International Agency for Research on Cancer (IARC) - Summaries & Evaluations


VOL.: 19 (1979) (p. 231)

CAS No.: 100-42-5
Chem. Abstr. Name: Ethenylbenzene

CAS No.: 9003-53-6
Chem. Abstr. Name: Ethenylbenzene homopolymer

Styrene-butadiene copolymers
CAS No.: 9003-55-8
Chem. Abstr. Name: Ethenylbenzene polymer with 1,3-butadiene

5. Summary of Data Reported and Evaluation

5.1 Experimental data

Styrene was tested by oral administration to mothers and offspring of two strains of mice and of one strain of rats. In one strain of mice, high doses of styrene increased the incidence of lung tumours in offspring. In the other strain, a lower dose of styrene slightly increased the incidence of liver-cell tumours in male offspring. In rats, the total incidence of tumours was not statistically different in styrene-treated and control animals.

Styrene is mutagenic.

Subcutaneous implantation of polystyrene discs, rods, spheres or powder in rats induced local sarcomas, the incidences of which varied with the size and form of the implant.

No data on the carcinogenicity of styrene-butadiene copolymers were available to the Working Group.

5.2 Human data

The extensive production of styrene and polystyrene and the widespread use of the polymer and the copolymers derived from styrene for consumer products and medical applications suggest that occupationally and medically exposed groups may be identified for epidemiological investigation. Extensive data on toxicity in workers and hygienic measurements indicate that exposures do occur. Skin absorption of styrene has been reported. The widespread occurrence of styrene in the environment and the fact that in some countries styrene and some of its polymers are approved as food additives and for use in contact with food (e.g, disposable dinnerware and drinking glasses) indicate that the general population is also exposed.

The only report that relates to possible human carcinogenicity of styrene has methodological deficiencies: the population at risk was not clearly defined and may have been exposed to a variety of chemicals, such as benzene. No conclusion could be made concerning the carcinogenicity of styrene.

No case reports or epidemiological studies with regard to the carcinogenicity of polystyrene were available to the Working Group.

The case reports and epidemiological studies that concern the carcinogenic effects of styrene-butadiene copolymers also have limitations: the usual ones apply to the case reports; the epidemiological studies involved small numbers of workers. However, the collective nature of the findings, together with the similarity of tumour types observed, clearly indicate the need for further studies.

5.3 Evaluation

Although no information is available on carcinogenicity in humans attributable to styrene, its wide use and the facility with which it can be absorbed by inhalation indicate that it may be possible to carry out studies measuring both dose and cancer incidence in exposed workers. The finding of chromosomal aberrations in workers exposed to styrene further supports the need for epidemiological investigations.

Results from polystyrene implant studies in animals point to the need for further investigations with regard to the polymer. Recent epidemiological information on styrene-butadiene copolymer workers, which indicates lymphato-haematopoeietic malignancies, clearly requires elucidation by further studies.

Subsequent evaluations: Suppl. 7 (1987) (Polystyrene, p. 70: Group 3) (Styrene-butadiene copolymers, p. 72: Group 3); Vol. 60 (1994) (Styrene)

For definition of Groups, see Preamble Evaluation.

Synonyms for Styrene

Synonyms for Polystyrene

Synonyms for Styrene-butadiene copolymers

Last updated: 30 March 1998

    See Also:
       Toxicological Abbreviations