NEUROLOGIC EFFECTS OF HGO EXPOSURE IN DENTAL PERSONNEL

描述：（改编自研究者摘要）。 行为和 由于职业暴露水平低， 元素汞（Hg）蒸气在50微克以下还没有很好的表征 尿中汞/升。 据报道，不良反应的平均水平低至 26微克汞/升，但由于缺乏可靠的剂量效应关系， 尿液和空气中的水平仍有待确定。 前提是 低水平元素的近期（亚慢性）和累积（慢性）剂量 汞可能对以下方面产生不利影响：a）运动功能（简单反应时间， 手指敲击、手稳定电池和加速度震颤），B） 信息处理（选择反应时间），c）记忆/注意（数字 跨度，斯滕贝格，和视觉记忆经常数字），d）认知技能 （线索制作B，乌鸦矩阵，转换注意，编码），e）情绪（POMS 和症状自评量表90修订版（SCL-90-R），f）症状，和g） 感觉功能（视觉对比敏感度、振动触觉敏感度和 姿势摇摆）。 对照测试是词汇和视力。 的 目标是首次确定潜在赤字是否 与低剂量相关，并准确确定阈值水平 效果。 潜在的神经系统缺陷预计将出现在 最近和累积的汞暴露水平明显低于 需要产生肾毒性 采用重复测量横断面研究设计，在200名 在华盛顿州执业的牙医和200名牙科助理， 从>3500例使用第一次晨尿作为 筛选措施 尿液水平的分布将用于 选择符合条件的代表性样本（25个样本） 牙医，其中最高和最低层将被过度采样， 增加接触的范围，并控制接触的年龄。 助理将从参与的牙科诊所中挑选。 测试 会议将通过测试一半的季节性暴露来平衡 冬后夏组，另一半冬后夏组，6个月 apart. 受试者内变异性将用于区分亚慢性 由于近期暴露于慢性效应而产生的影响。 24小时尿检 汞水平是一个稳定的剂量估计值，但将与 血液和头发中的含量。 累积剂量指数将基于工作 工作实践的历史加权。 尿液中的肾脏评估包括 谷胱甘肽转移酶同工酶、GST-α和GST-β 1的测量， 视黄醇结合蛋白和白蛋白，反映了肾小管结构 完整性、功能完整性和肾小球功能完整性， 分别 完成这个项目将描述相关的神经行为影响 职业暴露低于50微克/升， 建议的生物阈值为25和50微克/升。 结果 将确定潜在的赤字是慢性的还是亚慢性的 通过使用暴露和剂量的良好表征指数。 安全阈值 也可以在亚临床到 临床效果 这些结果都适用于职业 健康的牙科社区和公共卫生政策的影响， 一般人群中的元素汞暴露。

DESCRIPTION: (Adapted from the Investigator's Abstract). Behavioral and sensory health effects due to low levels of occupational exposure to elemental mercury (Hg) vapor have not been well characterized below 50 ug Hg/L in urine. Adverse effects have been reported at mean levels as low as 26 ug Hg/L but in the absence of reliable dose-effect relationships, a safe level in urine and air remains to be determined. The hypothesis is that recent (sub-chronic) and cumulative (chronic) doses of low level elemental Hg may adversely affect: a) motor function (simple reaction time, finger-tapping, the Hand Steadiness Battery, and acceleration tremor), b) information processing (choice reaction time), c) memory/attention (digit span, Sternberg, and visual memory recurrent figures), d) cognitive skill (Trailmaking B, Raven matrices, switching attention, coding), e) mood (POMS and the Symptom Check List 90 Revised (SCL-90-R), f) symptoms, and g) sensory function (visual contrast sensitivity, vibrotactile sensitivity, and postural sway). The control tests are vocabulary and visual acuity. The objectives are to determine for the first time whether potential deficits are associated with low doses and to accurately identify a threshold level of effect. Potential nervous system deficits are expected to appear at recent and cumulative mercury exposure levels significantly lower than those required to produce renal toxicity A repeated measures cross-sectional study design will be conducted among 200 dentists practicing in Washington State and 200 dental assistants, selected from a population of >3500 practices using first morning void urine as a screening measure. The distribution of urinary levels will be used to select a representative sample (twenty five percentiles) of eligible dentists where the highest and the lowest strata will be over sampled to increase the range of exposures and to control for age across exposures. The assistants will be selected from participating dental offices. Test sessions will be counter-balanced for seasonal exposure by testing half the group in winter then summer and the other half in reverse order, six months apart. Within subject variability will be used to distinguish sub-chronic effects due to recent exposures from chronic effects. A 24-hour urinary mercury level is a stable estimate of dose, but will be compared to the amount in blood and hair. An index of cumulative dose will be based on work histories weighted for work practices. Renal assessments in urine include measurement of glutathione transferase isoenzymes, GST-alpha and GST-pi, retinol binding protein, and albumin, reflecting tubular structural integrity, functional integrity, and glomerular functional integrity, respectively. Completion of this project will describe neuro-behavioral effects associated with occupational exposures below 50 micrograms/liter encompassing the proposed biologic thresholds of 25 and 50 micrograms/liter. The results will define whether potential deficits are chronic or sub-chronic in nature by using well characterized indices of exposure and dose. A safe threshold may also be identified on an anticipated continuum from sub-clinical to clinical effects. These results are both applicable to the occupational health of the dental community and to public health policy on the impact of elemental mercury exposure in the general population.