Ototoxicity of cypermethrin in Wistar rats

Abstract Introduction: This study presents the effect of cypermethrin on the cochlear function in Wistar rats post-subchronic inhalation exposure. Worldwide several pesticides are described as causing health disorders. Cypermethrin is currently one of the most commonly used, however, little is known about its harmful effects, especially related to hearing. Human studies have associated pesticides with hearing disorders, but they present limited conclusions due to the multiple factors to which the population is exposed, such as noise. Objective: Mimic human exposure to cypermethrin and to verify the effects on cochlear function. Methods: It is a subchronic inhalation animal study (6 weeks, 4 hours/day), using 36 male Wistar aged 60 day. Rats were randomly assigned into three groups: Control (12 rats exposed to inhalation of water); Positive Control for auditory lesion (12 rats administrated with 24 mg/kg intraperitoneal cisplatin); Experimental (12 rats exposed to inhalation of cypermethrin - 0.25 mg/L). Animals were evaluated by distortion product otoacoustic emissions pre- and post-exposure. Results: The frequencies of 8, 10 and 12 kHz in both ears (right p = 0.003; 0.004; 0.008 and left 0.003; 0.016; 0.005 respectively) and at frequencies 4 and 6 in the right ear (p = 0.007 and 0.015, respectively) in the animals exposed to cypermethrin resulted in reduction. Conclusion: Subchronic inhalation exposure to cypermethrin provided ototoxicity in rats.