Comparison of exposure to Pb and Mn levels by using environmental personal monitors and biomarkers in relation to cognitive and motor function

Abstract

We conducted a cross-sectional study of 130 participants living near a ferromanganese alloy plant, analyzing Pb and Mn exposure by biomarkers (blood, hair, and fingernails) and particulate matter personal environmental monitors (PEMs). Cognitive and motor function were assessed by five and three tests, respectively. Mean differences (MDs) adjusted for age, sex, and study level were determined. In addition, MDs for Pb were adjusted for Mn levels and vice versa. Medians of 9.14 µg/L, 149.04 ng/g, and 96.04 ng/g were obtained for blood, scalp hair, and fingernails Pb levels, respectively. Regarding PEMs, median Pb levels were 6.56 ng/m3 for the fine fraction and, for the coarse fraction, they were below the limit of detection in 97% of participants. Exposure to Pb at low levels was not associated with worse cognitive function. In comparison, exposure to high levels of Mn was associated with worse cognitive function at least in the domains evaluated through Stroop, Digit Span, and Verbal Fluency tests. In terms of motor function, our results suggest that even the currently low Pb levels may have negative health effects on dynamometer-determined strength—adjusted MD on dominant hand = −2.68; 95%CI (−4.85 to −0.51), p = 0.016. Further studies should investigate this association.