Document XRVQZBRe0N4OrY4Yyj6EmrLzJ

VE X / ' -1. '> iy X7 /; ,-L~-7S n - C'/1? DEPARTMENT Or HEALTH, EDUCATION, AND V/ZLFARE PUBLIC HEALTH SERVICE ^ iN i FOP. O; 5 i A S " CO'iTflOL : .e jj1-\ .1 >i__ NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND WEALTH 5 600 FISHERS LANE ROCKVILLE, MARYLAND 20852 December 4, 1975 R&S 108052 Dr. A. Ross Adams Air Products and Chemicals, Chemicals Group Five Executive Mall Swedesford Road Wayne, Pennsylvania 19087 Inc. DtC 0 8 1975 j\ R.Q55 AD>4 V\S Dear Dr. Adams: We have received your letter of October 31, and it has been discussed among staff of the Bureau of Epidemiology and the National Institute for Occupational Safety and Health (NI0SH) of the Center for Disease Control (CDC). Our scientists may differ in their interpretation of particular studies in relation to vinyl chloride exposure and teratogenesis. They are, however, in complete agreement that while the issue is not yet re solved, the potential public health ramifications remain a cause for concern. (In reference to your letter, please note that we are speaking only of vinyl chloride monomer-VCM, and not of polyvinyl chloride plastic.) The points raised in your letter deal specifically with the issue of teratogenicity of VCM among humans. Neither the Infante nor the CDC study resolve the matter. Dr. Infante's study used available birth and fetal death record information and identified three areas with increased rates of central nervous system malformations. The CDC investigation followed up cases in one city and found no parental association between VCM exposure and plant employment. There also appeared to be no differ ences between cases and controls with respect to location of residence relative to the plant in Painesville. In this circumstance no association could be established with VCM. However, the sentence following the one you quote from the MMWR article puts this in appropriate perspective. It states, "This study clearly does not rule out the possibility that vinyl chloride may be teratogenic." Because of the small numbers of cases involved, there still might be an effect that was not detectable in Painesville. R&S 108053 Dr. A. Ross Adams Page 2 It is pointed out that the possible effects of VCM exposure also include mutagenicity. Mutagenesis and carcinogenesis are sufficiently correlated that demonstration of one is cause for concern about the other. The carcinogenecity of VCM in humans is well demonstrated via the NIOSH cohort mortality study and by various animal studies. There are also data to demonstrate VCM-induced transplacental carcinogenesis in rats. In the past yearj several reports have indicated that VCM is mutagenic via the microbial test system, and that VCM metabolities have induced mutations in the mammalian cells. Likewise, four independent reports from four different countries have shown an excess of chromosomal aberrations in lymphocytes of workers exposed to VCM as compared to controls. Thus, while no conclusive data are available concerning mutagenesis in the human setting, such animal and laboratory findings suggest a need for caution with respect to human exposures. From information at hand, therefore, sufficient grounds exist for advising men and especially women in child-bearing years that VCM exposures can lead to an increased risk. In the future, if the OSKA standards for work place are adherred to, and if the EPA emissions standards are promulgated, there should be less reason for concern about the effects of VCM inasmuch as these regulations should ensure greatly reduced xrorkplace exposures and even lower community exposures. Sincerely yours John F. Finklea, M.D. Director