Increased Incidence of Foreign Body Rhinitis in F344 Rats during Two-year Inhalation Exposure to Methyl Bromide

Male and female F344 rats were exposed to 0 to 100ppm methyl bromide for 6 hr/day×5 days/week×104 weeks. Dose-dependent lesions were produced in the nasal passage of male rats, characterized by enhanced foreign body rhinitis mostly due to inhaled hairs as well as necrosis and respiratory metaplasia of the olfactory epithelium.