Registration Dossier

Administrative data

Key value for chemical safety assessment

Additional information

Four genotoxicity studies are available. Dibasic ester blend was tested in vitro in two bacterial reverse mutation assays, similar to an Ames test but using 3 or 4 strains of Salmonella typhimurium, and showed no mutagenic activity in this test system with or without S9 metabolic activation system (from liver or olfactory origin) up to the highest concentrations tested. The OECD test guideline 471 currently in force (1997) requires at least 5 tester strains and the use of E. coli WP2 or Salmonella typhimurium TA 102 strains to detect certain oxidizing mutagens, cross-linking agents and hydrazines. Dibasic ester blend was not tested on either recommended bacterial strain. However, dibasic esters are not considered highly reactive agents and based on their chemical structures are not expected to be cross-linking agents, have no oxidizing properties and are no hydrazine. Thus, the Salmonella typhimurium strains used in both Ames tests (TA1535, TA1537, TA98, TA100 and TM677) were considered appropriate and sufficient to evaluate the potential mutagenic activity of dibasic esters in this bacterial test system.

Dibasic ester blend was also tested in vitro in a chromosomal aberration assay in human lymphocytes. In the presence of liver S9 metabolic activation, a statistically significantly increased proportion of abnormal cells or cells with one or more aberration were observed at 0.3 and 0.4% (equivalent to 3.3 and 4.4 mg/mL, respectively), illustrating a clastogenic activity of the test substance under at high concentrations in the presence of S9. This result is not consistent with what is known about the hydrolysis products of the methyl esters. Methanol is not clastogenic or genotoxic. Adipic acid, glutaric acid and succinic acid are all endogenous and not considered to be clastogenic or genotoxic. As such it is possible that in the presence of S9 metabolic activation, the esters were hydrolysed and the acids released affected the pH, making it more acidic. This is known to cause false positive effects in cytogenicity assays.

In accordance with the REACH regulation, an in vivo genotoxicity assay on somatic cells was performed. A bone marrow micronucleus assay was performed in mice following a single inhalatory nose-only exposure to dibasic ester blend for 6 hours. There was no statistically significant differences in the proportion of micronucleated polychromatic erythrocytes between mice of all groups including controls at any sampling time up to 72 hours following exposure up to a very high concentration of 19 mg/L (equivalent to19000mg/m3), illustrating the absence of clastogenicity of the test substance in vivo.

No data are available for mammalian cell mutagenicity testing. However methanol is not genotoxic to bacteria or mammalian cells, and the acids are endogenous in mammals and therefore highly unlikely to be genotoxic at relevant exposure levels to humans.

In addition, in 90 -day studies by inhalation there was no evidence of pre-neoplastic lesions at the highest concentrations that could be tested, between 390 and 1000 mg/m3. Therefore there is sufficient data available to conclude that this substance is not mutagenic to mammalian cells.


Justification for selection of genetic toxicity endpoint
No specific study was selected since all available studies were used to assess the genotoxic potential of the registered substance

Short description of key information:
Clastogenic in vitro in a chromosomal aberration test on human lymphocytes but negative in in vitro bacterial reverse mutation assays and in in vivo mouse bone marrow micronucleus assay.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Overall, the genetic toxicity of dibasic ester blend is considered to be negative and therefore no classification is warranted according to the classification criteria of Annex VI Directive 67/548/EEC or EU Regulation 1272/2008 (CLP).