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Key value for chemical safety assessment

Additional information

Valid experimental data were available to assess the genetic toxicity of 3-chloro-o-toluidine in-vitro and in-vivo.


In vitro:

-Gene mutation in bacteria:

3-chloro-o-toluidine was tested for mutagenic activity in Salmonella typhimurium strains TA 97, TA 98, TA 100 and TA 1535 at concentrations ranging from 3 to 1666 µg per plate (NTP, A84599, 1996). The tests were conducted, using the pre-incubation method, on agar plates in the presence and absence of Aroclor 1254 induced rat liver and Syrian hamster liver preparations and co-factors (S9 mix) required for mixed-function oxidase activity. Positive control compounds demonstrated the sensitivity of the assay and the metabolizing potential of the S9 mix. No mutagenic activity was observed in any of the 4 bacterial strains, in either activation condition. Toxicity was noted with all the strains at the highest concentrations used. This study does not fully satisfy the guideline requirement for a bacterial gene mutation assay (OECD Guideline 471) as a 5th strain was missing, which has an AT base pair at the primary reversion site, and since 2-Aminoanthracene was used as the sole indicator of the efficacy of the S9-mix. The study is nonetheless sufficiently detailed and is considered acceptable for assessment. The result of this study is supported by a further study done with TA 98 and TA 100 (BASF, 1987). Here no genotoxicity was observed with and without metabolic activation.


In vivo:

3-chloro-o-toluidine was tested in the micronucleus test according to OECD guideline 474 (Hoechst, 1994). The test compound was dissolved in sesame oil and dosed once orally at 800 mg per kg bodyweight to male and female NMRI mice. According to the test procedure the animals were killed 12, 24 or 48 hours after administration. Endoxan® was used as positive control substance and was administered once orally at a dose of 50 mg per kg bodyweight. The number of polychromatic and normochromatic erythrocytes containing micronuclei was not increased. The ratio of polychromatid/normochromatic erythrocytes in both male and female animals remained unaffected by the treatment with the test substance and was statistically not different from the control values. Endoxan® induced in both males and females a marked statistically significant increase in the number of polychromatic cells with micronuclei, confirming the sensitivity of the test system. The ratio of polychromatic erythrocytes to normocytes was not changed to a significant extent. Under the conditions of the present study the results indicate that 3-chloro-o-toluidine is not mutagenic in the micronucleus test.


Conclusion: Since all studies done with 3-chloro-o-toluidine showed negative results a mutagenic potential for this test substance is not assumed.

Short description of key information:
in vitro: negative in Ames test with S. typhimurium TA 97, TA 98, TA 100 and TA 1535with and without metabolic activation (NTP, A84599, 1996)
in vivo: negative in micronucleus assay (Hoechst, 94.0106, 1994)

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is not considered to be classified for genetic toxicity under Directive 67/548/EEC, as amended for the 28th time in Directive 2001/59/EC.


Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for genetic toxicity under Regulation (EC) No. 1272/2008.