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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test material is readily biodegradable. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The ready biodegradability of n-propyl propionate was evaluated according to the OECD Guideline301D: Closed Bottle Test. This test examined biodegradation of the test chemical (3 mg/L) in adefined mineral medium after inoculation (3 mL/Liter) with secondary effluent from the City of

Midland, Michigan Wastewater Treatment Plant. Consumption of dissolved oxygen in replicateinoculum blanks (no test substance added) and test chemical suspensions was determined after 5, 7,10, 14, 21, and 28 days incubation at an average temperature (± 1 Standard Deviation) of 20.1 ±

0.4 °C. Average net oxygen consumption in the test suspensions, corrected for oxygen consumed inthe inoculum blanks, was equivalent to 32.2, 56.8, 56.5, 60.0, 64.9, and 64.0% of the theoreticaloxygen demand (ThOD) after 5, 7, 10, 14, 21, and 28 days, respectively. Since the time required to

achieve >10% biodegradation (i.e. lag period) was less than 5 days, a precise determination of the 10 -day window following this onset could not be made. However, the test chemical achieved 60.0%biodegradation within the first 14 days of the test. Therefore, n-propyl propionate can be considered

as “readily biodegradable” according to current OECD criteria for the Closed Bottle Test.

 

The reference compound, sodium benzoate (4 mg/L), achieved > 60% biodegradation (i.e. 76.6± 0.7%) after 14 days. Consumption of dissolved oxygen in the inoculum blanks did not exceed0.68 mg/L over the 28 day test. With the exception of day 5 determinations, the difference of extremes

in percent biodegradation among replicate test suspensions did not exceed 20% at any of the samplingintervals. Therefore, the results of this test met each of the validation criteria established for theOECD Closed Bottle Test.