As promised, #2 of two recent ProMed postings on Minamata disease in
Amazon Brazil. This one includes speculations and conclusions around
food and agricultural practices, as well as the mercury-related
deficits in people who haven't developed full-blown Minimata
disease.
peace
misha
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MINAMATA DISEASE - BRAZIL (AMAZON) (04)
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A ProMED-mail post
Date: Sat, 30 Jan 1999 12:43:16 -0500
From: Donna Mergler
MINAMATA DISEASE IN THE AMAZON: THE TIP OF THE ICEBERG
Montreal, January 29, 1999.
The recent revelation of 3 cases of Minamata disease, identified by
Japanese researchers in a village on the Tapajos River in the
Brazilian Amazon, is only the tip of the iceberg concerning the
situation of mercury pollution in the Amazon. Over the last ten
years, an increasing number of studies have reported mercury
contamination of fish in the various rivers of the Amazon region, and
relatively high mercury levels in the hair of riverine populations for
whom fish constitute the dietary mainstay. Up until recently, it was
believed that the widespread mercury contamination came primarily from
the use of this metal in gold-mining. Our research group from the
University of Quebec in Montreal and the Federal Universities of Para
and Rio de Janeiro have shown that the mercury released into the
atmosphere from the gold-mining activities, while highly toxic for the
miners and workers who burn the gold-mercury amalgam and the
populations living around the gold-mining areas and the shops in the
towns and cities that further burn the amalgam, remains in the local
environment. Our studies and others strongly suggest that in areas
remote from the gold mines, the mercury in the extensive Amazonian
waterways comes from soil lixiviation of natural mercury following
'slash and burn' agricultural practices. Following deforestation,
mercury leaches from the soil which contains high levels of this
metal. (For a description see: Roulet et al. Science of the Total
Environment 1998; 223:1-24).
Our international research group has likewise examined early
neurological deficits in riverine populations who do not display
clinical manifestations of Minamata disease. These studies reveal
that motor and visual functions decrease with increasing hair
mercury, at levels well below 50 ppm. (median values: 11 ppm). These
findings show that even in the absence of overt disease, mercury is
affecting the well-being of these populations (See: Lebel et al.
Neurotoxicology 1996; 17:157-167; Lebel et al. Environmental Research
1998; 79:20-32).
The tremendous biodiversity in the fish resources is reflected in the
differences in mercury levels in the abundant fish species. This in
turn, is reflected in hair mercury concentration of fish-eaters.
Herbivorous fish contain very little mercury and those who eat
predominantly herbivorous fish have less mercury than those who eat
predominantly piscivorous fish. There are seasonal variations in hair
mercury levels, dependent on the bioavailability of different fish
species during the rainy and the dry seasons (See: Lebel et al. Water,
Air & Soil Pollution 1997; 97:31-44).
The Amazonian ecosystem is very complex and much work must be done
to understand what is happening and instigate mitigation measures.
Researchers from Canada and Brazil, with local NGOs are currently
involved in a pilot project in a small village on the Tapajos River,
whose objective is to work with the community to find short, medium
and long term solutions. Since fish is the major source of protein
and is beneficial to their health and well-being, the short term
solution seeks to inform the villagers of the mercury levels in
various fish species and work with them to modify their diet in such
a way as to increase the proportion of fish with low mercury levels.
On the medium term, the factors that favor methylation will be
determined, allowing us to identify 'hot spots' in the river. And,
on a more long term basis, we have begun to work with the local
farmers on reforestation projects...
There is much to be done in this area. In 1989, UNAMAZ, the Union of
Amazonian Universities held a meeting on mercury, pointing out the
growing dangers of mercury in the Amazonian environment. Ten years
later, in January 1999, we organized a meeting in Santarem, a city at
the junction of the Amazon and Tapajos Rivers to establish a
collaborative network of researchers and NGOs working on the issues of
mercury contamination in the Amazon. NGOs from the region and
researchers from Santarem, Belem, Brasilia, Manaus, Bahia, Rio de
Janeiro in Brazil and from Venezuela, Peru, Ecuador, Canada and the
United States attended the meeting and set up the Forum on Mercury
Contamination of the Amazonian Ecosytem on the outreach campus of the
Federal University of Para in Santarem. We will soon be setting up a
website. The International Development Research Center has provided
funding to initiate this endeavor and we are seeking funding from
other sources to pursue it.
For information, you can contact Dr. Pascale Martineu
(martineu.pascale@uqam.ca), Dr. Donna Mergler (mergler.donna@uqam.ca)
or Dr. Marc Lucotte (lucotte.marc_michel@uqam.ca).
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Michele Gale-Sinex, communications manager
Center for Integrated Ag Systems
UW-Madison College of Ag and Life Sciences
Voice: (608) 262-8018 FAX: (608) 265-3020
http://www.wisc.edu/cias/
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In the towers of steel, belief goes on and on
in this heartland, in this heartland soil. --U2
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