Registration Dossier

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The results from a fully completed GLP study for short-term toxicity to daphniae according to OECD202 revealed that the substance does not show aquatic toxicity. The test results for acute toxicity of L-serine to daphnia were:

The 48h NOEC was determined to be nominal 100 mg test item/L corresponding to a geometric mean measured concentration of 83 mg test item/L. The 48h LOEC was determined to be > 100 mg test item/L (nominal) and the 48h EC50 value was determined to be > 100 mg test item/L (nominal). Non-GLP pre-experiments for this study further showed that even 1000 mg test item/L had no effect on the mobility of the daphnids.

The 96h LC50 for fish was estimated to be 120 g/l based on a trend analysis by using the OECD QSAR Toolbox (Version 3.0; data base version: 3.4.2/3.1.2). Although the substance was not in the applicability domain of the prediction due to the very low logKow of the substance the results clearly indicate a very low toxicity / absence of toxicity to fish. This very low fish toxicity was further confirmed by the result of a QSAR (EcoSAR, EpiSuite) that predicted a 96h LC50 of 354 g/L for L-serine (class Aliphatic Amines-acid) and fish toxicity data from other proteinogenic amino acids (L-valine, D/L-methionine, L-arginine) which clearly indicate that these substances show no/very low toxicity to fish even if applied in very high concentrations (>1 g/l). Taking all these results together in a weight of evidence approach the data provide convincingly evidence that L-serine has a very low/no toxicity to fish. Available data are sufficient for classification and risk characterisation and therefore further testing is not required also for animal welfare reasons.

Toxicity to aquatic algae by the test substance is not expected. Despite of that a study was conducted. The completed part of the study confirmed the assumption that L-serine does not cause toxicity to aquatic algae and cyanobacteria.

These results indicate that L-serine has a very low toxicity to aquatic organisms. This is not surprising, as L-serine is a naturally occurring none essential amino acid which is omnipresent in nature. It is a basic metabolite and building block of all living organisms and cells and therefore significant toxicity to aquatic organisms could be excluded.