Benzene, ethylenated, by-products from

Endpoint summary

Additional information

Mutagenicity in bacteria:

Monsanto (1985), ACC (2005) and Dow (1987) Ames assays are available with the UVCB substance. Overall, this substance was tested in 5 Salmonella strains (TA1535, TA1537, TA1538, TA100, TA98) and in the E.coli WP2 uvrA strain with and without metabolic activation. In one out of three Ames assays with TA100 strain, the ACC substance produced a weakly positive response with metabolic activation in some, but not all, assay trials and the response was without a clear concentration- related increase across tested doses. This equivocal response in TA100 was not reproduced in the other two Ames assays in TA100 strain with this UVCB substance. All other bacterial strains tested with the registered UVCB substance did not produce a positive response. Overall, it can be concluded that the UVCB substance 'benzene, ethylenated by- products from' does not present mutagenic activity in bacteria. Together with the results of testing in mammalian cells, the weight of evidence indicates that this substance has no mutagenic potential in vitro.   

Chromosome aberration in vitro:

Monsanto (1987), ACC (2006) and two Dow (1987) Chromosome Aberration assays in CHO cells are available with the UVCB substance. No biologically significant increases in structural or numerical aberrations were observed in chromosomes at any dose levels in any exposure regimen with and without metabolic activation. Therefore in all 4 assays, the UVCB substance 'benzene, ethylenated by- products from' was not clastogenic to mammalian cells in culture.

Mammalian gene mutation assay in vitro:

Monsanto (1986) HGPRT gene mutation assay in CHO cells is available with the UVCB substance. In the study, no statistically significant increases in mutant frequency were observed with the test substance with and without metabolic activation. Therefore, this outcome supports the spurious Ames results in one out of three assays with the TA100 strain that reverts by base pair  substitution at GC base pair as non reproducible and of low relevance to the general conclusions for this substance. Overall, the weight of evidence indicates that 'benzene, ethylenated by- products from' has no mutagenic potential in vitro.   

Unscheduled DNA synthesis:

Monsanto (1986) and three Dow (1987) unscheduled DNA synthesis (UDS) assays in primary rat hepatocyte cultures are available with the UVCB substance. Induction of DNA repair (via increased DNA synthesis) as a result of treatment with various UVCB 'benzene, ethylenated by- products from' substances was not observed in any of the four assays. Therefore, the UVCB substances did not produce any evidence of genotoxicity.

Together, the available in vitro genetic toxicology data indicate that this substance does not possess mutagenic potential in bacteria or mammalian cells, does not induce DNA repair activity, nor does it possess the ability to cause chromosome aberrations. Overall, the weight of evidence indicates that 'benzene, ethylenated by- products from' has no genotoxic potential in vitro. Thus, no in vivo follow up is proposed for 'benzene, ethylenated by- products from' substance.    

Short description of key information:
3 Ames assays on the UVCB REACH substance
4 unscheduled DNA synthesis assays
3 Chromosomal Aberration assays and an in vitro cytogenetics assay
1 Mammalian mutagenicity assay (CHO/HGPRT)

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

As the available genetic toxicity data demonstrate that the UVCB 'benzene, ethylenated by- products from' substance is not mutagenic or genotoxic in vitro, no classification for this endpoint is warranted.