2-methylbut-2-ene

Short-term toxicity to fish

Description of key information

After 96 hours, the highest measured concentration at which no mortality had occurred was 2.93 mg/L and the lowest at which there was 100% mortality was 8.51 mg/L. Treatment-related effects were exhibited at 5.33 mg/L and higher concentrations. Based on these findings the following values have been estimated: 96 hour LC50 value = 4.99 mg/L (95% confidence limits of 2.93 and 8.51 mg/L).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

4.99 mg/L

Additional information

One reliable proprietary freshwater study, Huntingdon (2004b) is available for 2-methylbut-2-ene. After 96 hours, the highest measured concentration at which no mortality had occurred was 2.93 mg/L and the lowest at which there was 100% mortality was 8.51 mg/L. Treatment-related effects were exhibited at 5.33 mg/L and higher concentrations. Based on these findings the following values have been estimated: 96 hour LC50 value = 4.99 mg/L (95% confidence limits of 2.93 and 8.51 mg/L).

The data were obtained from a reliable proprietary report and were given a reliability of 2 because some ASV values did not meet the validity criteria of the guidelines, although the results are still acceptable with restrictions. The source is used as the key study in the OECD SIDS (2005) for CAS 513-35-9 and given a reliability 1. The LC50 (96hrs) for Oncorhynchus mykiss was determined to be 4.99 mg/L (measured concentration) for 2-methylbut-2-ene. The LC50 figure indicates that 2 -methylbut-2-ene is not toxic, according to the criteria for PBT assessment. However, this endpoint in conjunction with the predicted non-biodegradability of the substance and an incomplete chronic dataset will result in a classification of a category Aquatic Chronic 2 toxicity to the environment and the hazard statement 'Toxic to aquatic life with long lasting effects'.