Personal Susceptibility and Familial Tendency in Occupational Deafness

Abstract

The problems of personal susceptibility and familial influence in relationship to hearing organs affected by noise have yet to be solved. In this work, the author presents data on progress made in studies on the influence of family relationship in occupational deafness. Twelve hundred and sixty-eight workers at Mitsubishi Heavy Industrial Company in Hiroshima were investigated. The workers were working under conditions in which the noise level reached at least 90 phons, and were tested by audiometric examination. The relationship of age and time of work under these noisy conditions was analysed. Among these workers, 43 were blood relatives. The family relationship, age of worker, years of experience and exposure to noise, hearing loss at 4,000 Hz, hearing average and symmetrical audiograms in both ears were examined. By analysing these data, familial and personal influence on hearing loss was recognized in 15 partners. Out of all the blood-related workers (43 partners) fifty-nine workers, i. e. 69 %, showed symmetrical audiograms in both ears, while the remaining 27 (31 %) showed asymmetrical audiograms.