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Key value for chemical safety assessment

Additional information

In vitro Studies

Gene mutation

There are several Ames-tests which are mostly performed according to OECD Guideline 471 with and without metabolic activation. In every study at least the highest dose levels exhibit 100 % toxicity. For example 1-chloro-2-nitrobenzene was evaluated as mutagenic in the tests reported by Haworth et al. (1983) (doses: 6-600 resp. 10-1000 µg/plate) and by Bayer (1984) (doses: 833.3-2073.6 µg/plate). An additional test, which was reported in JETOC (1996) (doses: 10-1000 µg/plate), yielded negative results. A repetition of the study (doses: 39.1-10000 µg/plate) showed positive results in TA 100 and TA98. Investigations with E. coli yielded positive and negative results (JETOC 1997).

In summary, the available tests withSalmonella typhimuriumshowed mostly negative results without the addition of a metabolic activation system in different strains. Only in strain TA98 and TA1538 there were obtained mostly negative and one resp. 2 positive results. In the presence of a metabolic activation system positive and negative results were obtained in TA 98 and TA 100 mostly at high but not bacteriotoxic concentrations.

 

In an HPRT Test which was performed with Chinese Hamster V79 lung cells according to OECD Guideline 476 1-chloro-2-nitrobenzene does not induce gene mutations. The doses used were 100-1200 µg/ml in the presence of S9-mix and 100-900 µg/ml without S9-mix. Cytotoxicity was noted in the highest concentration (TNO 1989).

 

Conclusion

1-Chloro-2-nitrobenzene yielded positive results only in 2 tester strains of Salmonella typhimurium and mostly at high but not bacteriotoxic concentrations. Therefore it can be regarded as a weak mutagen in bacterial test systems. It showed no mutagenic activity in mammalian cell test systems in vitro.

 

Cytogenicity

There is a study on cytogenicity using Chinese Hamster Ovary (CHO) cells and doses ranging from 10-100 µg/ml without addition of a metabolic activation system (S9-mix) and from 25-250 µg/ml in the presence of S9-mix. Harvest times were 8, 12, 21 hours. The study was performed according to OECD Guideline 473 and yielded negative results (Huntingdon 1988).

NTP (1993) reported additional cytogenetic tests with Chinese Hamster Ovary cells using different harvest times: Without metabolic activation an equivocal result at the highest concentration was obtained when the harvest time was 14 hours (doses: 16-160 µg/ml) and a negative result with a harvest time of 18.5 hours (dose: 47-216 µg/ml). In the presence of an activation system negative results were obtained after a harvest time of 14 hours (doses: 50-500 µg/ml) and weak positive results at the highest concentration when the harvest time was 13.6 hours (doses: 101-465 and 125-500 µg/ml).

 

Conclusion

1-Chloro-2-nitrobenzene showed weak clastogenic activity in CHO cells in vitro at high concentrations only.

 

Indicator Tests

1-Chloro-2-nitrobenzene did not increase Unscheduled DNA repair in rat hepatocytes using a dose range from 1.0 to 100 µg/ml DMSO. Cytotoxicity was determined in preliminary results (Monsanto 1984).

An increase in Sister Chromatid Exchange (SCE) rate was found in Chinese Hamster Ovary cells treated with 1-chloro-2-nitrobenzene in doses ranging from 5 to 500 µg/ml (NTP 1993). The biological relevance of SCE is not yet clear.

 

Conclusion

1-Chloro-2-nitrobenzene did not induce Unscheduled DNA repair. It induced increased rates of Sister Chromatid Exchanges, whereas the biological relevance of this effect is not yet clear.

 

In vivo Studies

Gene mutation

There are several Drosophila SLRL tests which are performed using different application routes: intraperitoneal injection, adult and larval feeding. Both dosing methods lead to negative results (Zimmering 1985, 1989).

 

Conclusion

1-Chloro-2-nitrobenzene showed no mutagenic activity inDrosophila melanogaster.

 

Cytogenicity

Intraperitoneal injection of 60 mg 1-chloro-2-nitrobenzene/kg bw of unknown purity into CD-1 mice (n=8) induced single DNA strand breaks in liver and kidneys which were identified by alkaline elution technique (Cesarone et al. 1982). Intraperitoneal injection, however, is not the recommended exposure route of the respective OECD guideline because it could expose the organs directly rather than via the circulatory system.

 

Conclusion

Intraperitoneal injection of 1-chloro-2-nitrobenzene into mice resulted in DNA damage in the liver and kidney.


Short description of key information:
1-Chloro-2-nitrobenzene showed weak mutagenic activity in bacterial test systems but not in mammalian cell test systems in vitro. It was not mutagenic inDrosophila melanogaster. In mammalian cells in vitro, it showed weak clastogenic activity. The substance induced increased rates of Sister Chromatid Exchanges, whereas the biological relevance of this effect is not yet clear.
Intraperitoneal injection into mice resulted in DNA damage in the liver and kidney. The inconsistent results of the available genotoxic studies are typical for nitroaromatics. As a whole 1-chloro-2-nitrobenzene is suspected of being genotoxic, at least a weak clastogen.

Endpoint Conclusion:

Justification for classification or non-classification

Based on the results of the genetic toxicity tests, 1-chloro-2-nitrobenzene does not need to be classified according to Directive 67/548/EEC and according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.