Occupational Lead Exposure Ototoxicity Evaluated With Distortion-Product Otoacoustic Emissions

Objectives:To evaluate the extent of hearing loss among pottery workers in Mexico exposed to lead. Design:The authors conducted a cross-sectional study including 315 adult pottery workers. Auditory function was evaluated by air conduction pure-tone audiometry (pure-tone average) and distortion-product otoacoustic emission (DPOAE) levels (amplitude and signal-to-noise ratio). Lead exposure was assessed with a single blood sample test and classified as low, medium, and high according to blood lead tertiles. Logistic regression models were calculated for the association between blood lead levels, pure-tone average, and DPOAE records. Results:Median (25th-75th) blood lead levels were 14 mu g/dL (7.5-22.6 mu g/dL). The audiometric pattern and DPOAE records were similar across blood lead levels groups in all frequencies, and no statistically significant differences were found. Adjusted logistic regression models showed no increase in the odds for hearing thresholds >25 dB (HL) and DPOAE absence associated with blood lead levels, and no dose-response pattern was observed (p > 0.05). Conclusions:Given the results from this cross-sectional study, no association was found between blood lead levels and hearing loss assessed with DPOAE. Future longitudinal work should consider chronic lead exposure estimates among underrepresented populations, which can potentially inform safer work practices to minimize the risk of ototoxicity.