A neurobehavioral study of current and former welders exposed to manganese Dag G. Ellingsen a, * , Roman Konstantinov b , Rita Bast-Pettersen a , Ludmila Merkurjeva b , Maxim Chashchin b , Yngvar Thomassen a , Valery Chashchin b a National Institute of Occupational Health, P.O. Box 8149 Dep, N-0033 Oslo, Norway b Northwest Public Health Research Centre, 191036 2-Sovetskaya, 4 St. Petersburg, Russia Received 18 May 2007; accepted 28 August 2007 Available online 7 September 2007 Abstract Neurobehavioral functions were studied in 96 welders currently exposed to the geometric mean (GM) concentration of 121 mg/m 3 (range 7–2322) manganese (Mn) in welding fume (air-Mn) based on the individual mean from two successive days of sampling. They were compared to 96 age-matched referents. The arithmetic mean (AM) concentration of Mn in whole blood (B-Mn) was 8.6 mg/L versus 6.9 mg/L in the referents. Associations between the Digit Symbol and Finger Tapping test scores and B-Mn and air-Mn, respectively, were observed. The welders exposed to the highest air-Mn concentrations (GM 423 mg/m 3 range 204–2322) had statistically significantly poorer Finger Tapping test score as compared to their age-matched referents. The welders with the highest AM concentration of B-Mn (12.6 mg/L) scored statistically significantly poorer on the Digit Symbol test when compared to the age-matched referents (AM B-Mn 7.5 mg/L). The same neurobehavioral test battery was applied to 27 patients diagnosed, and financially compensated, as having welding related manganism. They were on average 44.9 (range 34–51) years old at the time of diagnosis, which on average was 5.8 years prior to this study. They had worked as welders for 23.1 years on average (range 15–30). The most affected neurobehavioral functions were associated with impaired Finger Tapping speed and Grooved Pegboard performance. The patients had no alterations in hand tremor as assessed by the CATSYS system, while a few subjects had noticeable tremor as assessed by the Static Steadiness test. # 2007 Elsevier Inc. All rights reserved. Keywords: Welding; Manganese; Neurobehavioral tests; Manganism 1. Introduction High occupational exposure to manganese (Mn) can cause manganism, a severe disorder of the central nervous system (CNS) characterized mainly by movement disturbances and psychiatric features (Couper, 1837; McMillan, 1999). Mangan- ism has been diagnosed in workers employed in mining and crushing of Mn ore, Mn alloy production, and in the production of steel and dry cell batteries (Cook et al., 1974; Emara et al., 1971; Huang et al., 1989; Rodier, 1955; Tanaka and Lieben, 1969). There are few scientifically reported cases of manganism in welders, although they probably constitute the highest number of occupationally exposed workers. Their exposure to Mn may originate from the steel, but more important from the welding electrode and the flux. Particles in the respirable aerosol fraction ranging from 10 to 100 nm near the welding arc and agglomerates ranging from 0.5 to 2.0 mm in aerodynamic diameter have been measured (Antonini et al., 2003; Voitkevich, 1995). Welders examined with magnetic resonance imaging had increased amounts of Mn in the globus pallidus, midbrain and putamen (Kim et al., 1999). Despite this, there are few studies of currently exposed welders using neurobehavioral methods. Slightly inferior motor functions (Siegl and Bergert, 1982; Sjo ¨gren et al., 1996), but also severely impaired motor functions (Bowler et al., 2003, 2006) have been reported. Available online at www.sciencedirect.com NeuroToxicology 29 (2008) 48–59 * Corresponding author. Tel.: +47 23195205; fax: +47 23195205. E-mail address: dag.ellingsen@stami.no (D.G. Ellingsen). 0161-813X/$ – see front matter # 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.neuro.2007.08.014