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The results from a fully completed GLP study for short-term toxicity to daphniae according to OECD 202 revealed that the substance does not show aquatic toxicity. The test results for acute toxicity of L-threonine to daphnia were:

The 48h EC50 as well as the 48h EC0 were determined to be > 1000 mg test item/L.

The results from a fully completed GLP study for toxicity to aquatic algae according to OECD 201 revealed that the 72h EC50 was > 1000 mg test item/L. A NOEC could not be derived because the growth inhibition showed an invers dose-response relationship. The test concentration of 120 - 580 mg/l showed a growth inhibition of 14 - 17 %. At 1000 mg/L 6 % growth inhibition could be observed.

No experimental test results with regard to fish toxicity are available for the substance.

According to REACH Regulation (Annex VIII, 9.1.3, column 2), the study on the acute toxicity to fish does not need to be done if aquatic toxicity is unlikely. Based on the available experimental toxicity data for daphnids (48 h LC50>1000 mg/L) and algae (72 h EC50>1000 mg/L) it is to be expected that the acute toxicity of L-threonine to fish will be low as well. This assumption is supported by calculation. The estimation of the acute toxicity to fish by ECOSAR v1.00 predicted a 96 h LC50=225000 mg/L for the aliphatic amine-acid structure and a 96 h LC50=1680000 mg/L for the baseline toxicity (neutral organic SAR). Based on the experimental data for daphnids and algae and the estimated acute toxicity values the need for the performance of a fish, acute toxicity test is not indicated. Available data are sufficient for classification and risk characterisation and therefore further testing is not required also for animal welfare reasons.