Hearing of forest workers with vibration-induced white finger: a five-year follow-up.

To examine the association between vibration-induced white finger (VWF) and hearing loss, 108 male forest workers who regularly used vibrating tools were followed up for five years. Case-control pairs matched for initial age and hearing level and exposure time to noise during the study period were selected from men with and without VWF. The hearing levels significantly worsened during the follow-up period at 2, 4 and 8 kHz in the affected cases but only at 8 kHz in the controls. Since threshold shift at 4 kHz, which is a typical effect of noise exposure, was significant only in the affected cases, it is suggested that the hearing of people with VWF was more vulnerable to noise. A pathological change causing VWF might also increase the susceptibility of hearing to noise damage.