Document 4v8n6xxqb5bgR3GyVyEr54Nqx

f Memorandum February 1, 1962 VINYL CHLORIDE Vinyl chloride (monochlorethylene) h&a been used and handled safely for many years In Industry, It Is gaseous at ordinary temperatures and has a weak sweetish odor. It has a very slight Irritating effect and Is narcotic In Its action. At one time It was suggested as an anesthetic agent. According to Schaumann^ the narcotic limiting concentration for humans Is 7*10 vol. % (70,000-100,000 p.p.m.), and above 12 vol. % (120,000 p.p.m,) It Is dangerous. After absorption, vinyl chloride Is eliminated very quickly and la not cumulative. In the published list of Threshold Limit Values for 1961 as adopted by the American Conference of Governmental Industrial Hygienists, 500 parts per million Is given as th concentration of vinyl chloride In air considered safe for an eight-hour exposure. Host of the studies of the toxicity of vinyl chloride have consisted of acute and subaouto exposures of small animals. These are not considered adequate as a basis for conclusions as to possible chronic effects, although human eases of chronic poisoning have not been reported. In some twenty-five years of experience In our own ehemloal indus try, we are not aware of any human poisonings due to exposur to vinyl chloride. ucc 063548 -2 A report on "The Toxicity of Vinyl Chloride as Determined by Repeated Exposure of Laboratory Animals" by T. R. Torkelson, F. Oyen, and V. K. Rove was published in the AMERICAN INDUSTRIAL HVOIENE ASSOCIATION JOURNAL (Vol. 22. No. 5, PP* 354-361, October, 1961). In this study groups of laboratory animals were exposed up to six months to either 500, 300, 100, or 50 p.p.m. of vinyl chloride in air. Detect able changes occurred at all but the lowest concentration. It is of interest that the only effect noted after dally seven-hour exposures to 100 p.p.m. for six months was a slight increase in the average weight of the rat livers. The effe ts noted in animals at 500 p.p.m. were only slight to moderate; growth, mortality, and general appearance were unaffected. The data presented in this article indicate that there is little likelihood of injury to be expected if repeated daily seven-to-elght-hour exposures are limited to 100 p.p.m. or less. Application as an Aerosol Propellant In the proposed application and usage as an additive to an aerosol propellant, the suggested mixture is 22% vinyl ehlorlde and 78jf of a 50/50 mixture of fluorocarbons 11 and 12. * The following calculation was made of an exaggeratod condition: A 16-ounee container of a hair spray would contain 70% of the propellant mixture, or 11.2 ounces. Of ucc 063549 3H this, 22Jf, or 2.46 ounces, is vinyl chloride. This corresponds to 67*618 milligrams. The entire contents are sprayed into a room of 15' x 15' x 9'* or 2,025 cubic feet, which equals 58,317.5 liters. 67*618 milligrams divided by 58*317.5 liters equals 1.1 milligrams of vinyl chloride per liter of air. 1 milligram of vinyl chloride per liter is equal to 391 parts per million, 1.1 times 391 gives 430 parts per million, the concentration of vinyl chloride in such a room. This concentration is very far below the 70,000 to 100,000 p.p.m. necessary to produce an anesthetic effect. It is below the presently accepted threshold limit of 500 p.p.m. In aotual use such a spray would be applied only in bursts and not continually. It would seem that there is a large factor of safety. Ylnyl chloride would not be a skin Irritant because . the liquid would evaporate rapidly if It were spilled on the ; akin. Its use in industry has not indicated It to be a ' ' causative factor in production of skin sensitisations* Since it is gaseous at normal temperatures, test procedures such as patch tests are not practicable. T. V. Hale, N. D. ucc 063550 -4 Reference X. X* B. Lehmann and F. Flury, TOXICOLOGY AMD HYOIXHX OF INDUSTRIAL SOLVENTS, The Williams k Wilkins Company, Baltimore, 1943# page 171. i-' Si, ucc 063551