Grashow Rachel, Zhang Jinming, Fang Shona C, Weisskopf Marc G, Christiani David C, Cavallari Jennifer M
a Department of Environmental Health , Harvard School of Public Health , Boston , Massachusetts.
J Occup Environ Hyg. 2014;11(6):397-405. doi: 10.1080/15459624.2013.875182.
In populations exposed to heavy metals, there are few biomarkers that capture intermediate exposure windows. We sought to determine the correlation between toenail metal concentrations and prior 12-month work activity in welders with variable, metal-rich, welding fume exposures. Forty-eight participants, recruited through a local union, provided 69 sets of toenail clippings. Union-supplied and worker-verified personal work histories were used to quantify hours welded and respirator use. Toenail samples were digested and analyzed for lead (Pb), manganese (Mn), cadmium (Cd), nickel (Ni), and arsenic (As) using ICP-MS. Spearman correlation coefficients were used to examine the correlation between toenail metal concentrations. Using mixed models to account for multiple participation times, we divided hours welded into three-month intervals and examined how weld hours correlated with log-transformed toenail Pb, Mn, Cd, Ni, and As concentrations. Highest concentrations were found for Ni, followed by Mn, Pb and As, and Cd. All the metals were significantly correlated with one another (rho range = 0.28-0.51), with the exception of Ni and As (rho = 0.20, p = 0.17). Using mixed models adjusted for age, respirator use, smoking status, and BMI, we found that Mn was associated with weld hours 7-9 months prior to clipping (p = 0.003), Pb was associated with weld hours 10-12 months prior to clipping (p = 0.03) and over the entire year (p = 0.04). Cd was associated with weld hours 10-12 months prior to clipping (p = 0.05), and also with the previous year's total hours welded (p = 0.02). The association between Ni and weld hours 7-9 months prior to clipping approached significance (p = 0.06). Toenail metal concentrations were not associated with the long-term exposure metric, years as a welder. Results suggest Mn, Pb, and Cd may have particular windows of relevant exposure that reflect work activity. In a population with variable exposure, toenails may serve as useful biomarkers for occupational metal fume exposures to Mn, Pb, and Cd during distinct periods over the year prior to sample collection.
在接触重金属的人群中，能够反映中间暴露窗口期的生物标志物很少。我们试图确定在焊接烟尘金属暴露情况各异的焊工中，趾甲金属浓度与之前12个月工作活动之间的相关性。通过当地工会招募了48名参与者，他们提供了69套趾甲剪。工会提供并经工人核实的个人工作经历用于量化焊接时长和呼吸器使用情况。趾甲样本经消解后，使用电感耦合等离子体质谱法（ICP-MS）分析铅（Pb）、锰（Mn）、镉（Cd）、镍（Ni）和砷（As）的含量。使用斯皮尔曼相关系数来检验趾甲金属浓度之间的相关性。利用混合模型来考虑多次参与情况，我们将焊接时长划分为三个月的时间段，并研究焊接时长与经对数转换的趾甲铅、锰、镉、镍和砷浓度之间的相关性。镍的浓度最高，其次是锰、铅和砷，镉的浓度最低。除镍和砷外（rho = 0.20，p = 0.17），所有金属之间均显著相关（rho范围 = 0.28 - 0.51）。使用针对年龄、呼吸器使用情况、吸烟状况和体重指数（BMI）进行调整的混合模型，我们发现锰与剪趾甲前7 - 9个月的焊接时长相关（p = 0.003），铅与剪趾甲前10 - 12个月的焊接时长相关（p = 0.03）以及与全年的焊接时长相关（p = 0.04）。镉与剪趾甲前10 - 12个月的焊接时长相关（p = 0.05），也与上一年的总焊接时长相关（p = 0.02）。镍与剪趾甲前7 - 9个月的焊接时长之间的关联接近显著水平（p = 0.06）。趾甲金属浓度与长期暴露指标，即焊工工作年限无关。结果表明，锰、铅和镉可能有特定的相关暴露窗口期，反映工作活动情况。在暴露情况各异的人群中，趾甲可能是样本采集前一年不同时期职业金属烟尘暴露于锰、铅和镉的有用生物标志物。
