Registration Dossier

Administrative data

Description of key information

In the key oral gavage study conducted to the now deleted OECD 401 and to GLP (Huntingdon Life Sciences, 2000) the LD50 for triacetoxyethylsilane was 1460 mg/kg bw in rats. Clinical signs and macroscopic findings appeared to be related to the corrosive properties of the test substance on the stomach. 
There are no dermal or inhalation studies available, and it is not scientifically feasible to conduct new tests as the test substance has corrosive properties.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
1 460 mg/kg bw

Additional information

There are two reliable oral studies for the acute toxicity endpoint. The most recent and most reliable of the two studies was selected as the key study. The supporting study (Bayer AG, 1980), gave a higher LD50 value of 2400 mg/kg bw (dose given in ml/kg, converted using a relative density of 1.14).

Since one mole (234 g) of silane produces three moles (180 g) of acetic acid, it is expected that the LD50 for the silane would be (234/180)*LD50 of acetic acid. So, if the LD50 for the acid is 1083 mg/kg bw (as reported in SIAR, 2006), then the LD50 of the silane would be ca.1410 mg/kg bw. This assumes that the silanol does not contribute to the intrinsic toxicity of the substance.

The calculated value is in good agreement with the reported LD50of ethyltriacetoxysilane of 1460 mg/kg bw (rat), confirming the above assumption.

Justification for classification or non-classification

Based on the available acute oral toxicity data, triacetoxyethylsilane is classified 'Acute Toxic 4 (oral)' with the hazard statement 'H302: Harmful if swallowed' according to Regulation 1272/2008/EC.