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Categories

Category name:
High Benzene Naphthas LOA

Justifications and discussions

Category definition:
High Benzene Naphthas
Category rationale:
The high benzene naphthas category is driven by benzene as Category 1 Carcinogen, Category 2 Mutagen. All streams in this category contain >0.1% benzene. This category contains hydrocarbons (aliphatic, aromatic and olefinic) with carbon numbers predominantly in the C6-C12 range and boiling from 60°C to 300°C.

Category members are usually produced by the distillation of products from a steam cracking process or by pyrolysis. The category contains predominantly hydrocarbons greater than C6 and has a boiling point range 60°C to 300°C.

By definition, from the category, these streams have overlapping hydrocarbon compositions, within a defined range, and hence, will have similar properties. It is therefore reasonable to assume that the components of the high benzene naphthas will behave in a reasonably predictable manner, and with respect to phys-chem and environmental fate and effect properties read-across is valid.

The streams will have similar environmental effects as their constituents cover overlapping carbon ranges and all act in similar manner, via narcosis. It can therefore be assumed that streams meeting the applicability domain will behave in a similar manner and that the use of read-across is valid.

For mammalian endpoints, the category members are liquids that are of moderate to low volatility. Inhalation and skin contact represent the primary route of exposure. Benzene, as a component at greater than 0.1% in all streams in this category is considered the key driver in establishing and assessing health effects. It can therefore be assumed that streams meeting the applicability domain will behave in a similar manner and that the use of read-across is valid.
For mammalian endpoints, the classification of these streams will be driven by the content of benzene as this is more than 0.1% w/w for all category members. However other components which will affect the classification of UVCB streams in the category are naphthalene, n-hexane, xylenes, 1,3-butadiene, isoprene and toluene.