Prevalence of noise-induced hearing loss in maritime workers: A systematic review and meta-analysis

BACKGROUND: Occupational noise is a major global health risk and is responsible for 16% of disabling hearing loss in adults. In the maritime sector, workers are frequently exposed to hazardous noise levels despite the implementation of preventive measures, resulting in auditory and broader health effects. This systematic review aimed to clarify the prevalence of noise-induced hearing loss (NIHL) and other hearing disorders among maritime workers. MATERIAL AND METHODS: A systematic search of MEDLINE, CINAHL, the Cochrane Library, EMBASE, LILACS, and Web of Science databases was conducted up to February 28, 2024, without language or publication status restrictions. We included observational studies reporting the prevalence of NIHL or related auditory conditions in maritime workers. Methodological quality was assessed using the Joanna Briggs Institute (JBI) checklist. Meta-analyses were performed where appropriate, and the certainty of evidence was rated using the GRADE approach. RESULTS: Twelve studies comprising 285,818 maritime workers were included. The overall methodological quality was moderate; one-third of the studies were rated as high quality, and most met at least five JBI criteria. Based on very low-certainty evidence, the pooled prevalence of NIHL was estimated at 30% [95% confidence interval (CI): 19-42%], with substantial heterogeneity (I2 = 87%). Advancing age, longer occupational exposure, and specific job functions, particularly those performed in engine rooms and on petroleum vessels, were consistently identified as key risks for NIHL. Tinnitus was also commonly reported, affecting more than half of exposed individuals in some studies. CONCLUSIONS: Based on very low-certainty evidence, the prevalence of occupational noise-induced hearing disorders among maritime workers is estimated at 30%. Key risk factors include age, duration of service, and specific roles, such as engine room personnel and oil vessel workers. The findings underscore the urgent need for preventive measures, including the use of hearing protection, stricter legislation, and proper training.