Registration Dossier
Registration Dossier
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EC number: 213-773-6 | CAS number: 1009-93-4
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
A measured 48 hour EC50 value of >117 mg/l, and NOEC of 117 mg/l (highest concentration tested in both cases), have been determined for the effects of dimethylsilanediol (CAS 1066-42-8) on mobility of Daphnia magna. The results are read across for the purpose of chemical safety assessment of 2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4), which in view of the very rapid hydrolysis, focuses on its hydrolysis products, dimethylsilanediol and ammonia/ammonium ions.
Key value for chemical safety assessment
Fresh water invertebrates
Fresh water invertebrates
- Effect concentration:
- 117 mg/L
Additional information
2,2,4,4,6,6-Hexamethylcyclotrisilazane hydrolyses very rapidly in water to give dimethylsilanediol and ammonia/ammonium ions. There are no reliable short-term invertebrate toxicity data available for 2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4), therefore good quality data for dimethylsilanediol (CAS 1066-42-8) have been read across. Dimethylsilanediol (CAS 1066-42-8) is not susceptible to further hydrolysis under the conditions of the study. The other hydrolysis product is ammonia/ammonium ions.
Reliable 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. A 96 h LC50 of 0.16 mg unionised mg NH3/L has been reported for short-term toxicity of ammonia to aquatic invertebrates.
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