Document p8Dez9RNKrNKrKQ2py211R0E

F/*L QUANTITATIVE RISK ASSESSMENT FOR COMMUNITY EXPOSURE TO VINYL CHLORIDE SUMMARY Vinyl chloride has produced liver angiosarcoma, a very rare form of cancer, as well as primary cancers at other sites and serious liver damage in workers employed in plants producing vinyl chloride monomer (VCM) and polyvinyl chloride (PVC). People living near these plants are also at some risk of adverse effects due to their exposure to vinyl t chloride in the ambient air near the plants,- Should the environmentally exposed population be the same size as it is now, and should it remain exposed to current level of vinyl chloride, we estimate that between less than one and ten cases of angiosarcoma of the liver will occur per year due to environmental vinyl chloride exposure. Due to the 15 to 20 year latency time of this disease, cases initiated this year will probably not be diagnosed until 1991 to 1995. In addition we estimate that an equal number of cancers at other primary organ sites are being produced by vinyl chloride each year, bringing the total number of cancer cases to somewhere in the range between 20 and less than one case per~year. The successful implementation of the regulations is expected to reduce ambient vinyl chloride levels around plants to about 5 percent of current concentrations, ana1 consequently to reduce the frequency of adverse health, effects to 5 percent of the foregoing rates. These estimates are based on several considerations, From 1970 census data, it was estimated that 4.6 million people live within five miles of the plants affected by these regulations. Standard methods of diffusion modeling showed that the averageconcentration of vinyl chloride GENC 013654 over a five mile region surrounding the pi ants.is currently 17 parts per billion'. A^ linear dose-response relationship extrapolated to zero with no threshold dose was assumed for these effects. The estimateof liver;angiosarcoma frequency was based on the available animal dose- 1 response.information from controlled.experiments and on the available-. . information on adverse effects in highly exposed workers in the industry. The above estimates of the incidence of liver cancer involve a substantial degree of uncertainty. These estimates should be validated ' 1 5 by ep.idemioiogical studies of neighborhoods around VC plants, not only * I .rf t -w r ; . for ;Tiypr-cancer but other forms of cancer, liver disease, and birth ;-. "vi.-r di's defects-.--Suggestive evidence for an increased incidence of birth defects" : "cf sic NhaSi^ecently been reported. An.epidemiological study of the cancer ::: , i,, .i j experience., around VC plants has...been-initiated .but, at. least-one-year~wU1~. be required to obtain some solid information. 7^ Complete copies of the risk assessment are available from Gary Robinson EPA Press Office (202) 755-0344. ^ Qp/is .-C-cP /2 JbtC K. vr *''6- ' --'"V 'ZZ-lr; GB'C 013655