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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: Validation of in vivo toenail measurements of manganese and mercury using a portable X-ray fluorescence device.

Authors: Specht, Aaron J; Zhang, Xinxin; Young, Anna; Nguyen, Vy T; Christiani, David C; Ceballos, Diana M; Allen, Joseph G; Weuve, Jennifer; Nie, Linda H; Weisskopf, Marc G

Published In J Expo Sci Environ Epidemiol, (2022 May)

Abstract: BACKGROUND AND OBJECTIVE: Toenail metal concentrations can be used as an effective biomarker for exposure to environmental toxicants. Typically toenail clippings are measured ex vivo using inductively coupled plasma mass spectrometry (ICP-MS). X-ray fluorescence (XRF) toenail metal measurements done on intact toenails in vivo could be used as an alternative to alleviate some of the disadvantages of ICP-MS. In this study, we assessed the ability to use XRF to measure toenail metal concentrations in real-time without having to clip the toenails (i.e., in vivo) in two occupational settings for exposure assessment of manganese and mercury. MATERIALS AND METHODS: The portable XRF method used a 3-min in vivo measurement of toenails prior to clipping and was assessed against ICP-MS measurement of toenail clippings taken immediately after the XRF measurement and work history for a group of welders (n = 16) assessed for manganese exposure and nail salon workers (n = 10) assessed for mercury exposure. RESULTS AND CONCLUSIONS: We identified that in vivo XRF metal measurements were able to discern exposure to manganese in welders and mercury in nail salon workers. We identified significant positive correlations between ICP-MS of clippings and in vivo XRF measures of both toenail manganese (R = 0.59, p = 0.02) and mercury (R = 0.74, p < 0.001), as well as between in vivo XRF toenail manganese and work history among the welders (R = 0.55, p = 0.03). We identified in vivo XRF detection limits to be 0.5 µg/g for mercury and 2.6 µg/g for manganese. Further work should elucidate differences in the timing of exposure using the in vivo XRF method over toenail clippings and modification of measurement time and x-ray setting to further decrease the detection limit. In vivo portable, XRF measurements can be used to effectively measure toenail Mn and Hg in occupational participants in real-time during study visits and at a fraction of the cost.

PubMed ID: 34211112 Exiting the NIEHS site

MeSH Terms: Fluorescence; Humans; Manganese/analysis; Mercury*/analysis; Metals/analysis; Nails*/chemistry; Spectrometry, X-Ray Emission/methods; X-Rays

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