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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

In a valid GLP test according to OECD test method 310 (Ready Biodegradability - CO2 in Sealed Vessels, Headspace Test), 60% biodegradation was observed after 23 d within a 12-days window. GC-analysis demonstrated >99% elimination of the test substance after 16 days.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

In a MITI II test (OECD 302 B, 28 d) using a concentration of 30 mg/L of MIPN, only poor biodegradation was observed with a low BOD of about 12 % (NITE 2011a/2010). However, GC-analysis suggested significant primary degradation under test conditions (removal of the pristine test substance of about 93 %). 

In a valid follow-up study applying the OECD method 310 (Ready Biodegradability - CO2 in Sealed Vessels, Headspace Test), biodegradation of 60 % was reached after 23 d within a 12-days window, hence just failing the 10-days window (Fiebig/NOACK 2013). GC-analysis demonstrated >99% elimination of the original substance after 16 days.

Gafik

The NITE study has been disregarded, because a negative-selective stress usually imposed on the inoculum in these Japanese investigations favours the loss of indigenous potent microorganisms carrying special properties of decomposition.