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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Waiver. In accordance with Regulation (EC) No 1907/2006 Annex IX section 9.2.1.2 and 9.2.1.4 column 2, a water and sediment simulation testing study is not required as the substance is readily biodegradable.

Key value for chemical safety assessment

Additional information

Waiver. In accordance with Regulation (EC) No 1907/2006 Annex IX section 9.2.1.2 and 9.2.1.4 column 2, a water and sediment simulation testing study is not required as the substance is readily biodegradable. Due to the rapid hydrolysis of DMDMH, the degradation product DMH was considered for environmental fate studies as this is the substance which would be released into the environment. A ready biodegradability test has been performed with DMH which shows 87% biodegradability passing the 10 day-window criterion; therefore there is no requirement for an aerobic degradation study in soil.

 

For information, there are no reliable water and sediment simulation studies for DMDMH, however, there is a reliable sediment/water degradation study available for the hydrolysis product, DMH.   Due to the rapid hydrolysis of DMDMH to DMH studies conducted with the hydrolysis product, DMH, are considered relevant for environmental fate and ecotoxicology and are considered in this dossier.

 

De Vette and Schoonmade (2002) conducted reliable (Klimisch 1) GLP compliant study following OECD 308 methods. Test results showed that DMH was steadily degraded with whole systems and aqueous phase DT50 values of 13 to 24 days which indicates that DMH is not persistent in freshwater environments. The predominant degradation product was CO2which accounted for 55 to 65% of the applied radioactivity at the end of the incubation phase (17 weeks). 

 

It can be concluded that water and sediment simulation testing is not required as the test substance and its degradation product are readily biodegradable and not persistent in freshwater environments.