Diphenylsilanediol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In the key Buehler test with read-across substance dimethoxy(diphenyl)silane, conducted according OECD Test Guideline 406 and in compliance with GLP (Hüls AG, 1995), female Dunkin Hartley guinea pigs were treated (20/10 control/test group) three times with 300 µl of the test substance every 7 days during the induction period. The test substance was applied undiluted for 6 hours under occlusive conditions. In a pre-test the substance was found to be not irritating when applied undiluted. Two weeks after the last induction one challenge was performed in the same way as the induction procedure. 30 and 52 hours after the start of the challenge the skin reactions were scored. No reactions were observed at any time point and in any animal. In conclusion, the test substance is considered not to be a skin sensitiser under the applied conditions.

READ-ACROSS JUSTIFICATION

To reduce animal testing REACH recommends to make use of a read-across approach where appropriate based on the high accordance in properties relevant for the specific endpoint. In the case of sensitisation the relevant property is hydrolysis of the read-across substance to form the registered substance. The proposed read-across from the sensitisation study for dimethoxydiphenylsilane to diphenylsilanediol is discussed below.

Read-across hypothesis

The hypothesis is that at relevant physiological pH the read-across substance hydrolyses to form the registered substance, so in the key Buehler study the test animals will have been exposed primarily to diphenylsilanediol. The non-silanol hydrolysis product, methanol, to which the test animals will also have been exposed, does not contribute to any adverse effects for sensitisation at the relevant dose levels based on publicly available information. This is discussed further below.

Read-across justification

The predicted (QSAR) hydrolysis half-lives of the read-across substance, dimethoxy(diphenyl)silane are 0.1 hour at pH 4 and pH 5, 0.6 hour at pH 7, and <5 seconds at pH 9 and at 20-25°C. The products of hydrolysis are diphenylsilanediol and methanol. Therefore during the 6-hour dermal exposure period in the Buehler study, at physiological pH a minimum of 10 hydrolysis half-lives of the read-across substance would have occurred resulting in the formation of significant amounts of the registered substance, diphenylsilanediol.

Methanol is not classified for sensitisation in Annex VI of Regulation (EC) No 1272/2008.

Migrated from Short description of key information:
Read-across substance dimethoxydiphenylsilane was not sensitising in a Buehler test (OECD 406).

Justification for selection of skin sensitisation endpoint:
The study was conducting according to an appropriate 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 read-across data from dimethoxydiphenylsilane, diphenylsilanediol does not require classification for sensitisation according to Regulation (EC) No 1272/2008.