Evaluation at 72 months confirms the association between PCB exposure and cochlear status evaluated by otoacoustic emissions

Background: Epidemiological studies have demonstrated the ototoxic effects of exposure to polychlorinated biphenyls (PCBs). In a previous study, this effect was attributed to the PCB postnatal serum concentration. Objective: Testing if the ototoxic effect of the PCB exposure is permanent and if the association between PCB concentration and distortion product otoacoustic emission (DPOAE) level remains valid during development. Comparing the sensitivity of the DPOAE-based test to that of pure tone audiometry (PTA) in the detection of the cochlear dysfunction induced by PCB exposure. Methods: A follow-up population of 210 children from a PCB-exposed birth cohort underwent audiological and DPOAE test at the age of 72 months. The PCB blood serum concentration was determined at the same age and the association between DPOAE, PTA, and PCB was studied by means of multivariate ANOVA (MANOVA) and linear regression models. ROC curves were computed to estimate the DPOAE-test power in children. Results: PCB-153 concentration at 72 months is strongly correlated to that measured at 45 months. PCB-153 concentration is correlated with DPOAE level at 72 months, with a strength very similar to that found at 45 months. No significant association was found between PTA hearing levels and PCB-153 concentration. High diagnostic power of the DPOAE-test was found in children, similar to that found by the same authors in adults. Conclusions: Reproducing at 72 months the DPOAE-PCB correlation obtained at 45 months suggests a permanent and stable ototoxic effect of the PCB exposure. The lack of statistical significance of the PCB-PTA correlation suggests that DPOAEs are particularly sensitive biomarkers of cochlear damage, particularly useful in studies on children, and other subjects whose audiometric response might not be fully reliable.