Int Arch Occup Environ Health ( 1988) 60:129-137 Intemationa Archivesof 0 CCupabti Oamd- Envrroinmental Health © Springer-Verlag 1988 Back disorders in crane operators exposed to whole-body vibration* Paulien M Bongers, Hendriek C Boshuizen, Carel T J Hulshof, and Agaath P Koemeester Coronel Laboratory, University of Amsterdam, Meibergdreef 15, NL-1105 AZ Amsterdam, The Netherlands Summary In The Netherlands so far little research has been carried out to investigate the health effects of exposure to whole-body vibration at work In a retrospective ( 10-year) follow-up study, the incidence of permanent work disabilities in crane operators ex- posed to vibration was compared to that of a control group The emphasis in this presentation is on dis- ablement because of back disorders Among the crane operators with more than 5 years of exposure to vibration, more disability due to back trouble oc- curred than in the control group The incidence den- sity ratio (IDR) exceeded 2 for disability because of degeneration of the intervertebral disc, after adjust- ment for age, nationality, shift work and calendar year With increasing years of exposure, the risk ratio for disability because of intervertebral disc disorders also increased The risk ratio for a disability pension due to disease of the intervertebral disc for crane operators with more than 5 years of exposure was al- most 3 compared to the control group A combina- tion of exposure to whole-body vibration, an un- favorable posture, and climatic conditions is respon- sible for the development of these health effects. Key words: Whole-body vibration Back disorders - Disability pension Crane operators Intervertebral disc disorders Introduction In The Netherlands, research on health effects re- garding occupational exposure to whole-body vibra- * Supported by a grant from the Ministry of Social Affairs and Employment Offprint requests to: P M Bongers at the above address tion started in 1984 A recent estimate of the popula- tion at risk showed that in The Netherlands 300,000 professional drivers are exposed to vibration levels above 0 63 m/s 2 (weighted root mean square (RMS) acceleration a); another 10,000 industrial workers (such as crane operators) are exposed to vibration levels above 0 32 m/s 2 aw (Oortman Gerlings et al. 1987) In the international standard for evaluation of human exposure to whole-body vibration (ISO 2631/ 1/1985), a fatigue-decreased proficiency boundary 0.32 m/s 2 aw and an exposure limit of 0 63 m/s 2 aw are mentioned However, neither limit is based on valid data on the health effects of long-term exposure. Review of the literature In the international literature, numerous studies have been reported on the adverse health effects of whole- body vibration However, in several review papers it is concluded that many of these studies show several shortcomings (Heide 1978 ; Griffin 1982 ; Helmkamp et al 1984 ; Dupuis and Zerlett 1984) Recently, two up-to-date and comprehensive literature surveys have been published in which the health effects re- lated to whole-body vibration have been critically discussed (Seidel and Heide 1986 ; Hulshof and Veld- huijzen van Zanten 1987) Seidel and Heide con- cluded that there is an increased risk of disorders of the spine and peripheral nervous system to occur after intense long-term whole-body vibration Al- though the probability is lower, the digestive system, the peripheral veins, the female reproductive organs, and the vestibular system may also be affected As a rule, the risk to health increases with greater inten- sity or duration of exposure to whole-body vibration. Hulshof and Veldhuijzen van Zanten also concluded