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


VOL.: 40 (1986) (p. 161)

CAS No.: 128-37-0
Chem. Abstr. Name: 2,6-Bis(1,1-dimethylethyl)-4-methylphenol

5. Summary of Data Reported and Evaluation

5.1 Exposure

Butylated hydroxytoluene (BHT) has been used since 1947 as a common antioxidant in rubber and petroleum products and, more recently, in plastics. It has been used since 1949 as an antioxidant in many fat-containing foods, in edible fats and oils and in cosmetics. There is thus widespread human exposure to this compound.

5.2 Experimental data

Butylated hydroxytoluene was tested for carcinogenicity in mice and rats by oral administration in the diet. In one study in mice, there was no difference in tumour incidence among treated and control groups. Another study in mice showed an increased incidence of pulmonary tumors in females at the lower but not at the higher dose level. In another study in mice using one dose level and a small number of animals, the number of mice with lung tumours was increased by feeding of butylated hydroxytoluene; this finding was not confirmed in a further study by the same investigator using a larger number of animals. In one study in rats, no increase in tumour incidence was seen. An increased incidence of pituitary adenomas was observed in female rats at the lower but not at the higher dose level in another study. In one further experiment in rats, liver tumours were observed; however, this study could not be evaluated because of differential survival among control and treated groups.

Butylated hydroxytoluene was studied in mice and rats for its ability to modify the carcinogenicity of selected chemical agents. When administered with known carcinogens, butylated hydroxytoluene either enhanced, inhibited or had no effect on carcinogenicity.

No adequate data were available to evaluate the reproductive effects or prenatal toxicity of butylated hydroxytoluene to experimental animals.

In mice, a single intraperitoneal dose or feeding of butylated hydroxytoluene can cause pulmonary alveolar cell necrosis and proliferation. Butylated hydroxytoluene also induces proliferation of smooth endoplasmic reticulum in rat-liver cells, leading to hepatomegaly.

Butylated hydroxytoluene did not induce DNA damage in Bacillus subtilis or mutation in Salmonella typhimurium. It did not induce chromosomal aberrations in plants or mutation or chromosomal aberrations in Drosophila melanogaster. In one study, it was reported to be mutagenic to cultured Chinese hamster cells in the presence of an exogenous metabolic system. Binding of butylated hydroxytoluene to the DNA of liver of rats treated in vivo has been reported. It did not induce micronuclei in bone marrow or dominant lethal mutations in mice. It induced sperm abnormalities in mice.

When tested in combination with other chemicals (usually, known mutagens or carcinogens), butylated hydroxytoluene often modified the DNA-damaging, mutagenic and clastogenic activities. In most studies, butylated hydroxytoluene reduced the activity of indirectly-acting mutagens or carcinogens.

5.3 Human data

No data were available to evaluate the carcinogenicity of butlyated hydroxytoluene to humans.

5.4 Evaluation

There is limited evidence for the carcinogenicity of butylated hydroxytoluene in experimental animals.

No evaluation could be made of the carcinogenicity of butylated hydroxytoluene to humans.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluation: Suppl. 7 (1987) (p. 59: Group 3)


Last updated: 22 April 1998

    See Also:
       Toxicological Abbreviations
       Butylated hydroxytoluene (BHT) (WHO Food Additives Series 15)
       Butylated hydroxytoluene (BHT) (WHO Food Additives Series 18)
       Butylated hydroxytoluene (BHT) (WHO Food Additives Series 28)
       Butylated hydroxytoluene (BHT) (WHO Food Additives Series 42)