Effects of fluorocarbon propellants on respiratory flow and ECG.

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Abstract
Ten subjects were exposed to the propellants Freon 11, Freon 12, Freon 114, to 2 mixtures of Freon 11 and 12 and to a mixture of Freon 12 and 114. The length of exposure was 15, 45 or 60 s. Maximum expiratory flow-volume (MEF) curves and ECG were recorded before, and intermittently up to 1 h after, exposure. Breathing level concentrations of propellants during exposure were determined by gas chromatography. All freons induced biphasic reduction of ventilatory capacity on inhalation. The first fall occurred within a few minutes of exposure while the second was delayed 13-30 min after exposure. The effects of mixtures were greater than those of individual freons. The relative fall in MEF 75% was more pronounced than that in MEF 50%. No clear-cut pathological changes in ECG were found. Nevertheless, most subjects developed variations in heart rate exceeding those noted before exposure. In a few cases inversion of the T wave, and in 1 case atrioventricular block, were observed.