Registration Dossier



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 containing 0.1% or more benzene to be considered for inclusion. This category contains hydrocarbons (aliphatic, aromatic and olefinic) with carbon numbers predominantly in the C5-C12 range and boiling from 30C to 300C. Members of this category contain >0.1% benzene and contain varying amounts of toluene, xylenes and n-hexane. Some category members contain PAHs, where this is the case anthracene has been quantified. Some category members contain 1,3-butadiene and this has been quantified where needed. Category members are usually produced by the distillation of products from a steam cracking process or by pyrolysis Companies importing streams will need to confirm that such streams meet the chemical description and are in domain. The category contains streams that have claimed compositions of single substances up to over 80%. These are not considered as pure substances as the variability during manufacture is such that this is not always the case and usually the production processes are not designed to make substances at such a high purity.

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.

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.