Toenail, Blood, and Urine as Biomarkers of Manganese Exposure

OBJECTIVE: This study examined the correlation between manganese exposure and manganese concentrations in different biomarkers. METHODS: Air measurement data and work histories were used to determine manganese exposure over a work shift and cumulative exposure. Toenail samples (n = 49), as well as blood and urine before (n = 27) and after (urine, n = 26; blood, n = 24) a work shift were collected. RESULTS: Toenail manganese, adjusted for age and dietary manganese, was significantly correlated with cumulative exposure in 7 to 9, 10 to 12, and 7 to 12 months before toenail clipping date, but not 1 to 6 months. Manganese exposure over a work shift was not correlated with changes in blood nor urine manganese. CONCLUSIONS: Toenails appeared to be a valid measure of cumulative manganese exposure 7 to 12 months earlier. Neither change in blood nor urine manganese appeared to be suitable indicators of exposure over a typical work shift.