Mercury Villager

August 21, 2009 | Author admin

Mercury Villager

Canadian Researcher Studies Nutrition And Biodiversity In The Amazon

Water is everything for villagers living near Brazil’s Tapajós River. It is their highway, their livelihood and their main source of food. And it’s affecting their health. Canadian researchers are working to solve this problem.

In 1994, researchers in Brazil asked Dr. Donna Mergler, a neurotoxicologist, and Dr. Marc Lucotte, a biogeochemist, from the Université du Québec à Montréal to visit the Tapajós, a major tributary of the Amazon River, to find out why people living in the area had such high mercury levels in their bodies, and whether this mercury affected their health.

Dr. Lucotte’s team discovered that deforestation was the source of the problem. “There’s mercury naturally in the soil, and when you take away the forest cover, soil erosion increases and the soil goes into the water, where it is transformed into organic mercury, enters the food chain and accumulates in the fish,” says Dr. Mergler.

People along the Tapajós eat a lot of fish, especially predator fish. These fish at the top of the food chain tend to have high levels of mercury contamination.

“We looked at (the villagers’) motor coordination, fine motor movement and vision, and we found that the higher one’s mercury levels, the poorer their performance on tests that evaluate these skills,” says Dr. Mergler. “The person does not necessarily have a clinical disorder, but if you are a fisherman that needs to repair your net, the fact that you are losing motor coordination, fine movement and vision is very important.”

Dr. Mergler and her team worked with the villagers to find ways to reduce their exposure to mercury while keeping fish on the menu. They developed an educational campaign and slogan: Eat more fish that don’t eat other fish. Five years later, Dr. Mergler found that the villagers were eating more herbivorous fish (fish that eat only plants), the mercury levels in their hair had decreased and their motor skills were improving. But their performance on the vision tests hadn’t changed.

Funding from the Canadian Institutes of Health Research (CIHR) allowed the researchers to study this problem more closely. Their findings confirmed the negative effects of mercury on several visual functions, but they also discovered that the nutrient selenium, which is found in locally-grown Brazil nuts, seemed to prevent some of the visual damage caused by mercury exposure.

These studies have now inspired another project to reduce deforestation and stop the mercury contamination at its source. The project will help farmers move away from farming practices that speed up the erosion process, and encourage them to start growing local grains and trees to help preserve the soil.

“By taking an ecosystem approach and linking all of these ideas together, we’re trying to figure out how one can maintain the biodiversity of the Amazonian environment to foster good nutrition, reduce toxic risk and improve human health ,” says Dr. Mergler.

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