The association between occupational noise exposure, hearing loss, and metabolic syndrome among workers in a textile factory: A cross-sectional study

Rationale: Previous studies have examined the relationship between noise exposure and hearing loss with metabolic syndrome (MetS), but the results have been inconsistent. Aim: To assess an association between noise exposure, hearing loss, and the status of MetS. Methods: This cross-sectional study was carried out in 950 employees of a textile factory in 2023. Participants were categorized into two groups based on their noise exposure: under 85 dB versus 85–90 dB. Hearing loss was defined as a mean hearing threshold exceeding 25 dB in either or both ears within the relevant frequency ranges. MetS was diagnosed with the National Cholesterol Education Program Expert Panel and Adult Treatment Panel III criteria. Demographic, medical, and occupational data were collected during periodic examinations. Then, the relationship between MetS and its components with noise exposure and hearing loss was examined. Results: The median age of the study population was 33 years (IQR 28 to 38 years) and the median work experience was 3 years (IQR 2 to 9 years). 864 (90.9%) of the subjects were male, 774 (81.5%) were married, and 848 (89.3%) had shift work. 10.8% (n = 103) of the participants were diagnosed with MetS, and 72% (n = 684) had exposure to noise levels greater than 85 dB. Increased waist circumference (odds ratio (OR) = 1.61; 95% confidence interval (CI) 1.20–2.17, p = 0.002), elevated triglycerides (OR = 2.03; 95% CI 1.36–3.02, p 0.001), and reduced high-density lipoprotein (HDL) levels (OR = 1.71; 95% CI 1.28–2.29, p 0.001) were significantly associated with the noise exposure. There was also a significant relationship between MetS components and high-frequency hearing thresholds. Specifically, hearing loss at higher frequencies in both ears was linked to elevated fasting blood sugar, diastolic blood pressure, triglycerides, and low HDL. Conclusion: Our study showed a significant association between noise exposure and components of MetS including increased waist circumference, high triglycerides, and low HDL cholesterol. In addition, based on initial analysis, there was a significant association between MetS and its components, including dysregulated glucose and lipids, and elevated diastolic blood pressure, with the median hearing threshold at higher frequencies.