Mercury toxicity due to the smelting of placer gold recovered by mercury amalgam.
A 19-year-old man developed tremor in both hands and fatigue after starting work at a placer gold mine where he was exposed to mercury-gold amalgam. Examination revealed an intention tremor, dysdiadochokinesis and mild rigidity. The 24-h urinary mercury concentration reached a peak of 715 nmol/l (143 ug/l) shortly before the clinical examination, after which he was removed from working in the gold room [Mercury No. Adverse Effect Level: 250 nmol/l (50 ug/l)]. On review 7 weeks later his tremor had almost resolved and the dysdiadochokinesis and rigidity had gone. The 24-h urinary mercury concentration had fallen to 160 nmol/l (32 ug/l). The principal exposure to mercury was considered to be the smelting of retorted gold with previously unrecognized residual mercury in it. The peak air concentration of mercury vapour during gold smelting was 0.533 mg/m3 (Mercury Vapour ACGIH TLV: 0.05 mg/m3 TWA). Several engineering and procedural controls were instituted. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited. (+info)
Carbon disulphide absorption during xanthate reagent mixing in a gold mine concentrator.
A xanthate reagent mixer at a gold mine concentrator was exposed to carbon disulphide by extensive skin contamination with xanthate powder and solution during the reagent mixing process. Absorption of carbon disulphide was confirmed by the detection of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA). Drager colorimetric tube testing during subsequent mixing recorded a maximum concentration of at least 60 ppm carbon disulphide. An illness consisting of predominantly gastrointestinal symptoms began 20 h after the exposure. Although this may have been due to carbon disulphide toxicity this is by no means certain. The need for engineering controls, impervious protective clothing and full-face respirators with particulate and organic vapour cartridges is discussed. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited. (+info)
A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine.
The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals-grunerite (amosite) and riebeckite (crocidolite)-have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner's exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency. (+info)
Leptospirosis and Ebola virus infection in five gold-panning villages in northeastern Gabon.
An exhaustive epidemiologic and serologic survey was carried out in five gold-panning villages situated in northeastern Gabon to estimate the degree of exposure of to leptospirosis and Ebola virus. The seroprevalence was 15.7% for leptospirosis and 10.2% for Ebola virus. Sixty years after the last seroepidemiologic survey of leptospirosis in Gabon, this study demonstrates the persistence of this infection among the endemic population and the need to consider it as a potential cause of hemorrhagic fever in Gabon. There was no significant statistical correlation between the serologic status of populations exposed to both infectious agents, indicating the lack of common risk factors for these diseases. (+info)
Cellular responses to Plasmodium falciparum major surface antigens and their relationship to human activities associated with malaria transmission.
In Brazil, two types of activities have led to the worsening of malarial transmission in the Amazon region: prospecting/mining and agricultural settlements. In the present study, we analyze the cellular response of 52 of these individuals (14 gold-miners and 38 farmers) living within the same endemic area. Two Plasmodium falciparum major surface antigens (recombinant proteins) were used for cellular proliferative assays: circumsporozoite protein and merozoite surface protein-1. The frequency of these cellular responses were significantly higher among the miners (57-64%) than the farmers (10-20%) when either recombinant protein was used. Our data suggest that a higher exposure to malaria of the gold-miners contributed to their higher in vitro cellular response compared with the farmers. These findings point the way to further studies evaluating the influence of risk factors associated with the life styles of different social groups and the immune responses to these antigens. (+info)
Clinical and laboratory manifestations of systemic sclerosis (scleroderma) in Black South Africans.
A retrospective study of systemic sclerosis (SSc) in Blacks attending a tertiary hospital on the Witwatersrand, South Africa, was undertaken. The female:male ratio of the 63 patients was 4.6:1 and the mean age of onset of SSc was 36.1 yr. Four of the 11 males were ex-goldminers and nine females resided close to goldmines. Forty-one patients had diffuse cutaneous SSc (dcSSc), 18 had limited cutaneous SSc (lcSSc) and four were unclassified. Overall, 56% had pulmonary fibrosis, 37% had myositis and 98% were antinuclear antibody (ANA) positive, with a notable absence of anti-centromere antibodies. Subset comparisons showed myositis and a reduced forced vital capacity to be significantly more common with dcSSc than lcSSc. The only significant sex differences were that arthralgia/arthritis was more common in women, while calcinosis occurred more frequently in men. Seven of the eight known deaths occurred in patients with dcSSc. These findings, particularly the age of disease onset, predominance of the dcSSc subset, inflammatory features of myositis and a raised erythrocyte sedimentation rate, and absence of anti-centromere antibodies, are similar to those reported previously in African-Americans. (+info)
Radionuclides in the lichen-caribou-human food chain near uranium mining operations in northern Saskatchewan, Canada.
The richest uranium ore bodies ever discovered (Cigar Lake and McArthur River) are presently under development in northeastern Saskatchewan. This subarctic region is also home to several operating uranium mines and aboriginal communities, partly dependent upon caribou for subsistence. Because of concerns over mining impacts and the efficient transfer of airborne radionuclides through the lichen-caribou-human food chain, radionuclides were analyzed in tissues from 18 barren-ground caribou (Rangifer tarandus groenlandicus). Radionuclides included uranium (U), radium (226Ra), lead (210Pb), and polonium (210Po) from the uranium decay series; the fission product (137Cs) from fallout; and naturally occurring potassium (40K). Natural background radiation doses average 2-4 mSv/year from cosmic rays, external gamma rays, radon inhalation, and ingestion of food items. The ingestion of 210Po and 137Cs when caribou are consumed adds to these background doses. The dose increment was 0.85 mSv/year for adults who consumed 100 g of caribou meat per day and up to 1.7 mSv/year if one liver and 10 kidneys per year were also consumed. We discuss the cancer risk from these doses. Concentration ratios (CRs), relating caribou tissues to lichens or rumen (stomach) contents, were calculated to estimate food chain transfer. The CRs for caribou muscle ranged from 1 to 16% for U, 6 to 25% for 226Ra, 1 to 2% for 210Pb, 6 to 26% for 210Po, 260 to 370% for 137Cs, and 76 to 130% for 40K, with 137Cs biomagnifying by a factor of 3-4. These CRs are useful in predicting caribou meat concentrations from the lichens, measured in monitoring programs, for the future evaluation of uranium mining impacts on this critical food chain. (+info)
Methylmercury neurotoxicity in Amazonian children downstream from gold mining.
In widespread informal gold mining in the Amazon Basin, mercury is used to capture the gold particles as amalgam. Releases of mercury to the environment have resulted in the contamination of freshwater fish with methylmercury. In four comparable Amazonian communities, we examined 351 of 420 eligible children between 7 and 12 years of age. In three Tapajos villages with the highest exposures, more than 80% of 246 children had hair-mercury concentrations above 10 microg/g, a limit above which adverse effects on brain development are likely to occur. Neuropsychological tests of motor function, attention, and visuospatial performance showed decrements associated with the hair-mercury concentrations. Especially on the Santa Ana form board and the Stanford-Binet copying tests, similar associations were also apparent in the 105 children from the village with the lowest exposures, where all but two children had hair-mercury concentrations below 10 microg/g. Although average exposure levels may not have changed during recent years, prenatal exposure levels are unknown, and exact dose relationships cannot be generated from this cross-sectional study. However, the current mercury pollution seems sufficiently severe to cause adverse effects on brain development. (+info)