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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Toxicity to algae: 72 hr ErL50 >1.0 mg/l; 72 hr ErL10 >1.0 mg/l and NOELR 1.0 mg/l (nominal) (highest concentration tested) (OECD TG 201). The result is interpreted to indicate that the 72h-EL50 exceeded the maximum achievable concentration of the test substance (and / or its hydrolysis products) in test medium.

Key value for chemical safety assessment

EC50 for freshwater algae:
1 mg/L
EC10 or NOEC for freshwater algae:
1 mg/L

Additional information

A 72-h ErL50 value of >1.0 mg/l, 72 -h ErL10 value of >1.0 mg/l and NOELR of 1.0 mg/l (nominal) (highest concentration tested) have been determined for the effects of the registration substance on growth rate of Pseudokirchneriella subcapitata. 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. Dissolved complexes of chemical structures containing the butanedioate group are also likely. Formation of white solid precipitate, observed during test media preparation, is considered likely to be due to formation of insoluble butanedioate complexes and/or cross-linked reaction products, and ethanol. The aquatic test medium did not contain solid precipitate.

Given the chemical structural features of the registration substance, it is considered that the reactivity observed in test media preparation as part of method development for this study is likely to be realistic in respect of conditions in the event of environmental exposure (i.e. exposure via water in the presence of normal concentrations of common polyvalent ions).

It is therefore concluded that at the maximum achievable concentration of the test substance (and / or its hydrolysis products) in test medium, no effects were observed and the ErL50 is >1.0 mg/l.

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