View of the Mississippi River from Perot State Park

International Conference on Rivers and Civilization:
Multidisciplinary Perspectives on Major River Basins


La Crosse, Wisconsin USA
June 25-28, 2006

HOST AND PRESENTER INSTITUTIONS
University of Wisconsin-La Crosse Home Page National Mississippi River Museum and Aquarium Home Page

CONFERENCE SPEAKER

Donna Mergler (University of Quebec at Montreal, Canada): An Ecosystem Approach to Mercury and Health in the Amazon Basin. (Abstract)

photo of Donna MerglerDonna Mergler is a Professor of Biological Sciences at the Université du Québec à Montréal (UQAM), and a member of the University's Institute for Environmental Sciences and the research group CINBIOSE, a World Health Organisation and Pan-American Health Organisation Collaborating Centre for the Prevention of Occupational and Environmental Illness.  Since receiving her doctorate in neurophysiology from McGill University, her research has focused on early neurotoxic effects of exposure to pollutants in the workplace and environment. Her studies in occupational health have examined nervous‑system deficits associated with manganese exposure in industrial workers and the long-term effects of exposure to organic solvents and pesticides. As Team Leader for the health component in the Collaborative Mercury Research Network (COMERN), she and her research group have contributed to the development of an ecosystem framework that applies innovative approaches and participatory methods to examine the effects of mercury on women's health in Canada and the Amazon Basin.  These studies focus on preventive intervention, and combine quantitative and qualitative methods to bring about concrete and lasting solutions to problems of environmental degradation. Dr. Mergler is also involved in studies in Ecuador, Costa Rica, Chili, South Africa and the Ivory Coast.  She has published many scientific articles, given many keynote addresses at conferences, received several awards for her work in the environmental sciences, and served prominently on several national and multinational scientific advisory boards.
http://www.unites.uqam.ca/cinbiose/GENS/DMERGLER.HTML

Abstract: The Tapajós River is a major tributary of the Amazon. Here, over the past 10 years, our interdisciplinary group of Canadian and Brazilian researchers from the natural, health and social sciences has been working, using an ecosystem approach, with a strong participatory research component, to examine the pathways of mercury (Hg) contamination, human exposure and health effects, mitigation measures and their efficiency. Previous reports of high levels of mercury (Hg) in fish and in humans attributed the source of Hg to gold mining. Our study revealed that, in the mid-Tapajós region, where we were working, large-scale deforestation, mainly from "slash-and-burn" agricultural practices, was the major culprit, through soil erosion and lixiviation, releasing mercury into the river. The deforested areas are increasing in size due to large in-migration and the mounting need to clear the forest to produce food to feed the ever- increasing population.. Climatic conditions and aquatic vegetation are optimal for Hg methylation, accelerating the incorporation of Hg into the trophic chain and contaminating the fish, a dietary mainstay of this population. Measurements of hundreds of fish samples showed that Hg concentrations vary greatly, depending upon feeding habits, growth rate, age, and location. Hg in humans, measured in hair samples, cut in centimeters, provided a chronological portrait of exposure. Exposure increased with fish consumption, was higher among those who ate more piscivorous fish and varied seasonally. Evaluation of nervous system functions showed significant declines in motor and visual functions in relation to increasing exposure. The integrated findings of this study were returned to the communities and discussed during village workshops, which examined short- medium-, and long-term solutions with respect to diet, fishing, and farming practices. Since fish is a highly nutritious food, a positive slogan, inviting people to "Eat more fish that don't eat other fish" was adopted. In addition, a chart with drawings of 42 fish species in red (high mercury), yellow (medium levels) and green (low mercury) was posted in every house. Re-assessment of fish consumption, exposure and neuro-outcomes, 5 years later, showed that the villagers ate the same amount of fish, but had reversed the proportion of herbivorous to piscivorous fish. Their Hg exposure decreased by 40 percent! There was improvement in motor functions, but visual functions continued to decline in correlation with previous exposure levels. To further foster maximizing nutritional input from fish and minimizing toxic risk, an extensive dietary study was undertaken with 26 village women, coordinated by the village midwife, who, for 13 months, kept daily food-frequency diaries. Hair Hg (HHg) concentration, evaluated for each month, showed that fruit consumption was inversely related to HHg, after controlling for fish consumption. Thus, those that ate more fruit displayed lower HHg levels for the same amount of fish intake. This positive influence of fruit consumption was further confirmed in an epidemiological study of more than 400 persons. The success of this project is attributed to the synergy of scientific interdisciplinary inputs, coupled with community participation and an ecosystem approach to human health.