Document J3EMpDyJ6aMReLqy76y2jpzXO

r.VVIKONMKNI.M- (ttSKAKf.ll 14, 68 - 72 (1977) L/d O00OS73 #/37- Chromosomal Damage in Men Occupationally Exposed to Vinyl Chloride Monomer and Other Chemicals Clark W. Heath. Jr., ash Chkkvi. R. Dlmoni Cuncer and Birth Defect* Division, Burcm of Epidemiology, Center for Disease Control. J'tihlic Health Service. U.S. Department of Health, E,location, and Welfare. 1600 Clifton Hoad. N.E., Atlanta. Georgia 30JJJ John Gamule Occupational Health Studies Group, University of North Carolina at Chapel Hill. Chapel Hill, North Carolina 27? Id AND J.Richard Waxwkiler National Institute for On upationtd Safety and Health. Center for Disease Control, Cincinnati, Ohio -45226 Received July 14. 1976 INTRODUCTION Data from various sources suggest that the biologic effects of vinyl chloride monomer (VCM) include mutagenicity as well as oncogenicity. Pertinent studies include observations concerning the mutagenic effects of VCM in bacterial test systems (Rannug et at.. 1974; Bartsch et al., 1975), mutagenicity of VCM metabolites in mammalian cells (Huberman et til., 1975), and cytogenetic studies of polyvinyl chloride (PVC) polymerization workers (Ducatman el til., 1975; Funes-Cravioto, el al., 1975; Kilian et ul., 1975; Purchase et til., 1975). Also relevant may be observations suggesting increased fetal loss in families of PVC workers (Infante el al., 1976). Among the several cytogenetic studies reported, three have suggested increased chromosomal breakage among polymerization workers (Ducatman el til.. 1975; Funes-Cravioto et al.. 1975; Purchase et al,, 1975), and one has not (Kilian et al., 1975). This report concerns cytogenetic analyses conducted on workers employed at a rubber and plastics plant, some exposed to VCM and others not. MATERIALS AND METHODS The work described here was part of a cross-sectional study designed to provide multiphasic medical screening data on the health status of men employed at a large rubber and plastics plant. The overall study was conducted jointly by the Center for Disease Control (CDC) (National Institute for Occupational Safety and Health and Bureau of Epidemiology) and the Occupational Health Studies Group of the University of North Carolina in cooperation with the Firestone Corporation and the United Rubber Workers. Results of the entire study, together with a detailed description of the study's design and methodology, will be published separately. Cyto t chromo 3J re: inen; sp 1975 (2 sively ei FVC po 4 in PV munufnc CO ' --l --k ii 11 00U007 ii :s id history i VI records. Initially , the St exposed to VCf analyses showed was selected (Ap directly to any I; pared in the san workers at the t between April 1 VCM and indus worker slides. B industry control from the first re; dines (Moorhctu phytohcmaggluti Frequencies t Levels of break, were significant the P <0.01 leva At the same tinu groups themseb months worked not vary signific An effort was hence extent of was seen for int he is and been us No gradient wu iiicnt or of cmpl too small to pei Chromatid g; Simitar types c groups. When revie' (of>)rrhf ii/ l*J77 by I`re*s, Lk, All rights nf rcftrtKioi'iMn m .my furm reserved. 68 ISSS lull* 30 U> 00 00 d ii o> n\i use : W'ritarc. '.-I nm Gnyl chloride : iment studies bacterial lest city of VCM ivnetic studies rf L, 1975; . 1975). Also 'lilies of PVC dies reported, oivmerization chase ct at., cytogenetic - plant, some rd to provide * cd til ti la rye n the Center it and Health Gioiin of the porntion and oh a detailed i separately. I'NS i*H MUi jj i CHROMOSOMES AND VINYL CHLORIDE 69 i i Cytogenetic analyses, primarily designed to measure frequencies of chromosomal breakage, were performed on peripheral blood lymphocytes from 35 met;; specimens were obtained from IS men in October 1974 and 19 in January i 1975 (3 on both occasions). Subjects were restricted to men primarily or exclu sively employed for 10 years or longer, in 3 different employment categories: 14 in PVC polymerization (presumed high exposure to VCM, intermittent or sustained). 4 in -PVC processing (presumed low exposure to VCM), and 17 in rubber tire manufacture (industry controls; presumed negligible exposure to VCM). Work history details were obtained by interview and confirmed by review of company records. Initially, the study was designed to compare breakage frequencies in workers exposed to VCM with frequencies in other workers. However, when initial analyses showed no significant differences among worker groups, a control group was selected (April 1975) consisting of four male employees at CDC not exposed > t directly to any laboratory chemicals. Material for cytogenetic analysis was pre jjy pared in the same manner with the same reagents as the earlier material from workers at the plant. To assess comparability in microscopic reading of slides between April 1975 and the earlier dates, previously read slides from the high VCM and industry control groups were blindly interspersed among the CDC worker slides. Breakage frequency recorded on the second reading of high VCM/ industry control slides (6.0% of 150 scored metaphases) did not differ significantly from the first reading. Cytogenetic material was processed using standard proce dures (Moorhead et /., 1960). Cells were cultured for 72 hours in the presence of phytohemagglutinin. Giemsa staining was used without banding. RESULTS Frequencies of chromosomal breakage in each group are shown in Table I. l evels of breakage in all three industry groups, whether exposed to VCM or not, were significantly increased over the CDC control level, the high VCM group at the P <0.01 level, the low VCM and industry control groups at the P <0.05 level. At the same time, no significant differences were noted between the three industry groups themselves. Groups were comparable in terms of age and number of ) months worked. Breakage frequencies for individual subjects within groups did a not vary significantly one from another. An effort was made to relate levels of breakage to duration of employment and l hence extent of potential toxic exposure (Table 2). While a significant gradient i was seen for industry controls, interpretation is uncertain because of small num bers and because the mean age of subjects increased with employment duration. No gradient was seen for the high VCM group, whether in terms of total employ ment or of employment in contact with VCM. The low VCM exposure group was too small to permit analysis by exposure duration. I \5 Chromatid gaps comprised the majority (86%) of aberrations seen (Table 3). Similar types of aberrations were seen with similar frequencies among all four groups. DISCUSSION When reviewed in terms of comparisons between worker and nonworker tJ \ [ j I /t I i (, j ii ; i-t s * 70 HEATH ETAt.. TABLE I I.I.VHJ Of C'llkOMOSIIMAI. Hut AK Vf IIV KvilIM Mi GltOI ) Metaphuscx Exposure Number Avertigc Average Number of age of months worked subjects - (i tinge) (range i Number SCO! Vk! N'umber with breakage Percent w ith breakage' High VCM Low VCM Indlixtiy controls CDC controls 14 49.4 (44-65) 4 52.5 (46-58) 17 4S.5 (51-58) 4 44.5 (37-511 291.1 (215-546) 515.8 (261-541) 505. S (114-357, -- 1 105 74 ISP 14 1506 77 586 :i 6.7 7.8 5.9 3,6 " Levels of itatI'.ticul significance: High VCM vs CDC control. C - 7.1)9. / =.- - 0.0I; low VCM \s CDC conlrol, \J = 4.64, P * <.U.(>5: industry control vs CDC control. \- - 4.95. P - - 0.04: high VCM vs low VCM, x' = O.IK. P = '0.0.': high VCM vs industry conlrol. = o.M, P = 0.0s. TABLE 2 litl IS fit ClIROMIlSOM U BkiAKM.I IX Kl I Mills to KlEst'Osl DckAIIOS Melapkuscs Exposure High VCM (lota! employment) High VCM (VCM employment) Industry controls Months worked 100-199 200-299 300-399 100-199 200- 29V 300 - 399 UK)- 199 200-299 300-399 Number of subjects 0 ft 6 Average age _ 47.4 52.3 Average number of months wotkeJ --- 264.6 326.5 Number scored __ '00 405 Number with breaks _ 49 25 r 11 <//) = u. 16. / >0.05 s 60.0 9 47.7 3 47.7 179.0 252.3 318.3 loo 7 ^54 53 250 14 V 12 JJ) 0.58. F '0.05 31.0 1 44.5 M 51.ft 132.5 265.5 ?3ft.6 lixj 1130 0 1 7u 9.9|. ^ <0.01 Percent with breaks _ 7.0 6.: 7.0 7.0 5.6 0 13 6.7 groups, the present observations are not inconsistent with prior studies suggesting that industrial exposure to VCM is associated with an approximately twofold increase in levels of chromosome breakage as measured in culture of peripheral blood lymphocytes. In contrast with at least one prior report (Huberman ct til.. 1975), however, breakage consisted mostly of simple chromatid gaps rather than mote complex forms. R&S 114887 EZi- -~ "r3. Cj 3 . P'f**fcte W-^*Vr *,*J*r--Vr 's'-. 888frU- SSU \ ,- C lIKO M O SO M I-S A N D V IN V I, C M I.O R ID K Chromosomal aberration Chromatid gaps Isochromalid gaps Chromatid breaks Isochromatid breaks Isochromatid fragments Exchange figures Ring chromosomes Total breakage Total cells with breakage Hypodiplotd cells Hyperdiploid cells Total cells scored TABLE 3 Tyh s or Chhmmonomai Ant KHA 1 IONS OflSI nil High VCM Low VCM Industry controls Number Percent Number Percent Number Percent .19 5.3 12 6.7 7 0.6 *1 0.2 5 0.5 00 00 2 l.i 3 0.3 00 1 0.1 00 1 0.1 00 74 5.7 6 0.5 > 0.2 9 0.7 00 00 00 78 7.1 14 7.8 91 7.0 74 6.7 14 7.8 77 5.9 131 li.D 2 0.2 33 18.3 00 155 11.9 3 0.3 1105 -- 180 -- 1306 -- CI3C controls Number Percent 18 3.1 1 0.2 2 0.3 i 0.2 00 00 00 3.8 21 3.6 61 10.4 1 0.2 586 -- 72 IIK.V11I HT AL. The fact that overall breakage levels were similar in workers exposed heavily, lightly, or negligibly to VCM may imply, in this particular work setting at least, the presence of agents other than VCM capable of inducing chromosome breaks. Because of the wide range of chemicals to which rubber workers at this plant were exposed (primarily solvents of various kinds), it was impossible to relate any particular agents to the abnormal effects observed. No clear-cut pattern was seen to relate degree of breakage to duration of exposure. SUMMARY Measurements of chromosomal breakage were made in peripheral blood lym phocytes from workers exposed heavily, lightly, or negligibly to VCM at a large rubber/plastics plant. Breakage levels in all three groups were significantly in creased over levels in nonindustrial controls. Breakage consisted mostly of simple chromatid gaps. The results suggest that other agents, in addition to VCM, may cause cytogenetic damage in workers employed in the rubber/plastics industry. ACKNOWLEDGMENTS We wish to thank Mrs. Debra Jackson lor her technical assistance ami Mr. Jere Housworth far statistical advice. REFERENCES Bartsch. H., Matavcille. C.. and Montesano. K. 11975). Human, rat a ml mouse livej-mediaitJ mutagenicity of vinyl chloride in S. Typhintnrinm strains, hit. J. Com er IS. -t-0 --137. Ducatman, A., Hirschhorn. K... and Selikoff. I. J. 11975). Vinyl chloride exposure and human chromo some aberrations. Mutut. Res. 31, 163-168. Funes-Cravioto, F.. Lambert. B.. l.indslen, J.. el til. 11975). Letter to editor. Lum et 1, 459. Muberman, LL. Bartsch. H.. and Sachs. L. (1975). Mutation inJucnon in Chinese hamster V79 cells by two vinyl chloride metabolites, chloroelhylene oxide and 2-chloroacetaldehyUe. hu.J. Cancer 16, 639 - 644. Infante. P. t7.. Wagoner, J. K., McMichael. A. J., el ul. 11976). Genetic risks of vinyl chloride, turn et 1, 734-735. Kiliuu, D. J., Picciano, D. J.. and Jacobson, C, B. (1975). Industrial monitoring: A cytogenetic approach. Ann. X. V. Arm!. Sei. 269, 4 - 11. Moot head. P. S., Nowell, P. C.. Mcllman, W. ]..er ul. (I960). Chromosome preparation ofleukocytes cultured from human peripheral blood. Exp. Cell fliol. 20, 613-616. Purchase. I. F. H-, Richardson. G. R.. and Anderson, I). (1975). Letter to editor. Lancet 2, 410-411. Kanmtg U., Johansson A.. Kamel, C., and Wachtmeister, C, A. (1974). The mutagenicity of vinyl chloride after metabolic activation. Amhin 3. I94-- 197. INVimiSM**1' 'I. HIM- 33 9P </> and oo C(D> tP> /J t UJ Knvironmem: limited informal' cyle fi-aminolovi pregnant womci activity and cry; mean level of At data also show activity than ma and fetal erythr. inhibit erythror The adverse e years they have descriptions to m the toxic effects years, this area dissemination of The earliest m; inhibition of the involved in the b lead that it is pat lead are measura of this enzyme f general populali n.it fie policemet industrialized ci Nikkanen.19701 been found to ct One group oft toxic effects of I Agency, 1972). Agency has sag woman and fetus than the genera! further informali i sipyiigta '! Mi MglH'i W fc|ntt*lch*n i