Document BRQnpdZYwq5nKrOny9M0MwyKk

uc 149*2 INTERNAL CORRESPONDENCE UNION CARBIDE CORPORATION RECEIVED 1/c- AUG 1 5TS80- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - K N. Wheeler, Jr. 270 PARK AVENUE, NEW YORK, NEW YORK 10017 FTo (Nam#) * D Bess Division M Eisenhour Location Floor Number 511 515 ot August 14, 1980 Copy to Attached is a copy of a recent report prepared by the EPA Carcinogen Assessment Group (CAG) on vinyl chloride. The report and summary conclusion was directed to both Air and Water EPA officials. Please note the report concludes that exposure to 1 ug/m3 of vinyl chloride will result in the risk from lifetime exposure of 4.1 x 10-6. it has been my understanding that the EPA has set acceptable risks at a 1 x 10-6 level. LACimcc Attachment rjU/yV--* L. A.'Crisorio ucc 026232 N i Summary ana Conclusions Regaraing Carcinogenicity of Vinyl Chloride Vinyl chloride is a recognized human and animal car cinogen. Several occupational epidemiology studies in -V-. . ----- - ' highly exposed'workers have reported excess rates of liver .v- 'angiosarcoma .and ^tumors at other organ sites. Animal ex- periments using both inhalation and oral routes of exposure have also induced liver angiosarcoma. A water quality criteron based on a lifetime excess cancer risk of lu-5 iS calculated using the tumor incidence data from chronic rat inhalation studies. The validity of these incidence rates for humans was established, oy evaluating the cancer incidence in workers after * accounting for their exposure. The vinyl chloride intaxe was assumed to consist of only drinking water, and the bioaccummulation factor in fish was assumed to be l.u. With these assumptions, along with the assumptions common to other risk assessments, the -::;entration of vinyl chloride in surface waters must be less than U.53 mg/1 in order to result in an individual lifetime risk of less than lu_5. Participating Members Elizabeth L. Anoerson, Ph.D. Warren Hercules, b.S.E.E. pristine Hess, B.S. Charalingayya Hiremath, Ph.D. Robert Mcliaughy, Ph.D. Steven Miller, M.S. rs Wade T. Richardson-, J.D. Dharm Singh, D.V.M. Ph.D. Ruth Per tel , Ph, 0. Todd Thorslund, Sc. Adrienne Zahner, Ph U. D, Rpy{/-` Albert, M.D. .hairman JUL 14 1378 ucc 026233 h i g JAH 1978 SUBJECT: tanepdments to the Vinyl Chloride Standard FROM: Albert, Chairman far7innffon AceaccTnont TO: David Hawkins. Assistant Administrator for Air and Waste Management (AW-443) With regards^to your proposed amendments to the vinyl chloride standard, I believe that it is useful to keep two things in mind con cerning the possible human health risk. The first is that the average lifetime risk associated with the standard as currently set of 1 x 10"5 is relatively low with regards to. " lifetime risk associated with exposure to carcinogens for which regulatory actions have been taken (see Table I). While it is certainly desirable to reduce the risk from exposure to carcinogens to the lowest level possible, it will not always be possible to remove all risks completely. Therefore, I believe it serves a useful purpose to take a look at the relative lifetime risk from exposure to different carcinogens. The second point is that an "adequate margin of safety" might possibly be viewed as an extremely low probability that a person exposed to the standard for a full lifetime might possibly get cancer from this exposure. A similar approach to this has been adopted by the FDA, in defining a "safe" level for residues for suspected carcinogens in animal food stuffs as an average lifetime risk of 1 x 10"6o (or one chance in a million of getting cancer from a lifetime exposure to the residue (see attached copy of FDA Guidelines). Attachments cc: S. Gage M. James T. Just ucc 026234 '*1 AKjd UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON. D.C. 20460 i. 5 AUG 1978 OFFICE OF research and development SUBJECT: Vinyl Chloride Unit Risk Estimation FROM: Elizabeth L. Anderson, Executive Directo* Carcinogen Assessment Group TO: Jack McGinnity Strategies and Air Standards Division This memorandum is written In response to your May 19, 1978 request for our comments concerning the vinyl chloride unit risk estimation by George Wahl. We apologize for our delay. With minor differences we agree with Mr. Wahl's calculation that the risk from lifetime exposure to 1 ug/m3 of vinyl chloride is about 4.1 x 10-, with all the caveats necessary in explaining such estimates. However, we disagree with the calculation of relative risks on a ppb basis, as we explain below. In our previous memoranda we have arbitrarily used the density of dry air at 20C and 760 mm Hg pressure rather than at 25, as Mr. Wahl has done. For future reference the following table lists the ug/m3 equivalent of 1 part per billion of vinyl chloride and ethylene dichloride, where D(T) Is the density of dry air and Ma*28.8 Is the molecular weight of air. 0lT)xlG"=r (ug/ra3> VC EDC (M=99) 20 1.205 25 1.184 2.615 2.569 4.142 4.070 * ~u?Tn g " t h e "To riuTa-u g 7in3* ~T5-0TTT~m7M a / UCC 026235 We have no reason to prefer 20 other than the inconvenience of changing our previous estimates for other compounds. Using the 20'C temperature as the standard, the lifetime risk from breathing 1 ug/m3 of vinyl chloride is 1.5 x 10~4 x 70/2615 = 4.02 x 10-6, whereas for EDC the corresponding risk was found to be 7.2 x 10~6 or 1.2 x 10_s, depending on the method of calculation. Taking the higher of the two EDO risk values, the ratio of EDC to VC risks on a ug/m3 basis is therefore 1.2/0.402 = 2.99. To find the relative risks on a ppb basis, we note that for EDC the risk to 1 ppb is the same as the risk to 4.142 ug/m3, or 4.142 x 1.2x 10-5. Similarly for VC the risk to 1 ppb is the same as the risk to 2.615 ug/m3f 0r 2.615 x 4.02 x 1o~ Therefore the ratio of EDC to VC risks on a ppb basis is 4.142/2.615 x 2.99 = 1.58 x 2.99 = 4.74. This is larger than the relative risk on a ug/m3 basis rather than smaller, as Mr. Wahl's memorandum states. We would be happy to discuss this further if you wish. cc: W. Barber J. Padgett M. James