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


VOL.: 30 (1983) (p. 153)

CAS No.: 56-38-2
Chem. Abstr. Name: O,O-Diethyl O-4-nitrophenyl phosphorothioate

5. Summary of Data Reported and Evaluation

5.1 Experimental data

Parathion was tested for carcinogenicity in one strain of mice and in three strains of rats by administration in the diet. Although a dose-related increase in the incidence of adrenal cortical adenomas was observed in male and female rats of one strain, the significance of the occurrence of those lesions in aged rats is not well understood. A low incidence of carcinomas at this site was observed in each of the treated groups in animals of both sexes. The other experiments in rats and the experiment in mice were considered to be inadequate for evaluation.

Parathion produced embryocidal effects and foetal growth reduction but no malformation in mice and rats at doses that were generally below the level that is toxic for the maternal organism.

Parathion was not mutagenic to a wide range of microorganisms in the presence or absence of rat liver microsomal preparations. It did not induce unscheduled DNA synthesis in cultured mammalian cells, recessive lethal mutations in Drosophila melanogaster or dominant lethal mutations in mice. Thus, no evidence has been found that parathion is mutagenic.

5.2 Human data

Parathion was introduced in 1947. Its production, formulation and use as an insecticide in a variety of agricultural applications are potential sources of exposure, both of workers and of the general population.

No data were available to evaluate the teratogenic or chromosomal effects of parathion in humans.

No case report or epidemiological study of the carcinogenicity of parathion alone was available to the Working Group. (See, however, the section 'Cancer Epidemiology of Pesticide Manufacturers, Formulators and Users', in this volume.)

5.3 Evaluation

There is inadequate evidence to evaluate the carcinogenicity of parathion to experimental animals. No data on humans were available.

The available data are insufficient to evaluate the carcinogenicity of parathion to humans.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluation: Suppl. 7 (1987) (p. 69: Group 3)


Last updated: 9 April 1998

    See Also:
       Toxicological Abbreviations
       Parathion (HSG 74, 1992)
       Parathion (ICSC)
       Parathion (FAO Meeting Report PL/1965/10/1)
       Parathion (FAO/PL:1967/M/11/1)
       Parathion (FAO/PL:1969/M/17/1)
       Parathion (AGP:1970/M/12/1)
       Parathion (Pesticide residues in food: 1984 evaluations)
       Parathion (Pesticide residues in food: 1995 evaluations Part II Toxicological & Environmental)