Registration Dossier

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The substance is a gas at normal temperature and pressure and is expected to react violently and rapidly with water. This violent and rapid reaction of the gas with water would render aquatic ecotoxicology testing impossible and thus testing is waived on the basis of the technical difficulty to conduct such tests.

The hydrolysis half-life of dichlorosilane is estimated to be ≤17 seconds 1.5˚C and pH 7. The substance will hydrolyse rapidly to monosilicic acid and hydrogen. The read-across information is added here as supporting evidence that the silanol hydrolysis product is not toxic and adding to the weight of evidence for not carrying out any further testing.

No data are available for dichlorosilane. Reliable acute aquatic toxicity test results for freshwater fish, invertebrates and algae are however available from two read-across substances that hydrolyse to the same silicon containing hydrolysis product as the registration substance: trimethoxysilane (CAS 2487-90-3) and tetraethyl orthosilicate (CAS 78-10-4). Justification for the use of these data is given in the overall ecotoxicological information endpoint summary in IUCLID and in Section 7.0 of this CSR.

Trimethoxysilane (CAS 2487-90-3)

Reliable acute toxicity tests results are available for freshwater fish (Oncorhynchus mykiss), invertebrates (Daphnia magna) and algae (Pseudokirchneriella subcapitata).

The relevant values are:

Fish: A 96-h LC50 value of >100 mg/l has been determined for the effects of trimethoxysilane on mortality of Oncorhynchus mykiss based on nominal concentrations.

Invertebrates: A 48-h EC50 value of >100 mg/l has been determined for the effects of trimethoxysilane on mobility of Daphnia magna based on nominal concentrations.

Algae: A 72-h EC50 value of >100 mg/l and a NOEC of <6.3 mg/l have been determined for the effects of trimethoxysilane on growth rate of Pseudokirchneriella subcapitata based on nominal concentrations.

Tetraethyl orthosilicate (CAS 78-10-4)

Reliable acute toxicity tests results are available for freshwater fish (Brachydanio rerio), invertebrates (Daphnia magna) and algae (Pseudokirchneriella subcapitata).

The relevant values are:

Fish: A 96-h LC50 value of >245 mg/l has been determined for the effects of tetraethyl orthosilicate on mortality of Brachydanio rerio based on measured concentrations.

Invertebrates: A 48-h EC50 value of >844 mg/l has been determined for the effects of tetraethyl orthosilicate on mobility of Daphnia magna based on nominal concentrations.

Algae: A 72-h EC50 value of >100 mg/l and a NOEC of ≥100 mg/l have been determined for the effects of tetraethyl orthosilicate on growth rate of Pseudokirchneriella subcapitata based on nominal concentrations.

The long-term aquatic toxicity endpoints are waived as the chemical safety assessment according to Annex I, derived on the silanol hydrolysis product, indicates that they are not necessary.