Document DGOLqaoE92Qj0nGnZVGV4MXKd

ENVIRONMENTAL RESEARCH 14, 68 "72 (1977) Chromosomal Damage in Men Occupationally Exposed to Vinyl Chloride Monomer and Other Chemicals Clark W. Heath, Jr., and Cheryl R. Dumont Cancer and Birth Defects Division, Bureau of Epidemiology, Center for Disease Control, Public Health Service, U.S. Department of Health, Education, and Welfare. 1600 Clifton Road, N.E., Atlanta, Georgia 30333 John Gamble Occupational Health Studies Group, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514 AND Richard J. Waxweiler National Institute for Occupational 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 al., 1974; Bartsch et al., 1975), mutagenicity of VCM metabolites in mammalian cells (Huberman et al., 1975), and cytogenetic studies of polyvinyl chloride (PVC) polymerization workers (Ducatman et al., 1975. Funes-Cravioto, et al., 1975; Kilian et al., 1975; Purchase et al., 1975). Also relevant may be observations suggesting increased fetal loss in families of PVC workers (Infante et al., 1976). Among the several cytogenetic studies reported, three have suggested increased chromosomal breakage among polymerizatior, workers (Ducatman et al., 1975; Funes-Cravioto et al.. 1975; Purchase et a!. 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 provic . 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 Cente' for Disease Control (CDC) (National Institute for Occupational Safety and Heal;." 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 detailea description of the study's design and methodology, will be published separate^ Copyright 1977 by Academic Press, Inc. All nghu of reproduction in any form reserved. 68 ISS^ *' W/fl f * 3 CHROM' ; Cytogenetic analyses, pr y chromosomal breakage, were j~ * men; specimens were obtains. T 1975 (2 on both occasions). Sl v- sively employed for 10 years or f PVC polymerization (presume*.: y.- 4 in PVC processing (presum. i manufacture (industry' control % history details were obtained b records. Initially, the study was desL exposed to VCM with frequc * analyses showed no significant j; was selected (April 1975) cons: directly to any laboratory che: ; ^ pared in the same manner wit , ' workers at the plant. To asse j ' between April 1975 and the e | VCM and industry' control gv i ' worker slides. Breakage freque f industry control slides (6.0Vc c; j from the first reading. Cytoger t dures (Moorhead et al., 1960). phytohemagglutinin. Giemsa $: Frequencies of chromosom. v Levels of breakage in all three X. were significantly increased O'ft the P <0.01 level, the low VC.' At the same time, no significar. j, groups themselves. Groups w fff months w-orked. Breakage frc. -:T ' not vary significantly one fio rr. An effort was made to relate -f hence extent of potential toxie ^ was seen for industry controls bers and because the mean agr T- No gradient was seen for the b ment or of employment in cont too small to permit analysis b> %- Chromatid gaps comprised Similar types of aberrations v groups. % When reviewed in terms > if* " EC- I29e 'ally Exposed Chemicals !ON'T :/ for Disease .-.on, and Welfare, ui Chapel Hill, Disease Control, ects of vinyl chloride .city. Pertinent studies VCM in bacterial test, mutagenicity of VCM iJ cytogenetic studies .catman et al., 1975; et al., 1975). Also ss in families of PVC '.etic studies reported, -mong polymerization .975; Purchase et al., concerns cytogenetic J plastics plant, some Jy designed to provide ;n employed at a large - jointly by the Center :>nal Safety and Health Studies Group of the ''.one Corporation and 'gether with a detailed published separately. CHROMOSOMES AND VINYL CHLORIDE 69 Cytogenetic analyses, primarily designed to measure frequencies of chromosomal breakage, were performed on peripheral blood lymphocytes from 35 nen: specimens were obtained from 18 men in October 1974 and 19 in January ,975 (2 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), c 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 ..nalyses showed no significant differences among worker groups, a control group was selected (April 1975) consisting of four male employees at CDC not exposed directly to any laboratory chemicals. Material for cytogenetic analysis was pre 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 al., 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 1. Levels 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 he 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 not vary significantly one from another. An effort was made to relate levels of breakage to duration of employment and hence extent of potential toxic exposure (Table 2). While a significant gradient 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 :oo small to permit analysis by exposure duration. 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 ISSN 0013-9351 EC- 1299 J i l- j:* iI: 70 HEATH ETAL. Exposure High VCM Low VCM Industry controls CDC controls TABLE 1 Levels of Chromosomal Breakage by Exposlrl Gkolp Metapbases Number of subjects Average age (range) Average Number of months worked (range) Number scored Number with breakage Percent with breakage' 14 49.4 291.1 (44 - 65) (215-346) 4 52.5 315.8 (46-58) (261-341) 1105 180 74 14 6.7 7.8 17 48.5 305-8 (31-58) (114-357) 1306 77 5.9 4 44.3 (37-51) -- 586 21 3.6 * Levels of statistical significance: High VCM vs CDC control, jc = 7.09, P = <0.01: low VCM CDC control, x1 = 4,64, P = <0.05; industry control vs CDC control, x - 3-95. P = <0.05: high VC vs low VCM, x1 = 0.18, P >0.05: high VCM vs industry control, x5 = 0.81. P = >0.05. TABLE 2 Levels of Chromosomal Breakage in Relation to Enposl re Dcration Metaphascs Exposure High VCM (total employment) High VCM (VCM employment) Industry controls Months worked 100-199 200-299 300-399 100-199 200-299 300-399 100-199 200-299 300-399 Number of subjects Number Average Average Dumber Number with age of months worked scored breaks 0_ 8 47,4 6 52.2 _ 264.6 326.5 _ 700 49 405 25 X1 (!<#) = 0.16, P >0.05 2 60.0 9 47.7 3 47.7 179.0 252.3 318.3 100 7 755 53 250 14 X* (2 df)** 0.58, P>0.05 2 31.0 2 44.5 13 51.8 132.5 265.5 338.6 100 0 76 1 1130 76 X4 (2 df) 9.91, P <0.01 Perceuhr break - _ 6: 7,t* 7( ; n 1/6" groups, the present observations are not inconsistent with prior studies suggest ~.c that industrial exposure to VCM is associated with,an approximately two;'V increase in levels of chromosome breakage as measured in culture of periphc'.:' blood lymphocytes. In contrast with at least one prior report (Huberman e: 1975), however, breakage consisted mostly of simple chromatid gaps rather ;i more complex forms. CHROMOSOMES AND VIN YL CHLORIDE 6.7 7.8 5.9 3.6 w v> S Z* %C*1O Sp ' O 9 TO 3^*** o ' o*-*> (yv~>l ^ ,a^--a *< r*{rcrCaa ca>r op> Jp!. S.Ew O' o Kj w 'A b-Jo-J f^sr > | fj 1 B\ oa Xg o :? ar nr (r o< : ri.'( ?-. i ^h ii > I 1 ,L ' <i ;:. fV 1 v> ar i.7 |&I ; * #>i'JUfH*-' *!;f*'''t-JT I .'f--1 ',' 'u1 rf*/ v:v' , 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 Tvifi <>k Ciikomosomai. Aiii hhamons Oiim hvi n High VCM Low VCM Industry controls Number Percent Number Percent Number Percent 59 5.3 7 0.6 2 0.2 5 0.5 3 0.3 | 0.1 1 0.1 12 6.7 00 00 2 l.l 00 00 00 74 5.7 6 0.5 2 0.2 9 0.7 00 00 00 78 7.1 14 7.8 91 7.0 74 6.7 14 7.8 77 5.9 121 11.0 33 18.3 155 11.9 2 0.2 00 3 0.3 1105 -- 180 _ 1306 _ CDC controls Number Percent 18 ' 1 2 i 0 0 0 22 21 61 I 586 3.1 0.2 0.3 0.2 0 0 0 3.8 3.6 10.4 0.2 _ 72 HEATH ETAL. 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 w'ere 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 for her technical assistance and Mr. Jere Housworth for statistical advice. REFERENCES Bartsch, H., Malaveille, C,, and Montesano, R. (1975). Human, rat and mouse liver-mediated mutagenicity of vinyl chloride in S. Txphimurium strains. Int. J. Cancer 15, 429-437. Ducatman, A., Hirschhom, K., and SelikofF, I. J. (1975j. Vinyl chloride exposure and human chromo some aberrations. Murat. Res. 31, 163-168. Funes-Cravioto, F., Lambert, B., Lindsten, J., el al. (1975). Letter to editor. Lancet 1, 459. Huberman, E., Bartsch, H., and Sachs, L. (1975). Mutation induction in Chinese hamster V79 cells b> two vinyl chloride metabolites, chloroethylene oxide and 2-chloroacetaldehyde. Int. J. Cancer 16. 639-644. Infante, P. F., Wagoner, J. K., McMichael, A. J., et al. (1976). Genetic risks of vinyl chloride. Lam,; 1, 734 - 735. Kilian, D. J., Picciano, D, J., and Jacobson, C. B. (1975). Industrial monitoring: A cytogenetic approach. Ann. A'. Y. Acad. Sci. 269, 4-11. Moorhead. P. S., Nowell. P. C., Mellman, W. ].,et al. (1960). Chromosome preparation of leukocj iecultured from human peripheral blood. Exp. Cell Biol. 20, 613-616. Purchase, I. F. H., Richardson, G. R., and Anderson. D. (1975). Letter to editor. Lancet 2, 410-41! Rannug U., Johansson A., Ramel. C., and Wachtmeister, C. A. (1974). The mutagenicity of s in;. 1 chloride after metabolic activation. Ambio 3, 194-197. ENVIRONMENT *L R: I s Lead ant P Departnu. nt and the D-. Environment limited informscyte 6-amino!e\ pregnant womtactivity and er. mean level of A i data also show activity than it. andfetal eryth:, inhibit erythro; p. The adverse e > years they have descriptions to s: l^'the toxic effects f. years, this area o; ^ dissemination of tjjY The earliest ma inhibition of the ?=* involved in the bi> if lead that it is pan t.-v lead are measurar of this enzy me hi general populatio v traffic policemen 5*. industrialized citi Nikkanen, 1970). iTr been found tc cor r . One group of th. ^ toxic effects of ]e. '-y-Agency, 1972). R ^ Agency has sugg, > woman and fetus < ^than the general r ^'further informatie f' 19T- tv "*h ofreproda.-tior, ,-. .