Subclinical effects of environmental hazardous factors on nervous and renal functions in humans

本研究的目的是阐明环境危险因素如铅、镉和甲基汞（MeHg）对人类神经和肾功能的亚临床影响。(1)首次引入基准剂量法（BMD）估算铅对工人神经运动功能影响的临界剂量。用光谱分析方法比较了121名血铅浓度为6 ~ 89 μg/dl的铅工和60名未暴露的铅工的体位摇摆参数。所有的摇摆参数，除了睁着眼睛的矢状摆动，在领头工人中都明显大于对照组。体位摇摆的临界剂量为12.1 ~ 17.3 μg/dl。(2)为探讨头发、脚趾甲和尿液中总汞（THg）水平与甲汞摄入对肾小管功能的潜在影响，测定其水平与尿n -乙酰氨基葡萄糖酶（NAG）和α1微球蛋白（AMG）水平的关系，并采用食物频率问卷法对59名妇女进行了每日从鱼类和其他海产品中汞摄入量的估算。毛发中THg含量为1.51±0.91 (SD) μg/g，脚趾甲中为0.59±0.32 μg/g，尿中肌酐（Cre）为0.86±0.66 μg/g；并且，它们之间存在正相关。日汞摄入量（9.15±7.84 μg/d）与毛发、脚趾甲和尿液中THg水平显著相关。在女性中，NAG和AMG与每日汞摄入量和头发、脚趾甲和尿液中的THg水平呈正相关；当采用多元回归分析校正尿镉（0.47±0.28 μg/g Cre）等可能的混杂因素时，这些关系几乎相似。综上所述，食用鱼类产生的甲基汞在一定程度上可以解释头发、脚趾甲和尿液中的总汞含量，部分原因是汞会降解为无机形式。(3)为了阐明职业汞蒸气暴露对神经运动的影响，我们测量了27名矿工和冶炼厂以及52名未暴露者的手部震颤和姿势摇摆。尿汞水平均值（UHg）暴露工人为228 μg/g Cre，未暴露者为2.6 μg/g Cre。在1-6 Hz和10-14 Hz时，暴露工人的总震颤强度和频率特异性震颤强度显著高于未暴露者，但它们与暴露工人的UHg无显著相关性。与此相反，两组之间的姿势摇摆参数均无显著差异，但经多元回归分析，睁眼横摇与暴露工人UHg呈正相关。这些发现表明，姿势摇摆和手部震颤可能受到元素汞蒸气暴露的影响。少

The objectives of this research were to clarify the subclinical effects of environmental hazardous factors such as lead, cadmium, and methylmercury (MeHg), on nervous and renal functions in humans. (1) The first study was carried out to estimate the critical dose of lead affecting the neuromotor function in workers by introducing the benchmark dose (BMD) approach. Postural sway parameters with spectral analysis were compared between 121 lead workers with BPb levels of 6-89 μg/dl and 60 unexposed controls. All sway parameters, except for sagittal sways with eyes open, were significantly larger in the lead workers than in the controls. The critical dose of BPb was estimated to be 12.1-17.3 μg/dl for postural sway. (2) To investigate the relations among total mercury (THg) levels in hair, toenail, and urine, together with potential effects of MeHg intake on renal tubular function, their levels, and urinary N-acetyl-glucosaminidase activity (NAG) and α1-microglobulin (AMG) were determined … More in 59 women, and estimated daily mercury intakes from fish and other seafood using a food frequency questionnaire. THg levels in the women were 1.51±0.91 (SD) μg/g in hair, 0.59±0.32 μg/g in toenail, and 0.86±0.66 μg/g creatinine (Cre) in urine ; and, there were positive correlations among them. The daily mercury intake of 9.15±7.84 μg/day was significantly correlated with THg levels in hair, toenail, and urine. Among the women, the NAG and AMG were positively correlated with both the daily mercury intake and THg levels in hair, toenail, and urine ; and, these relations were almost similar when using multiple regression analysis to adjust for possible confounders such as urinary cadmium (0.47±0.28 μg/g Cre). In conclusion, MeHg resulting from fish consumption can explain total mercury levels in hair, toenail, and urine to some degree, partly through the degradation into the inorganic form. (3) To clarify the neuromotor effects of occupational exposure to mercury vapor, hand tremor and postural sway were measured in 27 miners and smelters and 52 unexposed subjects. The means of the urinary mercury level (UHg) were 228 μg/g Cre for the exposed workers and 2.6 μg/g Cre for the unexposed subjects. Total tremor intensity and frequency-specific tremor intensities at 1-6 and 10-14 Hz were significantly larger in the exposed workers than in the unexposed subjects, but they were not significantly related to the UHg among the exposed workers. In contrast, there were no significant differences in any postural sway parameters between the above two group, but the transversal sway with eyes open was positively related to the UHg among the exposed workers in using multiple regression analysis. These findings suggest that postural sway and hand tremor, may be affected by elemental mercury vapor exposure. Less