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Long-term toxicity to aquatic invertebrates

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Description of key information

Two studies are presented for two different read-across substances and the data is presented as a Weight of Evidence.

For the read across substance 931 -745 -8, the effects on reproduction were studied over a 21 day period. The effects on reproduction were evaluated based on the reproduction per introduced animal, since the most ecologically relevant response variable is the total number of living offspring produced per parent animal which does not die accidentally or inadvertently during the test.The overall effect threshold for effects of the test item under the test conditions was >145 µg/L NOEC and LC50 for reproductive output. The endpoint of adult mortality was also measured over the course of the experiment, with a NOEC of 46 µg/L calculated for parent mortality after 21 days, shown to be statistically significant compared to controls when tested with the step-down Cochran-Armitage test procedure (α = 0.05).

For the read across substance 937 -237 -2, the authors present a NOEC of >100 μg/l for Daphnia magna based on a three generation assessment. Some effects were observed in the F2 generation (growth rate decreased and the size and colour of the control animals were not reached. The reproduction rate was significantly lower than in the parental generation and the F1 generation. The mortality of the parental animals increased.). The authors consider the effects observed to be due to the test substance.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
46 µg/L

Additional information

The study on 931 -745 -8, 21-day-chronic toxicity of HH-2014-548 to Daphnia magna was studied under semi-static conditions. Test species were exposed to control and test chemical at nominal concentrations of 0.000460 – 0.00145 – 0.00460 – 0.0145 – 0.0460 – 0.145 mg pure compound/L.  The 21-day EC10 reproduction/EC20 adult mortalitywas > 145 µg a.i./L.  The 21-day NOEC based on adult mortality was 46 µg a.i./L.  The effect occured was an insignificant increase of mortality (10%) at a concentration of 14.5 µg/L. However, this effects was not significant and there was no dose dependent increase in mortality, thus, this effect was considered not toxicologically relevant. Production of offspring in the treated groups indicated that HH-2014-548 did not have an effect on the reproduction at concentrations greater than 145 µg a.i./L.  The most sensitive end point was total number of living offspring produced per parent animal.

 

This study is classified as acceptable and satisfies the guideline requirements for a chronic toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1stinstar):

Test Type: Semi-static

 

EC20: >145 µg a.i./L

NOEL:  46 µg a.i./L

LOEC:  145 µg a.i./L}                     Endpoint(s) Effected:  adult mortality

The study on 937 -237 -2, the 21-day-reproduction test of the effluent of a model activated sludge unit fed with 10 mg/L of the read across substance, fatty acids, C16-18 (even numbered) and C18 unsatd., reaction products with diethylene triamine, di-... / 937-237-2; Imidazolium compounds, 2-(C15-17(odd numbered), C17-unsatd. alkyl)-1-[2-(C16-18(even numbered), C18-...; partially unsaturated IQAC, DMS quaternised (comprising 3 constituents), to Daphnia magna was studied under static renewal conditions. Daphnids were exposed to the effluent of the activated sludge unit containing the degradation products of test item. A control activated sludge unit without test item was run in parallel. The test duration for every generation was 21 days. Neonates of the 14thtest day were exposed as filial generation under the same conditions as the parental generation. Filial generations 1 and 2 were monitored for reproduction rate, time of the first offspring and parental mortality.

No significant differences were measured in the parental generation and the F1 generation. In the F2 generation, 63 days after the start of exposition of the first parental generation, the second filial generation some adverse effects were observed for the exposed Daphnids. Growth rate decreased and the size and colour of the control animals were not reached. The reproduction rate was significantly lower than in the parental generation and the F1 generation. The mortality of the parental animals increased.

The authors present a NOEC of >100 μg/L based on a calculated estimate, considering removal/degradation of the test substance prior to exposure of the Daphnia in the simulation activated sludge setup and dilution. The authors consider the effects observed due to the test substance.

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