US EPA

8592496 

Journal Article 

Impurities in halothane and decomposition of halothane by soda lime. IV. Summary and conclusion (Japanese) 

Kodama, G 

1974 

9 

2 

43-46 

Japanese 

Gas chromatography and mass spectrography were used to show that when halothane vapor was repeatedly passed through soda lime, it was converted into difluoro 2 bromo 2 chloroethylene (CF2 = CBrCl) and 1,1,1-trifluoro 2 chloroethane (CF3-CH2Cl). A summary report has been published by Raventos with regard to the former but no consideration has yet been done on the latter product. Using a closed anesthetic circuit connected to a dummy lung, these 2 components were measured over 6 hr. CF2=CBrCl, rapidly increased during the initial 2 hr to reach a plateau in 6 hr of approximately 150 ppm. In the clinical concentration of 1-3% halothane, its concentration in the anesthetic circuit was estimated to be 1.5-4.5 ppm, and CF3-CH2Cl at 0.4-1.2 ppm. Based on the study of literature regarding the toxicity of these 2 compounds it was considered that the toxicity of these 2 compounds at the estimated clinical concentration was of the low level. It is well known that halothane is metabolized in the body and further it is expected that the impurities of halothane and the decomposed products by soda lime are subjected to change in the body. The chronic inhalation of halothane by nurses and anesthetists serving in the operating room has been reported to have a higher rate of halothane decomposition. A review of the literature was made on the possibility of the non volatile products being accumulated in the body. It was concluded that consideration should be made to develop an anesthetic device which prevents personnel in the operating room from inhaling impurities of halothane, decomposed products by soda lime and volatile components decomposed and metabolized by patients.