High human exposure to cobalt and other metals in Katanga, a mining area of the Democratic Republic of Congo

Background and objectives

The human health impact of the historic and current mining and processing of non-ferrous metals in the African Copperbelt is not known. This study assessed the exposure to metals in the population of Katanga, in the south east of the Democratic Republic of Congo, using biomonitoring.

Methods

Seventeen metals (including Cd, Co, Cu, Pb, U) and non-metals (including As) were measured by ICP-MS in urine spot samples from 351 subjects (32% women), aged 2-74 yr (mean 33 yr). Forty subjects (controls) lived 400 km outside the mining area; 311 subjects lived in the mining area, either very close (<3 km) (n=179; 6 communities) or moderately close (3-10 km) (n=132; 4 communities) to mines or smelting plants.

Results

For all metals (except Ni) urinary concentrations were significantly higher in subjects from the mining area than in control subjects. In subjects living very close to mines or smelting plants, the geometric means (25th-75th percentile) of urinary concentrations, expressed as μg/g creatinine, were 17.8 (10.9-29.0) for As, 0.75 (0.38-1.16) for Cd, 15.7 (5.27-43.2) for Co, 17.1 (8.44-43.2) for Cu, 3.17 (1.47-5.49) for Pb and 0.028 (0.013-0.065) for U, these values being significantly higher than those of subjects living 3-10 km from mines or industrial operations. Urinary Co concentrations were markedly elevated, exceeding 15 μg/g creatinine in 53% of the subjects, and even 87% of children (<14 yr), living very close to the mining areas. Urinary As was also high (79% above 10 μg/g creatinine in subjects living very close to the mining areas). Compared with background values from the US general population, subjects living very close to areas of mining or refining had 4-, 43-, 5- and 4-fold higher urinary concentrations of Cd, Co, Pb and U, respectively.

Conclusions

This first biomonitoring study of metal exposure in the African Copperbelt reveals a substantial exposure to several metals, especially in children. The urinary Co concentrations found in this population are the highest ever reported for a general population. The pathways of exposure and health significance of these findings need to be further investigated.     

Culture-dependent and -independent molecular analysis of the bacterial community within uranium ore

The bacterial community structure within a uranium ore was investigated using culture-dependent and -independent clone library analysis and denaturing gradient gel electrophoresis of 16S rRNA genes. The major aerobic heterotrophic bacteria were isolated and identified, and their resistance to uranium and other heavy metals was characterized. Together with near neutral pH, moderate organic carbon content, elevated U and other heavy metals (V, Ni, Mn, Cu, etc.), the ore showed high microbial counts and phylotype richness. The bacterial community mainly consisted of uncultured Proteobacteria, with the predominance of γ - over β - and α -subdivisions, along with Actinobacteria and Firmicutes. A phylogenetic study revealed that nearly one-third of the community was affiliated to as yet uncultured and unidentified bacteria having a closer relationship to Pseudomonas. Lineages of Burkholderiaceae and Moraxellaceae were relatively more abundant in the total community, while genera affiliated to Xanthomonadaceae and Microbacteriaceae and Exiguobacterium were detected in the culturable fraction. More than 50% of the bacterial isolates affiliated to Stenotrophomonas, Microbacterium, Acinetobacter, Pseudomonas and Enterobacter showed resistance to uranium and other heavy metals. The study showed for the first time that uranium ore harbors major bacterial groups related to organisms having a wide range of environmentally significant functional attributes, and the most abundant members are possibly new groups/taxa. These findings provide new insights into U-ore geomicrobiology that could be useful in biohydrometallurgy and bioremediation applications.     

大鼠吸入贫铀气溶胶后主要器官的病理损伤特点

目的 探讨大鼠吸入贫铀(DU)气溶胶后主要器官的病理和形态计量学改变,为贫铀武器损伤及其医学防护提供线索。方法 用常规病理技术和形态计量学方法观察了大鼠吸入DU气溶胶后1-14个月肺、肾、脾、肝、脑等组织病理和形态计量学改变。结果 吸入DU气溶胶后,部分大鼠发生肺实质内淋巴细胞浸润、严重支气管炎、肺出血、脓肿;部分大鼠肾皮质肾小管、肾乳头小管明显扩张;皮质、髓质和乳头肾小管中出现管型和间质出血;脾组织的白髓面积减少,巨核细胞的细胞数及核分裂相减少。且随吸入后时间延长或吸入剂量增高,肺、肾、脾组织病变发生率及病变程度均呈现增高的趋势。脑、肝组织未见明显病理改变。结论 大鼠吸入贫铀气溶胶对肺、肾、脾组织有明显的损伤作用。     

p53 mutations and codon 213 polymorphism of p53 in lung cancers of former uranium miners

Purpose: There is a high prevalence of G→T transversions of p53 in lung cancers of smokers. One study has reported a special “hotspot” mutation at codon 249 of p53 in lung cancers of former uranium miners. The aim of our study was to look for mutational spectra of p53 in former German uranium miners with lung cancers. Methods: We investigated 16 patients with lung cancer who had worked as uranium miners in Germany and 13 lung cancer patients without a mining history of the same region. By means of the polymerase chain reaction and sequencing we looked for mutations in exons 5–7 of the p53 gene. Results: We could not find any suggestion of hotspot mutations. The only G→T mutation in former uranium miners was detected in the only nonsmoker. In 3 patients (19% of the total) we found a codon 213/3 polymorphism. Conclusions: The results indicate that G → T transversions do not seem to be very common mutations in p53 in lung cancers probably caused by radiation. Therefore, p53 may be mutated early in lung cancer development if radiation exposure is a critical factor in carcinogenesis. In accordance with studies of thyroid cancer patients in the Chernobyl region, our results may indicate an overrepresentation of codon 213/3 polymorphism in p53 in radiation-caused cancers. Received: 24 September 1998 / Accepted: 16 December 1999     

Reproductive and developmental toxicity of natural and depleted uranium: a review

Although the biokinetics, metabolism, and chemical toxicity of uranium are well known, until recently little attention was paid to the potential toxic effects of uranium on reproduction and development in mammals. In recent years, it has been shown that uranium is a developmental toxicant when given orally or subcutaneously (SC) to mice. Decreased fertility, embryo/fetal toxicity including teratogenicity, and reduced growth of the offspring have been observed following uranium exposure at different gestation periods. The reproductive toxicity, maternal toxicity, embryo/fetal toxicity, and postnatal effects of uranium, as well as the prevention by chelating agents of uranium-induced maternal and developmental toxicity are reviewed here. Data on the toxic effects of depleted uranium on reproduction and development are also reviewed.