For definition of Groups, see Preamble Evaluation.
Supplement 7: (1987) (p.332)
A. Evidence for carcinogenicity to humans (sufficient)
A large number of studies have been conducted on the rubber industries in Canada, China, Finland, Norway, Sweden, Switzerland, the UK and the USA [ref: 1-19]. Workers employed in the industry before 1950 have a high risk of bladder cancer, probably associated with exposure to aromatic amines. Leukaemias have been associated with exposure to solvents and with employment in back processing, tyre curing, synthetic rubber production and vulcanization. Excess mortality from lymphomas has been noted among workers exposed to solvents in such departments as footwear and in tyre plants [ref: 20]. Other cancers, including those of the lung, renal tract, stomach, pancreas, oesophagus, liver, skin, colon, larynx and brain, have been reported as occurring in excess in various product areas and departments, but no consistent excess of any of these cancers is seen across the various studies.
B. Evidence for carcinogenicity to animals (inadequate)
In one inadequately reported experiment, three groups of rats were kept either in the compounding room, in the mixing area of a Banbury mill or in the mastication area of a Banbury mill at a tyre factory. Increased incidences of respiratory and digestive carcinomas were found in rats maintained for two years at the latter two locations when compared with control rats maintained in the institute laboratory [ref: 17].
C. Other relevant data
No increase in the incidence of chromosomal aberrations was observed among 55 rubber workers as compared to 35 control subjects, with the exception of a small group of nonsmokers involved in weighing rubber chemicals. Increased frequencies of sister chromatid exchanges were observed both in smoking and nonsmoking weighers and in mixers who smoked, compared with unexposed controls; the frequency of sister chromatid exchanges in vulcanizers was not statistically significantly increased. Negative results for chromosomal aberrations and sister chromatid exchanges were also obtained in another study of vulcanizers [ref: 21].
Urine samples from 55 workers in two rubber factories and from 35 controls were analysed for mutagenicity in bacteria in the presence of an exogenous metabolic system. Mutagenic activity was observed in the urine of workers involved in weighing and mixing rubber components and in the urine of some vulcanizers (Sorsa et al., 1983b). Similar results were reported by Falck (1983) in an extension of this study. No increase in bacterial mutagenicity was observed in urine samples from 72 tyre builders in a rubber factory and from 23 controls [ref: 21].
Overall evaluation
Working in the Rubber industry entails exposures that are carcinogenic to humans (Group 1).
For definition of the italicized terms, see Preamble Evaluation.
Also see previous evaluation: Vol. 28 (1982)
References
1. IARC Monographs, 28, 1982
2. Delzell, E. & Monson, R.R. (1981) Mortality among rubber workers. IV. General mortality patterns. J. occup. Med., 23, 850-856
3. Delzell, E. & Monson, R.R. (1982) Mortality among rubber workers. V. Processing workers. J. occup. Med., 24, 539-545
4. Delzell, E. & Monson, R.R. (1982) Mortality among rubber workers. VI. Men with potential exposure to acrylonitrile. J. occup. Med., 24, 767-769
5. Delzell, E. & Monson, R.R. (1984) Mortality among rubber workers. VIII. Industrial products workers. Am. J. ind. Med., 6, 273-279
6. Delzell, E. & Monson, R.R. (1985) Mortality among rubber workers. IX. Curing workers. Am. J. ind. Med., 8, 537-544
7. Delzell, E. & Monson, R.R. (1985) Mortality among rubber workers. X. Reclaim workers. Am. J. ind. Med., 7, 307-313
8. Delzell, E., Andjelkovich, D. & Tyroler, H.A. (1982) A case-control study of employment experience and lung cancer among rubber workers. Am. J. ind. Med., 3, 393-404
9. Holmberg, B., Westerholm, P., Maasing, R., Kestrup, L., Gumaelius, K., Holmlund, L. & Englund, A. (1983) Retrospective cohort study of two plants in the Swedish rubber industry. Scand. J. work Environ. Health, 9 (Suppl. 2), 59-68
10. Holmes, T.M., Buffler, P.A., Holguin, A.H. & Hsi, B.P. (1986) A mortality study of employees at a synthetic rubber manufacturing plant. Am. J. ind. Med., 9, 355-362
11. Kilpikari, I. (1982) Mortality among male rubber workers in Finland. Arch. environ. Health, 37, 295-299
12. Kilpikari, I., Pukkala, E., Lehtonen, M. & Hakama, M. (1982) Cancer incidence among Finnish rubber workers. Int. Arch. occup. environ. Health, 51, 65-71
13. Meinhardt, T.J., Lemen, R.A., Crandall, M.S. & Young, R.J. (1982) Environmental epidemiologic investigation of the styrene-butadiene rubber industry. Scand. J. Work Environ. Health, 8, 250-259
14. Norell, S., Ahlbom, A., Lipping, H. & Osterblom, L. (1983) Oesophageal cancer and vulcanisation work. Lancet, i, 462-463
15. Norseth, T., Andersen, A. & Giltvedt, J. (1983) Cancer incidence in the rubber industry in Norway. Scand. J. Work Environ. Health, 9 (Suppl. 2), 69-71
16. Wilcosky, T.C., Checkoway, H., Marshall, E.G. & Tyroler, H.A. (1984) Cancer mortality and solvent exposures in the rubber industry. Am. ind. Hyg. Assoc. J., 45, 809-811
17. Wang, H.-W., You, X.-J., Qu, Y.-H., Wang, W.-F., Long, Y.-M. & Ni, J.A. (1984) Investigation of cancer epidemiology and study of carcinogenic agents in the Shanghai rubber industry. Cancer Res., 44, 3101-3105
18. Arp, E.W., Jr, Wolf, P.H. & Checkoway, H. (1983) Lymphocytic leukemia and exposures to benzene and other solvents in the rubber industry. J. occup. Med., 25, 598-602
19. Gustavsson, P., Hogstedt, C. & Holmberg, B. (1986) Mortality and incidence of cancer among Swedish rubber workers. Scand. J. Work Environ. Health, 12, 538-544
20. Veys, C. (1982) The rubber industry: reflections on health risks. In: Gardner, A.W., ed., Current Approaches to Occupational Health, Vol. 2, Bristol, Wright PSG, pp. 1-29
21. IARC Monographs, Suppl. 6, 488, 1987
See Also:
Toxicological Abbreviations
The Rubber Industry (IARC Summary & Evaluation, Volume 28, 1982)