Texas Commission on Environmental Quality (TCEQ), Toxicology Division, MC-168, P.O. Box 13087, Austin, TX 78711-3087, USA.
Regul Toxicol Pharmacol. 2012 Feb;62(1):191-201. doi: 10.1016/j.yrtph.2011.10.005. Epub 2011 Oct 14.
The TCEQ has developed a URF for nickel based on excess lung cancer in two epidemiological studies of nickel refinery workers with nickel species exposure profiles most similar to emissions expected in Texas (i.e., low in sulfidic nickel). One of the studies (Enterline and Marsh, 1982) was used in the 1986 USEPA assessment, while the other (Grimsrud et al., 2003) is an update to an earlier study (Magnus et al., 1982) used by USEPA. The linear multiplicative relative risk model with Poisson regression modeling was used to obtain maximum likelihood estimates and asymptotic variances for cancer potency factors (β) using cumulative nickel exposure levels versus observed and expected lung cancer mortality (Enterline and Marsh, 1982) or lung cancer incidence cases (Grimsrud et al., 2003). Life-table analyses were then used to develop URFs from these two studies, which were combined using weighting factors relevant to confidence to derive the final URF for nickel of 1.7E-04 per μg/m³. The de minimis air concentration corresponding to a 1 in 100,000 extra lung cancer risk level is 0.059 μg/m³. The TCEQ will use this conservative value to protect the general public in Texas against the potential carcinogenic effects from chronic exposure to nickel.
TCEQ 制定了镍的 URF，该 URF 基于两项流行病学研究中镍精炼厂工人的肺癌超额发病率，这些研究中的镍暴露谱与德克萨斯州预期的排放情况最为相似（即低硫化镍）。其中一项研究（Enterline 和 Marsh，1982 年）用于 1986 年 USEPA 的评估，另一项研究（Grimsrud 等人，2003 年）是对早期 USEPA 使用的一项研究（Magnus 等人，1982 年）的更新。使用泊松回归模型的线性乘法相对风险模型，根据累积镍暴露水平与观察到的和预期的肺癌死亡率（Enterline 和 Marsh，1982 年）或肺癌发病率病例（Grimsrud 等人，2003 年），获得癌症效力因子（β）的最大似然估计和渐近方差。然后使用寿命表分析从这两项研究中得出 URF，使用与置信度相关的权重因素将这两项研究结合起来，得出镍的最终 URF 为 1.7E-04 每微克/立方米。对应于肺癌风险增加 1/100000 的最低空气浓度为 0.059 微克/立方米。TCEQ 将使用这个保守值来保护德克萨斯州的公众免受慢性接触镍的潜在致癌影响。
