Noise-induced hearing loss and blood factors: results from a comprehensive cross-sectional study in Iran

Noise-induced hearing loss (NIHL) is a common occupational hazard and a leading cause of hearing impairment among industrial workers. Previous studies have primarily focused on the association between physiological parameters and excessive noise exposure (above 85 dB). This study investigates the impact of sound exposure below the permissible limit (between 82 and 85 dB) on blood factors and hearing loss.

This cross-sectional analytical study examined 8946 male facility technicians from various industries in Iran, who were exposed to sound levels between 82 and 85 decibels (action limit) over a period of one year. The study examined various blood factors, including complete blood cell count (CBC), blood group (BG), fasting blood glucose (FBS), lipid factors such as triglycerides (TG) and cholesterol (Chol), and also blood pressure (BP). Additionally, the hearing status of participants was evaluated using pure tone audiometry for both ears.

The results indicated that age, work experience, SBP, FBS, Chol, Hb, Plt, and Hct were the main factors influencing hearing loss. FBS showed the highest impact on workers' hearing loss, accounting for 36.70% of the variance. Furthermore, Hb and PLT followed with weights of 19.10% and 12.4%, respectively. However, no significant relationship was observed concerning the blood group type.

Exposure to noise levels below the permissible limit can lead to hearing loss in individuals. Moreover, FBS, Hb, and PLT were identified as blood factors affecting hearing loss in people. Understanding this will provide the basis for future guidelines on how to care for these workers.