Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

There is one negative skin sensitisation study for tetrapropyl orthosilicate, but there was no evidence of a positive control or preliminary study in the study report, therefore the study is not sufficiently reliable to be a key study. There is also a skin sensitisation study on the structurally-related substance, tetraethyl orthosilicate, which was also negative. Together these two studies form a weight-of-evidence against a sensitising potential for tetrapropyl orthosilicate.

In the absence of reliable data for tetrapropyl orthosilicate, it is considered appropriate to use an additional study on tetraethyl orthosilicate to form a weight-of-evidence for the skin sensitisation endpoint.

The registered substance and read-across substance are both moderately lipophilic substances (log Kow3.4 and 3.0, respectively) for which dermal uptake is favourable. After uptake both substances hydrolyse rapidly with half-lives of 1.6 and 2.5 hours respectively at pH 7 and 37.5°C forming propanol or ethanol and silicic acid. N-propanol is not sensitising to skin (EC, 2008), nor is ethanol (OECD, 2004), therefore read-across based on the common hydrolysis product is relevant.

Migrated from Short description of key information:
Two studies form a weight-of-evidence for skin sensitisation potential of tetrapropyl orthosilicate.

In a guinea pig maximisation study conducted using a protocol comparable to OECD 406 (with restrictions: no positive control or preliminary study) and to GLP (Dow Corning Corporation, 1984; reliability score 4) tetrapropyl orthosilicate was not sensitising to the skin of guinea pigs.

In a skin sensitisation study (Buehler test; reliability score 2) conducted to OECD 406 (with restrictions: only 10 test animals and no positive control) tetraethyl orthosilicate was not sensitising to the skin of guinea-pigs (Degussa-Huls, 1992).

Justification for selection of skin sensitisation endpoint:
The assessment of skin sensitisation is based on a weight of evidence approach from two studies, one each on the registration substance itself and on a relevant surrogate substance.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the weight of evidence tetrapropyl orthosilicate is not classified for skin sensitisation according to Regulation (EC) No 1272/2008.