Registration Dossier

Administrative data

Description of key information

Acute toxicity:
Oral:
OECD TG 401: LD50≥ 5170 mg/kg bw
Inhalation
OECD TG 403: LC50> 22200 mg/m³
Dermal:
There are no measured acute dermal toxicity data available (data waiving according to Column 2 of REACH Annex VIII, Section 8.5.3).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
discriminating dose
Value:
5 170 mg/kg bw
Quality of whole database:
The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline. It was not compliant with GLP.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
Value:
22 200 mg/m³
Quality of whole database:
The study was conducted according to a test protocol that is according to the appropriate OECD test guideline, and in compliance with GLP.

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Studies were chosen as key when the available study was of relevance and of sufficient quality for classification, labelling and for risk assessment. Other available data are included as supporting studies.

The key acute oral toxicity study which was conducted in compliance with GLP and according to the now deleted OECD TG 401, reports an LD50 value of ≥ 5170 mg/kg bw, for male and female rats, respectively. These values indicate low acute toxicity by the oral route of the registered substance. The most common signs of toxicity were reduced locomotion, impaired co-ordination, loss of muscle tone and loss of righting reflex (ASTA Pharma, 1988). In an additional acute oral toxicity study similar to the now deleted OECD TG 401 and not to GLP with trimethoxy(propyl)silane identified an LD50 value in the rat of 7420 mg/kg bw (INBIFO, 1979a). The results of both experiments are in agreement with the low acute oral toxicity (lethality) potential of trimethoxy(propyl)silane.

The key acute inhalation toxicity study which was conducted in compliance with GLP and according to OECD TG 403 reports an LC50 value of > 22200 mg/m³ for trimethoxy(propyl)silane vapour in rats after 4 hours. Shortly after exposure, restlessness and irregular breathing was observed followed by narcosis and deep and irregular breathing. Wet noses and dirty fur were common observations on the first day of the observation period, but there were no abnormalities evident thereafter. Just before death the male demonstrated lethargy, showed flabby muscles, in coordination, piloerection and a visually increased breathing frequency (TNO, 1990). In an additional acute inhalation toxicity study similar to OECD TG 403, but not conducted according to GLP, the 6-hour LC50 value for trimethoxy(propyl)silane aerosol in rats was 15228 mg/m³ (dose given in ml/m3, converted using a relative density of 0.94) (INBIFO, 1979b). The results of both experiments are in agreement of the low acute inhalation (lethality) potential of the registered substance.

 

There are no measured acute dermal toxicity data available. However, systemic effects were not observed in the skin irritation and skin sensitisation studies.


Justification for selection of acute toxicity – oral endpoint
The key study was selected for assessment.

Justification for selection of acute toxicity – inhalation endpoint
The key study was selected for assessment.

Justification for selection of acute toxicity – dermal endpoint
In accordance with Column 2 of REACH Annex VIII, the acute toxicity study via the dermal route (required in Section 8.5.3) does not need to be conducted as reliable data via the oral and inhalation routes are available.

Justification for classification or non-classification

Based on the available acute toxicity data, trimethoxy(propyl)silane is not classified for acute toxicity (lethality) following a single exposure under Regulation 1272/2008/EC.

Classification as STOT-SE Cat 3, with the hazard statement 'H336: May cause drowsiness and dizziness' according to Regulation (EC) 1272/2008 is not warranted for the test substance. Although signs of narcosis were observed in the acute inhalation study, this was rather linked to the systemic effects provoked by the test substance after exposure at a concentration exceeding the limit dose stated in the corresponding OECD guideline. In addition the reported concentration could have been higher due to the whole-body inhalation and possible additional oral uptake of the test substance. Mortality and clinical signs as laboured breathing and lethargy were observed. At necropsy dark red discoloured lungs were reported, thus leading to the conclusion that the narcotic effects were rather a consequence of anoxia provoked by systemic effects.