title: Increased R2* in the Caudate Nucleus of Asymptomatic Welders.
abstract: Welding has been associated with neurobehavioral disorders. Welding fumes contain several metals including copper (Cu), manganese (Mn), and iron (Fe) that may 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 brain magnetic resonance imaging (MRI) were obtained. Complete exposure and MRI R2* and R1 (1/T1: measure to estimate Mn accumulation) data from 42 subjects with welding exposure and 29 controls were analyzed. Welders had significantly greater exposure metrics and higher whole-blood Fe levels compared with controls. R2* in the caudate nucleus was significantly higher in welders after controlling for age, body mass index, respirator use, caudate R1, and blood metals 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.
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Lee
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Michael R
authors.initials: MR
authors.lastname: Flynn
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Guangwei
authors.initials: G
authors.lastname: Du
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Li
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Mechelle M
authors.initials: MM
authors.lastname: Lewis
authors.affiliation: Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.affiliation: Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Eric
authors.initials: E
authors.lastname: Van Buren
authors.affiliation: Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Scott
authors.initials: S
authors.lastname: Van Buren
authors.affiliation: Department of Public Health Sciences, Pennsylvania State University, Hershey, Pennsylvania;
authors.forename: Lan
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina;
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Fry
authors.affiliation: Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Snyder
authors.affiliation: Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: James R
authors.initials: JR
authors.lastname: Connor
authors.affiliation: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; and.
authors.forename: Qing X
authors.initials: QX
authors.lastname: Yang
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania;
authors.forename: Richard B
authors.initials: RB
authors.lastname: Mailman
authors.affiliation: *Department of Neurology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina; Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; Department of Radiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania; and Department of Kinesiology, Pennsylvania State University, University Park, Pennsylvania Xuemei@psu.edu.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Huang
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000097:blood / Q000633:toxicity*; D002421:Caudate Nucleus / Q000187:drug effects* / Q000378:metabolism*; D003300:Copper / Q000097:blood / Q000633:toxicity; D006801:Humans; D007501:Iron / Q000097:blood / Q000633:toxicity; D008274:Magnesium / Q000097:blood / Q000633:toxicity; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D014896:Welding
chemical_list: D000395:Air Pollutants, Occupational; D003300:Copper; D007501:Iron; D008274:Magnesium
keywords: R2*; basal ganglia; caudate nucleus; iron; welders