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

为探讨铅致贫血的临界剂量，采用骨密度（BMD）方法，对388名18 ~ 67岁男性铅接触工人的血红蛋白（Hb）、红细胞压积（Hct）和红细胞（RBC）进行了测定。在血铅水平为1 ~ 115 μg/dl（中位数22）的工人中，血铅水平与血红蛋白（r=-0.240）、红细胞（r=-0.237）和红细胞压积（r=-0.201）相关，即使在控制了年龄和工作状态后，这些线性关系仍有统计学意义（p<0.001）。BPb的临界剂量（即，BMD的95%置信下限）估计为Hb 19.2 μg/dl、RBC 19.7 μg/dl和Hct 29.4 μg/dl。建议降低造血指标可以开始在BPbs低于目前认为没有影响的水平。为了估计铅对自主神经系统功能的影响，212名工人的心电图RR间期变异性进行了测量。用<LF><HF>自回归谱分析和成分分析方法，由各成分谱功率计算C-CV_（1/2）、C-CV_（1/2）、LF/HF比值和QTc。但这些指标与血铅和红细胞原卟啉水平无明显相关性。需要更大样本量的进一步研究来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.