Reaction mass of N, N'-hexane-1,6-diylbis [12-hydroxyoctadecanamide] and 12-hydroxy-N-[6-[1-oxoalkyl)amino] hexyl ] octadecanamide

Short-term toxicity to aquatic invertebrates

Description of key information

The Daphnia magna 48h-EC50 exceeded an average measured concentration of 4 µg/l, which was above the water solubility limit of < 0.7 µg/l.

Additional information

A combined limit/range-finding test was performed with twenty daphnia per test group (4 vessels with 5 daphnia each) exposed to a control and a WAF prepared at 100 mg/l in the limit test and ten daphnia per test group (2 vessels
with 5 daphnia each) exposed to WAFs prepared at 1.0 and 10 mg/l in the combined range-finding test. The total test
period was 48 hours and samples for analytical confirmation of actual exposure concentrations were taken at the start and the end of the test.
Mean recoveries of the procedural recovery samples were 57% and 47%. These relatively low recoveries were probably caused by the poor solubility of the test substance. 
Analysis of the samples taken from the WAF prepared at a loading rate of 100 mg/l showed that the measured concentration decreased from 5 µg/l at the start to 3 µg/l after 48 hours of exposure. The average concentration was
calculated to be 4 µg/l. This concentration was a factor of at least 5 higher than the water solubility, which was determined to be less than 0.7 µg/l (see water solubility).

Under the conditions of the present study AD-1000 did not induce acute immobilisation of Daphnia magna at or below a Water Accommodated Fraction prepared at a loading rate of 100 mg/l, which corresponded to an average measured concentration of 4 µg/l (NOEC). Hence, the 48h-EC50 exceeded an average measured concentration of 4 µg/l, which was above the water solubility limit of < 0.7 µg/l.