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Vinyl Chloride Cytogenetics Dante J. Picciano, Ph.D.; Ray E. Flake, M.D.; Peter C. Gay, M.D.; and D. Jack Kilian, M.D, This report presents cytogenetic findings from a group of 209 workers employed for up to 28 years in the manufacture of vinyl chloride monomer at the Texas Division of Dow Chemical U.S.A. Cytogenetic evaluation results from this group were compared to results found in examination of individuals being considered for employment. Statistical analyses were per formed on a group basis for chromatid aberrations, chromo some aberrations and proportion of abnormal cells; no statistical difference of significance was found between the two groups. Comparison of these results with reported studies suggests that the level of cytogenetic aberrations in vinyl chloride workers is probably related to the length and level of exposure, and that risk of adverse genetic effect can be avoided in cohtrolled, minimal-exposure environments. Vinvl chloride 'VC' has been reported to be carcinogenic in animals' ; and human beings' and mutagenic in bacterial test systems 4 1 " There have been reports of increased frequencies of chromosomal aberrations m workers exposed to vinvl chloride at polvvinvl chloride PVC*1 *fa*cilities 7 9 '4 Similar increases were not found upon cytogenetic evaluation of German PVC workers'" nor in our own preliminary investigation of a group of American VC workers " One study based on interviews with male employees has indicated an increased rate of fetal wastage among wives of VC-exposed workmen involved in polymerization operations We have recently completed cytogenetic evaluation of all currently-employed workers exposed to vinyl chloride at the Dow iFreeport) Texas Division Both vinyl chloride and vinylidene chloride are produced in this plant Vinylidene chloride has also been reported as mutagenic in bacterial test systems " However, while these Dow workers are involved with the production of both rompounds, the degree of contact with vinylidene chloride is rar less than the exposure to vinvl chloride from Oi s updfmn.il Health and M^du a\ Research Dow US \ Drs P_- i > ,md Xitijri' and Department or industrial Medicine Dow Chemical USA Tdxas Division Drs Flake and Gw Freeport TX '7541 Material from this report was presented at the 5th International Congress or Human CenetK s Mexico C'Cv October 10-15 1976 Vinyl chloride monomer has been produced at the Texas Divi sion of Dow Chemical U.S A since 1948. There are no vinyl chloride polymerization operations Average exposure levels, as is the case for almost all vinyl chloride monomer plants, have been generally lower than those reported for facilities involved in polymerization operations 11 Although the threshold limit values tor vinyl chloride had been 500 parts per million (ppm) untH 1974, Dow had established a goal of 50 ppm or below in 1959." The current Occupational Health and Safety Administration (OSHA) standard for vinyl chloride is one ppm as a time-weighted-average over an eight-hour workday. We have found that the TWA con centration of vinyl chloride for all VC-related job classifications was approximately 5 ppm from 1968 to 1973; in 1974, TWA con centrations were 1 to 2 ppm. Since 1975, average levels of expo sure have been lowered to less than 1 ppm Estimates of average exposure levels for the years prior to 1968 are less reliable. For the purposes of this study, estimates of exposure were calculated for specific |ob classifications, based on records of both personnel and area monitoring (Table 1), However, actual exposure may vary from individual to individual within the same job classification and accidental, short-term exposures of some workers to concentra tions in excess of the standard probably occur from time to time Documentation of such incidents is difficult Methods Our study group was composed of 209 workers who had worked in the vinyl chloride plant for periods ranging between one and H2 months (average, 48,3 months) at the time of this in vestigation As part of the medical surveillance program for this group, peripheral blood samples were obtained, and evaluation of lymphocyte chromosomes was performed. Lymphocytes were cultured using a modification of the Moorhead technique.'1' Stan dard procedures, as previously described,17 were used for incuba tion, processing, and analysis. Findings were compared to cytogenetic data from a group ot 295 "preemployment examinees'' who had chromosome evalua tion done as part of routine preemployment examination and who, at that time, had no known exposure to chromosome-break- ftaprlnted from Journal of Occupational Madlcina Aufluat. 1977. Voluma 19 No 8 pp 527-530 SL 101684 DA Chromosome oreoarat on' y ei;ko<^r*-`s < ultured Tom hurTi.in peripheral blixjd >Lx/> L-'k' kc- 20 6'1 nib i960 1" Kili.in Dl and Pm t 'ano D ( vfogenetn surceillanc e nr industrial oonulations In Chomuli Mu(.iy'>ns Pom m/ts jnd Melons -nr ?h'<r ,'Vm< non Vol 4 New York A Hollander ed Plenum Press 19~6 f>p 121'519 18 Funes-Oavioto ef al Reference ~ 19 Ducatman or .tl Reference 8 20 He<g & Thiess Reference 10 21 'urchdse ef ll Reference 0 22 v an et al Rererent e 11 21 Court Rrown WY Human population cvtogenetu s In Frnmmps nt Bioioqv Vol V A Neuberger and EL Tatum eds North Holland Publishing 1967 pp Ml 24 But kton KF lacobs PA, Court Brown WM and Doll R A study of chromosome damage persisting after x-rav therapv tor ankylosing spon dylitis Lirtrcr 2 676-682 1962 21 Bloom AD, Nakagome Y, Awa AA, and \ernshi S Chromosome aberrations and malignant disease among A-bomb survivors Amer / Pub tilth 60 041-M4 19~0 26 A augnan I Bone disease induced hv \tdiat on mf M - o> `n?rK 1 24 }-)96 1%2 2, Fisih*'r n fjMloh E kun.m-'viuhl E Haim AB et ii t.hr-imi ki imi* aberrations in ;*`riphepa| bl'xni cells in man tmlowng ' hr-mu > i ioiti,sn from 'nt^mal deposits of rhoroiMst P jiii.y Re- 29 101-'!! 28 Gama ' hana R Umh ("H Alvarez M \nci sane nez cl ` hren-'.^i-m*' inahsis m males -x t uoarionallv exposed tl} lead Ahern* t GD n ' f rac `' V Yjfe'naeor'a:' r'oog'esv . t Htimm f 7< ,'-t ' ^ s Aimtmo m s mo R lisker erjs Exc orpta Medic a Amsterdam 19*6 29 Sampson R| Ke\ CR Bunt her CR and h|ima A Thtroid < ir< <noma >n Hiroshima and Nagasaki I Prevalence of rhvrotd carcinoma at autoD'V Hiroshima 19S",-6fi, Nagasaki 1911-67 ABCC 7cm hnu il Reooo 21 68 N6rt 10 Muller |, David A Repkova M and Brezikova D Chrome occupation al exposure to strontium-90 and radium-225 Eancw 2 129-111 l%1 31 Fischer P Golob Kun/e-Muhf E and Milliner 7 Chromosomal aberrations in thorium dioxide patients Ann \Y Ac id Sc c 145 "'69-*''^ 1967, SL 101685