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Category name:
Xylenes isomers category (analogue)

Justifications and discussions

Category definition:
Xylene Isomers Category
Category rationale:
The Xylene isomers category consists of the isomers of xylene. The isomers included in the category are m-xylene (CAS 108-38-3), o-xylene (CAS 95-47-6) and p-xylene (CAS 106-42-3).

The isomers considered in the category share similar physical chemical properties and environmental fate and effect properties. They are liquid at standard temperature and pressure and the boiling points are reported as being in a very narrow range of 136-144°C. This range means that all category members will be expected to have similar partitioning in the environment. Degradation of the isomers has been shown to be rapid, and they will partition rapidly to the air from water, further reducing their potential for exposure. The isomers are predicted to have a low potential for bioaccumulation and low toxicity to aquatic organisms.

With regard to mammalian endpoints, the isomers are liquids of moderate volatility. Inhalation and skin contact therefore represent the primary route of exposure

Due to their similarities in structure, phys-chem properties, predicted environmental fate/effects and human health profile, it is justified to evaluate the xylene isomers as a category and read-across between members is acceptable.