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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Area under the growth curve (measured concentrations), EbC50 (72h): 10.5 mg/L (95% confidence limits, 9.55 & 11.7 mg/L), EbC50 (96h): 10.1 mg/l (95% confidence limits, 9.21 & 11.1 mg/L), NOEC:  3.61 mg/L
Average specific growth rate (measured concentrations): ErC50 (0-72h): 12.0 mg/L (95% confidence limits, 7.22 & 21.1 mg/L), ErC50 (0-96h): 13.2 mg/L (95% confidence limits, 12.2 & 14.3 mg/L), NOEC: 7.22 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
12 mg/L
EC10, LC10 or NOEC for freshwater algae:
7.22 mg/L

Additional information

One reliable proprietary freshwater study, Huntingdon (2004d) is available for 2-methylbut-2-ene. These results show that using area under average specific growth rate (measured concentrations), ErC50 (0-72h): 12.0 mg/L (95% confidence limits, 7.22 & 21.1 mg/L), ErC50 (0-96h): 13.2 mg/L (95% confidence limits, 12.2 & 14.3 mg/L), NOEC: 7.22 mg/L.

The data were obtained from a reliable proprietary report and were given a reliability of 2 because the validity criteria could not be assessed, 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 EC50 and NOEC values indicates that 2 -methylbut-2-ene is not toxic, according to the criteria for PBT assessment, nor will they result in any environmental hazard category for the substance.