Cardiac Toxicity of Aerosol Propellants

To the Editor.— Taylor and Harris 1 recently reported experiments which they interpreted as demonstrating that the fluorocarbon propellants used in asthma inhalers produced a toxic effect on the heart of anesthetized mice, which could explain sudden deaths in asthmatics and which casts doubt on the safety of other aerosol products. We believe that their findings may be explained on a physiologic basis which is related to the asphyxia rather than a specific chemical cardiotoxicity, and we believe that deductions made in the paper about the safety of other aerosol products therefore are open to question. The cardiac toxicity of the propellants was demonstrated by Taylor and Harris in the following manner. Mice anesthetized with pentobarbital sodium were exposed to the inhalation of an unknown but presumably very high concentration of the propellants for a few seconds. Following this, their heads were enclosed in a tightly fitting plastic bag. These