Hexanedioic acid, polymer with 2,2'-oxybis[ethanol]

Biodegradation in water: screening tests

Description of key information

Readily biodegradable (according to OECD criteria).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation potential of the substance was determined in a screening study according to OECD guideline No 301A (DOC Die Away Test) and in compliance with GLP criteria. In this study, the test substance (40 mg/L, expressed as DOC) was inoculated with non-adapted activated sludge from a domestic sewage treatment plant for 15 days under aerobic conditions in the dark. The substance was biodegraded almost completely (>97%) within 15 days and therefore the test was aborted early. The 10-day window criterion was met although this criterion is generally considered to be of lesser relevance for complex substances (i.e. UVCBs). An adsorption control and an abiotic control were included but both were contaminated and therefore considered useless for evaluation of results. The substance’s Koc value indicates that some adsorption to the inoculum and/or test flasks may be expected. Furthermore, the substance contains 30% of the volatile 2,2’-Oxy-diethylene, and as no measures to avoid volatilisation appear to have been taken, some loss from the test system cannot be ruled out. Therefore, biodegradation percentages may be overestimated. However, based on test substance recoveries in ecotoxicity testing (despite their shorter duration), adsorption and volatilisation are not expected to contribute to >27.1% DOC removal, and therefore the substance is assessed to be "readily biodegradable".