Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

No data are available for the submission substance, 3-(triethoxysilyl)propanethiol (CAS 14814-09-6), however, reliable test data are available for the substance, 3-(trimethoxysilyl)propane-1-thiol (CAS 4420-74-0) which rapidly hydrolyses to the same silanol hydrolysis product as the submission substance, 3-(trihydroxysilyl)propanethiol.

Reliable short-term toxicity test results are available for freshwater fish (Danio rerio), invertebrates (Daphnia magna) and algae (Desmodesmus subspicatus). The relevant short-term values have been read-across from 3-(trimethoxysilyl)propane-1-thiol (CAS 4420-74-0):

Fish (96 h): LC50 = 439 mg/L. This is equivalent to 345 mg/L when expressed in terms of the silanol hydrolysis product, 3-(trihydroxysilyl)propanethiol.

Invertebrates (48 h): EC50 = 6.7 mg/L. This is equivalent to 5.3 mg/L when expressed in terms of the silanol hydrolysis product, 3-(trihydroxysilyl)propanethiol.

Algae (72 h): ErC50 = 931mg/L, ErC10 = 92 mg/L and NOErC = 40 mg/L. These values are equivalent to 731, 72 and 31 mg/L when expressed in terms of the silanol hydrolysis product, 3-(trihydroxysilyl)propanethiol.

An activated respiration inhibition 3 hour EC50 463 mg/L and EC10 32.6 mg/L were determined in a reliable study with the read-across substance, 3-(trihydroxysilyl)propane-1-thiol (CAS 4420-74-0).

The substance will be exposed to the environment through wastewater treatment plant (WWTP) effluent only. The minimum residency time in the wastewater treatment plant is approximately 7 hours (although this is a conservative figure and wastewater treatment time may be hours longer) with an average temperature of 15°C (assumed to be at neutral pH). Some degradation by hydrolysis would be expected before the substance is released to the receiving waters, but a significant amount of parent could remain. The environmental hazard assessment for the aquatic compartment is therefore based on the properties of the parent substance, in accordance with REACH guidance.

 

Refer to IUCLID Section 6 endpoint summary (CSR Section 7.0) for further discussion of the approach to chemical safety assessment and justification for read across.

 

In line with ECHA Final Decision No. TPE-D-2114432420-65-01/F, there are ongoing acute studies with the registration substance, 3-(triethoxysilyl)propanethiol (CAS 14814-09-6), conducted according to OECD test guidelines and in compliance with GLP. After these results have been reviewed, a long-term study will be carried out with the most sensitive trophic level. However, the short-term study results will not be available in time for the final decision deadline of 26th January 2021. The study results will therefore be submitted at a later date. The acute toxicity study reports are expected to be available in March 2021, therefore an update will be submitted by July 2021.