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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The potential of the test substance to biodegrade aerobically was tested in the OECD 301B test. After 28 days a degradation of 66 % (CO2) resp. 78 % (DOC) was determined. The substance (UVCB) was judged to be readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Key study

The ultimate degradation of Octadecanoic acid, 9(or 10)-sulfo-, potassium salt (CAS-No. 67968 -63 -2) has been tested in the OECD 301B test. This test resulted in 66 % ultimate degradation (78 % based on DOC-removal) after 28 days. However, under the test conditions applied the bioavailability of the test substance was probably limited. This is deduced from the fact that the test substance was applied onto a glass plate and as such introduced into the test media, and the resulting degradation curve, which has not reached the plateau phase after 28 days.

Supporting study

The potential of the test substance to biodegrade was tested in an anaerobic biodegradation study. The study was conducted according to the ECETOC technical report No. 28. The inoculum was from the sewage plant Hilden. The domestic activated sludge was inoculated in an anaerobic system consisting of closed bottles under static pH conditions of 7.1 -7.2 and in a temperature of 35 +/- 2 °C. The test substance was applicated in a dose of 50 mg/L and tested for 84 days. The gas pressure and the dissolved inorganic carbon production (CO2 evolution) served as indicator for the anaerobic degradation of the test substance. After 84 days a degradation of 81.5 +/- 20.8 % was determined. According to this result the substance can be considered as anaerobic degradable.