GEO Brasil - UNEP

The state of health and the environment
the state of the environment in Brazil
A study carried out with 365 inhabitants – not exposed in
their occupation (mainly women and children), in the
municipality of Poconé (State of Mato Grosso), presented
two types of exposure The first in people living up to 400
metres far, and in the prevailing direction of the wind, from
shops that buy and purify gold These residents presented
an average of mercury in their urine (489 mg/L) that was
higher than presented by the people who lived in a control
area (125mg/L) Also, 14 people presented Hg levels in their
urine, which were higher than 10 mg/L, compared to a WHO
recommended limit of 40 mg/L for non-exposed people A
second type of exposure was found among people who
lived in the surrounding areas of the city, and burned goldmercury
amalgams inside their houses Of those people, 13
presented mercury levels in their urine that were higher
than 10 mg/L, and this study was used to develop a special
health education programme (Câmara et al 2000)
scientific studies have been finding strong relations
between methylmercury concentrations observed in the hair
and some motorial (Dolbec et al 2000), neurological (Lebel
et al 1998) and cytogenetic problems in lymphocytes of the
populations living in the banks of Tapajós River (Amrin et al
2000)
It is difficult to establish the number of people directly
exposed to mercury in gold mines, given the Amazon
amplitude In the end of the 80’s, approximately 300,000
miners were registered, in accordance with a census carried
out by the National Department for Mineral Production
Today, this number is certainly a lot smaller, considering
the substantial reduction of gold exploitation in the region,
both due to falling prices of this mineral in the market and
the international pressures related to the suspension of the
activity, because of its negative impact on the environment
The metallic mercury released in the environment can be
deposited in rivers and, through the biological chain, be
transformed in an organic compound called methylmercury
This substance, which is the most toxic form among mercury
derivatives, has been found in bottom silts and in
omnivorous (up to 07 ppm) and carnivorous fish (> 05
ppm, with the possibility of reaching 6 ppm in larger
samples), captured in metallic mercury polluted Amazon
rivers Considering that the major protein source for
riverbank populations is fish, human contamination has
also been reported Relatively high concentrations of
methylmercury have been identified in hair samples from
indigenous and riverbank populations (10 – 150 ppm) in
that region (Malm 1998) Also, studies carried out in three
fishermen villages along Tapajós River presented mercury
concentrations in their hair, which varied between 14 and 21
ppm, and 73 per cent of the assessed fishermen presented
higher concentrations than the limits considered normal
(maximum normal limit = 10 ppm) There were also studies
carried out by the Evandro Chagas Institute, in Tapajós River
Basin, that indicated averages of mercury levels over 10
mg/g for most communities in the study, compared to a
WHO established limit of 20 mg/g (Santos 1997), which
places these populations at the risk of diseases caused by
this substance
However, there are still some divergences in relation to the
clinical effects observed in Amazon populations exposed
to mercury, due to poor living conditions and the occurrence
of endemic diseases in that region Nevertheless, some
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