Jan MH. Department of Preventive Medicine and Biometrics,
Uniformed Services University of the Health Sciences, Bethesda, MD.
Background: Many Navy personnel are exposed to significant levels of noise in the course of their jobs. This study examines hearing loss in specific occupational groups using Hearing Conservation Program audiograms from a Navy active duty enlisted population.
Methods: Annual and termination audiograms with accompanying demographic information were analyzed in a database of Navy Hearing Conservation Program (HCP) audiograms. The definition of positive significant threshold shift (STS) followed current Navy policy using the 15 and 10 dB rules. The proportion of positive STS was determined overall and by occupation as represented by general rating (the 2 or 3 letter designator). Unconditional logistic regression of positive STS on age, sex, race, rating group, length of service, time interval between the current and reference audiogram, and the year the current audiogram was performed. The ratings group classification is used by the Navy Personnel Command (NPC) to organize related general ratings into manageable groups. Relative odds ratios for positive STS were calculated by year and ratings group.
Results: 3,387 annual or termination HCP audiograms from 1992-1998 were analyzed. The overall proportion of positive STS was 35.6% (95% CI 34.0-37.4). 16 general ratings demonstrated a lower 95% confidence limit for proportion of positive STS ( 25% and included Opticalman, Aviation Electrician's Mate, Machinery Repairman, Builder, Torpedoman's Mate, among others. The Medical/Dental ratings group demonstrated the lowest proportion of positive STS. Using this group as reference, significantly ((=0.05) elevated RORs for positive STS were obtained for Seabees (ROR 2.3, 95% CI 1.1-4.8) and the Technical group (ROR 2.1, 95% CI 1.1-3.8). RORs for positive STS by year of audiogram were not significantly different ((=0.05) with respect to the reference year of 1992.
Discussion: This study suggests that many Navy enlisted personnel continue to be exposed to high levels of noise in the occupational setting. Specific occupational groups that may be at highest risk include Seabees and the Technical ratings. In addition, the results suggest that the risk of positive STS did not significantly change from 1992-1998.