Author: Ulrike Dydak, Chia-Tien Hsu, Chang Geun Lee, Cora Mizimakoski, Humberto Monsivais, Jae Hong Park 👨🔬
Affiliation: Purdue University 🌍
Purpose: Overexposure to manganese (Mn) from inhaling welding fumes can lead to cognitive and motor deficits. We developed a whole-brain Mn-mapping approach to detect subtle but significant increases in Mn deposition in individual welders. In this pilot study, changes in brain Mn accumulation were monitored before and after welders began using powered air-purifying respirators (PAPRs), which significantly reduce exposure to airborne metal particles.
Methods: Four welders and 31 non-welding factory workers were recruited. Personal air sampling over one work shift measured respirable Mn concentrations in each subject’s breathing zone. MRI scans were conducted using a 3T Siemens Prisma scanner. Welders were scanned before and after PAPR use, while controls were scanned once. A normative T1 atlas was created by modeling the relaxation time variability within the control cohort. Individual z-score maps were then calculated against this atlas to quantify deviations specific to each subject. The total number of thresholded voxels was determined, and whole-brain z-score maps were visualized to assess brain changes pre- and post-PAPR use.
Results: The total number of thresholded voxels, indicating above-average Mn deposition, decreased by over 60% in 3 of the 4 welders after PAPR use, with no significant changes observed in one welder. For the 3 welders with significant changes, z-score maps acquired before PAPR use showed widespread significant z-scores of reduced T1 values compared to the control cohort, indicating excess Mn accumulation throughout much of the cerebral white matter and deep brain structures. However, the maps acquired two months after PAPR use showed a significant decrease in elevated Mn deposition.
Conclusion: Mn accumulation significantly decreased in welders in several brain regions within just 1-2 months of using PAPRs, with varying reduction rates observed across brain regions. One welder showed no significant change, likely due to co-exposure from his workstation’s proximity to a welding robot.