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EC number: 439-840-1 | CAS number: 20846-91-7
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
[S,S]-EDDS acid and its trisodium salt have been shown to be readily biodegradable - with biodegradation rates of at least 75% within 28 days - in the modified Sturm test (Guekens, 1993a; Schowanek et al. 1997), unacclimated river water die-away test (Jaworska et al. 1999; Schowanek et al. 1997), semi-continuous activated sludge test (Schowanek et al. 1997) and the batch-activated sludge tests with acclimated and unacclimated sludge (Schowanek et al. 1997). Where relevant, these tests were conducted in line with corresponding OECD Guidelines.
Key value for chemical safety assessment
- Biodegradation in water:
- readily biodegradable
Additional information
A ready biodegradability test using activated sludge and carried out according to OECD Guideline 301 B (in compliance with GLP) indicated that, in an aerobic aqueous medium, trisodium EDDS was readily biodegradable. In this modified Strum test, initial test concentrations were 10 and 20 mg/L, and biodegradation reached at least 83% and 88% by days 28 and 35, respectively (Geukens, 1993a; Schowanek et al. 1997).
In an unacclimated river water die-away test, degradation of [S,S]-EDDS [it is not clear whether the test was performed on the radio-labelled acid or its corresponding trisodium salt] was similar to that seen in the modified Sturm test, reaching 75%, corresponding to a half-life of about 6.3 days. This suggests that biodegradation also occurs under realistic environmental conditions (Jaworska et al. 1999; Schowanek et al. 1997).
In addition, in a (semi-)continuous activated sludge (SCAS) test carried out according to OECD Guideline 302A, trisodium EDDS was readily biodegradable. Over a 7 -day acclimation period 40 mg/L was added to the test system, and biodegradation reached 97% by day 7 of the test period (Schowanek et al. 1997).
Batch-activated sludge tests on [S,S]-EDDS [it is not clear whether the test was performed on the radio-labelled acid or its corresponding trisodium salt] with acclimated and unacclimated sludge indicated biodegradation of 94% and 84%, respectively, within 28 days (Schowanek et al. 1997).
[Data on trisodium EDDS is considered relevant to use for understanding the potential biodegradability of EDDS acid, and is acceptable for using as read-across information].
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