Sexual dysfunction and mining-related jobs: A cross-sectional study in the former Katanga Province, DR Congo

Aim: Based on a preliminary case-control study of erectile dysfunction among mineworkers in the former Katanga province of the DR Congo (Musa et al. Occ Environ Med 2020), we investigated the association between sexual dysfunction and metal exposure in mining-related-jobs. Methods: In a cross-sectional study, we included 138 miners and 140 bakers from Lubumbashi, Likasi, Kipushi and Kolwezi. Using questionnaires administered face-to-face, we obtained socio-demographic and occupational data and determined the International Index of Erectile Function (IIEF-15), a validated tool to evaluate five sexual domains (maximum score 75). We measured trace metals in blood and urine, and total + free testosterone and sex hormone binding globulin (SHBG) in serum. Results: Miners and bakers had similar median (IQR) age [35.6 y (30.6-40.0)]. For several trace metals, concentrations were higher in blood or urine among miners than bakers, this being most pronounced for lead. Thus, median blood lead (µg/dl) was higher (p=0.002) in miners [6.7 (4.5-16.7)] than in bakers [5.4 (4.1-7.5)]. Blood lead and free testosterone were inversely correlated (Spearman R=-0.25, p=0.002). The median IIEF-15 score was lower (p<0.001) among miners [66 (49-73)] than among bakers [73 (66-74)]. Total testosterone (ng/dl) did not differ between miners [505 (453-651)] and bakers [541 (447-709)], but free testosterone (ng/dl) was lower among miners [8.1 (6.8-10.1)] than among bakers [9.3 (8.7-12.5)]; conversely, SBGH (nmol/l) was higher (p<0.001) among miners [55 (44-65)] than among bakers [47 (33-52)]. Conclusion: We confirmed that miners had lower scores of erectile function than controls. Miners had lower free testosterone and higher SHBG than bakers, and evidence of higher exposure to trace metals, especially lead. The possible role of lead in sexual dysfunction needs to be clarified, especially as lead is not among the main ores mined in the region.