MIXED-SOLVENT EXPOSURE AND HEARING IMPAIRMENT - AN EPIDEMIOLOGIC-STUDY OF 3284 MEN - THE COPENHAGEN MALE STUDY

Animal experiments and human studies have indicated an effect on audit ory functions from exposure to organic solvents. In this study the rel ationship between self-assessed hearing problems and occupational expo sure to solvents was investigated in a cross-sectional design with 328 4 participating men aged 53-74 years. Exposure to solvents for five ye ars or more resulted in an adjusted relative risk (RR) for hearing imp airment of 1.4 (95 per cent Cl: 1.1-1.9) in men without occupational e xposure to noise. Factors adjusted for were age, noise traumas, chroni c middle ear infection and family history of hearing impairment. The p revalence of hearing impairment in men not exposed to organic solvents was 24 per cent and the attributable risk from solvent exposure was 9 .6 per cent. Exposure for less than five years had no effect on hearin g capacity. Occupational exposure to noise for five years or more had an effect twice that of solvents, RR: 1.9 (95 per cent Cl: 1.7-2.1). I n men exposed to both solvents and noise the effect of the latter domi nated and no additional effect from solvents was found. A subsample of 51 men was examined with pure tone audiometry and 20 of 21 men who re ported abnormal hearing also fulfilled an audiometric criterion for he aring impairment. In conclusion a damaging effect on hearing ability f rom long-term solvent exposure was found in the present study. The rel ative effect was moderate but with a high background frequency of hear ing problems in the unexposed sample the absolute effect, ie attributa ble risk, was considerable and of both clinical and preventive importa nce.