[The hand-arm vibration syndrome: (I) the clinical picture, exposure-response relationship and exposure limits]

Part I of this paper presents an overview of the medical aspects of the hand-arm vibration syndrome, as well as the relationship between occupational exposure to hand-transmitted vibration and the vascular, neurological, and musculoskeletal disorders occurring in the upper limbs of workers who use vibrating tools. There is epidemiologic evidence for an increased occurrence of peripheral sensorineural and vascular disorders in occupational groups using a great variety of vibrating tools. An excess risk for wrist osteoarthrosis and elbow arthrosis and osteophytosis has been reported in workers exposed to shocks and low frequency vibration of high magnitude from percussive tools. To date, the available epidemiologic data are insufficient to outline an exposure-response relationship for both sensorineural disturbances and bone and joint disorders caused by hand-transmitted vibration. The association between vibration white finger (VWF) and exposure to hand-transmitted vibration has been clearly established in both cross-sectional and longitudinal studies of vibration-exposed workers. A proposal of exposure-response relationship for VWF is included in an annex to ISO 5349 (1986). However, the shape of the relationship between vibration exposure and VWF is not yet fully understood. The results of several epidemiologic studies seem to indicate that the current ISO frequency-weighting may be inappropriate for all types of vibration and for all kinds of vibration injury. Alternative exposure-response relationship for VWF have been suggested in recent epidemiologic investigations. Regarding exposure limits for hand-transmitted vibration, the findings of clinical and epidemiologic studies have shown that the vibration exposure levels proposed by the European Directive for physical agents are sufficiently protective for the safety and health of workers exposed to hand-transmitted vibration.