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According to the data requirements outlined in EU Regulation No. 1907/2006, only screening tests in water are mandatory for this tonnage band.

In this context, both ready and inherent biodegradation of Cu(2Na)IDHA were experimentally investigated which is considered in detail in the following.

The inherent biodegradability of Cu(II)-IDHA was investigated according to OECD Guideline 302B (Adob, 2013).As starting point, an initial test concentration of 100 mg DOC/L was used. The test was performed for 28 days. Degradation was followed by DOC determinations at 0 h, 3 h, 1 d, 7 d, 14 d, 21 d, 27 d and 28 d. After 7 days, 53.4 % degradation of the test item was determined while after 28 days, 79.6 % degradation was obtained. The reference compound sodium benzoate showed 98 % degradation after 14 days. In conclusion and according to the criteria set out by OECD Guideline 302B, the substance Cu(II)-IDHA is inherently biodegradable under the test conditions.

The biodegradation of Cu(II)-IDHA and other metal complexes of IDHA was additionally investigated similar to OECD Guideline 301F (Cokesa et al., 2004) in a non-GLP study. Nevertheless, basic validity criteria of the study cannot be evaluated since results are only reported briefly. The test was carried out with the OxiTop Control system (WTW, Weilheim, Germany) and monitored for 42 days. Exact substance concentrations were not indicated in the publication. During the test, precipitation of the corresponding heavy metal hydroxide was observed, indicating liberation of free metal ions. Based on O2consumption, Cu(II)-IDHA revealed 40 % degradation after 28 days. The reference substance benzoic acid sodium salt showed > 50 % degradation after 4 days and > 75 % degradation after 10 days, both based on O2consumption. Prolonged exposure to the released Cu(II) ions was expected to lead to inactivation of the microorganisms but no toxicity control was conducted. Conclusively, it was shown that the test item is potentially biodegradable under the test conditions. Since sufficient experimental details (i.e. test substance concentrations) are missing and no toxicity control was undertaken, exact conclusions on the ready biodegradability of the test substance cannot be drawn.

In the OECD 302B non-GLP study (Adob, 2013) it was shown that > 50 % degradation of the test item was obtained after 7 days (initial substance concentration: 100 mg/L DOC). The following measurements after 14, 21, 27 and 28 days determined a substance degradation of 62.6 %, 72.7 %, 75 % and 79.6 %, respectively. The reference compound showed 100 % degradation after 14 days. The toxicity control (test and reference compound plus inoculums) indicated that the used concentrations of the test item did not show toxic effects to bacteria. 55 % degradation was observed during 28 days (based on DOC removal). Since the test substance showed > 50 % degradation after 7 days, a strong biodegradation potential is assumed for the test substance.