The epidemiologic study on hearing standard threshold shift using audiometric data and noise level among workers of Isfehan metal industry

Introduction: Standard threshold shifts (STS) as an important indicator for identifying hearing loss in industries that they perform hearing conservation programs. The aim of this study is the investigation of the occurrence of standard threshold shift (STS) among workers of Isfehan metal industry using audiometric data and noise measurement level. Materials and Methods: This is a cross-sectional and descriptive study that performed among 2016 of workers in Isfehan Metal Industry. All of subjects were men and the rate of using personal protective equipment among workers were sometime=189, often=865 and always=962. At the first we determined the parts of plant that exposed to non permissible noise level and then measured exposure to 8 hour equivalent noise level. Finally in regard to basic audiometric and current audiometric, the occurrences of STS were examined. Results: This study showed that 29.9 % of workers have a STS in these workplaces. There are significance relationship between age, exposure time, noise level, wearing time and number of workers with STS. But there is no relation between precedence of work and STS statistically. Conclusion: Findings of this study indicated that occurrences of STS among workers exposed to noise are high. Thus, it is concluded that hearing conservation programs in these industries was unsuccessful.