Simulated blood levels of CF3I in personnel exposed during its release from an F-15 jet engine nacelle and during intentional inhalation.

Of the agents under consideration for protecting unoccupied areas from fire, CF3I (trifluoroiodomethane) has physicochemical properties that give it potential as a "drop-in" replacement for halon 1301. One of the issues concerning the use of CF3I is the potential hazard to ground crews should an inadvertent discharge occur while workers are in or near an engine nacelle. A discharge test of CF3I was conducted on an F-15A jet to record CF3I concentration time histories at locations near the aircraft. The conditions of the discharges simulated an inadvertent ground discharge with the engine nacelle doors open and also with the doors closed. The use of three types of gas analysis instrumentation allowed gas sampling from several locations during the discharge tests. Concentrations measured at selected sensor locations were used as the input to a physiologically based pharmacokinetic model to simulate blood levels that would be attained by individuals inhaling CF3I at sensor locations. Blood levels reached during these exposures were compared with the blood level associated with the lowest observable adverse effect level (LOAEL) for cardiac sensitization to evaluate the possibility of safe egress. The highest blood concentrations simulated were twice the target blood concentration associated with cardiac sensitization. However, simulated blood concentrations of subjects who actually inhaled CF3I reached levels that were 100 times the target level without reported adverse effect. Thus, actual human data may supersede the use of the cardiac sensitization LOAEL obtained from animal studies.