HSE Health & Safety Executive Further investigation of possible musculoskeletal and cognitive deficit due to welding in divers identified in the ELTHI diving study Prepared by the University of Aberdeen for the Health and Safety Executive 2005 RESEARCH REPORT 390 HSE Health & Safety Executive Further investigation of possible musculoskeletal and cognitive deficit due to welding in divers identified in the ELTHI diving study Jennie I Macdiarmid PhD John AS Ross MB ChB PhD FRCA Sean Semple PhD *Liesl M Osman MA PhD Stephen J Watt MBBS FRCPEd AFOM **John R Crawford PhD FBPsS CclinPsychol Departments of Environmental and Occupational Medicine *Medicine & Therapeutics and **Psychology University of Aberdeen Aberdeen AB25 2ZP A questionnaire survey was conducted to assess the health of divers and welders. The aim of the study was to determine if the health impact of a career in diving and welding was greater than welding alone. The response rate was 48%, with 182 diver welders, 108 non-diver welders and 252 non-diver non- welders completing the questionnaire. Complaints of cognitive and musculoskeletal symptoms were more common in diver welders than non-diver welders, and non-diver non-welders. In spite of this observation there was no convincing correlation between symptom complaint and welding exposure or diving experience. Welding fume exposure was significantly higher in non-divers than divers. Sixty percent of divers had welded at pressure, but the prevalence of symptom complaints in these divers did not differ from divers who had not welded at pressure. Further analysis of the ELTHI Diving study showed that among divers other factors, such as diving accidents and chemical exposures (e.g. contaminated breathing gas, petrochemicals and hydrogen sulphide), were associated with reported symptoms. Welding remained a significant predictor of cognitive but not musculoskeletal complaint after adjusting for diving experience, diving accidents, chemical exposure and lifestyle factors. In summary, these studies suggest that welders who dive have an increased the risk of cognitive complaint which is not observed in absence of diving. The cause of this remains unclear. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. HSE BOOKS © Crown copyright 2005 First published 2005 ISBN 0 7176 6169 5 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. Applications for reproduction should be made in writing to: Licensing Division, Her Majesty's Stationery Office, St Clements House, 2-16 Colegate, Norwich NR3 1BQ or by e-mail to [email protected] ii Acknowledgements The authors of this report would like to thank Miss Eve Clarke and Mrs Linda Hamill (project secretaries) for their work on this project. We would also like to thank Dr David Caughey from CAPITA Health Solutions (Aberdeen) for collaborating in the study. iii iv EXECUTIVE SUMMARY INTRODUCTION Within a welding environment there is potential for exposure to various chemical and physical hazards. Welding generates toxic gases and high levels of fine particles containing a complex variety of metals, varying with the type of welding and material used. Welding has been associated with a number of acute and chronic health related hazards, including respiratory, cognitive, musculoskeletal and hearing complaints. The results of the ELTHI Diving study support these findings, showing that an occupational history of welding is associated with an increased prevalence of cognitive, musculoskeletal and hearing complaints. There were, however, insufficient numbers of non-diver welders in the ELTHI Diving study to determine whether diver welders were more at risk than non-divers welders. It is proposed that there could be an interaction between diving and welding, with divers being at greater risk to adverse health effects since many of them weld at pressure in small, poorly ventilated welding habitats. AIM To determine if the health impact of diving and welding is greater than welding alone, with particular interest in the effect on cognitive and musculoskeletal symptom complaint. METHODS The study consisted of a postal questionnaire survey. The 5 page questionnaire assessed welding and diving exposure, symptom complaints, diagnosed medical conditions, lifestyle history, cognitive failure (Cognitive Failure Questionnaire (CFQ)) and health related quality of life (SF-12). Study population: Three age matched study groups were targeted in the survey; diver welders, non-diver welders and non-diver non-welders. Non-divers were men who had worked offshore but never as a diver. Diver welders and non-diver non-welders were selected from men who had previously participated in the ELTHI Diving study. Due to an insufficient number of non-diver welders in the ELTHI Diving study, a new sample of non-diver welders were recruited through CAPITA Health Solutions. These were men who had had an offshore medical examination between 1990-2002, stated their occupation as a welder and had not dived. 361 diver welder, 352 non-diver welders and 503 non-diver non-welders were traced and sent a questionnaire. Non-responders were sent a maximum of 3 questionnaires at 4 week intervals. Re-analysis of the ELTHI Diving study data: In addition to the questionnaire survey, data from the ELTHI Diving study were re-analysed to include only divers. Using hierarchical logistic regression analysis, diving experience was related to symptoms complaint, adjusting for lifestyle factors, welding, diving accidents and chemical exposures. A separate model was used for each compliant, which were ‘forgetfulness or loss of concentration’, ‘joint pain or muscle stiffness’, ‘back or neck pain’ and ‘impaired hearing’ RESULTS The questionnaire survey had a response rate of 48%, with response being higher among those who had previously completed the ELTHI Diving study (53%) than newly recruited non-diver welders (30%). 182 diver welders, 108 non-diver welders and 252 non-diver non- welders were included in the analysis. v Cognitive complaint: The prevalence of complaint of ‘forgetfulness or loss of concentration’ was significantly higher among diver welders (33%) than both non-diver welders (10%) and non-diver non-welders (14%). Consistent with this, diver welders scored significantly higher on the CFQ than both non-diving groups, reflecting greater cognitive symptomatology. Non-diver welders and non-diver non-welders did not differ significantly on either of these measures of cognitive complaint. Musculoskeletal complaint: As observed for cognitive complaint, the complaint of ‘joint pain or muscle stiffness’ and ‘back or neck pain’ was significantly more common among diver welders than both non-diver welders and non-diver non-welders. The only other symptom to differ between the groups was ‘impaired hearing’, which was more common in diver welders (29%) and non-diver welders (32%), than non-diver non- welders (12%). Physical and mental health related quality of life did not differ significantly between the 3 study groups. Welding and diving exposure related to symptom complaint: Divers tended to have shorter welding careers and had been exposed to less welding fume than non-divers. The divers, on average, had been exposed to the equivalent of 11 years of welding fume at a concentration of 5mg.m-3 for 240 days per year, while in non-divers equivalent exposure was 36 years. Divers were more likely than non-divers to have welded aluminium (29% vs. 8%). Despite differences between diver and non-diver welders in welding experience, there were no convincing correlations between welding exposure and symptom complaint within this population. Divers who welded at pressure had longer diving careers and greater welding fume exposure than divers who had not welded at pressure, but they were no more likely to complain of cognitive or musculoskeletal symptoms. Re-analysis of the ELTHI Diving study data: Further analysis of the ELTHI Diving study data in divers, revealed other factors, such as diving accidents and chemical exposures, were related to cognitive, musculoskeletal and hearing complaint. Neurological decompression illness, exposure to contaminated gas while diving, exposure to petrochemicals and work as a welder were associated with the complaint of ‘forgetfulness or loss of concentration’. ‘Back or neck pain’ was associated with contaminated gas, exposure to petrochemicals and neurological decompression illness. ‘Joint pain or muscle stiffness’ was associated with pain only decompression illness, exposure to contaminated gas and exposure to petrochemicals. ‘Impaired hearing’ was associated with exposure to contaminated gas and noise. With respect to diving techniques, after adjusting for these other factors, only mixed gas bounce diving was associated with reported ‘forgetfulness or loss of concentration’ and reported ‘joint pain or muscle stiffness’, and saturation diving related to reported ‘impaired hearing’. SUMMARY The main finding of the study confirms the previous observations that the health impact of welding and diving is greater than that of welding alone. Cognitive and musculoskeletal complaints were found to be more common in