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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

- readily biodegradable > 60% BOD/COD | OECD 301 D | Fatty acid C 12-18, potassium salt 
- readily biodegradable | OECD 301 E | Fatty acids, C12-18, potassium salts
- readily biodegradable 84% | OECD 301 F | Tall oil fatty acid
- readily biodegradable | OECD 301 E | soidium oleate

Key value for chemical safety assessment

Additional information

Fatty acids, C12-18, potassium salts meets the OECD criteria for "readily biodegradable" (>60% BOD/COD ) in a closed bottle test (30 days), which corresponds to OECD test method 301 D.

In another study the ultimate biodegradability of Fatty acids, C12-18, potassium salts was tested in the Modified OECD Screening Test (OECD 301 E). Under the chosen conditions 86% of the test substance was degraded within the 28 days test period, i.e. Fatty acids, C12-18, potassium saltspmet the pass level for ready biodegradability. Since the pass level (= 70% DOC removal according to the OECD-Guideline 301) was reached , Fatty acids, C12-18, potassium salts can be regarded as readily degradable.

In the modified OECD 301 E test the biological degradation of sodium oleate was determined. A starting concentration of 150 mg/l of pure substance was incubated for 20 days. Before the analysis each sample had to be filtered. So the precipitated soap was removed, and only the reduction of the dissolved soap and carboxylates was determined. It must be noted that with an initial weight of 150 mg/l only a part of the test substance is present in true dissolved form.

Sodium oleate shows a high solubility. The degradation of oleate is with 98.9 or 94.6% very high.

The DOC and COD reduction confirm a high metabolism.

From these available test results, it can be deduced that the fatty acid sodium salts of high chain length up to C18 are readily degraded. Hence, it can be concluded that lower chain lengths of C16 -18, sodium salt is readily biodegradable as well.