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Category name:
Category N - Butenes

Justifications and discussions

Category definition:
Butenes is an analogue category and meets the criteria stipulated by ECHA Guidance on information requirements and chemical assessment Chapter R.6.
Category rationale:
The Butenes category consists of substances that are C4 olefins or contain a mixture of the C4 olefins. The CAS number 107-01-7 describes two isomers (cis and trans) and the CAS number 25167-67-3 describes a mixture of C4 olefins.
The substances considered in the category share similar physical chemical properties and environmental fate and effect properties. The Butenes are gases at standard temperature and pressure and the majority of the substances will partition to the atmosphere, reducing the likelihood of the substances being bioaccumulative or toxic. QSAR estimates show that the Butenes are predicted to degrade rapidly, with an estimated half life of 2.8 days and to have a low toxicity to aquatic organisms. The Butenes are not predicted to meet the screening criteria for persistence, bioaccumulation or and toxicity.
For mammalian endpoints members of the Butenes category behave in a similar manner where test data is available. None of the substances are classified for Human Health effects.
Due to their similarities in structure, phys-chem properties, predicted environmental fate/effects and human health profile, it is justified to evaluate the substances as a category and read-across between members is acceptable.