Urinary phenols and parabens in relation to hearing loss: The National Health and Nutrition Examination Survey

Introduction: The animal studies raise concerns about the possible ototoxicity of phenolic chemicals. Therefore, we conducted an epidemiologic study to examine the associations of phenols and parabens with hearing impairment. Materials and methods: Bisphenol A (BPA), benzophenone-3 (BP-3), and triclosan (TCS) were measured in urine samples in the National Health and Nutrition Examination Survey (NHANES) 2003–06 and 2009–12. Methyl paraben (MPB) and propyl paraben (PPB) were measured in urine samples in NHANES 2005–06 and 2009–12. Hearing impairment was defined as a hearing threshold of more than 25 dB at each hearing frequency in the better ear. Tests for linear trend were conducted using the median concentrations of urinary phenols or parabens in each quartile as a continuous variable. Results: A total of 1809 participants (women = 52.0%) aged 20 and above were included in the final analysis (For MPB and PPB, the sample size was 1188). After adjusting for potential confounders, we found positive associations between BPA and hearing impairment at 3 K (p-trend = 0.04); between TCS and hearing impairment at 6 K (p-trend = 0.03); However, the odds ratio (OR) for the highest compared with the lowest quartile of both BPA and TCS did not reach statistical significance. In contrast, we found unexpected negative associations between BP-3 and hearing impairment at 0.5 K (p-trend = 0.04), 1 K (p-trend = 0.02), 2 K (p-trend <0.01), 6 K (p-trend = 0.03), and 8 K Hz (p-trend = 0.02), respectively. Conclusions: The present study offers limited evidence that background phenol and paraben exposures are ototoxicants for the United States adult population.