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


VOL.: 20 (1979) (p. 259)

CAS No.: 72-43-5
Chem. Abstr. Name: 1,1'-(2,2,2-Trichloroethylidene)bis(4-methoxybenzene)

5. Summary of Data Reported and Evaluation

5.1 Experimental data

Methoxychlor was tested in one experiment in mice and in several experiments in rats by oral administration. The study in mice gave negative results. In at least four experiments in rats, dietary concentrations of 1000 mg/kg or more were used. A suggestion that it was hepatocarcinogenic, made in an earlier study that was inadequately reported, was not confirmed in three more recent experiments. Methoxychlor was inadequately tested in mice by repeated skin application and by subcutaneous injection of single doses.

Methoxychlor was not mutagenic in bacteria, yeast or Drosophila melanogaster. Cytogenic and dominant lethal tests in mice were also negative.

Methoxychlor is foetotoxic.

N.B. - Subsequent to the meeting of the Working Group, the Secretariat became aware of a paper by Reuber (1979a), reporting the results of a study carried out in 1969 in which oral administration of methoxychlor induced testicular carcinomas in 27/51 male Balb/c mice, compared with 8/71 controls, but in none of the C3H mice tested. A further paper by Reuber (1979b) reported the results of a study carried out in 1951 in which oral administration of methoxychlor to Osborne-Mendel rats induced liver carcinomas.

5.2 Human data

No case reports or epidemiological studies were available to the Working Group.

The extensive production and the widespread use of methoxychlor over the past several decades, together with the persistent nature of the compound, indicate that widespread human exposure occurs. This is confirmed by many reports of its occurrence in the general environment and by its presence in human blood.

5.3 Evaluation

The available data did not provide evidence that methoxychlor is carcinogenic in experimental animals.

Previous evaluation: Vol. 5 (1974)

Subsequent evaluation: Suppl. 7 (1987) (p. 66: Group 3)

For definition of groups, see Preamble Evaluation.


Last updated: 31 March 1998

    See Also:
       Toxicological Abbreviations
       Methoxychlor (ICSC)
       Methoxychlor (FAO Meeting Report PL/1965/10/1)
       Methoxychlor (Pesticide residues in food: 1977 evaluations)
       Methoxychlor (IARC Summary & Evaluation, Volume 5, 1974)