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Test (in vitro) : Ames test (Haddouk 2005)

The study was performed according to the international guidelines (OECD 471, Commission Directive No. B 13/14) and in compliance with the Principles of Good Laboratory Practice Regulations.

A preliminary toxicity test was performed to define the dose-levels of 1,2,4-triazole sodium salt to be used for the mutagenicity study. The test item was then tested in two independent experiments, with and without a metabolic activation system, the S9 mix, prepared from a liver microsomal fraction (S9 fraction) of rats induced with Aroclor 1254. Five strains of bacteria Salmonella Typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102 were used. Each strain was exposed to six dose-levels of the test item (three plates/dose-level). After 48 to 72 hours of incubation at 37°C, the revertant colonies were scored.

The evaluation of the toxicity was performed on the basis of the observation of the decrease in the number of revertant colonies and/or a thinning of the bacterial lawn. 1,2,4-triazole sodium salt was dissolved in water for injections.

The number of revertants for the vehicle and positive controls was as specified in the acceptance criteria. The study was therefore considered valid.

Since the test item was toxic in the preliminary test, the choice of the highest dose-level was based on the level of toxicity, according to the criteria specified in the international guidelines.

The selected treatment-levels were: 312.5, 625, 1250, 2500, 3750 and 5000 gg/plate, for both mutagenicity experiments with and without S9 mix.

No precipitate was observed in the Petri plates when scoring the revertants at any dose-level.

A moderate to marked toxicity was generally observed, both with and without S9 mix, mainly at dose-levels 2500 gg/plate, depending on the tester strains.

1,2,4-triazole sodium salt did not induce any noteworthy increase in the number of revertants, both with and without S9 mix, in any of the five strains.

Test (in vitro) : Chromosomic aberrations on human lymphocytes (Haddouk 2006)

The study was performed according to the international guidelines (OECD 473) and in compliance with the principles of GLP regulations. 1,2,4 -triazole sodium salt was tested in two independent experiments, both with and without a liver metabolizing system (S9 mix), obtained from rats previously treated with Aroclor 1254.

The highest dose-level for treatment in the first experiment was selected in the basis of pH, osmolarity and solubility. For selection of the dose-levels for the second experiment, any toxicity indicated by the reduction of mitotic index in the first experiment was also taken into account. In the first experiment, lymphocyte cultures were exposed to the test or control item (with or without S9 mix) for 3 hours then rinsed. Cekks were harvested 20 hours after the beginning of treatment. The second experiment was performed as follow : without S9 mix, cells were exposed continuously to the test or control item until harvest ; and with S9 mix, cells were exposed to the test or control item for 3 hours and then rinsed.Cells were harvested 20 hours and 44 hours after treatment.

One and a half hours before harvest, each cuture was treated with a colcemid solution to block cells at the metaphase-stage of mitosis. 1,2,4 -triazole sodium salt was dissolved in water for injections. Positive controls were used.

No significant increase in the frequency of cells with structural chromosomal aberrations was noted in either experiment and at either harvest time, without and with S9 mix. The frequency of cells with structural chromosome aberrations of the vehicle and positive controls was as specified in acceptance criteria. the study was therefore considered valid.

1,2,4-triazole sodium salt did not induce chromosome aberrations in cultured human lymphocytes.

Test (in vivo) : Micronucleus test (Allen 1985) with 1,2,4 -triazole (CAS no.288 -88 -0)

In this assessment of the effect of 1,2,4 -triazole on the incidence of micronucleated polychromatic erythrocytes in mice, a dosage of 1200 mg/kg bw was administered by oral gavage. A negative control group was dosed in an identical manner with the vehicle, aqueous 1% methylcellulose. A positive control group was dosed with mitomycin C by intraperitoneal injection.

Bone marrow smears were obtained from the negative control and test compound groups at 3 sampling times; these being 24, 48 or 72 hours after dosing. Bone marrow smears were obtained from the positive control group 24 hours after dosing. One smear from each animal was examined for the rpesence of micronuclei in 1000 polychromatic erythrocytes.

At all sampling times, mice treated with 1,2,4 -triazole showed no significant increase in the frequency of micronucleated polychromatic erythrocytes. There was no significant decrease in the ratio of polychromatic to normochromatic erythrocytes after treatment of the animals with 1,2,4 -triazole. The positive control produced large highly significant increases in the frequency of micronucleated polychromatic erythrocytes together with decreases in the ratio of polychromatic to normochromatic erythrocytes.

It is concluded from the results obtained that 1,2,4 -triazole shows no evidence of mutagenic potential or bone marrow cell toxicity when administered orally in this in vivo test procedure.


Short description of key information:
Three reliable studies was available for this endpoints : a Ames test, a in vitro chromosomic aberration test, and a in vivo micronucleus test.
All tests show negative results.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

According to EU Directive 67/584/EEC and EU regulation (EC) No 1272/2008 (CLP) :

1,2,4-triazole sodium salt was not mutagen (negative results in in vitro and in vivo studies).