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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Based on the results obtained in studies conducted according to OECD Guideline 201 (Biofert Plusz) and a national guideline (L-threonine mother liquor and modified waste), respectively, the 72 h ErC50 and EyC50 values of 148 and 71.4 mg dry matter/L (measured concentration), respectively, found for Biofert Plusz with Desmodesmus subspicatus as test organism can be regarded as worst case for the toxicity of L-threonine mother liquor.

Key value for chemical safety assessment

EC50 for freshwater algae:
148 mg/L
EC10 or NOEC for freshwater algae:
64.3 mg/L

Additional information

The toxicity of L-threonine mother liquor and modified waste (used microbiological material) to Scenedesmus quadricauda was investigated in studies conducted according to a national guideline. The 72 h EC50 values were determined to be comparable (L-threonine mother liquor: 72 h EC50=13.5 mL/L; modified waste: 48 h EC50=13.36 mL/L nominal each).

The toxicity of Biofert Plusz (mixture of L-threonine mother liquor and L-threonine biomass; L-threonine biomass is also named as modified waste (used microbial material sterilized), mortified biomass, mortified biomass of E. coli (K12), biomass concentrate of threonine production stem) towards the unicellular green alga Desmodesmus subspicatus was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test). Cultures of Desmodesmus subspicatus were exposed to 5 Biofert Plusz concentrations ranging from 339 to 3559 mg/L test material (nominal) corresponding to geometric mean measured concentrations ranging from 126 to 1579 mg/L test material. The concentration of the main component of Biofert Plusz L-threonine was determined by HPLC/UV. Based on geometric mean measured concentrations the 72 h ErC50 and 72 h EyC50 were determined to be 528 and 254 mg fresh material/L, respectively, corresponding to 148 (ErC50) and 71.4 mg dry matter/L (EyC50).

In conclusion of the available data, it can be assumed that the result obtained with Biofert Plusz represents a worst case situation for the test material under investigation (L-threonine mother liquor).