Increased R2* in the caudate nucleus of asymptomatic welders

Welding has been associated with neurobehavioral disorders.Welding fumes contain severalmetals including copper (Cu), manganese (Mn), and iron (Fe) thatmay interact to influence welding-related neurotoxicity. Although welding-related airborne Fe levels are about 10-fold higher than Mn, previous studies have focused on Mn and its accumulation in the basal ganglia. This study examined differences in the apparent transverse relaxation rates [R2* (1/T2*), estimate of Fe accumulation] in the basal ganglia (caudate nucleus, putamen, and globus pallidus) between welders and controls, and the dose-response relationship between estimated Fe exposure and R2* values. Occupational questionnaires estimated recent and lifetime Fe exposure, and blood Fe levels and brainmagnetic resonance imaging (MRI) were obtained. Complete exposure and MRI R2* and R1 (1/T1:measure to estimate Mn accumulation) data from42 subjects with welding exposure and 29 controls were analyzed.Welders had significantly greater exposuremetrics and higher whole-blood Fe levels compared with controls. R2* in the caudate nucleus was significantly higher in welders after controlling for age, bodymass index, respirator use, caudate R1, and bloodmetals of Cu and Mn, whereas there was no difference in R1 values in the basal ganglia between groups. The R2* in the caudate nucleus was positively correlated with whole-blood Fe concentration. This study provides the first evidence of higher R2* in the caudate nucleus of welders, which is suggestive of increased Fe accumulation in this area. Further studies are needed to replicate the findings and determine the neurobehavioral relevance.