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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

72h EC50 649.3 mg/L, the 72h EC10 and NOEC were 42.8 and 15 mg/L, respectively for Pseudokirhnerella subcapitata (OECD TG 201). Recalculated to EDTA-Mn(NH4)2 would give an EC50 of 651.2 mg/L and an EC10 of 42.9 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
651.2 mg/L
EC10 or NOEC for freshwater algae:
42.9 mg/L

Additional information

MnNa2 -EDTA was tested with multiple media compositions, due to the apparent high toxicity of this metal EDTA complex. A series of preliminary tests was conducted to determine the influence of enriched medium nutrients on the initial ErC10value. The nature of a chelating agent can cause potential nutrient depletion in the test media. This causes a growth related effect that is not due to substance toxicity. This series of preliminary studies was conducted to investigate this effect.

The final test (Geurts, 2009) was conducted with the following adjustments:

The NaHCO3 concentration of the test medium was 150 mg/L instead of 50 mg/L, in order to help maintain a more constant pH during the test.

The Fe-EDTA and Trace elements components of the OECD media were increased to 150% of the standard composition, in order to prevent

nutrient deprivation during the test.

The key study, conducted according to OECD guideline 201 under GLP, revealed a 72h EC50 of 649.3 mg/l and a 72h NOEC of 15 mg/l for Pseudokirchnerella subcapitata. The 72h-EC10 was 42.8 mg/l.