Document 6wD8BOO1RxDbnMy9qLVr6abgd

QUANTITATIVE RISK ASSESSMENT. FOR - - COMMUNITY EXPOSURE TO VINYL CHLORIDE - SUMMARY ' Vinyl chloride has produced liver angiosarcoma, a very rare form ' cf cancer, as well as primary cancers at other sites.and serious liver damage in workers employed in plants producing vinyl chloride monomer * - i, * (VCM) and polyvinyl Chloride (PVC). People living near these plants are also .at some risk of adverse effects due to their exposure to vinyl .* " 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 th^liver will occur- par- year duo 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 hetvieen 20 and less than one case per*year. The successful implementation of the regulations is expected to reduce ambient vinyl chloride'levels around piants to about 5 percent of current concentrations, and 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 average concentration of vinyl chloride over a five milevregion.surrounding the plants "is currently. 17 parts per billion. A'linear dose-response relationship extrapolated to zero , with no-threshold dose was assumed for these effects. The estimate of liver-angiosarcoma frequency was based on the available animal dose- . ..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 i ,w . by epidemiological studies of neighborhoods around-VC-plants, not only. * -1:... * i?. for liver cancer but other forms of cancer, .liver disease, and birth'.- - < i - defects. Suggestive evidence for an increased incidence of birth defects! ` *. : -.. has .recently been reported; An epidemiological stud^y .of -the.cancer.* .1 js ........... exneriftncft .around^VC plants has been-initiated but-atr'>ast`'one year_w111 ........... , be required-to.obtain some solid information. . .Complete copies of the risk assessment are available from Gary Robinson EPA-Press Office (202) 755-0344. j s 2-1 l-j nn o