Biomedical subjects
O Malm
Publications and source records attributed to O Malm.
A program for the control of indoor pollution by metallic mercury.
The objective of this study was to develop an educational program for preventing metallic mercury emissions due to the burning of mercury-gold amalgams inside houses. The main participants were adolescents from a school in the city of Poconé, State of Mato Grosso. The program was developed in five stages, including discussions of the methods and exhibition of slides showing people working in activities including the garimpos, planning activities as dramatizations, making posters and preparing a screenplay for the production of a video, discussing how to prevent indoor burning of gold-mercury amalgams, and a final evaluation of the adolescents about what they had learned during the program. The evaluation of the impact was done through a comparison of correct answers from a questionnaire before and after the development of the educational activities and by means of a comparison of urinary mercury in school students and a group of residents (women) at three different times: before the program (2.30 microgram/L), 6 months after (2.90 microgram/L), and 11 months after (1.49 microgram/L).
Mercury in a widely consumed fish Micropogonias furnieri (Demarest, 1823) from four main Brazilian estuaries.
We analyzed mercury levels in the white muscular tissue of a fish (Micropogonias furnieri) originated from four Brazilian estuaries during the period between the summer 1990 and spring 1991. Mercury levels were below the maximum permissible limit established for food by the Brazilian legislation (500.0 ng.g-1 wet wt.). The measured mercury concentrations ranged from 17.4 to 266.0 ng.g-1 (wet wt.), for Guanabara Bay 19.5-252.2 ng.g-1 (wet wt.), for Sepetiba Bay 23.0-433.7 ng.g-1 (wet wt.), for Ilha Grande Bay 13.8-296.3 ng.g-1 (wet wt.) for Conceição Lagoon. Positive relationships were observed between mercury concentration in fish and the length and weight of the fishes. Weight normalized concentration showed Guanabara Bay presented the higher levels and the Conceição Lagoon presented the lowest levels. Ilha Grande Bay presented the second highest levels after Sepetiba Bay, although the former is considered a non-contaminated area.
Gold mining as a source of mercury exposure in the Brazilian Amazon.
Amalgamation has been used for more than 4500 years in mining processes. Mercury has been extensively used in South America by Spanish colonizers for precious metal recovery. It is estimated that between 1550 and 1880, nearly 200,000 metric tonnes of mercury was released to the environment. During the present gold rush, Brazil is first in South America and second in the world in gold production (with 90% coming from informal mining or garimpos). At least 2000 tonnes of mercury has been released to the environment in the present gold rush. From the mid 1980s, environmental research has been carried out in impacted Amazon rivers, later followed by human exposure studies. The river basins studied were the Tapajós, Madeira, and Negro, but also some man-made reservoirs and areas in central Brazil. The analyses mainly involved sediments, soil, air, fish, human hair, and urine. The results show high variability, perhaps related to biological diversity, biogeochemical differences in the river basins, and seasonal changes. High mercury values also occur in some areas with no known history of gold mining. The results available document a considerable impact on environmental mercury concentrations and frequent occurrence of human exposure levels that may lead to adverse health effects.
Methylmercury in fish and hair samples from the Balbina Feservoir, Brazilian Amazon.
The present study aimed to evaluate methylmercury in fish and human hair samples from an important hydroelectrical reservoir, Balbina (Brazil, Amazon). It presents a quite intense fishing activity and there is no known goldmining activity in its watershed. Fish and human hair were analyzed with a new extraction technique and measured by GC-ECD. Analytical quality was checked through intercomparisons between two laboratories with local samples and certified standards from IAEA. Methylmercury in hair ranged from 2.0 to 21.6 microg . g-1 with a mean of 8.76+/-5.20 microg . g-1 (N=20), while the methylmercury percentages were above 90. Fish presented methylmercury levels ranging from 0.03 to 0.9 microg small middle dot g-1 wet wt with a mean of 0.24+/-0.18 microg small middle dot g-1 wet wt (N=32), which is below the limit established for food by Brazilian legislation (0.5 microg small middle dot g-1 wet wt) and methylmercury mean percentages were above 95%. The total mean daily methylmercury intake ranged from 11 to 55 microg for 70% of the sampled population from the village based on a daily consumption of about 110 g of fish with methylmercury concentrations in the range of 0.1 to 0.5 microg . g-1. This calculation is consistent with methylmercury concentrations in hair samples in the range of 2.6 to 13.1 microg . g-1.
Mercury in the Amazon.
Release and spreading of mercury from gold mining is a widespread problem in the Amazon area. Today we have rather good knowledge of the mercury situation. Tens of investigations have considered mainly concentrations in fish and human hair. Metallic mercury is used for amalgamation of gold, and the mercury is released by evaporation at reburning sites. The first extraction (burning) is performed in the field at the garimpos and the second (reburning) in gold shops in towns. This practice may cause severe exposure to elemental mercury by inhalation for people working with gold purification. Mercury is also released in substantial amounts to rivers and lakes. This mercury may be bioaccumulated as methylmercury in aquatic food chains. Predatory fish often contain mercury in concentrations that far exceed the safety norms in Brazil. As many people eat fish daily, there is a high exposure to methylmercury. Neurological disorders have been found in exposed persons. Methylmercury concentrations in hair are often at levels that may cause clinical symptoms of Minamata disease. The greatest health hazard index values have been estimated for people eating contaminated fish.
Elemental mercury contamination survey in a chlor-alkali plant by the use of transplanted Spanish moss, Tillandsia usneoides (L.).
Atmospheric Hg0 contamination and the potential risk of occupational exposure were evaluated in a chlor-alkali facility by the use of transplanted Tillandsia usneoides. This plant species was selected since it presents some features that makes it useful for air monitoring purposes. After short-term exposure (15 days), control plants showed a mean concentration of 0.2 microgram Hg.g-1 whereas Hg values in transplants ranged from 1 to 10,400 micrograms.g-1. This latter value was observed near an elemental Hg spillage. Even after exposure to toxic conditions plant metabolism was still operative, allowing the transplant technique to be employed to assess both Hg taken up through the stomata and Hg associated with particles deposited on the biomonitor.
Mercury and methylmercury in fish and human hair from the Tapajós river basin, Brazil.
Mercury is being released in the Amazon in an abusive way due to goldmining activities. The Tapajós river basin was the first to be intensively exploited in the modern Amazon gold rush. Fish and hair samples as the best indicators of human methylmercury contamination were investigated in the main cities and villages along the Tapajós river basin. The upper basin has typical fish fauna with much larger carnivorous fish with higher mercury levels reaching an average value of 0.69 microgram.g-1 wet wt. in 43 fish. This was accompanied by high levels in hair of the human population living in the same area. The maximum hair value reach 151 micrograms.g-1 dry wt. with two villages presenting an average value close to 25 micrograms.g-1 dry wt. An analytical laboratory intercalibration exercise was performed between Japanese and Brazilian laboratories for total mercury analysis. Critical fish, areas, and more exposed human groups are identified.
Mercury concentrations in inland waters of gold-mining areas in Rondônia, Brazil.
Total mercury concentrations in water, sediments and fish from the gold-mining areas of Brazil, 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 micrograms l-1, while in bottom sediments they reached 19,800 micrograms kg-1. Concentrations in edible parts of locally consumed fish reached up to 2700 micrograms kg-1 wet wt, surpassing by almost five times the Brazilian advisory level for human consumption.