Mercury Poisoning in the Brazilian Amazon
What’s the Issue: Methylmercury Exposure
Exposure to mercury affects the immune system, alters genetic and enzyme systems, and damages the nervous system, including coordination and the senses of touch, taste, and sight (1). Methylmercury is the most toxic form of mercury. People are exposed to methylmercury almost entirely by eating contaminated fish that are at the top of aquatic foodchains (2)
Research to Practice: Ecosystem Research to Characterize Methylmercury Exposure Routes in the Amazon
Regional increases of mercury levels in fish were generally thought to be directly attributable to mercury releases from local gold mining operations. However, an extensive three year study, conducted from 1994-1997 along the Tapajós River basin, shed new light on the question (3). These studies demonstrated that mercury from mining operations contributed only a small percentage of the total mercury found in the river (4).
As with any of the chemical elements, mercury exists naturally as part of the Earth and over time, the ultimate sink for mercury is in the sediments of the Earth's oceans and lakes (5). The scientists linked high mercury concentrations with the initiation of slash-and-burn agriculture, a common practice in the Amazon today. By removing trees, loggers and 'slash and burn' farmers unearth naturally occurring mercury deposits bound to soil particles and rains wash this mercury rich soil into nearby water ways where it is converted to methyl mercury (a form easily taken up by fish and humans).
Researchers established a close relationship with the community to educate community members about the risks of eating different fish species through posters depicting methylmercury concentrations in different types of fish. Local residents also began to change agricultural techniques. In a joint initiative with researchers, small farmers identified the crops that could improve diets and reduce the intake of mercury (6). The researchers also worked with local fishermen to identify the stretches of river that would have lower methylmercury levels and be safest for fishing.
These interventions based on scientific evidence and carried out in collaboration with the local community have produced concrete results: from 1995 to now, measured mercury levels in local residents dropped significantly (7)
What’s Next? Further Research on Ecosystem Health and its links to Human Health
Further research that examines the links between ecosystem and human health is vital to understand environmental determinants of human diseases. The rapid economic development and urbanization of countries in the Latin American and Caribbean region are exacerbating a whole host of emerging and re-emerging environmental health threats. The World Health Organization estimates that worldwide, 13 million deaths could be prevented every year by making our environments healthier (8).
For more information on environmental health visit the PAHO Sustainable Development and Environmental Health Website
(1) Edna M Yokoo, Joaquim G Valente, Lynn Grattan, Sérgio Luís Schmidt, Illeane Platt and Ellen K Silbergeld. 2003. Low level methylmercury exposure affects neuropsychological function in adults.Environmental Health: A Global Access Science Source 2:8.
(2) USGS Factsheet.
(3) IDRC Research Program Case Studies.
(4) René Canuel, Marc Lucotte and Sylvie Boucher de Grosbois. 2009. Mercury cycling and human health concerns in remote ecosystems in the Americas. S.A.P.I.EN.S, 2.1. Link.
(5) Wheeler, M. 1996. Measuring Mercury. Environmental Health Perspectives 104:8. Link.
(6) Lebel, J. 2005. Salud: um enfoque ecosistémico. Bogotá: Alfaomega.
(8)WHO Environmental Health:http://www.who.int/features/factfiles/environmental_health/en/index.html
Spring issue of the Research Newsletter
The Spring issue of the Research Newsletter is now available.
NIH, CARPHA, St. Georges University and PAHO offer Grant Writing Workshop. Extended through 24 July. Faculty welcome to apply
NIH, CARPHA, St. Georges University and PAHO offer Grant Writing Workshop for Caribbean researchers at St. Georges University in Grenada, 17-19 September. To learn more and apply select this link. Applications are due 24 July.
Call for Applications: PAHO-OAS Health Scholarships
New call for applications for PAHO-OAS health scholarships in Brazil. Students seeking master’s or PhD degrees in health and research for health may apply through 6 August 2014. More information here.
Who We Are
Why Invest in Research for Health?
A series of case studies examining the benefits of investment in research for health.
Framework & Mandates
Policy on Research for Health (abridged)
The 49th Directing Council approved PAHO’s Regional Policy on Research for Health which offers a strategic approach to strengthen research governance and knowledge translation.
Art for Research
PAHO has in-country representation throughout the region. Use the map provided to find the contact information for each PAHO focal point.
To read about internship opportunities in research at different PAHO entities, read testimonials from former interns, or apply, visit our internship section.