health emergency, 25 villages spread across 33,000 square miles will receive food and medical aid, including canned fish, multivitamins to help with anemia, and perhaps quinoa, which researchers say may help lower mercury levels. Community fish farms are also planned, but Peru's presidential election on June 5 may present a hurdle. One of two top candidates is a former mining minister and both support the industry, an analyst tells AFP. Some government officials also aren't convinced that fish consumption is responsible for the poisonings and worry the emergency declaration will hurt tourism. (See how seals play a part in the mercury cycle.)