Severe mercury contamination in Amazon prompts state of emergency, Peru

The Peruvian government has declared a 60-day state of emergency for 11 towns in Madre de Dios, a region in southeastern Peru’s Amazon Basin, after officials found alarmingly high levels of mercury. This highly toxic metal comes from illegal gold mines and causes chronic renal and neurological disorders. It is especially harmful to children and pregnant women.

Country's environmental ministry said that mercury levels taken from blood samples in the local population as well as water samples taken from local rivers were higher than legally permitted, prompting the emergency. The Harakmbut indigenous community suffered the most contamination, with mercury levels more than six times the legal limit.

In a press conference held Monday, May 23 Health Vice-Minister Percy Minaya said that mercury contamination may have affected 50 000 people, with deposits likely to be found in the air, water, fish, and sediment.

Peru is Latin America's largest producer of gold, with 15% of the country's gold coming from illegal mines. And this seems to be the culprit, according to government officials, as vast illegal miners deposit mercury used to separate the gold from rocks in nearby rivers or pits.

The environment ministry said they estimate that illegal miners dump 40 tons of mercury in the Amazon’s rivers every year and that illegal miners are also responsible for the deforestation of Madre de Dios region where they have destroyed almost 100 000 hectares of rainforest.

"The consequences of mining activity in this region will be present for the next 80 years," said environment minister Manuel Pulgar-Vidal and added that the root of the problem must be attacked by shutting down illegal mining operations.

The authorities promised to dispatch hospital boats to treat people in the concerned areas and provide uncontaminated food to residents of Madre de Dios.

The environment minister also said that 41% of the population of Madre de Dios is exposed to mercury pollution. However, this number might be far from real.

A recent study by Duke University researchers has found hazardous levels of mercury hundreds of kilometers downstream from Peruvian gold mines. The study determined that the health risks taken on by artisanal, small-scale gold miners extend far beyond the miners themselves.

Researchers say the miners’ practices not only contaminate local soil, sediment and water resources with mercury; they also create hazardous levels of the neurotoxin in the food chain at least 560 km (350 miles) downstream.

The study found that the miners and their families are highly vulnerable to the impacts of mercury, with limited knowledge of mining’s environmental or human health effects. Rarely do they have adequate safeguards to limit the release of mercury into the air, soil or water, the researchers said.

Once in river sediments, mercury is taken up by microorganisms that convert it to a highly neurotoxic form. As other animals consume the microorganisms, the levels of the neurotoxin accumulate in larger predators, such as carnivorous fish.

In the study, researchers and their colleagues took samples from river sediment, water, and fish at 62 sites near 17 communities over a 560-km stretch of the Madre de Dios River and its major tributaries. The results showed an increase in mercury concentrations in the mining areas as well as downstream, where concentrations in fish exceed World Health Organization guidelines for safe consumption for children and women of maternal age.

“The calculations were made assuming that people ate two fish meals per week,” said Heileen Hsu-Kim, professor of civil and environmental engineering at Duke University. “However, we have preliminary data from household health surveys indicating that fish consumption is actually much higher in many communities, which could increase the body burden and exceed safety limits even for healthy adults.” Indeed, indigenous residents are particularly at risk given their reliance on fish as their primary source of protein.

While mercury can be dangerous to adults, the primary concern is how it can impair neurological development in children, infants, and fetuses. Because mercury can cross the placental barrier if it is ingested by the mother, the metal can affect the development of a baby's cardiovascular and nervous systems.

A small-scale gold mining operation docks along the Madre de Dios River in Peru. Small boats remove sediment from nearby riverbank where mercury is added to extract gold. Recently, the Peruvian Navy has begun to crackdown on mining operations directly on the river by bombing small boats such as this one. Image credit: Sarah Diringer/Duke

As the price of gold has soared during the past decade, thousands of Peruvians – mostly from the Amazon and Sierra region of Cusco – have embraced artisanal small-scale gold mining to supplement their income. Mercury is used to bind loose flakes and bits of gold ore into hard chunks that can be more easily extracted from soil and sediment, and then burned off with blowtorches once the chunks are in hand.

Gold mining operations that take little to no care to the environment are present throughout South America, as well as in Africa and Asia.

Featured image: Madre de Dios Tambopata by Incacity (CC – Flickr)