2025 SETAC Europe Poster: Investigation into Reference Substance Degradation Rates in OECD 309 Tests
Simulation tests performed using a radiolabelled molecule are important in determining the primary and ultimate degradation of a chemical and evaluating its potential to persist in the environment. The surface water mineralisation test performed according to OECD test guideline 309 incorporates a reference substance as a positive control to demonstrate that the water contains an active microbial population. The test guideline recommends the use of aniline or sodium benzoate as the reference substance and that the expected time interval for degradation is usually less than two weeks.
The current work was undertaken to understand the expected rate of degradation of these reference substances when incubated under varying conditions. Surface water with suspended solids in the range 10 – 20 mg dry weight/L was freshly collected and treated with [14C]-aniline or [14C]-sodium benzoate at a rate of 10 µg/L. The treated samples were then incubated under aerobic conditions at 12 and 20°C, and the rate of mineralisation to 14CO2 was monitored at regular intervals throughout the incubation period. Further investigations were performed using surface water from different sources with different amounts of suspended solids
Desmond Kelly will present this research during the SETAC Europe 35th Annual Meeting, May 11-15, in Vienna, Austria.