Benchmark dose of lead inducing neuromotor dysfunction and potential health adverse effects.

[目的]采用混合基准剂量法估算铅对工人血液学指标和神经运动功能障碍的影响临界值。方法对3 88名血铅水平为1~115μg/dl(0.0 5~5.5μμ/dl)的男性铅接触工人进行血铅水平、红细胞压积和红细胞计数的检测。结果血铅水平与Hb(r=-0.240)、RBC(r=-0.237)和Hct(r=-0.201)相关，血铅水平在1~115(中位数22)μg/dl之间，即使在控制年龄和工作状态后，这些线性关系仍有统计学意义(p&lt；0.001)。铅作业工人骨密度95%可信下限为：Hb 19.5μg/dl(0.94μμ/L)，红细胞19.4μg/dl(0.94μ/L)，Hc29.6μg/dl(1.43 Mol/L)。BPB水平与1~2赫兹和2~4赫兹的矢状摆动、1~2公顷和2~4赫兹的矢状摆动和2~4赫兹闭眼时的矢向摆动和横向摆动有关。姿势摆动作业工人的平均骨密度为14.4μg/dl(范围0.5 8~0.83，平均值0.6 9μ/L)。

ObjectivesThis study was carried out to estimate the critical dose of lead to influence the hematological indicators and to cause neuromotor dysfunction in workers by using the benchmark dose (BMD) method of a hybrid approach.MethodsThe effects of lead on hemoglobin (Hb) and hematocrit (Hct) levels, and red blood cell (RBC) count were examined in 388 male lead-exposed workers with blood lead (BPb) levels of 1〜115 μg/dl (0.05〜5.5 μmol/L). In addition, postural sway parameters with spectral analysis were compared between 121 lead workers and 60 unexposed controls.ResultsThe 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 1〜115 (median 22) μg/dl ; these linear relations were statistically significant (p<0.001) even after controlling for age and working status. The lower 95% confidence limits of BMD (BMDL) of BPb were estimated to be 19.5 μg/dl (0.94 μmol/L) for Hb, 19.4 μg/dl (0.94 μmol/L) for RBC, and 29.6 μg/dl (1.43 μmol/L) for Hct.All sway parameters, except for sagittal sways with eyes open, were significantly larger in the lead workers than in the controls. The BPb level was significantly related to sagittal sways at 1-2 Hz and 2-4 Hz with eyes open, and sagittal and transversal sways at 1-2Ha and 2-4 Hz with eyes closed. The mean BMDL of BPb for postural sway were estimated to be 14.4 μg/dl (range 0.58〜0.83, mean 0.69 μmol/L).ConclusionsThe reduction in hematopoietic indicators and postural instability in lead workers may be initiated at BPbs below the level currently considered no effect.