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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

To determinate the biodegradability of 12-ketochenodeoxycholic acid, experimental data on a similar substance (ursodeoxycholic acid) have been used in read-across. The test has been performed according to the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test), the EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test) and the EPA OPPTS 835.3110 (Ready Biodegradability).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

Basing on a similar substance (ursodeoxycholic acid), 12-ketochenodeoxycholic acid, although it is not used in a detergent, can be considered a surfactant as defined in Regulation 648/2004/EC: “any organic substance and/or mixture used in detergent, which has surface-active properties and which consist of one or more hydrophilic and one or more hydrophobic groups of such a nature and size that is capable of reducing the surface tension of water, and of forming spreading or adsorption monolayers at the water-air interface, and of forming emulsions and /or microemulsions and/or micelles, and of adsorption at water-solid interfaces”. Therefore, a surfactant shall be considered as biodegradable if the level of biodegradability is at least 60% within 28 days, irrespectively from 10-day window principle. In this test carried out according to OECD TG 301F, ursodeoxycholic acid reached 53.4% of degradation after the 10-d window, and 82% after 28 days. Therefore the substance, basing on a read-across approach, is considered readily biodegradable.