Manganese air exposure assessment and biological monitoring in the manganese alloy production industry

Abstract

One hundred workers carried personal air sampling equipment during three days to assess exposure to inhalable and respirable Mn. A novel four-step chemical fractionation procedure developed for the speciation of Mn in workroom aerosols was applied for selected aerosol filters. Blood and urine samples were analysed for Mn. The geometric mean (GM) concentrations of inhalable (n = 265) and respirable (n = 167) Mn determined in all filters were 254 µg m⁻³ and 28 µg m⁻³ respectively. Only 10.6% (95% CI 8.9–12.5) respirable Mn was found in the inhalable fraction when inhalable and respirable samples collected in parallel were considered (n = 153 pairs). There was a high correlation (Pearson's r = 0.70; p < 0.001) between respirable and inhalable Mn. The largest amounts of Mn in the inhalable aerosol fraction were found as Mn⁰ and Mn²⁺ (47.4%), whereas 28% was practically “insoluble”. The associations between B–Mn and aerosol concentrations of Mn were weak, but an association was found between U–Mn and respirable Mn; Pearson's r being 0.38 between “soluble” respirable Mn and U–Mn. No significant association was found between the “insoluble” components (probably SiMn) and Mn in biological samples.