Otoacoustic emissions and biomarkers of oxidative stress in students of a tobacco-producing region

To verify the association between the amplitude of distortion-product otoacoustic emissions (DPOAE) and biomarkers of oxidative stress (OS) in resident students of the tobacco-producing region. Participated in the study group (SG) 21 normal-hearing students from the tobacco-producing region, and in the control group (CG) 25 normal-hearing students who did not live in the countryside. The auditory system was assessed by DPOAE and the following biomarkers: dichlorofluorescein diacetate (DCFH-DA) and micronucleus test (MN). Both groups showed DPOAE present in both ears. Significant difference was detected between groups--in the right ear in the frequency of 4.000 Hz and in the left ear in the frequency of 2.000 Hz--with the mean amplitude of the DPOAE of the SG lower than the one found in the CG. Considering both ears, the SG presented lower mean across all frequencies and it was found a significant difference in the frequencies of 2.000 and 4.000 Hz. The overall mean of DPOAE, by ear, no significant differences were observed. In relation to the rate of production of free radicals, the mean of the SG was significantly higher than that of the mean of the CG. For the frequency of abnormal cells in the MN test, the mean of the SG was also considerate significantly higher than the mean of the CG. The SG showed a lower response level of DPOAE at all frequencies and high levels of biomarkers of EO, however there was no association between assessments.