Department of Neurology, University of North Carolina at Chapel Hill, North Carolina 27599, USA.
Toxicol Sci. 2011 May;121(1):160-7. doi: 10.1093/toxsci/kfr033. Epub 2011 Feb 9.
Welding-generated metallic fumes contain a substantial amount of manganese (Mn), making welders susceptible to Mn toxicity. Although overt Mn toxicity manifests as a type of parkinsonism, the consequences of chronic, low-level Mn exposure are unknown. To explore region-specific Mn accumulation and its potential functional consequences at subclinical levels of Mn exposure, we studied seven welders without obvious neurological deficits and seven age- and gender-matched controls. Mn exposure for welders was estimated by an occupational questionnaire. High-resolution brain magnetic resonance imaging (MRI), Grooved Pegboard performance of both hands, Trail making, and olfactory function tests were obtained from all subjects. Compared with controls, the welders had a significantly higher T1 relaxation rate (R1) in the olfactory bulb (OB, p = 0.02), mean T1-weighted intensity at frontal white matter (FWM; p = 0.01), bilateral globus pallidus (GP; p = 0.03), and putamen (p = 0.03). The welders scored worse than the controls on the Grooved Pegboard test for both dominant (p = 0.06) and nondominant hand (p = 0.03). The dominant hand Grooved Pegboard scores correlated best with mean MRI intensity of FWM (R² = 0.51, p = 0.004), GP (R² = 0.51, p = 0.004), putamen (R² = 0.49, p= 0.006), and frontal gray matter (R² = 0.42, p = 0.01), whereas the nondominant hand scores correlated best with intensity of FWM (R² = 0.37, p = 0.02) and GP (R² = 0.28, p = 0.05). No statistical differences were observed in either the Trail-making test or the olfactory test between the two groups. This study suggests that Mn accumulates in OB and multiple other brain regions in "asymptomatic" welders and that MRI abnormalities correlate with fine motor but not cognitive deficits. Further investigations of subclinical Mn exposure are warranted.
焊接产生的金属烟雾含有大量的锰（Mn），使焊工易患锰毒性。虽然明显的锰毒性表现为一种帕金森病，但慢性、低水平锰暴露的后果尚不清楚。为了探索亚临床水平锰暴露时特定区域的锰积累及其潜在的功能后果，我们研究了 7 名无明显神经功能缺损的焊工和 7 名年龄和性别匹配的对照者。通过职业问卷估计焊工的锰暴露情况。所有受试者均接受高分辨率脑磁共振成像（MRI）、双手格罗斯佩格板测试、连线测试和嗅觉功能测试。与对照组相比，焊工的嗅球（OB）T1 弛豫率（R1）明显升高（p = 0.02），额白质（FWM）的平均 T1 加权强度（p = 0.01）、双侧苍白球（GP；p = 0.03）和壳核（p = 0.03）也升高。焊工在格罗斯佩格板测试中，无论是优势手（p = 0.06）还是非优势手（p = 0.03）的得分均低于对照组。优势手格罗斯佩格板测试得分与 FWM（R² = 0.51，p = 0.004）、GP（R² = 0.51，p = 0.004）、壳核（R² = 0.49，p= 0.006）和额灰质（R² = 0.42，p = 0.01）的平均 MRI 强度相关性最佳，而非优势手的得分与 FWM（R² = 0.37，p = 0.02）和 GP（R² = 0.28，p = 0.05）的强度相关性最佳。两组间在连线测试或嗅觉测试中均未观察到统计学差异。本研究表明，在“无症状”焊工中，锰会在 OB 和其他多个脑区积累，MRI 异常与精细运动功能障碍相关，而与认知功能障碍无关。有必要进一步研究亚临床水平的锰暴露。
