Glyoxylic acid

Endpoint summary

Additional information

In a reverse gene mutation assay in bacteria strains TA 1535, TA 1537, TA 1538, TA 98 and TA 100 of S. typhimurium and WP2 uvrA of E. Coli were exposed to Glyoxylic Acid at concentrations of 0, 4, 20, 100, 500, 2500, 5000 or 10000 µg/plate (3 plates/dose) in the presence and absence of mammalian metabolic activation applying the standard plate method. Cytotoxicity was observed at 2500 µg/plate and higher doses. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.

This study is classified as acceptable and satisfies the requirement for test guideline OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data.

An in vitro mammalian cell mutagenicity study was performed to investigate the potential of Glyoxylic Acid 50 % to induce mutations at the mouse lymphoma thymidine kinase locus using the cell line L5178Y. The treatment period was 4 h in the first experiment with and without metabolic activation. In the second experiment, the treatment period was 24 h without metabolic activation and 4 h in the presence of metabolic activation.

The highest applied concentration in the pre-test on toxicity (750 µg/mL about 10 mM) was chosen with regard to the current OECD Guideline 476.

No substantial and reproducible dose dependent increase in mutant colony numbers was observed in both main experiments. No relevant and reproducible shift of the ratio of small versus large colonies was observed up to the maximal concentration of the test item. A moderate increase of the mutation frequency observed in the first experiment at 112.5 µg/mL was not reproduced in the second experiment and therefore, judged as biologically irrelevant. Appropriate reference mutagens were used as positive controls and showed a distinct increase in induced mutant colonies, indicating that the tests were sensitive and valid.

In a Crl:Cobs CD-1 mouse bone marrow micronucleus assay, 4 animals/sex/dose were treated by gavage with Glyoxylic Acid 50% at doses of 0, 183, 366, or 914 mg/kg bw. The vehicle was water. The highest dose corresponded to 1/2 of the mouse LD50 and thus represents the maximum tolerable dose. Bone marrow cells were harvested 24 hours post-treatment. There were no signs of toxicity during the study. The positive controls (Benzo(a)pyrene and Cyclophosphamide) induced the appropriate response. There was not a significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow up to the dose of 914 mg/kg bw after treatment time.

Short description of key information:
No potential for genetic toxicity of Glyoxylic Acid 50% was indicated in the Ames Test, the Mouse Lymphoma Test and the Bone Marrow Micronucleus Test.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the negative in vitro results supported by negative in vivo testing, Glyoxylic Acid 50% has not to be classified and labelled mutagenic according to EU Regulation No. 1272/2008 and EU Directive 67/548/EEC.