San Francisco State University, Department of Psychology, San Francisco, CA 94132, United States.
Neurotoxicology. 2011 Oct;32(5):596-605. doi: 10.1016/j.neuro.2011.06.004. Epub 2011 Jul 5.
In a group of 43 confined space welders dose-effect relationships had been identified for adverse neurological/neuropsychological functional effects in relation to manganese (Mn) in blood or air (cumulative exposure index). The welders' exposure to Mn was unprotected and with poor ventilation, lasting on average 16.5 months. A follow-up examination 3.5 years later, after cessation of confined space welding, was carried out to re-assess the status of mood, movement/neuromotor and cognitive functions, and olfaction.
In 2008, 26 welders (70% response rate) were retested using a similar methodology as at baseline (Bowler et al., 2007). A general linear model was used to estimate individual-specific endpoint differences over time. Mean age was 47 years, mean years of education 12.4, and mean total years of welding 16.9 years. Thirteen participants no longer welded.
At follow-up, mean blood Mn concentration had decreased from 10.0 to 8.4 μg/L (p=0.002). Those still welding had higher blood Mn than those no longer welding (9.9 μg/L vs. 6.8 μg/L, p=0.002). Several domains of cognitive functioning improved substantially as shown by large effect sizes. Emotional disturbance improved only slightly clinically, but complaints of depression and anxiety persisted. Motor dexterity/tactile function and graphomotor tremor improved significantly, while psychomotor speed remained unchanged. The findings of the neurological examination (UPDRS) did not change compared to baseline, whereas rigidity, dominant postural hand tremor and body sway worsened. Olfactory test scores remained depressed.
After 3.5 years of cessation of confined space welding, only cognitive function improved significantly, while olfactory, extrapyramidal, and mood disturbances remained constant or were exacerbated. This suggests differential intrinsic vulnerabilities of the brain loci involved with Mn exposure. As the Mn exposure of the Bay Bridge welders frequently exceeded the Cal-OSHA TLV of 0.2 mg Mn/m(3) at baseline, a more stringent preventive measure is recommended for confined space welding.
在一组 43 名密闭空间焊工中，已经确定了与血液或空气中的锰（Mn）（累积暴露指数）相关的不良神经/神经心理学功能影响的剂量-效应关系。这些焊工的 Mn 暴露是无保护的，通风不良，平均持续 16.5 个月。在停止密闭空间焊接 3.5 年后进行了随访检查，以重新评估情绪、运动/神经运动和认知功能以及嗅觉状况。
2008 年，26 名焊工（70%的应答率）采用与基线时类似的方法进行了重新测试（Bowler 等人，2007）。使用一般线性模型来估计个体特定终点随时间的差异。平均年龄为 47 岁，平均受教育年限为 12.4 年，平均焊接总年限为 16.9 年。13 名参与者不再焊接。
随访时，平均血 Mn 浓度从 10.0 降至 8.4μg/L（p=0.002）。仍在焊接的人的血 Mn 浓度高于不再焊接的人（9.9μg/L 比 6.8μg/L，p=0.002）。几个认知功能领域的表现显著改善，表现出较大的效应量。情绪障碍在临床上仅略有改善，但抑郁和焦虑的抱怨仍然存在。运动灵巧/触觉功能和书写震颤明显改善，而精神运动速度保持不变。与基线相比，神经系统检查（UPDRS）的发现没有变化，而僵硬、优势姿势手震颤和身体摇晃恶化。嗅觉测试分数仍然低落。
停止密闭空间焊接 3.5 年后，只有认知功能显著改善，而嗅觉、锥体外系和情绪障碍保持不变或恶化。这表明与 Mn 暴露相关的脑位的内在脆弱性存在差异。由于海湾大桥焊工的 Mn 暴露经常超过 Cal-OSHA 的 TLV（基线时为 0.2mgMn/m3），建议对密闭空间焊接采取更严格的预防措施。
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