Amitrole

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

- Ames Test (OECD 471, GLP, K, rel. 1): non mutagenic in S. typhimurium TA 98, , TA 100, TA 1535, TA1537 and E. coli WP2uvrA.
- MLA Mammalian Cell Gene Mutation Assay (OECD 476, GLP, K, rel. 2): not mutagenic.
- CAT in vitro chromosomic aberration (OECD 473, GLP, K, rel. 1): not clastogenic and not aneugenic.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Table 7.6.1/1: Summary of Genetic Toxicity Tests:

Test n°	Test guideline / reliability	Focus	Strains tested	Metabolic activation	Test concentration	Statement
1 (Wallner, 2009)	Ames Test (OECD 471) K, rel.1	Gene mutation	TA 98, TA 100, TA 1535, TA 1537, E. coli WP2 uvrA	-S9 +S9	Up to limit concentrations	-S9 : non mutagenic +S9 : non mutagenic
2 (McGregor, 1987)	MLA/tk test (OECD 476) K, rel.2	Gene mutation	L5178Y Mouse Lymphoma cells	-S9 +S9	Up to limit concentrations	-S9 : non mutagenic +S9 : non mutagenic
3 (Oppong-Nketiah, 2009)	CAT (OECD 4873) K, rel.1	Chromosomal aberration	Human lymphocytes	-S9 +S9	Up to limit concentrations	-S9 : Non clastogenic +S9 : non clastogenic

Gene mutation Assays (Tests n° 1-2):

- A Bacterial Reverse mutation Assay (Ames test) was performed according to OECD guideline No. 471 with the substance (See Table 7.6/1). No precipitation of the test item was observed in any tester strain used. No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains under the test condition, with any dose of the substance, either in the presence or absence of metabolic activation. The substance does not induce gene mutations in bacteria whereas all positive control chemicals (with and without metabolic activation) induced significant increase of colonies. The substance is therefore considered as non-mutagenic according to the Ames test.

- Inability to produce gene mutation was confirmed in an in vitro mutation assay in Mouse lymphoma cells (MLA/tk test) (Test n°2). None of the dose levels up to 5000 µg/mL with the substance, either in the presence or absence of metabolic activation, induced significant mutant frequency increases in the five experiments. The substance does not induce mutagenic response at the tk locus in L5178Y TK +/- cells under activation and non-activation conditions whereas the both positive control chemicals (with and without metabolic activation) induced significant mutant frequency increases. The substance is therefore not mutagenic at the tk locus in L5178Y TK +/- cells under activation and non-activation conditions used in this assay. This result confirms the results of the Ames test and extends the non-mutagenic effect of the substance to mammalian cells.

Chromosomal aberration (test n°3)

The clastogenic potential of the substance was determined using an in vitro chromosome aberration test (Test n°3). Human promary lymphocyte cultures were exposed to the test item up to 5000 µg/mL with and without metabolic activation as follow :

Experiment 1: with and without metabolic activation, 4 h treatment, 24 h preparation interval

- Experiment 2: without metabolic activation, 24 h treatment, 24 h preparation interval; with metabolic activation, 4 h treatment, 24 h preparation interval

No precipitation of the test item was noted with and without metabolic activation. Toxic effect of the test item was observed only in experiment 2 without metabolic activation (long time exposure) at a concentration of 2500 µg/mL. In both experiments, no biologically relevant increase of the aberration rates or in the frequency of polyploid cells was noted after treatment with the test item with and without metabolic activation as compared to the controls. The both positive controls induced distinct and biologically relevant increases in cells with structural chromosomal aberrations.

The test item is therefore considered as non-clastogenic in human lymphocytes.

In accordance with section 1.1 (Use of existing data) of Annex XI to the REACH Regulation, an in vivo mutagenicity study (section 8.4) does not need to be conducted as all of the three in vitro studies gave a negative result.

Justification for classification or non-classification

Harmonized classification:

The test material has no harmonized classification for genetic toxicity according to the Regulation (EC) No. 1272/2008 (CLP).

Self-classification:

Based on the available data, no additional classification is proposed regarding genetic toxicity according to the Annex VI of the Regulation (EC) No. 1272/2008 (CLP) and to the GHS.