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Biodegradation in water: screening tests


There was early on evidence that Tert-butyl-4-methoxy-4'-dibenzoylmethane (BMDBM) would not be readily biodegradable under aerobic conditions. Therefore, an anaerobic biodegradation study was conducted, using digested sludge from a municipal wastewater treatment facility. The test result was also negative. The following study on inherent biodegradability revealed that the test item is not biodegradable.


 


Biodegradation water and sediment: simulation tests


Ultimate degradation in surface water (OECD 309)


The half-life, DT50, of the parent compound in natural water at 12 °C was determined to be 10.8 days at high dose (0.015 mg/L) and 10.2 days at low dose (0.005 mg/L). Under sterile conditions the parent compound degraded slower than in a non-sterile conditions. The half-life at 12 °C was 54.7 days at a concentration of 0.015 mg/L. The parent compound degraded to two major metabolites, depending on the placement of the radiolabel and a common metabolite for both labels.


 


Biodegradation in sediment (OECD 308)


The half-life, DT50, of the parent compound in freshwater sediment was determined to be 111 days at 12 °C in a river water/sediment system. The half-life in the water phase was 0.13 days at 12 °C and from the entire river water/sediment system the DT50 was determined to be 72.1 days at 12 °C.


Using a pond water/sediment system, the DT50 for the parent compound in the sediment phase was 139 days at 12 °C, for the pond water phase 1.4 days at 12 °C and for the entire pond water/sediment system, the DT50 was 99 days at 12 °C.

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