Maria da Conceição Nascimento Pinheiro

Mercury and selenium - a review on aspects related to the health of human populations in the Amazon.

Mercury (Hg) toxicity is governed by cellular thiol compounds and its capacity to generate reactive oxygen radicals and oxidative stress. Selenium (Se) plays a key role in the prevention of the toxic effects of Hg by modulating the activity of several Se-dependent enzymes, including glutathione peroxidase (GSH-Px). In addition, dietary Se can reduce Hg toxicity by directly interacting with either Hg(II) or methylmercury (MeHg) to form inert products, such as HgSe complexes.. Although experimental and environmental data have indicated a protective role for selenium against Hg toxicity, human data are more limited and somewhat conroversial In the Amazon Region of Brazil, Hg pollution is rampant as a result of gold (Au) mining and other anthropogenic factors, leading to pervasive release of large quantities of metallic Hg0 into the environment. Exposure to Hg in this region is associated with direct occupational exposure in the gold mining industry, as well as consumption by in inhabitants of riverside communities of a diet rich in MeHg-contaminated fish. Human exposure to MeHg in the Amazon through the diet has been monitored by measuring Hg and MeHg in hair samples. In this paper, we review the environmental contamination of Hg in the Amazon and detail human exposures in populations of this region. We conclude with a brief synopsis on Se levels in the Amazon population and provide a brief review of data available on the interaction between Hg and Se in this region. Overall, the literature supports the notion that low environmental Se is linked to susceptibility to Hg toxicity and that Se levels could be used as a bioindicator to monitor the health of Hg exposed subjects. However, in light of the limited human data on this subject, further epidemiological studies are needed to clarify how changes in Se levels modify the toxicity of environmental Hg.

Genotoxicity of mercury: Contributing for the analysis of Amazonian populations

Mercury is an important source of environmental contamination affecting human beings throughout the world and especially in the Amazon. Riverside populations have been chronically exposed to relatively high levels of methylmercury for many years. Long-term effects of mercury exposure are not well known, but human genotoxicity was already showed in both in vitro and epidemiological studies. However, to date, only two studies were carried out in Amazonian populations with conflicting results and without comparing to a non-exposed population. Aiming to highlight this question and avoid interference factors, this work analyzed in vitro genotoxicity of mercury in blood lymphocytes of Amazonian individuals by two methods (micronucleus and chromosomal aberrations). Deleterious effects of low levels (1-500 μg/l or 0,004-2 μM) of methylmercury were only detected with the method to detect chromosomal aberrations. Mitotic index (proportion of cells in metaphase) was the parameter most sensible. Thus, this technique was applied for the analysis of an Amazonian non-exposed population (Panacauera) with similar social-economical characteristics of the exposed populations studied elsewhere. The mean of the mitotic index for Panacauera population was 0.0814 ± 0.0097. Inter-individual variability of this index had no relation with sex or age. This value was above those registered for some groups of exposed populations. This fact points to mercury as the main responsible for inhibiting the cell cycle and/or the loss of proliferative capacity of the cells. These results already support mitotic index as an essential parameter for the early diagnose of mercury genotoxicity in humans, and especially in Amazonian populations.

Total mercury in hair samples of inhabitants of Tapajós river, Pará State, Brazil

This study evaluates human exposure to methylmercury in fishermen and their families in four villages on the Tapajós river: Rainha, Barreiras, São Luís do Tapajós and Paraná-Mirim. Hair analyses were performed with atomic absorption spectophotometry. Total hair mercury levels varied between 2.9mg/g and 71.5mg/g. Paraná-Mirim showed the lowest level. The highest level was found in São Luís do Tapajós and Barreiras. The hair mercury was six to seven times higher than the established safe limit of 10mg/g. No statistically significant difference was found between the mean level of total mercury taken from the inhabitants living downstream and upstream in Itaituba village (p > 0.05). These results confirm that human exposure to methylmercury is occurring on the Tapajós river and suggest that continued fish ingestion in that region is a potential risk factor for the appearance of symptoms and signs of Minamata disease. An immediate epidemiological survey program is recommended.

Exposição humana ao metilmercúrio em comunidades ribeirinhas da Região do Tapajós, Pará, Brasil

Avaliou-se a exposicao humana ao metilmercurio e ao mercurio total em comunidades ribeirinhas do rio Tapajos e da regiao metropolitana de Belem, no Estado do Para, Brasil, atraves da determinacao de mercurio total e metilmercurio em amostras de cabelo nos anos de 1994 e 1995. Observou-se que as concentracoes medias de mercurio total variaram de 2 ± 1µg/g-1 a 20,5 ± 12,1µg/g-1, enquanto que as concentracoes medias de metilmercurio variaram de 1,4 ± 0,7µg/g-1 a 18,5 ± 11µg/g-1. Estes resultados confirmam a contaminacao mercurial na regiao do rio Tapajos, admitem a possibilidade do aparecimento de sinais e sintomas de intoxicacao mercurial e recomendam a manutencao da monitorizacao do mercurio total e do metilmercurio nas amostras de cabelo, bem como a necessidade de estudos clinico-epidemiologicos para implantacao de medidas de prevencao e controle da intoxicacao mercurial.

Estudo da eficácia e tolerância do artesunato oral isolado e em associaçäo com mefloquina, no tratamento da malária falciparum näo complicada em área endêmica do Pará, Brasil

With the objective to evaluate the efficacy and tolerance of artesunate in the treatment of non-complicatedfalciparum malaria in endemic area of the State of Para, 153 patients were randomized and studied in three groups, distributed by therapeutical scheme (I received mefloquine lOOOmg, II used artesunate 600mg followed by mefloquine 500mg). Evaluation was made by daily clinical and parasithological examination, in the first 7 days, and weekly until the 35th day of the follow up. Biochemical and hematological analysis previously done and on the 7th day, targetting cure control and identification of possible effects related to drugs administration. As to sex, parasitemy and fever, studied groups were homogeneous. Time for parasitemy disappearence was shorter in the groups II and III respectively, whose therapeutical schemes had artesunate. Fever disappereance was quicker in the group treated with the combination of drugs. Clinical and biochemical alterations associated with drugs administration did not show significant differences among the studied groups. Early disappearence of fever and parasitemy, and absence of important side effects suggest that artesunate, isolated or administrated in combination with mefloquine, constitutes an able therapeutical procedure to contribute for disease control in that region.

Análise quantitativa de mastócitos e de granulócitos eosinófilos no miocárdio de ratos wistar cronicamente infectados pelo Trypanosoma cruzi. Contribuição ao conhecimento da fibrose miocárdia

Foi feito o estudo quantitativo de mastocitos e de granulocitos eosinofilos no miocardio de 40 ratos albinos Wistar. Trinta animais encontravam-se nafase tardia da infeccao (8o mes) produzida pelas cepas Sao Felipe, Y e Colombiana do Trypanosoma cruzi, e apresentavam graus variaveis de miocardite cronica; 10 ratos serviram como controles. Miocardite cronica fibrosante (fibrose) ocorreu em 40% dos animais infectados e detectou-se aumento do numero de mastocitos nos animais, chagasicos, o qual se associou a infeccao mas nao a fibrose miocardica. Nao se constatou aumento do numero de eosinofilos.

Manifestações emocionais e motoras de ribeirinhos expostos ao mercúrio na Amazônia

Introduction: The investigation of clinical and neurological impactations associated with exposure to mercury levels in exposed populations is necessary in the Amazon. Objective: To analyze emotional and motor symptoms of riverside dwellers exposed by diet in the municipalities of Itaituba and Acará, in Pará, Brazil. Methods: Hair samples were collected to assess the total mercury (HgT). Demographic data as well as emotional (depression, anxiety and insomnia) and motor (paresthesia, muscle weakness, loss of balance when walking, tremors, limb pain and dysarthria) symptomatology data were obtained. Results: Mean levels of HgT in Itaituba were significantly higher (p < 0.0001) than in Acará. Emotional symptoms were identified in 26 (26.5%) participants from Itaituba and in 24 (52.2%) from Acará. Specific motor complaints in Itaituba occurred in 63 (64.3%) volunteers; the most frequently mentioned afflictions were limb pain (36.7%), paresthesia (32.6%) and muscle weakness (27.5%). In Acará, 33 (71.7%) participants had motor symptoms, the majority of which complained of paresthesia (54.3%), limb pain (52.2%) and tremors (34.8%). Average HgT levels in Itaituba in those with emotional and motor symptoms were above the tolerable levels (6 µg/g) determined by the World Health Organization. Conclusion: Results showed that mercury levels in emotional and motor symptoms in Itaituba are higher than in riverside dwellers in Acará. Further studies, including the application of specific qualitative and/or quantitative standard tests, as well as the investigation of other clinical signs are necessary.

Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved

The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13–53 years old. Mercury analysis was performed in head hair samples weighting 0.1–0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age—mercury-exposed and non-exposed—the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population.

Caso fatal de balantidíase intestinal

A fatal case of a 63-year old pig-raising country woman with an eight-day course of nausea, vomiting. dysentery with intestinal bleeding the latter being the direct cause of death. The autopsy showed ulcerative colitis due to B. coli, which was easily observed on histological examination of the large bowel.

A first evaluation on the use of Ardea albus feathers as bioindicators of mercury burden in Amazonian ecosystems

O objetivo deste estudo foi avaliar as concentracoes de mercurio total em penas de Ardea albus coletadas em uma assembleia de aves localizada nas imediacoes da cidade de Belem, Para, com vistas a investigar a possibilidade do uso desta especie nos estudos de biomonitoramento deste metal. Para determinacao de mercurio total foi utilizada a espectrofotometria de absorcao atomica com amalgamacao. A concentracao media de mercurio total nas penas do corpo foi 2,2 ± 1,5 µg.g-1 e nas penas das asas foi 1.3 ± 0.9 µg/g-1. Nao foi observada correlacao entre a concentracao de mercurio total e o comprimento das penas do corpo e da asa. Foi observado teor de mercurio total superior a 5 µg.g-1 em apenas uma amostra de pena do corpo.