Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Short-term toxicity to aquatic invertebrates:

EC50 (Daphnia magna, 48 h) > 37 mg/L (meas. (geom. mean); corresponding to 100 mg/L nominal concentration)

Toxicity to aquatic plants other than algae:

ErC50 (Lemna minor, 7d, frond number) > 47.96 mg/L (meas. (geom. mean); corresponding to 100 mg/L nominal concentration)

Additional information

The following experimental data were obtained for Similar Substance 01. It is expected that the Target Substance will present similar effect levels on Daphnia magna. Justification for the use of the Read Across approach is given in Section 13 of IUCLID.

Firstly, it is worth saying that Similar Substance 01 is very water soluble (i.e. > 10 g/L); it has a log Kow value which is lower than 4, indicating a low potential for bioaccumulation, and is not rapidly degradable.

Short-term toxicity to aquatic invertebrates

A limit test was conducted to determine the acute toxicity of the test substance to Daphnia magna, according to the OECD Guideline 202 (2004) and the EU method C.2 of the Regulation EC 440/2008. The study was performed using the concentration of 100 mg/L test item (nominal). For the test concentration, 20 daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted. The concentration showed no significant toxicity. Only 1 animal (5 %) was immobilised in the treatment which can be stated as not significant. None of the animals were immobilised in the blank control. Potassium dichromate was used as positive control in a current reference study to assure that the test conditions are reliable. At the beginning and at the end of the test, the content of the test item in the test solutions was determined using a photometer method. At the beginning of the test the measured concentration was 38 % of the nominal concentration and after 48 hours the measured test concentration was 37 % of the nominal concentration. Therefore, the determination of the biological results was based on the geometric mean of the measured concentrations.

Based on the results of this experimental study, the EC50 of the test item was found to be higher than 37 mg/l (meas. (geom. mean)) when exposed to Daphnia magna for 48 hours, which is equivalent to a nominal concentration of 100 mg/L.

Similarly, a study conducted on D. magna using five concentrations of Similar Substance 02 (ranging from 10 to 100 mg/L), according to the EU Method C.2, demonstrated an EC50 value greater than 100 mg/L (nominal concentration) when Daphnia magna were exposed for 48 hours. An additional study conducted on D. magna using five concentrations of Similar Substance 03 ranging from 62.5 to 1000 mg/L, according to OECD Guideline 202 part I (1984), demonstrated an EC50 value greated than 1000 mg/L (nominal concentration; not analysed) when exposed to D. magna for 24 hours. These data, combined, support the use of the read-across approach for determining the toxicity of the test item to Daphnia magna.

Toxicity to aquatic plants other than algae

The acute toxicity of the test item to aquatic plants was investigated in a 7–day static test to Lemna minor, according to the OECD Guideline 221 (2006). The study was performed using 6 concentrations ranging from 0.32 to 100 mg/L (nominal concentration). The frond number of each replicate was determined at the beginning, at day 3 and 6 during the test and at the end of the experiment. Additionally, the dry mass of each replicate was determined at the beginning and at the end of the experiment. Growth rate µ and the yield were determined from the frond number and the dry mass at the respective observation times.

At the end of test, replicates with and without plants were analysed. The measured concentrations in the replicates with and without plants are in the same range. Therefore, the measured values in the replicates without plants were used for evaluation.

The measured concentrations lay between 22 % and 47 % of the nominal concentrations at the beginning of the test and between 20 % and 51 % of the nominal concentrations at the end of the test (without plants). Therefore, the determination of the NOEC / LOEC / ECx was based on the geometric mean of the measured concentrations. The 7 day EC50 values of positive control were determined in a separate reference test; the value of the growth rate lay within the desired range of 1.7 - 5.7 mg/L.

Similar Substance 01 was therefore found to have a ErC50 value greater than 37 mg/L when exposed to Lemna minor for 7 days, based on frond number and based on the measured concentrations, which corresponded to 100 mg/L nominal concentration. In addition, another substance (Similar Substance 02) was found to have an ErC50 value of 124.1 mg/L when Scenedesmus subspipcatus were exposed to concentrations from 10 to 120 mg/L of Similar Substance 02 for a duration of 72 hours, according to the EU Method C.3. Although this was an algal inhibition test, the resulting ErC50 value reflects that of Similar Substance 01 and therefore supports the use of the read-across method for determining the toxicity of the test item to the photosynthetic aquatic organisms.

 

JUSTIFICATION FOR CLASSIFICATION OR NON-CLASSIFICATION

According to the CLP Regulation (EC n. 1272/2008), Part 4: Environmental Hazards, the substances can be classified for hazardous to the aquatic environment when the following criteria are met:

A) Acute (short-term) aquatic hazard Category Acute 1: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants) ≤ 1 mg/l.

B) Long-term aquatic hazard (iii) Substances for which adequate chronic toxicity data are not available and the substance is not rapidly degradable and/or the experimentally determined BCF ≥ 500 (or, if absent, the log K ow ≥ 4).

Category Chronic 1: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants) ≤ 1 mg/L

Category Chronic 2: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants)> 1 to ≤10 mg/L

Category Chronic 3: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC 50 (for algae or other aquatic plants) > 10 to ≤ 100 mg/L.

The substance is not rapidly degradable and the available acute toxicity test to Daphnia magna and Lemna minor fixed effect levels that do not meet these classification criteria. Therefore, the substance is not classified for aquatic toxicity according to the CLP Regulation (EC 1272/2008).