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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Determination of the ready biodegradability and the inherent biodegradability of FAT 40863/A TE.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The inherent biodegradability study was performed to the test item in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 302B, “Inherent Biodegradability; Modified Zahn-Wellens/EMPA Test”.

The test item attained 0% biodegradation after 28 days.

OECD Guideline No 302B does not give any definitive pass levels for test items, however the “Summary of Considerations in the Report from the OECD Expert Group on Degradation and Accumulation” suggests that a figure of more than 20% biodegradation may be regarded as evidence for inherent, primary biodegradability. A figure of more than 70% mineralization may be regarded as evidence for ultimate biodegradation.

The test item cannot therefore be considered as inherently biodegradable under the experimental conditions employed in this study.

The second experiment was performed to assess the ready biodegradability of the test item in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301F, “Ready Biodegradability; Manometric Respirometry Test”.

 The test item attained a mean degradation value of -26 % biodegradation calculated from oxygen consumption after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

Statistical analysis carried on the Day 28 Biological Oxygen Demand (BOD) values indicated a statistical difference between the test item and inoculum control vessels, thereby indicating that the test item may be exhibiting an inhibitory effect on the sewage treatment micro-organisms.