2-ethoxyphenol

Endpoint summary

Additional information

Only one study consisting at a reverse bacterial mutation (Ames) test was available. It was selected as key study with reliability 1 according to Klimisch scale.

The summary of this study is the following:

In a study (CIT, 2003), the potential of the test item GUETOL to induce reverse mutation in Salmonella typhimurium was evaluated according to the international guidelines (OECD 471, Commission Directive No. B13/14) and in compliance with the Principles of Good Laboratory Practice Regulations.

 

A preliminary toxicity test was performed to define the dose-levels of GUETOL 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.

Both experiments were performed according to the direct plate incorporation method except for the second test with S9 mix, which was performed according to the preincubation method (60 minutes,37°C).

Five strains of bacteria Salmonella typhimurium: TA 1535, TA 1537, TA 98, TA 100 and TA 102 were used. Each strain was exposed to five dose-levels of the test item (three plates/dose-level). After 48 to 72 hours of incubation at37°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.

The test item GUETOL was dissolved in dimethylsulfoxide (DMSO).

 

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 and 5000μg/plate, for the TA 98, TA 100, TA 1535 and TA 1537 strains with and without S9 mix in the first experiment as well as for all the tester strains with and without S9 mix in the second experiment,

⋅156.3, 312.5, 625, 1250 and 2500μg/plate, for the TA 102 strain in the first experiment with and without S9 mix.

 

No precipitate was observed in the Petri plates when scoring the revertants at all dose-levels.

A moderate to marked toxicity was noted with S9 mix in the preincubation method, in all the tester strains at 5000μg/plate as well as in the TA 102 strain without S9 mix at 5000μg/plate.

The test item did not induce any noteworthy increase in the number of revertants, both with and without S9 mix, in any of the five strains.

 

Under these experimental conditions, the test item GUETOL did not show mutagenic activity in the bacterial reverse mutation test with Salmonella typhimurium.

Justification for classification or non-classification

Guetol showed negative results in Ames test.

No more genotoxic tests are available. No further genetic toxicity evaluation is required for this registration dossier.