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Environmental fate & pathways

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Biodegradation in water: screening test

In a study conducted according to OECD 301B, under GLP conditions, the test material attained 26% degradation after 28 days and, therefore, is not readily biodegradable

Biodegradation in water and sediment

In an OECD 308 study, conducted according to GLP, the test material dissipated rapidly from the water of both aquatic sediment systems, with DT50 values of 2.6 days (Calwich Abbey Lake) and 10.4 days (Emperor Lake).  The DT50 value in the sediment phase of Calwich Abbey Lake was 811 days, based on two sampling intervals.  The DT50 value for the decline in the sediment phase of Emperor Lake could not be calculated, as the test material (as % applied parent) continued to increase until the last sampling interval.  Decline in the overall aquatic sediment system was slow and corresponded to DT50 values of 657 days (Calwich Abbey Lake) and 636 days (Emperor Lake).

Due to the low solubility of the test material and rapid partitioning from the aqueous phase to the sediment, aerobic mineralisation in surface water – simulation biodegradation testing according to OECD Testing Guideline No. 309 is considered technically not feasible.  

Biodegradation in soil

In an OECD 307 study, conducted according to GLP, the mean distribution and recovery of radioactivity ranged from 99.7 to 106.2% AR in Cuckney soil, 93.9 to 103.4% AR in Drayton soil, 97.6 to 107.2% AR in Elmton soil, and 95.2 to 106.2% AR in Calke soil.  Low levels of radioactivity were detected in the bound residues (mean values ≤10.6% applied radioactivity) and mean mineralization of the test item to CO2 was less than or equal to 0.9% applied radioactivity.  There was little or no evidence for degradation of test material in soil at 12 +/- 2 deg C and pF2, under aerobic conditions, and kinetic analysis of the data was therefore considered inappropriate.