Document reQwyDjMm9mE5ZO0NM3y2Labr

< INTON CARBIDE CORPORATION 'L;AemU*l 6 Plastics 270 Park Avenue, New York, New York 10017 to: (See Attached Distribution List) Date: July 2, 1974 From: Dfc. A,. B, Steele Subject: UOC Contribution to the SPI Presentation before the CSHA Hearing on Pro posed Standards for Occu pational Exposure to Vinyl Chloride______ Many of you have contributed ideas and data In support of the position taken by the Society of the Plastics Industry; namely, that the actual human ex perience in the 36 plants operated in the United States in the manufacture, of Polyvinyl chloride resins does not identify vinyl chloride as a material that impairs worker health when reasonable limits are imposed on its concentration in the workplace air. The industry's position was strengthened significantly by the testimony of our Dr. Carl U. Dernehl, who summarized the finding of no case of angiosarcoma of the liver among some 1,402 men working in 32 FVC plants even though their exposure time was sufficient for disease to have occurred and expo sures were believed to have been in excess of 50 ppm on a time weighted average. Appended for your reading and reference, please find a copy of the text submitted to SPI on the matter of industry experience as compiled and analyzed by us on behalf of SPI. ABSrml Attachment A. B. Steele UCC 090667 stm.ment o n-c !';>.OL!ua;u3 in ti:e united states relative to health cxpekifnm: oi~ worm:ns tn piants rni.VMEiuzTNc vrxvL chloride Sl'VN'RY The Department, of Labor has imposed major restrictions on the exposure levels of workers in the VCM anJ PVC industry based on a possible connection between vinyl chloride exposure and deaths of a limited number of workers from angiorarccmw-a rare form of liver cancer. The Department's regulation on vinyl chloride limits in the workplace air is based, in part, on the findings of several scientists who report that vinyl chloride exposure in mice and rats f causes cancer. Because animal, data are unreliable in measuring impact on man unless the test animal and man have been shown to have similar metabolic pathways and as such del-a have indicated a hazard from vinyl chloride exposure far greater than chat generally .experienced by workers and technicians in individual vinyl chloride monomer and polymer plants, a study was initiated to determine the actual experience in all operating plants within the United States where workers have l>otn exposed to significant concentrations of vinyl chloride in the work place air over extended periods of time. Reconstructions of past frequencies levels of vinyl chloride exposure have been correlated with recent and cur rent experience in 36 plants manufacturing PVC resins. The health status of individual workers has been determined by extensive medical examination and the cause of death of all PVC workers has been tabulated. Based on these evidences, we conclude; - that there is no significant impairment of health to workers exposed to restricted amounts of vinyl chloride monomer for extended time periods, - that exposures to high concentrations for short periods do not impair health; hi^h concentrations being at or above the odor level of 230 - 300 ppm. UCC 090668 that an cight-h ur time-weighted average (TWA) of 50 ppm represents a realistic exposure limit; at higher levels respiratory protection is appropriate. (2) r UCC 090669 *_ t (3) RELEVANCY OF ANTMM- TOXICITY DATA Extrapolation of animal toxicity data directly to man is fraught with gross uncertainty without prior knowledge of the manner in which man metabolizes the compound. Thus, in the case of vinyl chloride monomer, the finding of angiosarcomas in mice and rats should not be considered pertinent to man until it is demonstrated that rodents metabolize vinyl chloride in a manner and at a rate similar to man. While methods have been established for the determination (1) of metabolites in man and rodents , such experimental procedures have yet to / be applied to vinyl chloride, leaving in serious doubt the relevancy of the animal test data that are used to brand vinyl chloride a carcinogen in man. Because vinyl chloride Is a carcinogen for rats and presumably even a more potent one for mice does not mean that the same rapid induction can or will (2) ccur in man. The evidence provided by the industry survey in itself is evidence that very few men have been involved to date*. Witness more than thirty years of manufacturing experience with only limited cases of angiosarcoma among more than 1500 workmen variously exposed for 15 years or more. Additionally, no case should be charged solely to vinyl chloride exposure if the victim has a his tory of exposure to other chemicals. (1) In vitro vs in vivo chromatographic profiles of Carbaryl anionic metabolites in man and lower animals. Sullivan, L. J., B. H. Chin and C. P. Carpenter. Tox. Appl. Phnrm. 22: 161-174 (1972). (2) Deringer, M. K. - Journal of National Cancer Institute; 12_, p. 437 - 445, October 1951. (3) EPIDEMIOLO 'ICAL STUDY OF VINYL CHLORIDE WORKERS - FINAL RETORT - May 3, 1974; Tabershaw-looper Associates Berkeley, Calif, for Manufacturing Chemists Association. UCC 090670 LEVELS OF VTNT,,L CHLORIDE EXPOSURE TN PVC OITRMTON'S Experience within the PVC industry generally has shown that workers ex posed to vinyl chloride have maintained health status comparing .favorably to that of workers in other chemical and resin operations and to other industrial populations, yet the PVC workers have been exposed to significant concentrations of vinyl chloride in the workplace air over extended periods of time and to con centrations well in excess of the limits now imposed on the industry by the pre sent .temporary OSHA standard of 50 ppm ceiling level. Attempts to^ quantify the levels of exposure to which workmen were subjected in past years on each job and in each plant had to be abandoned because reliable measurements of vinyl chloride levels in the workplace air over extended periods of time are generally not avail able. However careful examination of certain plants and of their operating data has provided insight into the vinyl chloride exposure levels of workmen in speci fic assignments. Case studies have been documented and support the view that there is no discernible impairment to health of workers exposed either to restricted amounts of vinyl chloride for extended time periods or to high concentrations for short periods. UCC 090671 / (5) The solvent process as operated by Union Carbide has remained essen tially unchanged as to process, recipe, equipment and operating procedures since about 1951. It Is the testimony of those closely associated with the plant op eration that vinyl chloride emissions are presently of th same order of magni tude In the Solvent polymer plant as has been experienced regularly over the ** past twenty years, Purthermore, measurements of vinyl chloride monomer In the workplace air and of exposure of operators to ir.onoraer made recently are represen / tative of the continuing condition since 1953 in which significant and frequent xcuraions beyond the 50 ppm ceiling standard were experienced as determined by detection of vinyl chloride odor (250 - 300 ppm VCM assumed as the odor thresh- hold. Recent determinations (January and February, 1974) identified the fol lowing VCM exposures to operators in the polymerization section of the plant: Operator Number 1. 2. 3. 4. 5. 6. Time' V.elghted Average - PP.-t - ? uour 16.9 9.8 23.6 3.5 4.8 21.3 ttie of the tasks assigned to these operators is the taking and testing of autoclave samples to determine degree of conversion. During sampling and testing, which occurs four times each shift and requires about eight minutes to complete the cask, workplace environmental levels range as high as 400 ppm UCC 090672 V* . ` , (6) >< tn the sampling area. Exposure time has been gathered on all employees working this job at the Texas City plant from 1948 to the present. There were 53 such employees; 24 had more than 1 year work experience on this Job; 2 employees had 12 years *of exposure. None of these have liver abnormalities, based on recent medical evi- dencc. At South Charleston where a similar line is operated with almost iden 0tical exposure levels, a similar breakdown on operators is not available due to differences in job dynamics. Nevertheless, health of PVC workers 'is statis tically similar to that of other workers in the same plant and no case of angio sarcoma has been identified among these operators. UCC 090673 CASE STUDY -- IMPROVED CONVF.U3ION OF VINYL Cl'LOUT:')- YJ-rOMER in pvc suspees ior: and pvr ptspcksmw r.,"i:nATio;;s The economic realities of the VCM resin business since 1965 have forced all resin producers to seek improved efficiencies in conversion of VCM to PVC through modification of operating procedures and plant facilities. Increases in monomer efficiency (Polymer/Konomor Cr-xrged >: 100) from 85 per cent in 1968 to 96 per cent in 1974 in suspension io.:in manufacture are documented. Improved machinery for recovering VCM from vapo.-s released in ven ting and stripping sections is estimated to have accounted for more than half of the Improvement. Similar improvements in monomer efficiency within the PVC dispersion resin process have been recorded; i.e. 787. in 19uS increasing to 91 per cent in 1973 is representative of the improvement. I'hile such increases in monomer efficiency were oriented toward economic consideroti.-rs, reductions in monomer lost to the air lessened the amount that emitted to era workplace at mosphere . Graphs A and B record the annual improvements being achieved in mono mer efficiency in polymer production of both suspension and dispersion resins. Recent measurements within both FVC suspension and dispersion operations established that maximum VCM levels in the workplace air pereximated 30 ppm TOA (eight hour) at a ceiling of 45 ppm. Based on the known i:iprevement in monomer efficiency, it is certain that the VCM levels in the workplace environment in 1974 are below those of prior years when recovery was less efficient; and that PVC workers in the prior years wore exposed to significantly higher concentrations than is presently experienced. The employee health records of workmen operating in the majority of the plants where the data show a significant and continuing reduction in VCM losses from the experience of 1967 show no measurable deterioration in the health of the workmen exposed during this period. ucc 090674 POLYVINYL CHLORIDE DISPERSION RESIN OPERATIONS V INYL CHLORIDE EFFICIENCY TOTAL P 0 LY \A E R / f/` 0 N 0 i .1 E R CHARGED X 100 EFFICENCY PER CENT UCC 090675 POLYVINYL CHLORIOE SUSPENSION RESIN OPERATIONS VINYL CHLORIDE EFFICIENCY TOTAL POLYfuER/MONOUER CHARGED X IOO PE R CENT ioor ESTIMATED 90 -- 85 ucc O SoO 75 iV-L 1963 1969 19 70 JL 1971 19 72 JL 1973 J, 1974 OS