Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

There are no reliable aquatic toxicity data available for 2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4). 2,2,4,4,6,6-Hexamethylcyclotrisilazane hydrolyses very rapidly in water to give dimethylsilanediol and ammonia/ammonium ions, therefore good quality data for dimethylsilanediol (CAS 1066-42-8) have been read across.

Reliable short-term toxicity test results are available for freshwater invertebrates (Daphnia magna) and algae (Pseudokirchneriella subcapitata) for dimethylsilanediol (CAS 1066-42-8).

The relevant short-term values are:

Daphnia: EC50 (48 h): >117 mg/l; NOEC: 117 mg/l (highest concentration tested).

Algae: EC50 (72 h): >118 mg/l; NOEC: 118 mg/l (highest concentration tested).

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

Ammonia ecotoxicity data have been reviewed by various regulatory programmes. Toxicity of ammonia is dependent on the degree of ionization and, therefore, is highly pH dependent and also dependent on temperature. Reliable long and short-term test results are available for ammonia sourced from the Environment Agency Proposed EQS for Water Framework Directive Annex VIII Substances: Ammonia (un-ionized) 2007. In the short-term tests the most sensitive species to ammonia was found to be fish (rainbow trout), with an LC50 of 0.083 mg un-ionised NH3/L (Rice and Bailey, 1980). Long-term test results also showed fish as the most sensitive species with a NOEC of 0.014 mg un-ionised NH3/L for rainbow trout (Solbe et al, 1989).