Dibutoxy(dimethyl)silane

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The key study for sensitisation used the Buehler method, conducted according to OECD TG 406 and in compliance with GLP (BSL Bioservice, 2015e). The test group was administered the test material undiluted, under occlusive dressing, for 6 hours at weekly intervals for three weeks. The challenge exposure followed 14 days after the induction, and the test material was applied at 25% concentration onto the skin of the guinea pigs and held in contact under occlusive dressing for 6 hours. Skin reactions were observed at 24 and 48 hours. There were no signs of sensitisation in any of the 20 test animals, and the test material was concluded to be not sensitising. Appropriate positive and negative controls were in place with expected results.

The current accepted and preferred method for skin sensitisation testing according to the REACH legislation (EC no 1907/2006) and CLP Regulation (EC No 1272/2008) is the murine local lymph node assay (LLNA). A validated test method, OECD TG 429 (OECD 2002) is available for the LLNA. The guideline acknowledges the limits of the LLNA, and states that there are instances where ‘test substance classes or substances containing functional groups shown to act as potential confounders’ make the use of guinea pig tests more appropriate. It is concluded that the LLNA is not applicable where the properties of the test material cause interference in the accuracy of the LLNA (OECD 2002). The statement in the OECD TG 429 is given with reference to the findings of Basketter et al. (2009a), who demonstrated false positives in silicone based substances which had previously been demonstrated to be non-sensitisers in the guinea pig maximisation test (GPMT). The importance of available evidence from guinea pig results, consideration of chemical reactivity, epidermal bioavailability and clinical and experimental human data are emphasised as central to reaching appropriate regulatory decisions for substances which have been shown to fall outside the specificity of the LLNA (Basketter et al., 2009b). The non-applicability of the LLNA for silicone based substances has also been demonstrated by Petry et al. (2012). The sensitisation potential of polyfunctional silicone materials was tested in a comparative study investigating the GPMT and the LLNA assays, which found the five tested substances to be negative in the GPMT whereas they were concluded to be weak to moderate skin sensitisers in the LLNA (Petry et al., 2012).

References

Basketter D, Ball N, Cagen S, Carillo JC, Certa H, Eigler D, Garcia C, Esch H, Graham C, Haux C, Kreiling R, Mehling A (2009a). Application of weight of evidence approach to assessing discordant sensitisation datasets: implication for REACH. Reg. Toxicol. Pharmacol., 55, 90-96.

Basketter D, McFadden JF, Gerberick F, Cockshott A, Kimber I (2009b) Nothing is perfect, not even the local lymph node assay: a commentary and the implications for REACH.Contact Dermatitis, 60, 65-69.

Petry, T., Bosch, A., Coste, X., Dupuis, V., Eigler, D., Germain, P. (2012). An assessment of the skin sensitisation hazard of a group of polyfunctional silicones using a weight of evidence approach. Regulatory Toxicology and Pharmacology, 64, 305-314.

Migrated from Short description of key information:
The key study for sensitisation found the test material not sensitising in a Buehler test, in a study conducted according to OECD TG 406 and in compliance with GLP (BSL Bioservice, 2015e).

Justification for selection of skin sensitisation endpoint:
The study was conducted according to current guideline and in compliance with GLP.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data, no classification is required for sensitisation in accordance with Regulation (EC) No. 1272/2008.