Registration Dossier

Administrative data

Description of key information

The key acute oral study (LPT, 2002), conducted according to the guideline for the Acute Toxic Class method and GLP, reported an LD50 in male and female rats in the range 200-2000 mg/kg bw. At 2000 mg/kg bw all animals died, at 200 mg/kg bw no deaths and no overt signs of systemic toxicity were observed. In accordance with OECD 423 (1996) this implicates the LD50 to be between 300 and 500 mg/kg bw.  
A limited, non-guideline, non-GLP inhalation study (Dow Corning, 1969) reported the death of all rats exposed to an atmosphere said to be saturated with the test material within 27 minutes. Extensive ocular and respiratory irritation were reported within 3 minutes.
There are no data for the dermal route and the corrosive nature of the test material means that (adequate) acute studies via the inhalation and dermal routes (required in Section 8.5.2 and 8.5.3, Annex VIII) do not need to be conducted.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
Value:
200 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The key study for acute toxicity with the registered substance identified an acute oral LD50 between 200 and 2000 mg/kg bw for male and females rats, treated via gavage (LPT, 2002). Clinical signs included reduced motility, ataxia in all animals, reduced muscle tone, dyspnoea and vocalisation in one animal, at 2000 mg/kg bw. No remarkable gross pathology was reported.

A reliability 4 supporting study on acute toxicity was also available which reports the death of all animals with extensive ocular and respiratory irritation (Dow Corning Corporation, 1969).

Acute toxicity data for trimethylsilanol (CAS 1066-40-6) are included in the data set to support validity of the repeated dose toxicity read-across approach, discussed in more detail in Section 7.5 Repeated dose toxicity. The data are summarised below.

An acute oral toxicity study with trimethylsilanol (CAS 1066-40-6) was conducted using an appropriate protocol, but not in compliance with GLP (Bayer, 1985). An LD50 of 3.5 ml/kg bw (equivalent to 2835 mg/kg bw) is reported in rats. A general deterioration in the animals' health was observed including anaesthesia, lateral position and ruffled fur. All surviving animals appeared symptom-free after ten days.

An acute inhalation study with trimethylsilanol (CAS 1066-40-6) was conducted according to current OECD guideline and to GLP (WIL, 2007). The 4 hour LC50 of trimethylsilanol was reported to be 3151 ppm (11.8 mg/l) in rats. Significant clinical observations for the surviving animals during the 14-day post-exposure observation period consisted of yellow material on the urogenital area, decreased, shallow respiration, rales, hypoactivity, prostration and ataxia. All surviving animals were considered normal by study day 5.


Justification for selection of acute toxicity – oral endpoint
The selected key study is the only study available for the acute oral toxicity endpoint. It was conducted according to an appropriate OECD test guideline and in compliance with GLP.

Justification for selection of acute toxicity – inhalation endpoint
The selected study is the only study available for the acute inhalation toxicity endpoint. It is a non-standard study and no LC50 was established. Further testing is not appropriate due to the corrosive nature of the test substance.

Justification for classification or non-classification

On the basis of the available data chloro(dimethyl)vinylsilane is classified Acute Toxic 4 (oral) according to Regulation (EC) No 1272/2008.