Hand-arm vibration and working women : Consequences and affecting factors

Sammanfattning: The use of hand-held vibrating tools may lead to hand-arm vibration syndrome (HAVS), a condition with vascular, neurological and musculoskeletal symptoms. Vibrating tools are used in several occupations in which women can be found, e.g. by metal- and wood workers, drivers, and dental personnel. The risk of women developing HAVS is hard to estimate, as little research has been done on women exposed to hand-arm vibration. The overall aim of this thesis has been to fill this gap of knowledge. It is based upon one questionnaire study and one interview study on women who have reported an occupational injury related to hand-arm vibration. The thesis also comprises two laboratory studies of female and male subjects exposed to hand-arm vibration from a handle. The questionnaire and the interview study showed that the women had a high prevalence of symptoms, such as numbness, weakness, pain and white fingers. Neurological symptoms were more common and developed after shorter time of exposure compared to vascular symptoms. The symptoms had a considerable impact on all domains of the women’s lives, not only on their physical functioning, such as the ability to work, to participate in leisure activities and to do household activities, but also on their relationships and identity. Forty per cent of the women had retired or retrained due to the injury. Dental personnel had the highest relative risk of vibration injuries. In one of the laboratory studies 12 female and 12 male subjects were exposed to vibration in two vibration directions, (Xh and Zh) and at two vibration levels. The absorbed power was higher in the Zh direction and at the higher vibration level. The volumes of the subjects’ arms affected the power absorption in the Zh direction. There were no indications of a gender difference in the absorption of power. In the other laboratory study, the effect of handle size, vibration level, anthropometric measures and maximal grip force on the ability to perform a precision task was studied in 20 female and 20 male subjects. Ratings of difficulty and discomfort were made after each test round. The results indicate that the male subjects performed better in all the tests, but no gender difference was seen in the ratings. The higher vibration level resulted in higher ratings of discomfort. In the female subjects, the handle size, the anthropometric measures and maximal grip force affected both the performance and the ratings. In conclusion, the studies indicate that vibration injuries are severely disabling and influence many parts of the sufferer’s life. Vibration injuries are preventable, and the extensive consequences found underscore the importance of preventive action. This can be done by informing employees about the risks, and by giving them the opportunity to choose suitable machines and to practice work tasks when starting a new job.