[Clinical and experimental studies on ototoxicity of potassium bromate].

A case of potassium bromate intoxication showing a severe hearing loss and anuria was reported. This 19 years old female patient had no vertigo nor vestibular disorders, but a strong cochlear damage was suspected by electerochleography. In order to investigate the effects of potassium bromate on the inner ear, the authors performed experiments by using guinea pigs. At first, various concentration of potassium bromate (KBrO3) were injected through the guinea pigs peritoneum, and changes of cochlear function were tested by electrocochleography. Then, the animals were sacrified and the inner ear was observed by transmission and scanning plectron microscopy. The animals to which the dosis under 100mg/kg BW was injected, showed no remarkable changes. However, the animals, to which 100-150mg BW was given, showed the threshold elevation of 10-30dB and the following morphological findings: I) The stria vascularis was affected more severely than Corti's organ. II) Outer hair cells were impaired more severely than inner hair cells. III) Changes of hair cells were more clearly found in the upper turn of the Corti's organ than in the lower turn. IV) Changes of vestibular organ were not found. The animals to which the dosis over 150mg/kg BW was injected, showed no response in electrocochleogram and showed strong morphological changes.