“…These studies link arrhythmias to "epinephrine sensitization," in which the myocardium's transmembrane electrical milieu is altered by the halocarbon to become more sensitive to catecholamineinduced arrhythmias. Although many fluorocarbons alone can cause arrhythmias at high exposure levels, some fluorocarbons produce serious arrhythmias in mammals at exposure levels as low as 5,000 ppm, when combined with intravenous epinephrine at tachycardia-producing doses [Reinhardt et al, 19711. There have been several cases of presumed cardiac sudden death with workplace exposure to these chemicals, especially to CFC 1 13 (1,1,2-trichloro-l,2,2-trifluoroethane), and 1 , l , l -trichloroethane [Hatfield and Maykoski, 1970;Jones and Winter, 1983;May and Blotzer, 1984;Lehmann, 1980;Yonemitsu et al, 1983;Clark et al, 1985;NIOSH, 19891. In addition, the widely used fire extinguishing agent, halon 121 1, has caused sudden death when abused for recreation and, most recently, when used to extinguish a fire in a confined space [Smeeton and Clark, 1985;Steadman et al, 1984;Lerman et al, 19911.…”