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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Readily biodegradable according to OECD criteria: 77% after 30 days based on DOC removal (OECD 301 D).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Several studies proving ready biodegradation of C16-18AS Na (CAS 68955-20-4) are available.

In the non-GLP key study according to OECD 301 D guideline (Richterich 2001) effluent of a municipal sewage treatment plant was used as inoculum. The initial concentration of the test substance was 5 mg/L as DOC. Biodegradation based on DOC removal reached 59% after 5 days and 77% after 30 days. The test substance can therefore be considered as readily biodegradable.

Supporting studies confirm the above result. The publication of Steber (1988) includes several biodegradability tests with C16-18AS Na (CAS 68955-20-4).

The OECD screening test, conf. to Directive 73/405/EEC (MBAS removal) was performed with effluent of a sewage treatment plant (predominantly domestic) and initial concentration of the test substance was 5 mg/L. After 19 days 99% of the test substance was biodegraded (measured as MBAS removal). Another available test was performed according to EU Method C.4-E. Again, effluent of a predominantly domestic sewage treatment plant was used as inoculum and the initial concentration of the test substance was 5 mg/L. Based on O2 consumption biodegradation reached 77% after 28 days. 52% of the substance was biodegraded after 5 days.

Moreover, the OECD 301 E guideline study is available. An effluent of a predominantly domestic sewage treatment plant served as inoculum and the initial concentration of the test substance was 10 mg/L. Biodegradation measured as TOC removal reached 85-88% after 28 days. Finally, the OECD confirmatory test - coupled units test is available. Activated domestic sludge was used as inoculum and the initial concentration of the test substance was 20 mg/L as DOC. Biodegradation of 96% was measured based on DOC removal after 3 hours.

Based on the above data it can be concluded that C16-18AS Na (68955-20-4) is readily biodegradable according to OECD criteria.

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