Studies relating sensory hearing impairment to lead (Pb) exposure in children have presented inconsistent results. This study measured distortion product otoacoustic emissions (DPOAE), sounds emanating from the outer hair cells of the inner ear, in Pb-exposed children to determine the effects of Pb poisoning on the inner ear. DPOAE were recorded for 9 f2 frequencies from 1187 to 7625 Hz on 102 ears of 53 Pb-exposed children (aged 6-16 yr) residing in Pb-contaminated environments in the Andes Mountains of Ecuador where Pb glazing of ceramics is the primary livelihood. Blood lead (PbB) levels ranged from 4.2 to 94.3íg/dL (mean: 37.7; SD: 25.7; median: 36.4). The median PbB level was markedly higher than the Centres for Disease Control and Prevention (CDC) and World Health Organisation (WHO) 10-íg/dL action level. Spearman rho correlation analyses of the relation between PbB level and DPOAE amplitude and between PbB level and DPOAE signal-to-noise ratio revealed no significant associations at any of the f2 frequencies tested. In addition, no significant correlation (Spearman rho) between PbB level and hearing sensitivity for 6 pure-tone test frequencies from 1000 to 8000 Hz was found. The authors concluded that although the study group was found to have abnormally elevated PbB levels, in contrast to some earlier reports, the results of the current study showed no consistent Pb-induced sensory effects on the cochlea of Pb-intoxicated children.
Authors: Buchanan, Leo H.; Counter, S. Allen; Ortega, Fernando Full Source: Journal of Toxicology and Environmental Health, Part A: Current Issues [online computer file] 2011, 74(19), 1280-1293 (Eng) ;