Assessment of Hearing Standard Threshold Shift based on Audiometric Findings in Steel Company Workers

Exposure of workers to excessive noise and its complications including hearing loss as one of the most important health problems in industries. Standard Threshold Shift (STS) is considered as an indicator for monitoring of the effectiveness of hearing conservation program (HCP) implemented in the industries. This study was designed to determine the frequency of STS and hearing loss in steel industry workers. 310 steel workers with sound level exposure to unauthorized noise (85 dBA or higher) that had at least 3 years work experience were enrolled. Required data were recorded in a questionnaire through direct interview. STS was investigated using baseline audiogram and audiometric evaluations. 22.3% of workers in 2008 and 41.3% of workers in 2009 had STS in both ears. There was a significant relationship between the sound exposure level and work experience with STS, while the relationship between age and STS was not significant. High frequency of STS in workers indicates unsuccessful hearing conservation program in the factory and careful implementation and reassessment of HCP seem necessary.