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

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 73 (1999) (p. 115)

CAS No.: 85-68-7
Chem. Abstr. Name: 1,2-Benzenedicarboxylic acid, butyl phenylmethyl ester

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Exposure to butyl benzyl phthalate occurs during its production and use as a plasticizer, mainly in polyvinyl chloride products. It has been detected at low levels in indoor air, water and a few foods.

5.2 Human carcinogenicity data

No data were available to the Working Group.

5.3 Animal carcinogenicity data

Butyl benzyl phthalate was tested for carcinogenicity by oral administration in one experiment in mice and three experiments in rats, including two studies with dietary restriction. No increase in the incidence of tumours was observed in mice. A marginal increase in the incidence of bladder tumours was observed in female rats after 32 months of dietary restriction. An increased incidence of benign pancreatic tumours was seen in one conventional study in male rats, but not after dietary restriction, despite extension of the period of dosing to 32 months.

In one study in rats, butyl benzyl phthalate inhibited mammary carcinogenesis produced by prior administration of 7,12-dimethylbenz[a]anthracene.

5.4 Other relevant data

Butyl benzyl phthalate is hydrolysed in the gastrointestinal tract to mono-n-butyl phthalate and monobenzyl phthalate, which are absorbed, further metabolized, glucuronidated and excreted in the urine. Butyl benzyl phthalate weakly stimulated hepatic peroxisome proliferation. Although the compound binds weakly to oestrogen receptors in vitro, it had no oestrogenic activity in vivo in tests which included uterotropic effects and vaginal cornification.

Butyl benzyl phthalate has been tested for developmental toxicity in mice by administration in the diet and in rats by administration in the diet, by gavage and in drinking-water. Malformations and embryonic deaths were observed in both species, generally at maternally toxic doses. In rats, alterations in ovarian and/or uterine function appeared to be involved in the decreased embryonic viability. Testicular toxicity has been observed in male rats exposed to butyl benzyl phthalate.

No data were available on the genetic and related effects of butyl benzyl phthalate in humans. Butyl benzyl phthalate was not genotoxic in experimental systems, except for weak clastogenicity in bone-marrow cells of mice treated in vivo in one study.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of butyl benzyl phthalate.

There is limited evidence in experimental animals for the carcinogenicity of butyl benzyl phthalate.

Overall evaluation

Butyl benzyl phthalate is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluations: Vol. 29 (1982); Suppl. 7 (1987) (p. 59)


Last updated: 30 September 1999

    See Also:
       Toxicological Abbreviations
       Butyl benzyl phthalate (ICSC)
       Butyl benzyl phthalate (CICADS 17, 1999)
       Butyl Benzyl Phthalate  (IARC Summary & Evaluation, Volume 29, 1982)