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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Toxicity to algae: 72 hour NOEC 100 mg/l (nominal; highest concentration tested) (OECD TG 201), in terms of the substance as tested, when the pH is maintained near neutral (pH ca. 8.1 throughout exposure period).

In the same study, 72 hour ErC50 56.3 mg/l and ErC10 35.5 mg/l (nominal) (OECD TG 201), in terms of the substance as tested, were determined under parallel exposures without adjustment of pH (maximum pH of 9.92).

The observations in this study are attributed to the exposure of test organisms to the parent substance in the test system.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

A 72 hour ErC50 value of >100 mg/l and NOEC of ≥100 mg/l (nominal) have been determined for the effects of the registration substance on growth rate of Pseudokirchneriella subcapitata, at pH-neutral conditions. In view of the test media preparation method and exposure regime it is likely that the test organisms were exposed predominantly to the tested substance at least at the start of the test, although hydrolysis may have occurred to some extent during the exposure period.

In parallel testing under conditions in which the pH was not adjusted to neutral, a 72 hour ErC50 value of 56.3 mg/l and ErC10 of 35.5 mg/l (nominal) were determined. The findings are consistent with other amine-containing substances in that toxicity is often significantly higher under near-neutral pH conditions similar to the wider environment, than when the pH is allowed to vary (algal respiration can cause significant elevation of pH under laboratory test conditions). It is inferred by the reviewer that the non-protonated form of the amine is considerably more toxic than the protonated form (as is the case with other amines, ammonium salts, and ammonia). At elevated pHs, the proportion of the non-protonated form is much higher.

The study was supported by TOC analysis of the parent substance and concentrations ranged between 91.5 and 102% of nominal (highest two test concentrations) and <LOQ - 183% of nominal (lowest three test concentrations) with consistent TOC measurements at the start and end of the test suggesting no losses occurred by physicochemical processes, although this non-specific method cannot identify degradation by hydrolysis.