Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The calculated freshwater algae 96 hour EC50 for butenes range from 13.6 mg/L to 16.9 mg/L and the NOEC ranged from 2.64 mg/L to 3.18 mg/L. These ranges were derived from the members of the butenes category: but-1-ene (CAS 106-98-9), 2-butene (CAS 107-01-7) and 2-methylpropene (CAS 115-11-7) using QSAR estimates (Nabholz and Mayo-Bean 2009).

Key value for chemical safety assessment

EC50 for freshwater algae:
13.6 mg/L
EC10 or NOEC for freshwater algae:
2.64 mg/L

Additional information

Butenes are gases at standard temperature and pressure and are expected to partition primarily to air; therefore aquatic toxicity tests may not be relevant. In addition, it is technically difficult to maintain aqueous concentrations of gases for toxicity testing.

Measured data are not available for butenes for this endpoint. Due to the practical difficulties associated with the ecotoxicity testing of gases (i.e. maintaining exposure concentrations), the use of QSAR toxicity estimates is an appropriate alternative. The ECOSAR model is a reliable and appropriate QSAR model to apply to butenes as it is based on a related chemical dataset that calculates the toxicity of neutral organic hydrocarbons whose mode of action is non-polar narcosis. The endpoint calculated here is therefore a reasonable estimate of the baseline toxicity.

A QSAR (ECOWIN v1 ECOSAR, Nabholz and Mayo-Bean 2009) have been used to give an indication of the toxicity of butenes to algae. The calculated 96 hour EC50 are 14.9 mg/L for but-1-ene, 16.9 mg/L for 2-butene and 13.6 mg/L for 2-methylpropene. The calculated ChV are 4.04 mg/L for but-1-ene, 4.50 ,g/L for 2-butene and 3.73 mg/L for 2-methylpropene. These ChV values correspond to a NOEC values of 2.85 mg/L, 3.18 mg/L and 2.64 mg/L respectively.