Comparative effects of insect repellent N,N-diethylbenzamide, N,N-diethylphenylacetamide, and N,N-diethyl-3- methylbenzamide aerosols on the breathing pattern and respiratory variables in mice

Abstract

Comparative inhalation toxicity studies of aerosols of insect repellents N,N-diethylbenzamide (DEB), N,N-diethylphenylacetamide (DEPA), and N,N-diethyl-3-methylbenzamide (DEET) were carried out in mice. The respiratory pattern was monitored using a computer program that recognizes the modifications of the breathing pattern. Exposure to the aerosols caused a dose-dependent decrease in normal breath, with an increase in airway obstruction. All the three insect “sensilla irritants” showed no significant mammalian sensory irritation. The acute LC50 value for a 4-h exposure of DEB, DEPA, and DEET aerosols in male mice was found to be >2.5 g/m3, 1714 mg/m3, and 1369 mg/m3, respectively. Irreversible depression in respiratory frequency was observed after exposure to DEB aerosol at a concentration of 277 mg/m3 and above, which did not revert back to normal level even after aerosol exposure was stopped. At a concentration of 156 mg/m3 of DEB, no respiratory depression was observed. DEPA and DEET caused no depression in respiratory frequency up to a concentration 1292 and 950 mg/m3, respectively. Hence the two insect repellents DEET and DEPA do not cause any harmful effect to the respiratory parameters in acute exposure, showing that they are more suitable chemicals to be used as insect repellents as compared to DEB.