Assessment of saliva, hair and toenails as biomarkers of low level exposure to manganese from drinking water in children

We evaluated hair, toenails, and saliva (whole and supernatant) as biomarkers of exposure to manganese (Mn) in 274 school age children (6-13 years) consuming well water in southeastern New Brunswick, Canada. Mn concentrations in tap water ranged from <0.03 to 1046 μg L−1 (geometric mean 5.96 μg L−1). The geometric mean of Mn intake resulting from the consumption of water was 0.25 (0-34.95) μg kg−1 day−1. Both Mn concentration in water and Mn intake were significantly correlated with Mn in hair (r = 0.60 and r = 0.53, respectively), Mn in toenail (r = 0.29 and r = 0.37 respectively) and to a lesser extent with Mn in saliva supernatant (r = 0.14 and r = 0.18, respectively). Mn in whole saliva did not correlate with Mn in water or Mn intake. Both Mn in hair and Mn in toenail allowed to discriminate the most exposed group from the least exposed group, based on Mn in water and Mn intake from water. In this group of children with low level Mn exposure, Mn concentrations in hair, and toenails reflected reasonably well Mn exposure from drinking water, whereas Mn content in saliva correlated less strongly.