UC Santa Cruz

The absence of well-validated biomarkers of manganese (Mn) exposure in children remains a major obstacle for studies of Mn toxicity. We developed a hair cleaning methodology to improve the potential utility of hair as an exposure biomarker for Mn and other environmental metals. The cleaned hair was then subjected to analysis by ICP-MS, scanning electron microscopy, and laser ablation ICP-MS. Exogenous, but not endogenous, Mn contamination on hair that was uncontaminated or intentionally contaminated with dust or Mn-contaminated water was effectively removed with a cleaning method using 0.5%Triton X-100 sonication plus 1N nitric acid sonication. This optimal cleaning method was then used on hair samples from children (n=121) in an ongoing study of environmental Mn exposure and related health effects. Mean hair Mn levels were 0.121 μg/g (median = 0.073 μg/g, range = 0.011 - 0.736 μg/g), which are ~4 to 70-fold lower than levels reported in other pediatric Mn studies (1,2,27,32). Hair Mn levels were also significantly higher in children living in the vicinity of active, but not historic, ferroalloy plant emissions compared to controls (P<0.001). These data show that hair can be effectively cleaned of exogenous contamination, and they provide validation of hair Mn levels as a biomarker of environmental Mn exposure in children.