Transplacental transfer of cobalt: Evidence from a study of mothers and their neonates in the African Copperbelt.

BACKGROUND: Transfer of the trace metal cobalt (Co) from mother to foetus has not been documented in populations with high environmental exposure to Co, as is the case in the African Copperbelt mining region. We analysed data obtained from 246 mother-infant pairs included (at delivery) in a previously published case-control study on birth defects, done in Lubumbashi (Democratic Republic of Congo) between March 1, 2013, and Feb 28, 2015. METHODS: Co was measured by Inductively Coupled Plasma Mass Spectrometry in maternal blood, maternal urine, umbilical cord blood and placental tissue, as available. RESULTS: The Co concentrations [geometric mean (GM) with interquartile range (IQR)] in maternal blood (GM 1.77 µg/L, IQR 1.07-2.93) and urine (GM 7.42 µg/g creatinine, IQR 4.41-11.0) were highly correlated (Spearman r = 0.71, n = 166; p < 0.001) and considerably higher than reference values determined for general populations elsewhere in the world. The concentrations of Co in umbilical cord blood (GM 2.41 µg/L) were higher (Wilcoxon test, p < 0.001) than in maternal blood (GM 1.37 µg/L), with a correlation between both values (Spearman r = 0.34; n = 127, p < 0.001). Co concentrations in placental tissue (geometric mean 0.02 µg/g wet weight) correlated with concentrations in maternal blood (Spearman r = 0.50, n = 86, p < 0.001) and in neonatal blood (Spearman r = 0.23, n = 83, p = 0.039). CONCLUSION: This first study of maternal and neonatal Co concentrations in the African Copperbelt provides strong evidence of a high transfer of Co from mother to foetus.

[Ovarian pregnancy: a case report]. / A propos d'un cas de grossesse ovarienne.

We here report a case of left ovarian pregnancy passively detected in the General Reference Hospital outpatient clinic in Dilolo, Democratic Republic of Congo. The diagnosis was confirmed by ultrasound; the patient underwent surgery with uneventful postoperative course. Pregnant women and healthcare personnel should be aware of the importance of proper clinical and echographic monitoring in pregnancy for early diagnosis of abnormal implantations.

Pathways of human exposure to cobalt in Katanga, a mining area of the D.R. Congo.

Human exposure biomonitoring in the African Copperbelt (Katanga, southern D.R. Congo) revealed elevated cobalt (Co) exposure in the general population. This study was designed to identify the Co exposure routes for the non-occupationally exposed population in that area. The concentration of Co was measured in environmental and urine samples collected in urban and rural communities close to metal mining and/or refining plants, villages near a lake receiving effluents from metal refining plants, and control rural areas without industrial pollution. Drinking water, uncooked food items (maize flour, washed vegetables, fish and meat), indoor and outdoor dust samples were collected at each location. A food questionnaire was used to estimate dietary Co intake for adults and children. Geometric mean urine-Co (U-Co) concentrations were 4.5-fold (adults) and 6.6-fold (children) higher in the polluted than in the control area, with U-Co values being intermediate in the lakeside area. Average Co concentrations in environmental samples differed 6-40-fold between these areas. U-Co was positively correlated with most environmental Co concentrations, the highest correlations being found with Co in drinking water, vegetables and fruit. Estimated average total Co intake for adults was 63 (±42) µg/day in the control area, 94 (±55) µg/day in the lakeside villages and 570 (±100) µg Co/day in the polluted areas. U-Co was significantly related to modelled Co intake (R(2)=0.48, adults and R(2)=0.47, children; log-log relationship). Consumption of legumes, i.e. sweet potato leaves (polluted) and cereals+fish (lakeside) was the largest contributor to Co intake in adults, whereas dust ingestion appeared to contribute substantially in children in the polluted area. In conclusion, dietary Co is the main source of Co exposure in the polluted area and Co is efficiently transferred from soil and water in the human food chain.