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

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 73 (1999) (p. 625)

Chem. Abstr. No.: 122-34-9
Chem. Abstr. Name: 6-Chloro-N,N¢ -diethyl-1,3,5-triazine-2,4-diamine

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Exposure to simazine occurs during its production, formulation and use as a herbicide. Simazine and its degradation products have been detected at low levels in ambient rural and urban air, rainwater, surface and groundwater and, less frequently, in drinking-water samples.

5.2 Human carcinogenicity data

No data were available on simazine alone (see the monograph on atrazine).

5.3 Animal carcinogenicity data

Simazine was tested for carcinogenicity in one experiment by oral administration to Sprague-Dawley rats. It increased the incidences of benign and malignant mammary gland tumours in females.

5.4 Other relevant data

Simazine is metabolized by dealkylation. No interaction with an oestrogen receptor was seen in vitro. In Sprague-Dawley rats, simazine was not uterotrophic but prolonged the duration of the oestrus cycle. Long-term administration resulted in haematological effects in rats and dogs.

Simazine did not show developmental toxicity in one study by inhalation in rats, but it was embryolethal and decreased fetal body weights in a study in which it was administered orally.

No data were available on the genetic and related effects of simazine in humans. Simazine was not genotoxic to rodents in vivo or in cultured mammalian cells, yeast or bacteria. It induced genetic damage in Drosophila and in plants.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of simazine.

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

Overall evaluation

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

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Vol. 53 (1991)


Last updated: 30 September 1999

    See Also:
       Toxicological Abbreviations
       Simazine (ICSC)
       Simazine  (IARC Summary & Evaluation, Volume 53, 1991)