Neuromotor function in ship welders after cessation of manganese exposure.
OBJECTIVE
The aim of the present study was to investigate whether previous long-term exposure to manganese (Mn) via inhalation of welding fumes can cause persistent impairment in neuromotor function even long after cessation of exposure.


METHODS
Quantitative tests of tremor, motor speed, manual dexterity, diadochokinesis, eye-hand coordination and postural stability were administered to 17 retired ship welders (mean age 69 years), with mean exposure time 28 years. The welders' exposure had ceased on average 18 years before the study. A cumulative exposure index (CEI) was calculated for each of the former welders. The welders were compared with 21 referents from the same shipyards (mean age was 66 years).


RESULTS
Former welders performed less well than referents in the grooved pegboard test, and poorer performance was associated with CEI. The performance in most of the other neurobehavioral tests was similar between groups, but the welders tended to perform slightly better than the referents in tests demanding hand steadiness. The latter finding may be due to a training effect from their former working tasks or selection bias into or out of this occupation.


CONCLUSIONS
In the present study of welders with previous welding fume exposure, former welders and referents performed similarly in most of the neurobehavioral tests. Previous adverse effects on the neuromotor system might have ceased, and decreased neuromotor function due to normal aging processes in both groups might have disguised any slight effect of previous Mn exposure. The poorer performance in the grooved pegboard test among welders may indicate an adverse effect on motor function of long-term exposure to Mn, but this finding has to be confirmed by other studies.
Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, P.O. Box 414, 405 30, Gothenburg, Sweden. gunilla.wastensson@amm.gu.se
Gunilla
G
Wastensson
Gerd
G
Sallsten
Rita
R
Bast-Pettersen
Lars
L
Barregard
D000368:Aged; D000395:Air Pollutants, Occupational / Q000494:pharmacology / Q000633:toxicity*; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008297:Male; D020149:Manganese Poisoning / Q000150:complications* / Q000503:physiopathology; D008875:Middle Aged; D009420:Nervous System / Q000187:drug effects / Q000503:physiopathology; D009483:Neuropsychological Tests; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D011597:Psychomotor Performance / Q000187:drug effects*; D012767:Ships; D011795:Surveys and Questionnaires; D013548:Sweden; D014202:Tremor / Q000139:chemically induced; D014896:Welding
D000395:Air Pollutants, Occupational