Bowler Rosemarie M, Roels Harry A, Nakagawa Sanae, Drezgic Marija, Diamond Emily, Park Robert, Koller William, Bowler Russell P, Mergler Donna, Bouchard Maryse, Smith Donald, Gwiazda Roberto, Doty Richard L
San Francisco State University, El Cerrito, CA 94530, USA.
Occup Environ Med. 2007 Mar;64(3):167-77. doi: 10.1136/oem.2006.028761. Epub 2006 Oct 3.
Although adverse neuropsychological and neurological health effects are well known among workers with high manganese (Mn) exposures in mining, ore-processing and ferroalloy production, the risks among welders with lower exposures are less well understood.
Confined space welding in construction of a new span of the San Francisco-Oakland Bay Bridge without adequate protection was studied using a multidisciplinary method to identify the dose-effect relationship between adverse health effects and Mn in air or whole blood. Bridge welders (n = 43) with little or no personal protection equipment and exposed to a welding fume containing Mn, were administered neurological, neuropsychological, neurophysiological and pulmonary tests. Outcome variables were analysed in relation to whole blood Mn (MnB) and a Cumulative Exposure Index (CEI) based on Mn-air, duration and type of welding. Welders performed a mean of 16.5 months of welding on the bridge, were on average 43.8 years of age and had on average 12.6 years of education.
The mean time weighted average of Mn-air ranged from 0.11-0.46 mg/m(3) (55% >0.20 mg/m(3)). MnB >10 microg/l was found in 43% of the workers, but the concentrations of Mn in urine, lead in blood and copper and iron in plasma were normal. Forced expiratory volume at 1s: forced vital capacity ratios (FEV(1)/FVC) were found to be abnormal in 33.3% of the welders after about 1.5 years of welding at the bridge. Mean scores of bradykinesia and Unified Parkinson Disease Rating Scale exceeded 4 and 6, respectively. Computer assisted tremor analysis system hand tremor and body sway tests, and University of Pennsylvania Smell Identification Test showed impairment in 38.5/61.5, 51.4 and 88% of the welders, respectively. Significant inverse dose-effect relationships with CEI and/or MnB were found for IQ (p<or=0.05), executive function (p<or=0.03), sustaining concentration and sequencing (p<or=0.04), verbal learning (p<or=0.01), working (p<or=0.04) and immediate memory (p<or=0.02), even when adjusted for demographics and years of welding before Bay Bridge. Symptoms reported by the welders while working were: tremors (41.9%); numbness (60.5%); excessive fatigue (65.1%); sleep disturbance (79.1%); sexual dysfunction (58.1%); toxic hallucinations (18.6%); depression (53.5%); and anxiety (39.5%). Dose-effect associations between CEI and sexual function (p<0.05), fatigue (p<0.05), depression (p<0.01) and headache (p<0.05) were statistically significant.
Confined space welding was shown to be associated with neurological, neuropsychological and pulmonary adverse health effects. A careful enquiry of occupational histories is recommended for all welders presenting with neurological or pulmonary complaints, and a more stringent prevention strategy should be considered for Mn exposure due to inhalation of welding fume.
尽管在采矿、矿石加工和铁合金生产中，高锰（Mn）暴露的工人存在不良神经心理和神经健康影响已为人熟知，但低暴露水平的焊工所面临的风险却了解较少。
采用多学科方法研究了在旧金山 - 奥克兰海湾大桥新建桥段施工中，在没有充分防护的情况下进行有限空间焊接作业，以确定健康不良影响与空气中或全血中锰之间的剂量 - 效应关系。对几乎没有或未使用个人防护设备、暴露于含锰焊接烟尘的桥梁焊工（n = 43）进行了神经学、神经心理学、神经生理学和肺部测试。根据全血锰（MnB）以及基于锰空气浓度、焊接持续时间和焊接类型的累积暴露指数（CEI）对结果变量进行分析。焊工在桥上平均焊接16.5个月，平均年龄43.8岁，平均受教育年限12.6年。
空气中锰的平均时间加权平均值为0.11 - 0.46毫克/立方米（55% > 0.20毫克/立方米）。43%的工人全血锰> 10微克/升，但尿锰、血铅以及血浆中铜和铁的浓度正常。在桥上焊接约1.5年后，33.3%的焊工第1秒用力呼气容积与用力肺活量比值（FEV₁/FVC）异常。运动迟缓的平均得分和统一帕金森病评定量表得分分别超过4分和6分。计算机辅助震颤分析系统的手部震颤和身体摇摆测试以及宾夕法尼亚大学嗅觉识别测试显示，分别有38.5/61.5%、51.4%和88%的焊工存在功能受损。即使在对人口统计学特征和在海湾大桥焊接前的工作年限进行调整后，智商（p≤0.05）、执行功能（p≤0.03）、持续注意力和排序能力（p≤0.04）、言语学习能力（p≤0.01）、工作记忆（p≤0.04）和即时记忆（p≤0.02）与CEI和/或MnB之间仍存在显著的负剂量 - 效应关系。焊工工作时报告的症状有：震颤（41.9%）；麻木（60.5%）；过度疲劳（65.1%）；睡眠障碍（79.1%）；性功能障碍（58.1%）；中毒性幻觉（18.6%）；抑郁（53.5%）；以及焦虑（39.5%）。CEI与性功能（p < 0.05）、疲劳（p < 0.05）、抑郁（p < 0.01）和头痛（p < 0.05）之间的剂量 - 效应关联具有统计学意义。
有限空间焊接作业被证明与神经、神经心理和肺部的不良健康影响相关。对于所有出现神经或肺部不适的焊工，建议仔细询问职业史，并且应考虑针对因吸入焊接烟尘导致的锰暴露制定更严格的预防策略。
