Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Reliable short-term toxicity tests results are available for freshwater fish (Brachydanio rerio), invertebrates (Daphnia magna) and algae (Pseudokirchneriella subcapitata) for the registration substance.

The relevant short-term values are:

Fish: LL₅₀ (96 h): >100 mg/l; NOEL: 100 mg/l

Daphnia: EL₅₀ (48 h): >1.0 mg/l; NOEL: 1.0 mg/l

Algae: ErL₅₀ (72 h): >1.0 mg/l; ErL10 (72 h): >1.0 mg/l; NOELR: 1.0 mg/l

In view of the test media preparation method and static exposure regime it is likely that the test organisms were exposed predominantly to a mixture of the parent substance, its butanedioic acid- containing hydrolysis products, silanol hydrolysis products and potentially cross-linked by-products, and ethanol. Dissolved complexes of chemical structures containing the butanedioate group are also likely. Formation of white solid precipitate, observed in the invertebrate and algal studies during test media preparation, is considered likely to be due to formation of insoluble butanedioate complexes and/or cross-linked reaction products. The aquatic test medium did not contain solid precipitate.

An activated sludge respiration inhibition 3 hour EL50 value of 819 mg/l and EC20 value of 150 mg/l (nominal) were determined in a reliable study.

It is noted that other studies have consistently reported formation of white solid precipitates even at loadings as low as 1 mg/l. The fish and activated sludge studies do not report any observation of precipitates. It is unclear how such high concentrations were achieved in these studies. It is possible that the test medium was a dispersion rather than a true solution or used test media with particularly low mineral concentrations.