Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 200-798-2 | CAS number: 73-32-5
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
Acute toxicity to daphnia is not expected to occur upon exposure to the L-isoleucine based on information available on read-across substance L-valine.
L-valine was found to have an EC50 (mobility) > 10000 mg/L and a NOEC (slower movement) of 3200 mg/L.
Recalculation of this value taking into account the molecular weight of L-isoleucine results in a predicted EC50 value > 11200 mg/L for L-isoleucine, and a NOEC of 3583 mg/L.
The low toxicity of L-isoleucine towards daphnia is further confirmed by the result of the QSAR (EcoSAR, EpiSuite) that predicted an 48h-LC50 of 5148 mg/L.
Key value for chemical safety assessment
Fresh water invertebrates
Fresh water invertebrates
- Effect concentration:
- 11 200 mg/L
Additional information
No test results for L-isoleucine are available. However, read-across to the test results available for structural analogue L-valine is deemed justified based on a comparison of the main factors driving environmental toxicity: pH, water solubility, log Kow and chemical reactivity (functional groups).
- both are essential amino acids that are in the zwitterion state at physiological pH
- the chemical structure differs only in that L-isoleucine has one extra methylene group in the aliphatic side chain
- the pKa values of the α-COOH group is very similar: 2.36 for ILE, 2.32 for VAL
- the pKa values of the α-NH2 group is very similar: 9.60 for ILE, 9.62 for VAL
- the substances both have a high water solubility: 34 - 41 g/L for ILE, 58 g/L for VAL
- the substances both have a low log Kow value: -1.72 for ILE (experimental value obtained from EpiSuite's WSKOW model database), -2.08 for VAL (calculated by EpiWin QSAR)
As the chemical structure and reactivity, and the water solubility, low Kow and pKa values of L-isoleucine and L-valine are almost identical, it can be concluded that read-across for aquatic toxicity information between those 2 substances is acceptable.
The test available for L-valine is carried out according to OECD guidelines and does not reveal mortality to daphnia at the highest tested concentrations (10000 mg/L) after 24 hours.
Recalculation of this value taking into account the molecular weight of L-isoleucine results in a predicted EC50 value > 11200 mg/L for L-isoleucine.
Furthermore, the EcoSAR model predicted an 48h-LC50 of 5418 mg/L. As a consequence, acute toxicity to aquatic invertebrates is not expected to occur upon exposure to the L-isoleucine.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
