Metal distributions in human hair strand cross-section: Advanced analysis using LA-ICP-MS in dentistry

Human hair is a biomarker that is crucial in investigating toxic metal exposures. Thirteen elements (Li, Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ag, Ba, and Hg) commonly found in hair strands from dentistry environments were investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Previous studies have employed partial ablation along hair strands to avoid contamination from mounting materials. The partial ablation can be problematic if element chemistry within the hair is not homogeneous. In this study, element variations along cross-sections of human hair strands were investigated. A number of elements showed internal variations with most elements enriched at the cuticle, emphasizing the importance of complete ablation for the characterization of human hair element chemistry. Complete and partial ablation LA-ICP-MS results were verified against solution nebulization SN-ICP-MS. Complete LA-ICP-MS showed a better agreement with SN-ICP-MS. Therefore, the developed LA-ICP-MS method can be applied to monitor the health of dental workers and students exposed to dental environments.