Our Work

Evaluating the Impact of Mercury Contamination on Human and Environmental Health in Madre de Dios Watershed

Project Objectives

The Madre de Dios (MDD) and Beni Rivers together comprise a major tributary to the Amazon River, flowing from the MDD region in Peru, Peru through to Pando, Bolivia. It is home to over 150,000 Indigenous and non-Indigenous people and has one of the largest concentrations of biodiversity in the world with at least four protected parks. Leading causes of morbidity and mortality are respiratory, malaria, and gastrointestinal infections, but other common diseases include dengue, rabies, arenaviruses and hantaviruses, which have been emerging due to increased anthropogenic activities, among which, gold mining, agriculture, and road construction are the most important.

In MDD alone, gold mining is incipient due to rising global demand. These artisanal mining operations are devastating to an ecosystem. Mercury is used for the amalgamation of gold, a process in which up to 60% of the mercury used gets released directly into the environment and wastes containing mercury accumulate in the alluvial sediment and biaccumulates as methyl-mercury (MeHg) in fish that are consumed by humans. Of all mercury forms, MeHg is by far the most toxic as it accumulates in the food web. MeHg production in aquatic environments is mediated by anaerobic bacteria, particularly sulfate reducing bacteria. A detailed understanding of the factors affecting mercury bioavailability to sulfate reducing bacteria and the fate and transport of the various mercury species is required to understand the broad impacts of mercury, and has not previously been done in the region. As has been demonstrated in Brazil, rural riverine communities similar to those in the MDD/Beni watersheds, face not only moderate exposure to mercury, but also exposure to other heavy metals from geogenic (naturally occurring in the soil that get released from activities such as deforestation) and anthropogenic sources (e.g., inputs from mining activities) that potentially affect their health, including Arsenic and Selenium.

The goals of this study are to obtain preliminary data to:

1. measure and predict the level of mercury exposure among persons living in the MDD watershed;
2. identify the major health issues affecting persons living in the MDD watershed; and
3. better understand the diversification of livelihoods among persons living in the watershed.

We hypothesize that the MDD watershed is heavily contaminated with mercury and that people living in the watershed are extremely vulnerable to increasing contamination due to their limited ability to diversify risks.

Project Outcomes

We expect to produce the following outcomes:

1. Evaluation of mercury contamination in areas not involved in mining, but indirectly impacted by mining activities.
2. Development of a sediment transport model that predicts the transportation of potentially contaminated sediment throughout the watershed
3. Identification of major health problems for people living in the Madre de Dios River watershed and evaluate the extent to which mercury and mining activities are related to these health problems

Project Policy Impact Description

If our study reveals significant mercury contamination in regions that are not involved in gold mining and our hydrological models demonstrate that contaminants are potentially affecting indigenous and non-indigenous regions across the border to Bolivia, there are major policy implications to our research. We have already reached out to the Ministries of Environment, Health and Production in Peru, the US Embassy, USAID and the Pan American Health Organization in case our study reveals such relationships.




  • DGHI
  • NSOE
  • Duke University-PRATT

Project Status


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