S11-3Laser ablation ICP-MS of hair strands for time-resolved exposure measurements to support health studies of welders exposed to manganese

Hair has been proposed as a tool to assess individual's exposures to manganese (Mn). Previous health effect studies have shown increasing concentrations of Mn in hair with increased levels of Mn exposure (Bader et al. 1999; Reiss et al. 2016), and years of exposure (Xie et al. 1995; Lin 2002) However, individual exposures were not quantified. Use of Laser ablation-ICP-MS is explored as a tool for time-resolved Mn exposure among welders. We present calibration methods for hair and gelatin as a proxy-matrix, and the challenges and opportunities for analysing time-specific exposures in individual hair strands. Triplicate hair strands were selected from 23 one-cm hair bundle samples that were collected from welding school students in the US. The bundles were acid digested and analysed with ICP-MS for Mn content. The individual hair strands and ten flakes of each dried Mn gelatin mixture (0.05-250 ppm) were analysed with LA-ICPMS. Ablated Mn concentrations were normalised to sulfur. Preliminary results suggest very good associations between ablated and digest hair (log-log: 0.90) and between ablated gelatin and gelatin mixtures (log-log: 0.89). A LOD of approximately 1 ppm was estimated. This suggests that gelatin could be a suitable proxy calibration standard for hair. From a cohort of welding trainees with variable exposure, twelve individual hair strands of at least 2 cm length were ablated. MnS profiles in the hair strands will be compared with time specific exposure profiles of the apprentice. Results of this work could provide the basis for using hair strands as a means of measuring individual manganese exposure in welders with much higher time resolution than has previously been done.