Registration Dossier

Administrative data

Description of key information

No acute toxicity data are available for the registered substance and the substance is classified as corrosive to skin, therefore new testing is not scientifically necessary.

Acute oral and inhalation tests on the structurally analogous substances trimethoxy(propyl)silane (CAS 1067-25-0) and trimethoxy(methyl)silane (CAS 1185 -55 -3) are included to support the read-across approach proposed to fill data gaps for higher tier endpoints.

The key study for acute oral toxicity reports an LD50 value of >5000 mg/kg bw determined in a reliable study conducted according to OECD TG 401 (ASTA Pharma, 1988). The key study for acute inhalation toxicity, reports an LC50 value of >22200 mg/m³, determined in a reliable study conducted according to OECD TG 403 (TNO 1990).  

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
Value:
5 170 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
Value:
22 200 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

In accordance with Column 2 of REACH Annex VIII acute toxicity studies do not need to be conducted as tripotassium propylsilanetriolate is classified as corrosive due to its high pH. However the following data from read-across substance are included for information.

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 ≥ 5000 mg/kg bw, for male and female rats, respectively. 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 trimethoxypropylsilane 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 trimethoxypropylsilane. This value indicates low acute toxicity by the oral route of the registered substance.

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 trimethoxypropylsilane 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 trimethoxypropylsilane 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 support the low acute inhalation (lethality) potential of the registered substance.

Key acute oral and inhalation toxicity studies from the dossier on trimethoxy(methyl)silane (CAS 1185 -55 -3) are included in support of the read-across for the repeated dose toxicity endpoints, and support low acute toxicity of the source substance and its hydrolysis products.


Justification for classification or non-classification

Based on the available read-across acute toxicity data, tripotassium propylsilanetriolate is not classified for acute toxicity (lethality) following a single exposure under Regulation (EC) No 1272/2008.

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