Three cases of inhalation of household pyrethroid and metoxadiazone insecticides with remarkable dyspnea

: Household insecticides containing pyrethroids as their active ingredient are widely used in Japan. We encountered three cases of dyspnea caused by insecticides containing pyrethroids and metoxadiazone. The first case was a 52-year-old woman who suffered with dyspnea after breathing interior air following use of a fumigating insecticide. Although bronchoscopy revealed laryngotracheal edema, symptoms improved following administration of hydrocortisone and midazolam. Although the second case was a 63-year-old man who suffered with dyspnea as a result of direct aerosol insecticide inhalation due to missuse, symptoms had dissipated when the patient arrived at the hospital. The third case was a 20-year-old man with allergies who presented with dyspnea due to exposure to an aerosol insecticide three days after use. An allergic mechanism was thought to be involved. Reports of respiratory symptoms and allergic reactions caused by inhalation of pyrethroids are rare. Although the levels of exposure were low in all three cases compared to oral lethal dosage, these cases presented with serious respiratory symptoms, thus suggesting the need for further considerations regarding latent cases and safety.