Oxybenzone

Endpoint summary

Additional information

in vitro

Oxybenzone was found negative for inducing gene mutations in four in vitro studies (two Ames tests according to OECD 471, Mammalian Chromosome Aberration test according to OECD 473 and Mammalian Cells Gene Mutation test according to OECD 476), all conducted in the presence and absence of metabolic activation. The key Ames test studied five mutant strains of Salmonella typhimurium (TA1535, TA1537, TA 1538, TA98, and TA100) with and without liver homogenate (S9) as well as E. coli WP2 with and without liver homogenate (S9) in test concentrations up to 1250 µg per plate. No increase in revertant colony numbers of any of the tester strains was observed following treatment with oxybenzone at any dose level, neither in the presence nor absence of metabolic activation (S9 mix). The second supporting Ames test was performed using four strains of Salmonella typhimurium (TA1535, TA1537, TA98, and TA100) with and without liver homogenate (S9) as well as E. coli WP2 with and without liver homogenate (S9) in test concentrations up to 5000 µg per plate. In both studies there was no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance.

Appropriate reference mutagens were used as positive controls in both studies and showed a distinct increase of induced revertant colonies.

In conclusion, these results indicated that test article was not mutagenic to Salmonella typhimurium strains TA1535,TA1537, TA 1538, TA98, and TA100 or to E. coli WP2 in the absence and presence of a metabolic system.

 

The third in vitro study was performed to evaluate the potential to induce structural chromosomal aberrations in V79 Chinese Hamster cells in the absence and the presence of artificial sunlight (with and without metabolic activation) in two independent experiments according to OECD guideline 473. The test article was applied up to 75 µM. In the assay, based on the results given in this study, oxybenzone, was found not to induce structural chromosome aberrations in the absence or presence of artificial sunlight in V79 Chinese Hamster cells. Therefore, the test article was shown to be non-clastogenic in this chromosomal aberration photomutagenicity test when tested up to cytotoxic concentrations.

 

The third in vitro study was performed to investigate the potential of oxybenzone to induce gene mutations at the HPRT locus in V79 cells of the Chinese hamster according to OECD guideline 476.The test article was applied up to 2283 µg/ml in the pre-test and up to 160 µg/ml in the two main tests. No substantial and reproducible dose dependent increase of the mutation frequency was observed in either of the main experiments. Thus, the test item did not induce gene mutation effects at the HPRT locus in V79 cells.

In vivo

As all available in vitro tests were negative, in vivo data are not required.

Justification for selection of genetic toxicity endpoint
All three available key in vitro tests contribute to the final assessment for the substance being considered negative inducing gene mutations, supported by an additional Ames test.

Short description of key information:
Based on the available data, oxybenzone was found negative inducing gene mutagenicity under the experimental conditions of four in vitro tests .

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Oxybenzone does not have to be classified for mutagenicity according to the criteria laid down in the EU Dangerous Substances Directive (67/548/EEC) and in the EU Classification Labelling and Packaging Regulation (1272/2008/EC) because it did not reveal any mutagenic effect in the bacterial reverse mutation assay in the presence or absence of metabolic activation, in the mammalian cell gene (HPRT) mutation test in V79 cells or in an in vitro chromosomal aberration test.