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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

No experimental result is available for the commercial product alcohols, C9-C11 (odd numbered), branched and linear. The properties of the linear isomer are expected to give a preliminary indication of the approximate value. Readily biodegradable: based on read across and expert judgement in the context of the Category of C6-24 alcohols

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Alcohols, C9 -C11 (odd numbered), branched and linear is a member of a category of homologous alcohols in the range C6 - C24. These alcohols have been demonstrated to be readily biodegradable in OECD guideline studies throughout the range C6 - C22. It is expected that alcohols, C9 -C11 (odd numbered), branched and linear would be rapidly degraded by micro-organisms, though no OECD 301 test of ready biodegradability is available for this substance as such. The weight of evidence of ready biodegradation (OECD 301) of a number of analogous substances with the closest chain lengths C8, C9 including multi-constituent substances containing C6 -C12 alcohols, are taken into consideration in this evaluation.

The Category hypothesis is that the long chain linear aliphatic alcohol family has at its centre an homologous series of increasing carbon chain length, which is associated with a consistency and predictability in the property data across the group, for the physicochemical, environmental, and toxicological property data sets.

Many biodegradation assays have been carried out on this family of alcohols. Table 4.5 lists the best quality data (Klimisch reliability score of 1 or 2) generated on single carbon chain length alcohols for tests that conform most closely to ready test biodegradability methods (OECD 301 series). In all cases the inoculum was not acclimated. These data show that alcohols with chain lengths up to C22 are readily biodegradable. Older reliable data suggest that chain lengths above C18 are not readily biodegradable, however those studies used loading techniques which while in general is still reliable, did not make allowance for the reduced bioavailability caused by the low water solubility of these highest chains. Where the substances are introduced into the test vessels by coating onto the flask, very rapid biodegradation was confirmed at all chain lengths tested. Please refer to the CSR for additional details.