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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 202-603-6 | CAS number: 97-72-3
Short-term toxicity to fish
Administrative data
Link to relevant study record(s)
Description of key information
The key study for this endpoint is from a study on the registered substance, isobutyric anhydride, while the remaining suporting studies were conducted on the hydrolysis substance, isobutryic acid. The results from the key study was the most sensitive. Three different fish species were tested in these short term toxicity fish tests.
Key value for chemical safety assessment
Fresh water fish
Fresh water fish
- Effect concentration:
- 26 mg/L
Additional information
The key study for this endpoint was conducted on the registered substance, isobutyric anhydride. The key study using isobutyric anhydride in a 96 -hour test with golden orfe (Leuciscus idus) resulted in a LC50 range of 22 -32 mg/L. The value utilized for the hazard/risk assessment from this study is 26 mg/L.
However, hydrolysis studies show that isobutyric anhydride added to water rapidly converts to isobutyric acid. Isobutyric acid data is being used by read across as supporting data for this endpoint. In three individual short term (96 hr) tests, the toxicity of isobutyric acid to three fish species was tested. All tests were performed using the same method (similar to OECD TG 203). Although there are some restrictions (test substance concentration not measured, only four concentrations tested) the studies are assessed as acceptable.
There was no adjustment of pH. In two tests (Hoechst AG), pH-values were measured after addition of the test substance to the dilution water. Values in the test medium declined in a concentration dependent manner within 24 hours to a pH as low as 4.6.
The 96 -h LC50 for golden orfe (Leuciscus idus) was 146.6 mg/L (BASF AG, 1989).
The 96-h LC50 for rainbow trout (Oncorhynchus mykiss) was 286 mg/L (Hoechst AG, 1979).
The 96-h LC50 for pumpkinseed (Lepomis gibbosus) was 435 mg/L (Hoechst AG, 1979).
Sublethal effects were discoloration, imbalance, uncoordinated movements, and dorsal and lateral position. Fish of the three highest dose groups were narcotized. In sacrificed pumpkinseed (dose group 315 and 500 mg/L), light discoloration of livers were observed.
For high test substance concentrations, the observed toxicity may have been influenced by the acidic conditions of the test medium.
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.
