Exposição ao mercúrio e ao arsênio em Estados da Amazônia: síntese dos estudos do Instituto Evandro Chagas/FUNASA Exposure to mercury and arsenic in Amazon States: a summary of studies by the Evandro Chagas Institute/FUNASA

Este artigo é uma revisão das pesquisas da Seção de Meio Ambiente do Instituto Evandro Chagas/FUNASA sobre exposição ao mercúrio (Hg) no vale do rio Tapajós e Estado do Acre, e exposição ao arsênio (As) através de resíduos da exploração de manganês (Mn) realizada pela ICOMI deixados no Porto de Santana-AP. Em relação ao mercúrio, têm sido pesquisadas populações sob risco através da via respiratória ou alimentar. No primeiro caso, os trabalhadores de casas de compra e venda de ouro têm apresentado teores mais elevados de Hg em urina do que os garimpeiros estudados. No segundo caso, as populações ribeirinhas têm mostrado níveis diferenciados de exposição (Hg em cabelo). Comunidades ribeirinhas situadas em áreas não afetadas pelo mercúrio da garimpagem e com hábitos alimentares semelhantes às de área de risco têm sido avaliadas, visando a construção de parâmetros de normalidade regional. São também pesquisados os teores de Hg em materiais ambientais e na biota aquática. Os estudos de saúde humana e ambiente na cidade de Santana-AP objetivaram avaliar as fontes e possíveis vias de exposição da população da comunidade do Elesbão ao arsênio. Verificou-se a existência de fonte de risco através dos rejeitos de Mn, porém os níveis de As na água consumida pela população mostraram-se dentro dos parâmetros de normalidade. As médias encontradas em sangue e cabelo coincidem com médias de normalidade referidas na literatura, em populações não expostas, e as associações entre variáveis epidemiológicas, avaliação clínico-laboratorial e os teores de arsênio não mostraram significância estatística.<br>This article is a review of the studies carried out by Environmental Section of the Evandro Chagas Institute/FUNASA on mercury (Hg) exposure in the Tapajós river basin, and arsenic exposure (As) due to residues of the manganese (Mn) exploration, performed by ICOMI and left at the port of Santana-AP. Regarding mercury exposure, the populations under respiratory or ingestion risk have been studied. In the first case, gold shop workers have been showing higher Hg levels in urine than gold miners. In the second case, riverine populations have been showing differentiated exposure levels (Hg in hair). Riverine communities from areas not affected by gold mining mercury and with similar dietary habits to those of a risk area are studied seeking to establish what the normal parameters for the region area. Levels of Hg in environmental materials and in the aquatic biota were also studied. The studies of human and environmental health in the city of Santana-AP were carried out to evaluate sources and possible exposure routes of the Elesbão community to Arsenic. The existence of a risk source for As was verified through Mn wastes, although the As levels in the water consumed by the population were within normal standards. The averages found in blood and hair match normal averages found in the literature in non-exposed population, and the statistical associations between epidemiological variables, clinical evaluation, laboratorial results and arsenic levels were not significant

Effects of mercury intoxication on the response of horizontal cells of the retina of thraira fish (Hoplias malabaricus)

Methyl mercury (MeHg) is highly neurotoxic, affecting visual function in addition to other central nervous system functions. The effect of mercury intoxication on the amplitude of horizontal cell responses to light was studied in the retina of the fish Hoplias malabaricus. Intracellular responses were recorded from horizontal cells of fish previously intoxicated with MeHg by intraperitoneal injection (IP group) or by trophic exposure (T group). Only one retina per fish was used. The doses of MeHg chloride administered to the IP group were 0.01, 0.05, 0.1, 1.0, 2.0, and 6.0 mg/kg. The amplitudes of the horizontal cell responses were lower than control in individuals exposed to 0.01 (N = 4 retinas), 0.05 (N = 2 retinas) and 0.1 mg/kg (N = 1 retina), whereas no responses were recorded in the 1.0, 2.0, and 6.0 mg/kg groups. T group individuals were fed young specimens of Astyanax sp previously injected with MeHg corresponding to 0.75 (N = 1 retina), 0.075 (N = 8 retinas) or 0.0075 (N = 4 retinas) mg/kg fish body weight. After 14 doses, one every 5 days, the amplitude of the horizontal cell response was higher than control in individuals exposed to 0.075 and 0.0075 mg/kg, and lower in individuals exposed to 0.75 mg/kg. We conclude that intoxication with MeHg affects the electrophysiological response of the horizontal cells in the retina, either reducing or increasing its amplitude compared to control, and that these effects are related to the dose and/or to the mode of administration

An overview of mercury contamination research in the Amazon basin with an emphasis on Brazil Uma revisão das pesquisas sobre contaminação por mercúrio na Amazônia com ênfase no território brasileiro

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.<br>Esta pesquisa apresenta uma visão geral dos estudos desenvolvidos sobre a contaminação por mercúrio na bacia Amazônica e a evolução destes estudos no período 1990-2005. O estudo baseou-se em extensiva e sistemática revisão utilizando bases de dados bibliográficas disponíveis na Internet e em uma revisão dos projetos de pesquisa realizados por grupos de pesquisa. Além disso, os grupos de pesquisa brasileiros foram identificados pela base de dados do Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Um sistema de informação geográfica foi usado para localizar os estudos conduzidos. Diferentes aspectos da contaminação por mercúrio na Amazônia foram analisados (estudos ambientais, impactos na saúde humana, melhorias tecnológicas). No período de 1990-2005, foram identificadas 455 publicações. As principais realizações e as lacunas existentes em relação aos estudos ambientais e de saúde humana foram identificadas e discutidas. Apesar de variações, há um aumento geral do número total de publicações por ano desde o começo da década de 1990 (menos de 20) para o final do período estudado (mais de 30), expresso por meio dos artigos publicados em revistas indexadas

Evolutionary social and biogeophysical changes in the Amazon, Ganges–Brahmaputra–Meghna and Mekong deltas

Policy-making in social-ecological systems increasingly looks to iterative, evolutionary approaches that can address the inherent complexity of interactions between human wellbeing, provision of goods, and the maintenance of ecosystem services. Here, we show how the analysis of available time-series in tropical delta regions over past decades can provide important insight into the social-ecological system dynamics in deltaic regions. The paper provides an exploratory analysis of the recent changes that have occurred in the major elements of three tropical deltaic social-ecological systems, such as demography, economy, health, climate, food, and water. Time-series data from official statistics, monitoring programmes, and Earth observation data are analysed to explore possible trends, slow and fast variables, and observed drivers of change in the Amazon, Ganges–Brahmaputra–Meghna and Mekong deltas. In the Ganges–Brahmaputra–Meghna delta zone, increasing gross domestic product and per capita income levels since the 1980s mirror rising levels of food and inland fish production. In contrast, non-food ecosystem services, such as water availability, water quality, and land stability appear to be deteriorating. In the Amazon delta, natural and anthropogenic perturbations are continuously degrading key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance, and the modulation of regional climate patterns. In the Mekong delta, rapid economic development, changing land-use practices, and salinity intrusion are progressively putting more pressure on the delivery of important provisioning services, such as rice and inland aquaculture production, which are key sources of staple food, farm incomes, and export revenue. Observed changes in many key indicators of ecosystem services point to a changing dynamic state and increased probability of systemic threshold transformations in the near future