排铅后再接铅生物指标的观测

目的：探讨排铅工人再接铅后，某些生物监测指标和卟啉代谢指标的动态变化。方法：110名冶炼厂工人排铅治疗后，回生产岗位2周，7周，24周，分别采样进行血铅（PbB)，尿铅（PbU)，尿道基酮戊酸（δ－ALA），血氨基酮戊酸脱水酶 （δ－ALAD），红细胞游离原卟啉（FEP），血红蛋白（Hb)的监测，同时进行作业场所空气铅烟的监测。结果：低水平接触组以PbB变化较早和灵敏，其次为δ－ALAD，δ－ALA和FEP的增高出现较晚；中等水平接触组以PbB，PbU和δ－ALAD变化出现最早和敏感，其后变化趋势变缓，但δ－ALA，FEP持续增高；高水平接触组各项指标均出现明显的改变，以δ－ALA变化幅度较大，其次为FEP，PbU,PbB，而δ－ALAD的变化与中等水平组相似，Hb仅在24周出现降低。经相关和聚类分析，PbB,PbU,δ-ALAD活性具有相似变化规律，而EP与δ－ALA具有相似的时间序列变化规律。结论：工人排铅后再接铅，在较短时间内出现铅的毒性效应，应加强一级预防，接铅后各项指标呈现两种不同类型的变化态势。

Dynamic changes in biomarkers in the workers re-exposed to lead after treatment with chelating therapy

Objective To explore the dynamic changes in some markers in biological monitoring and porphyrin metabolism．Methods Blood lead（PbB），urine lead（PbU），urine δ-aminolevulinic acid（δ-ALA），activity of δ-aminolevulinic acid dehydrase（δ-ALAD），free erythrocyte protoprophyrin（FEP）and hemoglobin（Hb）were measured for 110 workers in the smelters re-exposed to lead after chelating treatment，as well as the air level of lead fume in the workplaces was monitored．Results In the low-level exposure group，PbB was a more sensitive indicator and changed earlier，and δ-ALA，δ-ALAD and FEP changed later．In the medium-level exposure group，PbB，PbU and δ-ALAD were more sensitive and the earliest indicator to increase，but δ-ALA and FEP increased later and kept in a higher level．In the high-level group，all indicators changed significantly，with an increase in δ-ALA to a greater extent than that in FEP，PbB and PbU，but δ-ALAD increased as that in the medium-level exposure．Correlation and cluster analysis showed that PbB，PbU and δ-ALAD appeared similarly regular changes，but FEP and δ-ALA appeared similar time-series changes．Conclusions Toxic effects could be revealed in a shorter time period in the workers re-exposed to lead after chelating agent treatment．All indicators appeared two different types of change trends after re-exposure to lead．It is emphasized that primary prevention should be strengthened．