Hypoxaemia and risk of asphyxia during underground work in artisanal cobalt mines.

BACKGROUND: More than half the cobalt needed for vehicle electrification originates from the southern part of the Democratic Republic of the Congo (DRC), with a substantial part being extracted by artisanal miners. AIMS: To investigate oxygen saturation during underground work among cobalt artisanal miners. METHODS: In a field survey, we measured oxygen saturation (SpO2) and heart rate by pulse oximetry in 86 miners from two underground mines and 24 miners from a surface mine at four different time points: before descent into the mine (T1), at 50 minutes in the mine (T2), upon leaving the shaft (T3), and 10 minutes after having left the mine (T4). RESULTS: Miners working underground (-36 to -112 meters) were somewhat older (34.8 ±â€…6.7 years) than those working in the surface mine (32.0 ±â€…6.5 years), and they worked more hours daily (12.6 ±â€…1.2 hours) than controls (9.0 ±â€…0.0 hours). All participants had SpO2 >95% at T1 and T4. At T2, SpO2 dropped below 93% and 80% in 35% and 10% underground miners, respectively; SpO2 was still <93% at T3 in 13%. SpO2 remained stable among surface miners. Later, we showed that underground ambient oxygen levels decreased well below 21% in several pits. CONCLUSIONS: Pulse oximetry revealed relevant hypoxaemia during underground work in a substantial proportion of artisanal miners. Such hypoxaemia without evidence of underlying cardiovascular disease is indicative of low ambient oxygen, due to insufficient mine ventilation. This may cause deaths from asphyxia. The hazards of low ambient oxygen in artisanal mines must be prevented by appropriate technical measures ensuring the supply of sufficient fresh air.

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.

Environmental and anthropogenic factors associated with increased malaria incidence in South-Kivu Province, Democratic Republic of the Congo.

OBJECTIVE: To examine environmental and human factors that affect the spatial and temporal dynamism of malaria in DRC's South-Kivu province. METHODS: In a cross-sectional study conducted between 1 January 2010 and 31 December 2015, spatial distribution was determined through thematic maps of malaria attack rate. SatScan ™ software and Monte Carlo test were used to identify spatial risk clusters. Temporal evolutions were analysed using the Cleveland algorithm. Generalized Additive Models for Location Scale and Shape and negative binomial regression were used to assess the independent human and environmental factors associated with incident malaria. RESULTS: The cumulative annual incidence of malaria increased from 10 968/100 000 in 2013 to 15 501/100 000 in 2015 (P for trend ˂0.001); malaria lethality increased from 0.1% in 2013 to 0.3% in 2015 (P for trend = 0.62). Between 2010 and 2015, 18 of 34 health zones consistently reported the highest attack rates, which ranged from 25 000 to 50 000/100 000. Four risk clusters areas were identified, with relative risk (RR) of 1.2 to 3.0, from which malaria was reported continuously during each year. Factors significantly associated with malaria cases were agro-pisciculture practices (Incidence Risk Ratio [IRR]: 1.96; 95% CI: 1.23-3.13) and the presence of a lake in the health zone (IRR: 2.48, 95% CI: 1.51-4.42). CONCLUSIONS: Malaria control in this setting must be intensified in peri-lacustrine areas and those in which the population is intensively engaged in standing water-associated activities.

OBJECTIF: Examiner les facteurs environnementaux et humains qui affectent le dynamisme spatial et temporel du paludisme dans la province du Sud-Kivu en RDC. MÉTHODES: Dans une étude transversale menée entre le 1er janvier 2010 et le 31 décembre 2015, la distribution spatiale a été déterminée à l'aide de cartes thématiques du taux de cas de paludisme. Le logiciel SatScan™ et le test Monte Carlo ont été utilisés pour identifier les grappes de risques spatiaux. Les évolutions temporelles ont été analysées à l'aide de l'algorithme de Cleveland. Des modèles additifs généralisés pour l'échelle et la forme de l'emplacement et la régression binomiale négative ont été utilisés pour évaluer les facteurs humains et environnementaux indépendants associés à l'incidence du paludisme. RÉSULTATS: L'incidence annuelle cumulée du paludisme est passée de 10.968/100 000 en 2013 à 15.501/100 000 en 2015 (p pour la tendance ˂0,001); la létalité du paludisme est passée de 0,1% en 2013 à 0,3% en 2015 (p pour tendance = 0,62). Entre 2010 et 2015, 18 des 34 zones de santé ont constamment rapporté des taux de cas les plus élevés, qui variaient de 25.000 à 50.000/100 000. Quatre zones de risques de grappes ont été identifiées, avec un risque relatif (RR) de 1,2 à 3,0 à partir desquelles le paludisme a été rapporté en continu chaque année. Les facteurs significativement associés aux cas de paludisme étaient: les pratiques agro-piscicoles (Ratio d'Incidence de Risque [IRR]: 1,96 ; IC95%: 1,23-3,13) et la présence d'un lac dans la zone de santé (TRI: 2,48 ; IC95%: 1,51-4,42). CONCLUSIONS: La lutte contre le paludisme dans ce contexte doit être intensifiée dans les zones péri-lacustres et celles dans lesquelles la population est intensément engagée dans des activités liées à l'eau stagnante.