Cognitive symptoms and welding fume exposure

Background
The prevalence of a moderate to severe cognitive symptom is markedly higher in UK professional divers who have also worked as a welder (28%) than either divers who have not welded (18%) or offshore workers who have worked neither as a diver nor welder (6%).

Objectives
To determine whether cognitive symptoms were related to welding fume exposure or diving.

Methods
Three age-matched groups of male workers were studied by postal questionnaire: professional divers who had worked as a welder (PDW, n=361); professional welders who had not dived (NDW, n=352); offshore oilfield workers who had neither dived or welded (NDNW, n=503). Health related quality of life was assessed by the Short Form 12 questionnaire (SF12). Cognitive symptomatology was assessed using the Cognitive Failures Questionnaire (CFQ). A single variable for welding fume exposure (mg m-3 days) was calculated incorporating welding experience in different environments, different welding techniques and use of respiratory protective equipment. The level of fume exposure during hyperbaric welding operations was measured during such work as ambient PM10. Diving exposure was assessed as the number of dives performed plus the number of days spent working during saturation diving.

Results
Questionnaires were returned by 153 PDW, 108 NDW and 252 NDNW. SF12 scores were the same in all groups and fell within normative values. Mean (95% CI) CFQ scores were higher in PDW (40.3 (37.7 42.9)) than in both NDW (34.6 (31.6-37.7)) and NDNW (32.1 (30.4-33.9)) but no groups fell outside the normative range. Mean (95% CI) NCSS was higher in PDW (16.2 (15.4-16.9)) and NDW (15.7 (14.9-16.4)) than in NDNW (14.6 (14.1-15.1)). The mean PM10 exposure during hyperbaric welding operations was 2.58 mg m-3. The geometric mean mg m-3 days (95% CI) for welding fume exposure in NDW (33128 (24625-44567) n=85) was higher than for PDW (10904 (8103-14673) n=112). For PDW geometric mean (95% CI) diving exposure was 1491 ((1192-1866) n=94) dives and days in saturation. In general linear model regression analyses adjusted for age, alcohol consumption and somatisation there was no signification association of CFQ score with either welding fume exposure (F=0.072, p=0.79, n=152) or diving exposure (F=0.042, p=0.84, n=74).

Conclusion
In conclusion, cognitive sympomatology was not related to retrospectively assessed measures of welding fume exposure or diving experience. In addition, the levels of cognitive symptomatology, even in PDW, did not exceed normative values.