DEET Metabolite and Hearing Loss in United States Adults

Hearing loss (HL) causes numerous challenges for individuals. N,N-diethyl-meta-toluamide (DEET) is a common ingredient in insect repellants and some sunscreens. M-(diethylcarbamoyl) benzoic acid (DCBA) is a DEET metabolite measured in the urine of National Health and Nutrition Examination Survey participants. This study examines potential associations between HL and urinary DCBA in U.S. adults. Speech-frequency hearing loss (SFHL) was defined as an average hearing threshold above 25 dB across four frequencies (0.5, 1, 2, and 4 kHz). In comparison, high-frequency hearing loss (HFHL) was based on the average threshold above 25 dB at three higher frequencies (3, 4, and 6 kHz) in the better hearing ear. Hearing loss severity was categorized as normal (≤25 dB), mild (26-40 dB), and moderate or worse (≥41 dB). Higher DCBA exposure was significantly associated with increased odds of high-frequency hearing loss (HFHL). Participants in the highest exposure quartile had greater odds of HFHL (aOR = 2.34; 95% CI: 1.14-4.81), with a dose-response trend (p < 0.05) confirmed in sensitivity analyses controlling for chronic conditions and inflammation. Multinomial models further showed elevated odds of both slight/mild (aOR = 2.15; 95% CI: 1.05-4.42) and moderate/worse HFHL (aOR = 2.84; 95% CI: 1.10-7.37), supporting the robustness of the association. To our knowledge, this is the first report of HL being associated with a DEET metabolite in a nationally representative cross-sectional sample.