4-amino-m-cresol

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

According to the results of the 3 key studies (3 in vitro studies performed with 4 -amino-m-cresol), the registered substance was considered as genotoxic, precisely clastogenic substance n micronucleus test.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

According to the key studies available to assess the potential genotoxicity of the registered substance 4 -amino-m-phenol, this substance was considered as non mutagenic on in vivo test system.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Three in vitro studies were available to assess the potential genotoxicity of the test item 4-amino-m-cresol on in vitro test systems :

- Ames test was performed according to OECD guideline 471 method and OECD GLP principle. Five strains were used (TA 1538, TA1535, TA98, TA 100 and TA1537) with or without metabolic activation. Two independants experiments were perfomed (preliminary study and main study). Plate incorporation method was used in the first experiment with 3, 10, 33, 100, 333, 1000, 2500, 5000 μg/plate (diluted in DSMO). The second experiment was performed with preincubation method at : without S9 mix: 1, 3, 10, 33, 100, 333, 1000 μg/plate ; with S9 mix: 3, 10, 33, 100, 333, 1000, 2500 μg/plate. Test substance did not induce gene mutations in S. typhimurium in the absence or presence of S9 mix. (Sokolowski, 2004)

-An in vitro gene mutation test on mammalian cells (L5871Y mouse lymphoma cells) was realised according to OECD method 476 and was GLP compliant. The test targeted the Thymidine Kinase locus. The test item was applied at 0.391, 0.781, 1.563, 3.125, 6.25, 12.5, 25.0 and 47.5 µg/mL with metabolic activation and 0.048, 0.098, 0.195, 0.391, 0.781, 1.563, 3.125 and 6.25 µg/mL without metabolic activation. The treatment period was about 4 hours. No dose dependency could be observed in either experiment and the mutation frequencies found in the groups treated with the test substance did not show a biologically relevant increase as compared to the controls. Some isolated small mutagenic effects were determined which lack biological significance. (Hamman U, 2002)

-A micronucleus test was performed according to OECD GLP principle, the method used was comparable/similar to OECD 487 guideline method using human lymphocytes. Two experiments were performed, this first with 24 hours of pretreatment with mitogen : without S9 : 20 hours of treatment and 28 hours of recovery period, with S9, 3 hours of exposure and 45 hours of recovery. The second experiment was performed after 48 hours of mitogen pretreatment. The dose level selected were : - Experiment 1 : Without S9 : 0, 5, 10, 15, 20, 22.5, 25, 27.50 30, 32.5, 40, and 45 µg/mL, with S9: 0, 50, 100, 125, 150, 175, 200, 225, 250, 275, 300, 350, and 400 µg/mL -Experiment 2 : without S9 : 0, 5, 10, 20, 30, 35, 40, 45, 50, 55, 60, 65, 70 and 80 µg/mL, with metabolic activation : 0, 25, 50, 100, 125, 150, 175, 200, 225, 250, 275, 300 350, and 400 µg/mL. With and without metabolic activation: The test material induced micronuclei in cultured human peripheral blood lymphocytes following treatment in the absence and presence of S9. In experiment 1, at the three high concentrations doses, higher frequencies of micronuclei and binucleated cells was observed with metabolic activation but the increase was small. However in the second experiment, the frequencies of MNBN cells in the solvent control cultures were relatively low (0.30%) and the cultures treated with the test material showed frequencies of MNBN cells that significantly exceeded the vehicle control values. Based on above, 4-amino-3-methylphenol induced micronuclei in cultured human peripheral blood lymphocytes following stimulation with mitogen (commenced 48 hours prior to treatment) in the absence and presence of S9. (Clare G, 2005)

-One in vivo genotoxicity key study was performed on 4 amino-m-cresol :

The mutagenic potential of 4-amino-3-methylphenolin in micronucleus assay (OECD guideline 474 was performed on Male and female NMRI mice. The groups of 5 animals/sex received the test substance prepared with 0.9% NaCl solution during 24 h preparation interval: 20, 100 and 200 mg/kg bw and 48 h preparation interval: 200 mg/kg bw.

After treatment, animals were sacrificed and the bone marrow tissues were isolated fromboth femora. Slides were prepared,stained with May-Gruenwald-Giemsa and were examined under a microscope. 2000 immature erythrocytes per animal were scored for the incidence of micronucleated immature erythrocytes. At least 200 immature erythrocytes were counted per animal and the result wasexpressed as relative PCE (rel. PCE=proportion of polychromatic (immature) erythrocytes among total erythrocytes).

Based on above,4-amino-3-methylphenol was non-mutagenic in the micronucleus test with bone marrow cells of the mouse when administered intraperitoneally at 20, 100 and 200 mg/kg bw. 

According to the REACh requirement, for genotoxicity endpoint for the registered substance, no further studies were required for the assessment. The read across analogy between sulfate and free base form was not performed for the genotoxicity endpoint, because enougth data on the free base are available. According to the data, the 4 -amino-m-cresol was not classified as Mutagenic substance, no positive effect was observed in the in vivo study.

Justification for classification or non-classification

According to the in vitro key studies, the registered substance 4 -amino-m-cresol induced clastogenic effetcs on mammalian cells and micronucleus test. No mutagenic response was observed on bacteria strains (Ames test). The in vivo key studies performed as Micronucleus, did not showed mutagenic effect on in vivo test system. Hence, the registered substance can be classified as non mutagenic substance according CLP regulation.