Evaluation of potential health effects by lead exposure using the benchmark dose analysislea

为明确铅致贫血的临界剂量，采用基准剂量法(BMD)对388名8~67岁男性铅作业工人进行了Hb、Hct及红细胞计数的测定。在血铅水平为1~15(中位数22)μg/dl的工人中，血铅水平与Hb(r=-0.240)、RBC(r=-0.237)和Hct(r=-0.201)呈正相关，即使在控制了年龄和工作状态后，这些直线和关系仍具有统计学意义(p&lt；0.001)。血铅的临界剂量(即骨密度的95%可信限下限)估计为：血红蛋白19.2μg/dl，红细胞19.7μg/dl，红细胞29.4μg/dl。为了评估铅对自主神经系统功能的影响，我们测量了212名工人的心电图RR间期变异性。通过自回归谱分析和成分分析计算了C-Cv&lt；Lf&gt；，C-Cv&lt；Hf&Gt；，Lf/Hf比值和QTc值。然而，这些指标与BPB和红细胞原卟啉水平没有明显的相关性。需要进行更大样本量的进一步研究，以证实铅对自主神经毒性的影响。

To clarify the critical dose of lead inducing anemia, the effects of lead on hemoglobin (Hb) and hematocrit (Hct) levels, and red blood cell (RBC) count were examined in 388 male lead-exposed workers aged I 8-67 years, by using the benchmark dose (BMD) approach. The blood lead (BPb) level was associated with Hb (r=-0.240), RBC (r=-0.237) and Hct (r=-0.201) among the workers with BPb levels of 1-i 15 (median 22) μg/dl; these line& relations were statistically significant (p<0.001) even after controlling for age and working status. The critical doses of BPb (i.e., lower 95% confidence limits of BMD) were estimated to be 19.2 μg/dl for Hb, 19.7 μg/dl for RBC, and 29.4 μg/dl for Hct. It is suggested that reduction in hematopoietic indicators may be initiated at BPbs below the level currently considered no effect.To estimate the effects of lead on autonomic nervous system functions, electrocardiographic RR interval variability was measured in 212 workers. The C-CV_<LF>, C-CV_<HF>, LF/HF ratio and QTc were also computed from component spectral powers by means of autoregressive spectral and component analyses. However, these indicators showed no significant associations with BPb and erythrocyte protoporphyrin levels. Further studies with a larger sample size would be needed to confirm the effect of lead on autonomic neurotoxicity.