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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Description of key information

The calculated earthworm 14 day LC50 for butenes range from 92.4 mg/kg soil dw to 95.5 mg/kg soil dw. This range was 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

Short-term EC50 or LC50 for soil macroorganisms:
92.4 mg/kg soil dw

Additional information

Butenes are gases at standard temperature and pressure and are expected to partition primarily to air; therefore terrestrial toxicity tests may not be relevant. In addition, it is technically difficult to maintain terrestrial 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 its baseline toxicity.

A QSAR (ECOWIN v1 ECOSAR, Nabholz and Mayo-Bean 2009) has been used to give an indication of the toxicity of butenes to the earthwom. The calculated 14 day LC50 are 93.7 mg/kg soil dw for but-1-ene, 95.5 mg/kg soil dw for 2-butene and 92.4 mg/kg soil dw for 2-methylpropene.