Gold Mining as a Source of Mercury Exposure in the Brazilian Amazon

The Science of the total environment, 1995

A massive increase in gold mining in the Amazon region of Brazil has led to an enormous discharge of metallic mercury into the aquatic ecosystem. To investigate the dispersion, total and inorganic mercury concentrations were measured in water, fish and animal tissues, and in blood, urine and hair from members of the local populations. Mercury concentrations in river water, sediments and fish were high compared with those of non-contaminated areas. Cattle and pigs kept in the area and with access to the contaminated rivers had concentrations of mercury of 0.1-1.28 micrograms/g and 11.7-15.7 micrograms/l in hair and blood, respectively. These results are approximately twice those measured in specimens from control animals. Mean mercury concentrations in blood, urine and hair of residents were increased at 11.4 micrograms/l, 22.8 micrograms/l and 4.3 micrograms/g, respectively, and the urine mercury of workers from the gold mining sites were up to 155 micrograms/l. The results demonstr...

Journal of Geochemical Exploration, 1997

Gold has been exploited intensively in the Brazilian Amazon during the past fifteen years using garimpo methods (small-scale gold mining). In this study, two gold mining areas were investigated, the municipalities of Pocone and Alta Fh)resta located in the state of Mato Grosso, Central Brazil. The elemental mercury (Hg) used in amalgamating the gold, the ritual stage of the ore dressing process, has caused abnormal Hg concentrations in waterways. This has occurred principally in the Amazon region, where most of the ore prospected is alluvial. Background levels of metals were determined by analyzing sediments and soils located upstream of the anthropogenic inputs and unaffected by mining activities. The study aimed to evaluate the pollution level in sediments and soils, taking into account drainage waters directly affected by gold mining. 'Geoaccumulation indexes' (Igeo) of Hg in sediments from both study areas were used to assesses the pollution level in the aquatic environment, The geoaccumulation indexes of Hg in sediments of the Bento Gomes River in Pocone indicate a relatively high degree of pollution at some sites, even reaching class 4 (1.85 mg/kg). However, when the river reaches the Pantanal swamp, Hg concentrations drop considerably to 0.30 mg/kg. This drop seems to be due to accumulation of metals in the sediments of a lake (sampling site PG-24), which retains most of the sediments transported by the Bento Gomes River. Accumulation of metals in the lake also occurred for Cu, Pb, Zn, Fe and Mn. In the region of Alta Floresta, total Hg concentrations in sediments of the Teles Pires River were studied in the grain size fractions < 74/zm and > 74 gin. Hg concentrations in bottom sediments of this fiver were higher than those found in the Pocone region, with increases of 1.5 to 30 times the background, and thus reaching an lgeo up to class 5.

Bulletin of Environmental Contamination and Toxicology, 2002

Science of The Total Environment, 2006

This work presents quality control results on the mercury concentrations in different environmental (river sediments, forest soils, river suspended matter and fish) and human samples from the lower Madeira River, Amazon sampled between 2001 and 2003, about 15-20 years after the nearly cessation of gold mining activities in the region, which reached its peak in the late 1980s. The study aimed to compare mercury concentrations in these environmental samples with those reported by other authors during the gold rush of the Madeira River Basin. Today, in the Madeira River the releases of mercury register a sudden reduction due the gold price fall in the international trade. However, about 100 t of Hg were released to the atmosphere and to aquatic systems in the region during the gold rush. The present survey shows that notwithstanding the reduction of Hg emissions to the Madeira River Basin from gold mining proper, concentrations in fish and humans are similar to those measured during the gold rush. Reduction in Hg concentrations is restricted to areas close to old point sources and only for abiotic compartments (air and sediments). Remobilization of Hg from bottom sediments plus re-emission from soils due to land use changes are probably responsible for keeping high Hg concentrations in biological samples.

Environmental Science and Pollution Research, 2015

Mercury (Hg) contamination is an issue of concern in the Amazon region due to potential health effects associated with Hg exposure in artisanal gold mining areas. The study presents a human health risk assessment associated with Hg vapor inhalation and MeHg-contaminated fish ingestion, as well as Hg determination in urine, blood, and hair, of human populations (about 325 miners and 321 non-miners) from two gold mining areas in the Brazilian Amazon (São Chico and Creporizinho, Pará State). In São Chico and Creporizinho, 73 fish specimens of 13 freshwater species, and 161 specimens of 11 species, were collected for total Hg determination, respectively. The hazard quotient (HQ) is a risk indicator which defines the ratio of the exposure level and the toxicological reference dose and was applied to determine the threat of MeHg exposure. The mean Hg concentrations in fish from São Chico and Creporizinho were 0.83± 0.43 and 0.36±0.33 μg/g, respectively. More than 60 and 22 % of fish collected in São Chico and Creporizinho, respectively, were above the Hg limit (0.5 μg/g) recommended by WHO for human consumption. For all sampling sites, HQ resulted from 1.5 to 28.5, except for the reference area. In Creporizinho, the values of HQ are close to 2 for most sites, whereas in São Chico, there is a hot spot of MeHg contamination in fish (A2-São Chico Reservoir) with the highest risk level (HQ=28) associated with its human consumption. Mean Hg concentrations in urine, blood, and hair samples indicated that the miners group (in São Chico: urine=17.37 μg/L; blood=27.74 μg/L; hair=4.50 μg/g and in Creporizinho: urine=13.75 μg/L; blood=25.23 μg/L; hair: 4.58 μg/g) was more exposed to mercury compared to non-miners (in São Chico: urine = 5.73 μg/L; blood = 16.50 μg/L; hair=3.16 μg/g and in Creporizinho: urine= 3.91 μg/L; blood=21.04 μg/L, hair=1.88 μg/g). These high Hg levels (found not only in miners but also in non-miners who live near the mining areas) are likely to be related to a potential hazard due to exposure to both Hg vapor by inhalation and to MeHg-contaminated fish ingestion.

Environmental Research, 2000

Cross-sectional studies were conducted in three riverside communities in the state of Para H in the Amazon Region of Brazil. Two of these communities, Bras1H lia Legal and Sa o Lu1H s do Tapajo H s, are located in a watershed exposed to mercury pollution from artisanal gold mining, and the third, Santana do Ituqui, is outside this area. The studies were based upon a community census and included all persons volunteering for participation in each community. All participants were surveyed by questionnaire for health history, occupation, residence, and diet. Clinical evaluations were also done on each subject, along with collection of blood, urine, feces, and hair. Fish samples were collected to represent the most frequently consumed species. Mercury was measured in hair and Ash. Although no signs or symptoms of overt mercury intoxication were observed, persons in Bras1H lia Legal and Sa o Lu1H s do Tapajo H s had higher levels of mercury in hair than residents of Santana de Ituqui, located out of the risk area. Levels of mercury in Ash were below Brazilian health guidance limits, but the high rates of Ash consumption among these populations raise concerns for the possible effects of chronic exposure, especially among young children and women of childbearing age.

The Science of The Total Environment, 2000

Previous site-specific investigations have found that mercury concentrations in water, sediments, and biota of the Brazilian Amazon are elevated above global averages, and that these concentrations are a direct result of widespread mercury amalgamation mining operations conducted by non-organized prospectors. In order to assess the regional impacts of Hg contamination from these non-organized gold mining activities, water, sediments, and fish were systematically collected in 1997 along a 900-km reach of the Madeira River. The sampling program extended from the Amazon River upstream to Porto Velho, the site of historic and ongoing mercury amalgamation mining. Mercury concentrations were found to be elevated above global averages in all sampled media. However, the geochemical data suggest that the high mercury levels are due largely to natural sources and natural biogeochemical processes, and that the impacts of anthropogenically released mercury from mine sites is relatively localized. ᮊ P.J. Lechler . 0048-9697r00r$ -see front matter ᮊ 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 4 8 -9 6 9 7 0 0 0 0 5 4 3 -X ( ) P.J. Lechler et al. r The Science of the Total En¨ironment 260 2000 87᎐96 88

Cadernos De Saude Publica, 2008

This article provides an overview of research on mercury contamination in the Amazon Basin and its evolution from 1990 to 2005. The assessment was based on an extensive and systematic review using bibliographic databases available online and a review of projects by research groups. Brazilian research groups were identified using the database of the Brazilian National Research Council (CNPq). A geographic information system was used to determine the location of the studies. Different aspects of mercury contamination were evaluated (environmental studies, impacts on human health, technological improvements). For 1990-2005, a total of 455 publications were identified. The main advances and remaining gaps in relation to environmental issues and human health were identified and discussed. Although the scientific output varied considerably over the period, there was a general increase in the total number of publications per year from the early 1990s (fewer than 20) until 2005 (more than 30), considering the articles published in indexed journals.

Science of The Total Environment, 1989

Total mercury concentrations in water, sediments and fish from the gold.mining areas of Brasil, especially the Amazon region, are presented. Mercury concentrations were variable among rivers, with the highest values found in samples from tributary forest rivers. Concentrations in water samples varied between 0.1 and 8.6/4g 1-1, while in bottom sediments they reached 19 800/Jg kg -1. Concentrations in edible parts of locally consumed fish reached up to 2700/4g kg -1 wet wt, surpassing by almost five times the Brazilian advisory level for human consumption.

Environmental Research, 2000

Cross-sectional studies were conducted in three riverside communities in the state of Para H in the Amazon Region of Brazil. Two of these communities, Bras1H lia Legal and Sa o Lu1H s do Tapajo H s, are located in a watershed exposed to mercury pollution from artisanal gold mining, and the third, Santana do Ituqui, is outside this area. The studies were based upon a community census and included all persons volunteering for participation in each community. All participants were surveyed by questionnaire for health history, occupation, residence, and diet. Clinical evaluations were also done on each subject, along with collection of blood, urine, feces, and hair. Fish samples were collected to represent the most frequently consumed species. Mercury was measured in hair and Ash. Although no signs or symptoms of overt mercury intoxication were observed, persons in Bras1H lia Legal and Sa o Lu1H s do Tapajo H s had higher levels of mercury in hair than residents of Santana de Ituqui, located out of the risk area. Levels of mercury in Ash were below Brazilian health guidance limits, but the high rates of Ash consumption among these populations raise concerns for the possible effects of chronic exposure, especially among young children and women of childbearing age.