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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

No significant growth inhibition was detected in the algal growth inhibition test performed by the Japanese Ministry of the Environment employing disudium succinate using Selenastrum capricornutum, following OECD test guideline 201. Test was peerformed under GLP. .

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
998 mg/L
EC10 or NOEC for marine water algae:
600

Additional information

No significant growth inhibition was detected in the algal growth inhibition test performed by the Japanese Ministry of the Environment employing disudium succinate using Selenastrum capricornutum. Test was performed according to OECD Guideline 201 employing a control and 3 test concentrations, up to 1 g/L nominal. Test was performed in triplicate employing a healthy exponentially growing culture, with no solvents added and under continuous illumination and shaking. No solubility or other problems or anomalies were detected throughout the test. Concentrations of the test substance was measured at the beginning and at the end of the experiment. No significant effect was detected even at the highest concentration. ErC50 was determined as > 998 mg/L (disodium succinate, anhydrous, measured) and NOEC was determined to be 998 mg/L. Thereby disodium succinate can be considered to have a verly low toxicity towards the freshwater algal species tested.

Anecdotal evidence on 72 h toxicity of tartaric acid used as solvent control in a peer-reviewed 72 h algal growth inhibition study performed with 9 species of marine microalgae indicate no or very limited growth inhibition (max. 11.3%) after exposure to 0.06% tartaric acid. Study validity is limited as data on the solvent controls is not reported, however test method, design, duration and biomass estimation method is considered acceptable. Study results indicate an EC50 well above 600 mg/L and a NOEC of at least 600 mg/L for tartaric acid in all the species tested.

Finally, the oxicity of fumaric acid on fresh-water alga Scenedesmus subspicatus is reported to be of 41 mg/L (EC50) and 32 mg/L (EC10) supporting the low aquatic toxicity of C4 dicarboxyllic acid salts. However the study report could no be assessed in any detail, although is reported as valid Klimish 2 and RSS is provided in USEPA HPV Challenge programme report for Fumaric Acid.

Given that potassium sodium tartrate is a structurally very similar C4 dicarboxyllic acid salt to disodium succinate this result is considered as relevant towards read-across. Identical reasoning applies to results reported on 9 species of marine microalgae. Due to the acidity of the acids, it is to be expected that toxicity of the sodium or potassium salts of tartaric and fumaric acid will be smaller than for the acid.

In addition the EC50 estimated value (965 mg/L) for Pseudokirchneriella subcapitata (Selenastrum capricornutum) using the MultiCASE model included in the DK EPA database shows the low accute toxicity of the potassium sodium tartrate to algae, yielding a value which corresponds well and is of the same order than those obtained experimentally with analogues.. This estimation is considered appropriate in a weight of evidence approach.