Registration Dossier

Administrative data

Description of key information

No studies were available to assess the acute oral toxicity potential of dimethoxydimethylsilane (CAS: 1112-39-6), however, data are available for the structural analogue substances trimethoxymethylsilane (CAS: 1185-55-3) and triethoxymethylsilane (CAS: 2031-67-6), respectively.
Oral:
WoE approach CAS: 1185-55-3 and CAS: 2031-67-6: LD50 > 2000 mg/kg bw
Inhalation:
OECD TG 403: LC50 >4700 mg/m³
There are no data available for acute toxicity via the dermal route (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:
2 000 mg/kg bw
Quality of whole database:
The data was obtained from reliable studies with a structural analogue substance. The read-across is considered suitable as both the submissionn subsrtance and the read-across substance rapidly hydrolyse under formation of structural analogue degradation products.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
discriminating conc.
Value:
4 700 mg/m³
Quality of whole database:
The study was conducted 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

No studies were identified to assess the acute oral toxicity potential of dimethoxydimethylsilane (CAS: 1112-39-6), however, reliable data are available for the structural analogue substances trimethoxymethylsilane (CAS: 1185-55-3) and triethoxymethylsilane (CAS: 2031-67-6). Details on read across justifications can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

In an acute oral toxicity study which was conducted in compliance with GLP and according to the now deleted OECD TG 401, reports an LD50value of >2007 mg/kg bw for the structural analogue substance triethoxy(methyl)silane. There were no mortality or marked systemic effect in rats at the limit dose of 2007 mg/kg bw (Hazleton France, 1992a). An additional acute oral toxicity study conducted without compliance to GLP and according to OECD TG 401 was also available on triethoxy(methyl)silane, which reported oral LD50 values of 10 057 and 7627 mg/kg bw (dose given in ml/kg, converted using a relative density of 0.89), for males and females, respectively (Bushy Run Research Centreer , 1981a). Furthermore acute oral toxicity studies equivalent or similar to OECD TG 401 and according to accepted scientific principles are available for the structural analogue substance trimethoxymethylsilane (CAS 1185-55-3), which reports LD50 values of 7000 mg/kg in mice (Julou, 1972) and 11685 mg/kg in male rats (Mellon Institute, 1963), respectively. All the studies are in agreement of the lack of acute toxicity potential by the oral route for the structural analogue substances, triethoxymethylsilane and trimethoxymethylsilane. This therefore strengthens the overall assumption that the registered substance, dimethoxydimethylsilane, will not be acutely toxic by the oral route.

The key acute inhalation study was the only study available. The study was conducted in compliance with GLP and according to OECD TG 403. Exposure of rats to dimethoxydimethylsilane (CAS 1112-39-6) vapour at a concentration of 4.7 mg/L (4700 mg/m³) for four hours resulted in no mortality. Therefore LC50 was determined to be >4700 mg/m³ (Dow Corning Corporation, 1989).

No studies were available to assess the acute dermal toxicity potential of dimethoxydimethylsilane (CAS 1112-39-6). However, 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

The available data on acute toxicity by the oral route for the structural analogue substances, triethoxymethylsilane (CAS 2031 -67 -6) and trimethoxymethylsilane (CAS 1185 -55 -3), respectively, do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification of the registered substance.

The available data on acute toxicity by the inhalation route for the registered substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.