低浓度铅环境作业工人周围神经传导速度与生物学指标的变化

背景:在国家最高容许铅浓度范围内作业长期接触铅时,是否仍可对人体健康产生影响?目的:调查分析低浓度铅作业工人周围神经传导速度和生物学指标的变化.设计:以低浓度铅作业工人为观察对象的检验.单位:上海第二医科大学新华医院职业病科及电生理科.对象:以2000-09/2002-10上海第二医科大学附属新华医院职业病科职业健康体检的铅作业工人和同地科室人员为调查对象,共106例.接触组为热处理工人66人,对照组为同期同地科室人员40人.方法:采用问卷调查和实验室检查对接触组和对照组进行周围神经传导速度和生物学指标血铅、血锌原卟啉、游离原卟啉、血红蛋白的检测.对检测数据进行相对危险度分析.主要观察指标:①接触组和对照组周围神经传导速度.②各项生物学指标变化.结果:进入结果分析106人,对照组40人,接触组66人,接触组中工龄＞10年34例,＜10年32例.①接触组工龄＞10年工人周围神经运动传导速度中正中神经比对照组加快(50.11±4.76),(47.59±4.86)m/s,P＜0.05],尺神经比对照组加快(63.11±2.58),(61.83±3.03)m/s,P＜0.05].②接触组工龄＞10年工人血铅高于＜10年工人(0.568±0.28),(0.425±0.31)μmol/L,P＜0.05],接触组工龄＞10年工人血游离原卟啉高于＜10年工人(2.24±0.32),(2.09±0.27)μmol/L,P＜0.05],接触组工龄＞10年工人尿铅高于＜10年工人(0.087±0.008),(0.083±0.007)mg/L,P＜0.05].接触组工龄＞10年工人血锌原卟啉为(1.42±0.33)μmol/L,高于接触组工龄＜10年工人(1.25±0.35)μmol/L,P＜0.05]及对照组(1.22±0.44)μmol/L,P＜0.05].接触组工龄＞10年工人血红蛋白为(12.26±4.5)g/L,低于接触组工龄＜10年工人(14.55±4.81)μmol/L,P＜0.05]及对照组(14.88±4.30)μmol/L,P＜0.05].③接触组工龄＜10年工人周围神经感觉传导异常1例,异常率3%(1/32),接触组工龄＞10年工人4例,异常率12%(4/34).接触组工龄＜10年工人有生物指标超过正常范围1例,异常率3%(1/32),接触组工龄＞10年工人5例,异常率15%(5/34).工龄＞10年工人神经传导速度、生物指标异常率较工龄＜10年工人高,相对危险度分别为4.1,5.3倍.结论:长期接触低浓度铅不仅能使生物学指标有改变,同时会对周围神经系统产生不同程度的损害,以下肢感觉神经、上肢运动神经潜伏期较先受累.工龄大于10年的铅作业工人已存在周围神经病损.由于神经系统再生能力差,损害往往是不可逆的,神经电生理变化是预示神经损害的早期变化,可以此做为预防的监测手段.

Changes in the nerve conducting velocity and biological indices of workers exposed to low-concentration lead

BACKGROUND:Whether long time exposure to the lead concentration which is withinthe state allowed range will cause any bad effects on people's health?OBJECTIVE: To investigate the nerve conducting velocity (NCV) and other biological indices of workers who are exposed to low concentration lead.DESIGN: It was an investigation and the subjects were workers exposed to low concentration lead.SETTING: Occupational Disease Department and Electrophysiological Department of Xinhua Affiliated Hospital of the Shanghai Second Medical University.PARTICIPANTS: In lead contact group were 66 heat treatment workers who were exposed to lead and received physical examination from September 2000 to October 2002. In control group were 40 office workers that worked at the same factory but were not exposed to lead.METHODS: Questionnaire and laboratory examination were adopted for measurement of NCV and other biological indices like blood lead, blood zinc protoaetioporphyrin (ZPP), blood free protoporphyrin (FPP) and hemoglobin content in the two groups. And the relative risk analysis was conducted.biological indices in both groups.RESULTS: All the 106 subjects entered analysis stage. In lead contact group there were 34 workers of more than 10 working years and the other ulnar nerve in those of over 10 working years were faster than those in control group (50.11 ±4.76) m/s, (63.11±2.58) m/s vs (47.59±4.86)m/s,those of over 10 working years was higher than those of less than 10years (0.568±0.28), (0.425±0.31) μmol/ L, P ＜ 0.05]. So was the FPP level (2.24±0.32), (2.09±0.27) μmol/L, P ＜ 0.05] and urine lead level (0.087±0.008), (0.083±0.007) μmg/L, P ＜ 0.05]. The ZPP level of those of over 10 working years was also higher than those less than 10 years (1.42±0.33) μmol/L vs (1.25±0.35) μmol/L, P ＜ 0.05] and control (1.42±0.33) μmol/L vs (1.22±0.44) μmol/L, P＜ 0.05]. The hemoglobin of those of over 10 working years was lower than those of less than 10 years (12.26±4.5) g/L vs (14.55±4.81) μmol/L, P ＜ 0.05] and control (12.26±4.5) g/L years presented abnormality in conducting sensory signals and the abnormality rate was 3% (1/32). Whereas four cases in those with more than 10working years did so and the abnormality rate was 12% (4/34). As for biological indices, one case in those less than 10 working years was beyond normal values (abnormality rate 3%) and five did so in those of over 10working years (abnormality rate 15%). It could be seen that changes in both NCV and biological indices of those of over 10 working years were more serious than those les than 10 years exposure with the relative risks of 4.1 and 5.3 respectively.CONCLUSION: Persistent exposure to lead not only alters biological indices but also damages nervous system in different degrees. Sensory verve of lower extremities and motor nerves of upper extremities are usually damaged first. Peripheral nerve injury is common in workers of over 10 working years. Because the regeneration of nervous system is poor, so the nerve injury is usually irreversible. Therefore the neuroelectrophysiological changes always predict early nerve injury and so neuroelectrophysiological monitoring can be adopted for prevention of nerve injury.