CARDIAC SENSITIZATION TESTING OF THE HALON REPLACEMENT CANDIDATES TRIFLUOROIODOMETHANE (CF3I) AND 1,1,2,2,3,3,3-HEPTAFLUORO-1-IODOPROPANE (C3F7I)

Trifluoroiodomethane (CF3I) and 1,1,2,2,3,3,3-heptafluoro-1-iodopropan e (C(3)F(7)1) have been considered as replacement candidates for halon fire suppressants due to their excellent fire extinguishant capabilit ies and low ozone depletion potential compared to halon fire extinguis hants in use currently. As part of the process to develop environmenta l and health effects criteria for halon substitutes, a cardiac sensiti zation test was conducted in beagle dogs. Cardiac sensitization to adr enaline is a phenomenon associated with the inhalation of a number of unsubstituted and halogenated hydrocarbons. Adrenaline was administere d by intravenous injection before and during inhalation of the test su bstance. CF3I was administered to dogs at concentrations in air of 0.1 , 0.2, 0.4 or 1% v/v. At each of 0.4 and 1.0% CF3I, the first dog expo sed developed fatal ventricular fibrillation, and no further dogs were exposed at these concentrations. There was no cardiac sensitization a t 0.1 or 0.2% CF3I. For the C3F7I experiment, dogs were exposed to con centrations in air of 0.1, 0.2 or 0.4% v/v. At each of 0.1 and 0.4% C3 F7I, one dog responded with multifocal ventricular ectopic beats. Thus , CF3I and C3F7I are potent cardiac sensitizers in the adrenaline-chal lenged dog model.