Reaction mass of disodium [2,2'-(imino-κN)dibutanedioato-κ2O1,O4(4-)]cuprum(2-) and sodium sulphate

Endpoint summary

Additional information

General considerations

Ecotoxicological investigations concerning fish, aquatic invertebrates and algae were performed with the target substance Cu(II)-IDHA. However, experimental data referring to the toxicity to aquatic microorganisms are only available for the read-across substance Mn(II)-EDTA. For the detailed procedure of the read-across principle and justifications, please refer to the separate Read-Across Statement by Chemservice S.A. (2014).

Toxicity to fish

The acute toxicity of Cu(II)-IDHA towards Rainbow trout was investigated according to OECD Guideline 203 in compliance with GLP (Świerkot, 2011). After performing a preliminary test, Oncorhynchus mykiss was exposed in a static freshwater test to the test item at nominal concentrations of 0 (control), 10, 18, 32, 56 and 100.0 mg/L.

The exposure took place in glass aquaria with a capacity of 10 L. Seven fish were introduced into each aquarium. The fish were observed for mortality and intoxication symptoms after 3, 6, 24, 48, 72, and 96 hours exposure. In all the test concentrations and in control neither mortality nor symptoms were observed during the test. Chemical analyses were performed using LC-UV/VIS. Samples collected at the exposure initiation (t0) and at the exposure termination (t96) were analysed. The concentration of Cu(II)-IDHA in samples collected at the exposure initiation (t0) was between 88 and 120 % of the nominal concentration. The average concentration of Cu(II)-IDHA in samples collected at the exposure termination (t96) was between 89 and 104 % of the initial concentration. Since the concentration of the test item in the solution was higher than 80 % of the initial concentration after 96 hours, the LCx values were calculated on the basis of the nominal concentration.

Median concentration causing 50 % mortality of the fish population during 96 hours exposure time (LC50 (96 h)) is higher than 100 mg/L. The LC0 (96 h) is equal or higher than 100 mg/L and LC100 (96 h) is higher than 100 mg/L of nominal test item concentration. Due to the absence of mortality and any intoxication symptoms at the highest concentration tested, the NOEC (96 h) value can be indicated as ≥ 100 mg/L based on the nominal concentration.

 

Toxicity to aquatic invertebrates

In a static acute toxicity study according to OECD Guideline 202 (Konfederak, 2011), young Daphnia magna individuals (< 24 h old) were exposed to the test item for 48 hours. Four replicates of each test concentration and control were tested with 5 daphnids per replicate (100 mL test volume). The test item Cu(II) IDHA was applied in five test concentrations: 6.25; 12.5; 25.0; 50.0 and 100 mg/L. Daphnids were observed for immobilization after 24 and 48 hours of exposure. The animals are considered immobile if they showed no ability to swim within 15 seconds after shaking the test vessel. The chemical analyses performed by validated method confirmed correct preparation of test concentrations. At test initiation the content of Cu(II) IDHA was 99.1 -104.9 % of nominal concentrations. At test termination the content of Cu(II) IDHA was 93.56 – 113.39 % of initial concentrations. The endpoint ECx values were determined based on nominal concentrations of Cu(II) IDHA. The test item caused immobilization of 30 % daphnids in test concentration 25 mg/L, 60 % in 50 mg/L and 100 % in 100 mg/L. As final results, the EC50 (48 h) is 37.72 mg/L and EC100 (48 h) value is 100 mg/L - based on nominal concentrations of Cu(II) IDHA. The NOEC/EC0 value after 48 h amounts to 12.5 mg/L. The LOEC value after 48 h is 25 mg/L.

 

Toxicity to aquatic algae

The acute toxicity of Cu(II)IDHA towards the green algae Pseudokirchneriella subcapitata was investigated in a 72 hours static toxicity laboratory study according to OECD 201 and in compliance with GLP (Rzodeczko, 2011). The initial density of algae was 1 E4cells/mL. The following concentrations of the test item Cu(II) IDHA were applied: 1.0; 2.6; 6.4; 16; 40; 100 and 250 mg/L. The test item Cu(II) IDHA contains aspartic acid (N-1,2 dicarboxyethyl) complexed with copper. The effect of algal growth inhibition is related with test item and increases with test concentration. In highest test concentration 250 mg/L the observed inhibition of algal growth may be overlapped with indirect effect related to blue colour of the solution. In test concentrations 6.4; 16; 40 and 100 mg/L few algae cells of twice the size of algal cells in the control were observed with microscope. In the highest test concentration 250 mg/L different types of algae cells were observed, i.e. some rod-shaped cells, some S-shaped cells, few cells bigger of twice the size of normal cells, few cells without changes of normal size and shape. No differences in size or shape of algal cells in lowest test concentrations 1.0 and 2.6 mg/L were observed as compared to the algae cells in the control. The ECx values were determined based on nominal concentrations of Cu(II) IDHA.

The determined ErC50 (72h) is higher than 250 mg/L (the highest test concentration) whereas EyC50 (72h) amounts to 54.57 mg/L. The ErC10 (72h) value is 18.41 mg/L. The LOEC (Lowest Observed Effect Concentration) and NOEC (No Observed Effect Concentration) values are 2.6 mg/L and 1.0 mg/L, respectively.

Toxicity to aquatic microorganisms

Data referring to the toxicity towards aquatic microorganisms of the target substance was only indirectly assessed for the inherent biodegradation study (Adob, 2013; see section below).

However, sufficient data from a read-across substance can be used to fill this data gap. The toxicity of the read-across substance EDTA-MnNa2 to activated sludge was investigated in an activated sludge respiration inhibition test, conducted according to OECD TG 209 under GLP (Geerts, 2010). In this test, no inhibition of the respiration of the activated sludge was measured at the highest concentration tested, i.e. 640 mg/L. EDTA-MnNa2 is therefore considered not harmful to activated sludge.

This conclusion is confirmed by the inherent biodegradation study of Cu(II)IDHA according to OECD Guideline 302B (Adob, 2013). A solution of Cu(II)IDHA in a mineral medium was inoculated with activated sludge and incubated under aerobic conditions for 28 days. The test substance was the sole source of organic carbon. In addition to the investigations referring to the degradation of the test substance, a toxicity control (containing 100 mg DOC/L of Cu(II)IDHA and also 100 mg DOC/L of the easily biodegradable substance sodium benzoate) was performed. Due to the fact that sodium benzoate and Cu(II)IDHA were degraded (55 % degradation after 28 days, based on DOC), the substance Cu(II)IDHA had no toxic effects on the microorganisms. The corresponding result (NOEC (28d) = 100 mg DOC/L) shows that the substance is not harmful to activated sludge.