346 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Shepherd's view 7, that small quantities of vinyl chloride have an anaesthetic effect, could not be confirmed. Like Hoffmann 8, no reference to the litera- ture was given. The anaesthetic concentrations of fluorohydrocarbons 11, 12, 113 and 114 have been examined by Scholz 9. Rats and guinea pigs were exposed to increasing concentrations by volume, with the air circulating in a closed room. Carbon dioxide was absorbed, and the oxygen content was kept at a constant level. Rats and guineapigs behaved differently. Table 2 Anaesthetic concentrations for rats _Propellant Condition Concentration Time % minutes 114 G 30 120 1N 50 120 tN 60 120 T -- -- -- 12 G 30 120 1N 50 60 tN 60 60 r -- -- 113 G 10 30 1N 15 15 tN 20 20 T 20 45 11 G 5 40 1N 10 20 tN 10 90 T 20 5 G - disturbance of equilibrium 1N - slight anaesthesia tN- deep anaesthesia T - death. According to Scholz these results just about agree with American data. In addition, propellant 11 was compared with chloroform and carbon tetra- chloride. With cats, already an exposure for one hour with approximately 1.5% chloroform and approximately 2% carbon tetra chloride has a lethal effect with propellant 11 an exposure with 10% by volume for one hour is necessary in order to obtain a lethal effect. Scholz also explains, that such high concentrations (by volume) which were used for these tests, are not achieved when spraying from pressurized packs. In any event, mixtures of propellant 11 and 12 are mainly used. The tests carried out in the Battelle Institute confirm this insofar as a mixture of 2.5% by volume of propellant 11 and 2.5% by volume of propellant 12

PHYSIOLOGICAL PROPERTIES OF PROPELLANTS 347 did not cause any disturbance of the equilibrium in the test animals. Finally, inhalation tests were carried out by Scholz in currents of mixtures, with concentrations which did not cause the stimulating conditions which precede anaesthesia. With 114 and 12 this concentration amounted to 10% by volume, and with 113 and 11 to 2.5 or 1.25% by volume depending on the animal group. The blood and urine controls showed no change, nor did the liver show any signs of degenerative changes, as opposed to exposures with 0.25•o by volume of chloroform. While carbon tetrachloride should be rejected because of its high toxicity, and the importance of chloroform, a highly toxic solvent and anaesthetic agent, decreases, it is evident that a partial replacement of C1 by F atoms considerably reduces the toxicity of a substance. The anaesthetic and toxic properties are affected not only by the number of C1 atoms but also by the human absorption capacity and by the metabolic rate. The methane derivatives, as far as they are not fluorinated sufficiently, are more toxic than the ethene and ethane derivatives. Methyl chloride is more toxic than ethyl chloride and methylene chloride, although it contains only one C1 atom. Trichloroethylene has a greater anaesthetic effect than tetra~ chloroethylene, but neither surpass chloroform and carbon tetrachloride. The higher chlorinated ethanes are also more toxic than the ethenes. Vinyl chloride, another ethene derivative with only one C1 atom, is indeed the most harmless derivative of a chlorinated hydrocarbon. It is therefore possible to state that propellants 11, 12, 113, 114 and vinyl chloride will not cause any definite injuries to health, in the con- centrations obtained during the spraying of pressurized packs. The MAC values, and the classification into toxicity groupings permits the conclusion that the same is true for propellant C318, and for propane, butane and isobutane. We have no data on the inhalation compatibility of gaseous hydrocarbons, and we only know that the MAC values of the low molecular hydrocarbons is 100, and of the higher ones 500. INHALATION It is recommended that the general directions for the handling of pressur- ized packs should include the legend: "Do not spray into an open flame," because toxic gases can be formed during the thermal decomposition of halogenated hydrocarbons. This was investigated at the Battelle Institute, with propellants 11, 12, 114, vinyl chloride, and methylene chloride. The amount of carbon monoxide and phosgene, formed between 100 and 1000øC, and the amount of HC1, formed at 1000øC, were determined. The values for propellant 11 and for methylene chloride were derived from the results obtained with 11/12 mixture and with methylene chloride/12 mixture (both 50: 50% by weight).