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Environmental fate & pathways

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Anthracene oil (benzo[a]pyrene < 50 ppm, AOL) is a liquid to pasty organic UVCB substance, which is difficult to test for biodegradation under standard test conditions. The complex mixture consists mostly of three- and four-ring polycyclic aromatic hydrocarbons from acenaphthene to pyrene. Major constituents (concentration > 5 %) are fluorene, phenanthrene, anthracene, and fluoranthene amounting to about 50 %.

Biodegradation data on anthracene oil itself is not available. But the biodegradation potential of the substance can be characterised by taking into account the biodegradability of its different constituents having a combined view on their properties.

Most PAH are not readily biodegradable, but few of them are considered to be at least inherently biodegradable. Due to lack of valid evidence from standard biodegradation tests, additional information obtained from non-standard tests was evaluated. Consistent findings for several constituents of anthracene oil (especially three-ring aromatics) provide evidence that some PAH components of anthracene oil are biodegradable at least under aerobic conditions.

In an aerobic biodegradation study in two soils, half-lives of four key constituents of anthracene oil (two three-ring and two four-ring PAH) were demonstrated to fall into the range between ca. 16 (phenanthrene) and 377 (fluorene) days (eight values) resulting in an average value of 167 days and a 90th percentile of 300 days. This data indicate that some of the anthracene oil constituents can be biodegraded in soil (e.g. phenanthrene), but that others have to be considered persistent/very persistent.

Based on results taken from its constituents, anthracene oil has to be considered as not biodegradable.