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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Reliable OECD guideline ready biodegradation studies have shown the read-across substance C12-16 ADBAC to be readily biodegradable. The same degradation behaviour is expected for C12-14 ADBAC.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

An OECD guideline 301 D study (closed bottle test) was performed to determine the biodegradation potential of the read-across substance C12-16 ADBAC in water. Since C12-16 ADBAC was toxic to microorganisms, it was tested in the presence of silica gel to reduce the concentration in the water phase. During the test period, the test substance was released slowly from the silica gel. The validity of the test was demonstrated by an endogenous respiration of 1.3 mg/L at Day 28. Furthermore, the differences between the replicate values at Day 28 were less than 20%. The biodegradation of the reference substance, sodium acetate, at Day 14 was 78%. Finally, the validity of the test was shown by oxygen concentrations > 0.5 mg/L in the bottles. The test substance biodegraded by 63% within 28 days. Hence, C12-16 ADBAC can be considered readily biodegradable (van Ginkel CG and Stroo CA, 1992).

In a similar study, the biodegradability of C12-16 ADBAC in a CO2evolution test (OECD 301 B) was evaluated. Flasks containing inoculum from a household water treating plant dosed with the equivalent of 5 mg C/L test or 20 mg C/L reference substances were maintained for 28 days. Biodegradability was calculated from the released CO2over time in the test and reference flasks relative to that which was released in the blank control (a flask prepared as above without test or reference substance). CO2production in the blank (inoculum control) was 39.2 mg. Biodegradability in the reference flask was determined to be 88.9% in 28 days. Biodegradability in the test flask was determined to be 95.5% in 28 days. Under the test conditions, the test substance was considered to be readily biodegradable (van Dievoet F and Bouillon V, 2005).