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

(Group 3)

For definition of Groups, see Preamble Evaluation.

Supplement 7: (1987) (p. 392)

CAS No.: 298-00-0
Chem. Abstr. Name: Phosphorothioic acid, O,O-dimethyl O-(4-nitrophenyl) ester

A. Evidence for carcinogenicity to animals (evidence suggesting lack of carcinogenicity)

Methyl parathion was tested adequately by oral administration in the diet of mice and rats. There was no increase in tumour incidence over that in controls [ref: 1].

B. Other relevant data

The incidences of chromosomal aberrations and of dominant lethal mutations were not increased in mice treated in vivo with methyl parathion. In mammalian cells, sister chromatid exchange and presumed gene mutations were induced, but neither chromosomal aberration nor unscheduled DNA synthesis was elicited. Methyl parathion was weakly or nonmutagenic in Drosophila melanogaster and in bacterial systems, but it was mutagenic in yeasts [ref: 1].

Overall evaluation

Methyl parathion is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.

Also see previous evaluation: Vol. 30 (1983)


1. IARC Monographs, 30, 131-152, 1983


Last updated: 11 March 1998

    See Also:
       Toxicological Abbreviations
       Methyl parathion (EHC 145, 1992)
       Methyl parathion (HSG 75, 1992)
       Methyl parathion (ICSC)
       Methyl Parathion (FAO Meeting Report PL/1965/10/1)
       Methyl Parathion (IARC Summary & Evaluation, Volume 30, 1983)