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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Urea is considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The degradation of urea was investigated in psychrophilic bacteria in an aqueous test system. The maximum degradation rate per hour at 20 C was 11.6 mg/L. The average degradation rate per hour at 20 C was 10.9 mg/L. The maximum degradation rate per hour at 2 C was 4.0 mg/L. The average degradation rate per hour at 2 C was 3.2 mg/L.

The biodegradation of urea was investigated in activated sludge from a laboratory sewage treatment facility fed with adapted domestic and synthetic sewage. Degradation levels of 3% (3 hours), 52% (7 hours), 60% (10 days), 85% (14 days) and 96% (16 days) was seen. Urea is ultimately biodegradable according to this study.

The biodegradation of dimethyl urea was investigated in a DOC-die away study. The biodegradation (DOC removal) after 21 days is 90-100%. Dimethyl urea is therefore readily biodegradable according to OECD criteria. The degree of degradation of the reference substance was 100% after 21 day and the degradation degree in inhibition control was 101%. The validity criteria is therefore met according to OECD criteria.