Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

RA_CAS_15375-84-5_OECD_209_Activated_sludge: NOEC (3h) =  640 mg/L 

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
640 mg/L

Additional information

Data referring to the toxicity towards 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 (NOEC 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 (57.8 % degradation after 28 days, based on DOC), the substance Cu(II)IDHA had no toxic effects on the microorganisms. The corresponding result (NOEC (28 d) = 100 mg DOC/L) shows that the substance is not harmful to activated sludge.

Assuming that DOC is identical to TOC and according to the following equation C substance = (TOC x Molar mass substance) / (12.01 g/mol x Number of C-atoms), the actual substance concentration (based on 100 mg DOC/L) amounts to C substance = (100 mg/L x 354.59 g/mol) / (12.01 g/mol x 8) = 369.2 mg/L.