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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Reliable measured data show that Guerbet alcohols of chain lengths up to C32 are readily biodegradable.

At carbon chain length of C16 the data show that the pass level for ready biodegradation was reached within the 10-day window with removal levels up to 96%. Shorter and longer carbon chain lengths (for example, C12 and C20) achieved ready test pass levels but not in all cases within the 10d window. The C24 Guerbet alcohol showed biodegradation rates of 84% after 28 days and reached the pass levels of the 10 day window. Guerbet alcohols with chain lengths of C32-36 showed only degradation of up to 47%. The data demonstrate a decrease in biodegradation rates with increasing chain length if the biodegradation test is conducted according to the standard procedure. It is assumed that this decrease is associated to the decrease in water solubility and the resulting decrease in bioavailability. This assumption is supported by the biodegradation tests of the C24- and C32-Guerbet alcohols. In this test the substance was administered to test system by applying it on the whole surface of the test flask. With this increased surface and resulting improvement of bioavailability higher biodegradation rates were achieved than for the C20 -Guerbet alcohols. Therefore the whole category of the Guerbet alcohols with carbon chain lengths of C12 -C32 is considered to be readily biodegradable.