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Hair as a biomarker of environmental manganese exposure
Rachel R Eastman1, Tom P Jursa, Chiara Benedetti
1Microbiology and Environmental Toxicology Department, University of California, Santa Cruz, California 95064, United States.
Abstract:
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 establish the utility of hair as an exposure biomarker for Mn and other metals (Pb, Cr, Cu), using ICPMS, scanning electron microscopy, and laser ablation ICPMS to evaluate cleaning efficacy. Exogenous metal contamination on hair that was untreated or intentionally contaminated with dust or Mn-contaminated water was effectively removed using a cleaning method of 0.5%Triton X-100 sonication plus 1 N nitric acid sonication. This 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. 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 metal contamination, and they substantiate the use of hair Mn levels as a biomarker of environmental Mn exposure in children.
Insights
A new hair cleaning method effectively removes external metal contamination. This validates using children's hair manganese levels as a biomarker for environmental exposure.
Area of Science:
- Environmental Health
- Toxicology
- Biomarker Development
Background:
- Validated biomarkers for manganese (Mn) exposure in children are lacking, hindering Mn toxicity research.
- Hair is a potential biomarker, but external metal contamination is a significant challenge.
- Previous studies have not established effective hair cleaning protocols for Mn.
Purpose of the Study:
- To develop and validate a hair cleaning methodology for assessing manganese (Mn) exposure in children.
- To evaluate the utility of cleaned hair as a biomarker for environmental Mn exposure.
- To compare hair Mn levels in children with varying proximity to industrial sources.
Main Methods:
- Developed a hair cleaning protocol involving Triton X-100 sonication and nitric acid sonication.
- Utilized ICP-MS, SEM, and laser ablation ICP-MS to assess cleaning efficacy on untreated and contaminated hair.
- Applied the cleaning method to hair samples from 121 children in an environmental exposure study.
Main Results:
- The cleaning method effectively removed exogenous metal contamination from hair.
- Mean hair Mn levels in the study children were significantly lower than previously reported.
- Children near active ferroalloy plant emissions showed significantly higher hair Mn levels compared to controls.
Conclusions:
- Hair can be reliably cleaned of exogenous metal contamination, establishing it as a viable matrix for metal exposure assessment.
- Hair manganese levels serve as a valid biomarker for environmental Mn exposure in pediatric populations.
- Proximity to industrial sources like ferroalloy plants is associated with increased environmental Mn exposure in children.
