Crump K S
ICF Kaiser Engineers, Inc., KS Crump Group, Ruston, Louisiana 71270.
J Toxicol Environ Health. 1994 Jun;42(2):219-42. doi: 10.1080/15287399409531875.
This report updates the risk assessment by Crump and Allen (1984) for benzene-induced leukemia that was used by OSHA (1987) to support its reduction of the permissible exposure limit (PEL) to 1 ppm and that also was the basis for EPA's (1985) interim "unit risk" for benzene. The present study derives new risk estimates using data from follow-up through 1987 (whereas the earlier assessment only had follow-up available through 1978), and using new exposure estimates for this cohort developed by Paustenbach et al. (1992) that account for a number of factors that were unknown or not fully evaluated in earlier exposure assessments. There was a significant excess of acute myelocytic or acute monocytic leukemia (AMML, the only forms of acute nonlymphatic leukemia observed) in this cohort, and this end point also exhibited a strong dose-response trend. AMML was the only hematopoietic or lymphatic cancer that was clearly linked to benzene exposure. However, quantitative estimates of risk based on modeling either AMML or all leukemia differed by only 20%. Differences between the two Pliofilm plant locations in the occurrence of AMML were not statistically significant (.12 < or = p < or = .21) after differences in levels of benzene exposure were taken into account. The Paustenbach et al. exposures predicted a quadratic dose response, based on a measure of exposure that weighted intensity of exposure more heavily than duration of exposure. The best-fitting quadratic models predicted an additional lifetime risk of a benzene-related death from 45 yr of exposure to 1 ppm of between 0.020 and 0.036 per thousand. Statistical confidence intervals (90%) on these estimates were barely wide enough to include risk estimates based on linear dose response models. These linear models predicted risks of between 1.6 and 3.1 per thousand.
本报告更新了Crump和Allen（1984年）对苯所致白血病的风险评估，OSHA（1987年）曾用该评估来支持其将允许接触限值（PEL）降至1 ppm，同时该评估也是EPA（1985年）对苯的临时“单位风险”的依据。本研究使用了截至1987年的随访数据（而早期评估仅有截至1978年的随访数据）以及Paustenbach等人（1992年）为该队列制定的新暴露估计值得出了新的风险估计值，这些新暴露估计值考虑了一些在早期暴露评估中未知或未充分评估的因素。该队列中急性髓细胞性或急性单核细胞性白血病（AMML，观察到的急性非淋巴细胞白血病的唯一形式）显著过量，且该终点也呈现出强烈的剂量反应趋势。AMML是唯一明确与苯暴露相关的造血或淋巴系统癌症。然而，基于AMML或所有白血病建模的风险定量估计仅相差20%。在考虑苯暴露水平差异后，两个赛璐珞工厂地点AMML发生率的差异无统计学意义（0.12≤p≤0.21）。Paustenbach等人的暴露预测了一种二次剂量反应，该反应基于一种对暴露强度的加权比暴露持续时间更重的暴露量度。拟合度最佳的二次模型预测，从45年接触1 ppm苯导致与苯相关死亡的额外终生风险为千分之0.020至0.036。这些估计值的统计置信区间（90%）勉强足够宽，以纳入基于线性剂量反应模型的风险估计值。这些线性模型预测的风险为千分之1.6至3.1。
