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Environmental fate & pathways

Biodegradation in water: screening tests

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The ready biodegradability of IOA was assessed in two non-GLP studies utilizing OECD TG301D (Closed Bottle Test) and measuring IOA concentration via GC analyses as well as oxygen depletion. In the key study, IOA was readily biodegraded, with 93%-95% depletion of dissolved oxygen by day 28. In the supporting study, IOA was also readily biodegraded, showing 64% - 69% depletion of dissolved oxygen by day 28.

 

In the key study, IOA underwent substantial primary degradation by day 5 according to GC analysis, with mineralization lagging. Dissolved oxygen measurements demonstrate that IOA was readily biodegraded, with 93%-95% depletion of dissolved oxygen by day 28. This study was conducted in accord with a draft version of test guidance OECD301D. Differences between this and the currently-adopted method are slight, but the test data were too sparse to permit evaluation of either the 10-day or the 14-day windows for biodegradability. Also, the test was not conducted according to GLP criteria. It is therefore classified as reliable with restrictions.

 

In the supporting study, IOA was again seen to undergo substantial primary degradation by day 5 according to GC analysis, with mineralization lagging. Dissolved oxygen measurements demonstrate that IOA was readily biodegraded, with 64% - 69% depletion of dissolved oxygen by day 28. Test data were too sparse to permit evaluation of either the 10-day or the 14-day windows for biodegradability. This study was nominally conducted in accord with a draft version of test guidance OECD301D. However, the report provides summary data only and has few details on conduct of the study. Also, the test was not conducted according to GLP criteria. Study reliability could therefore not be classified. However, this study clearly supports the results of the key study. Therefore, IOA is considered to be readily biodegradable.