Cardiac Toxicity of Aerosol Propellants

To the Editor.— Since the writing of my letter on "Aerosols and Aerosol Propellants in Asthma" (215:118, 1971), two new pieces of information which shed considerable light on the subject have come to my attention. Azar and his colleagues (above) noted one. Additionally, Dollery et al1recently reported that measurable amounts of trichloromonofluoromethane ( fluorocarbon 11) were demonstrated in the blood of human subjects. After 30 consecutive inhalations of a Medihaler aerosol propellant within two minutes, the amount of trichloromonofluoromethane in the blood was only one-hundreth of that obtained with halothane during stage three anesthesia. This comparison is signficant since halothane has a chemical structure similar to that of the propellants and the anesthetic agent is known to sensitize the heart to epinephrine. Dichlorodifluoromethane and cryofluorane (fluorocarbon 114) yielded amounts too small to quantify, but were said to be one tenth of the amount of propellant 11. It remains