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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Three tests have been performed to assess the ready biodegradability of Erucamide: one close bottle test (van Ginkel, 1993) and two CO2 evolution tests (Coenen, 1991 and Mead, 2000).  All studies have been performed according to GLP with all validity criteria fulfilled. In the van Ginkel and the Coenen tests biodegradation is observed but don't pass the ready biodegradability criteria. In the Mead test, readily biodegradability is observed but fails the 10-day window criterion. However, during the tests the biodegradation of the substance was limited by low bioavailability due to its poor water solubility. Therefore the 10-day criterion can not be used and ready biodegradability is claimed for Erucamide.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The readily biodegradabilty of Erucamide has been evaluated in three different tests: one close bottle test (van Ginkel, 1993) and two CO2 evolution tests (Coenen, 1991 and Mead, 2000). All of the tests are of good quality with GLP certificate and all validity criteria fulfilled. Biodegradation was measured in all tests (28/ 15% degradation after 28 days for 10/ 20 mg/l, respectively, in Coenen test and 15/ 43% after 28/ 140 days, respectively, in van Ginkel test) and one test (Mead, 2000) passed the readily biodegradability criteria ( 64% degradation after 28 days). However this last test missed the 10-days window criterion. Looking at the studies it appears that the tests were conducted with concentrations of Erucamide well above its water solubilty (<0.1 mg/l) and it is foreseen that its biodegradation was limitated by its bioavalability in the test media. This is confimed by the negative correlation existing between the biodegradation rate and the test concentration in the Coenen test and by the staight line that can be drawn from day 6 to 28 in the Mead test which suggests that the biodegradation rate was limitated by dissolution. The Mead test is considered as the key study for readily biodegradability because an enhanced methodology was used to dissolve the poorly soluble Erucamide (ultrasonication) and the homogeneity of the stock was good enough as suggested by similar results between duplicates. Moreover, the initial organic carbon content was checked (about 10 mg/l). Based on the results of the key study where the 10-day window cannot be used as a criterion, readily biodegradability is claimed for Erucamide.