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


VOL.: 41 (1986) (p. 261)

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Polybrominated biphenyls were produced primarily in the 1970s as flame retardants. Occupational exposure occurred during their production and use. The accidental addition of a hexabromobiphenyl product (FireMaster FF-1) to a large quantity of farm animal feed in Michigan (USA) in 1973 resulted in widespread population exposure.

5.2 Experimental data

The carcinogenicity of a commercial preparation of polybrominated biphenyls (FireMaster FF-1, various lots), composed primarily of hexabromobiphenyl with smaller amounts of penta- and heptabrominated isomers, was tested by oral administration by gavage in one strain of mice and two strains of rats and by perinatal exposure in one strain of rats. It produced malignant hepatic tumours in mice of each sex. In rats of each sex, it produced benign and malignant hepatic tumours, including cholangiocarcinomas, after single or multiple administrations.

Short-term exposures of rats to high doses of commercial preparations of polybrominated biphenyls induce embryonic death, growth retardation and malformation; malformations have not been observed following exposure to lower doses throughout gestation. Pre- and perinatal exposure of rats to polybrominated biphenyls reduces postnatal growth and viability.

Various commercial preparations of polybrominated biphenyls are not mutagenic to bacteria in the presence or absence of exogenous metabolic systems or in a host-mediated assay. Polybrominated biphenyls do not induce DNA damage, or mutation, in cultured mammalian cells or chromosomal aberrations in rat or mouse bone marrow, nor micronuclei in mouse bone marrow, but they do inhibit junctional intercellular communication in cultured mammalian cells.

5.3 Human data

No relevant data were available to evaluate the reproductive effects or prenatal toxicity of polybrominated biphenyls to humans.

A small cohort study of chemical workers potentially exposed to polybrominated biphenyls together with other chemicals was uninformative with regard to cancer.

5.4 Evaluation

There is sufficient evidence for the carcinogenicity of commercial mixtures of polybrominated biphenyls to experimental animals.

There is inadequate evidence for the carcinogenicity of polybrominated biphenyls to humans.

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Vol. 18 (1978)

Subsequent evaluation: Suppl. 7 (1987)

Last updated: 23 April 1998

    See Also:
       Toxicological Abbreviations
       Polybrominated biphenyls (EHC 152, 1994)