Progressive Ototoxicity of Baby Shampoo As An Antifog Agent: An Experimental Study

Abstract

BACKGROUND: Endoscopes play an important role in otologic surgery. Baby shampoos, known for their hypoallergenic, anti-irritant, and anti-fogging properties, are increasingly being used. The purpose of this study was to evaluate the safety and ototoxic effects of baby shampoo in an animal model using both electrophysiological and histological methods. METHODS: Twenty-eight male Sprague-Dawley rats were divided into 4 groups: 7 control (group 1), 7 saline (group 2), 7 isopropyl alcohol (70%) +chlorhexidine (2%) antiseptic (group 3), and 7 baby shampoo (group 4). Baseline hearing was assessed by auditory brainstem response (ABR). All groups except the control received 3 doses of their respective substances by intratympanic injection. Auditory brainstem response measurements were performed on day 7 and day 21, after which the temporal bones were dissected. Histological evaluation of the cochlea and vascular endothelial growth factor (VEGF) immunoreactivity studies were performed. RESULTS: Baseline hearing thresholds were similar and within normal limits. On days 7 and 21, hearing thresholds were significantly impaired at all frequencies in the experimental groups. In particular, groups 3 and 4 had higher thresholds than the other groups. Baby shampoo caused significant damage to outer hair cells and sustentacular cells and decreased VEGF immunoreactivity in the stria vascularis, spiral ligament, and organ of Corti. CONCLUSION: Baby shampoo was found to progressively impair hearing over time, indicating its potential to cause long-term ototoxicity.