Prevalence, subtypes, and risk factors of noise-Induced hearing loss in high-risk occupations: a cross-sectional...

This study aimed to determine the prevalence of hearing loss among welders, grinders, and stampers in a district of Ningbo City, identify distinct subtypes of hearing loss, and explore associated risk factors.

A cross-sectional analysis was conducted using occupational health examination records and on-site environmental monitoring data from enterprises in a district of Ningbo City in 2023. A data-driven clustering approach with a Gaussian mixture model, was used to identify subtypes of hearing loss. Mixed-effects logistic regression was used to assess factors associated with hearing loss.

The prevalence of hearing loss was 54.24% among welders (n = 695), 58.95% among grinders (n = 497), and 64.36% among stampers (n = 390). Increased age, male sex, high noise exposure, and employment within the Construction and Related Services were significant risk factors. Three subtypes of hearing loss were identified: Class 1 (mild, flat threshold elevation at 4-6 kHz), Class 2 (steep threshold elevation at 3-6 kHz), and Class 3 (elevation in speech-frequency ranges). Class 2 was the most prevalent and showed the strongest association with occupational noise exposure.

Hearing loss is common among welders, grinders, and stampers, with stampers being the most affected. Class 2 audiometric pattern was consistent with noise - induced hearing loss. These findings highlight the need for targeted preventive measures in high-risk occupational settings.