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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Two screening tests were performed according to the OECD 301D testing guideline to assess the biodegradability of the test substance in water.

The first one used non-adapted activated sludge as source of inoculum whereas non-adapted river water was used in the second.

In those two studies, the test item reached 24% and 43% of biodegradation after 28 days, respectively. These studies were extended and biodegradations of 54% and 66% were reached at Day 63 and 60, respectively. Therefore, the test item cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301D. However, the biodegradation continued after Day 28 to reach value higher than 60% indicating a high potential for ultimate biodegradation.

The data generated for an analogue (Ethoxylated bisphenol A diacrylate) (20-21% of biodegradation at Day 28 and 61% at Day 60) according to OECD testing guideline 301B and were similar to the one obtained for the test item. Another analogue (2 moles ethoxylated bisphenol A dimethacrylate) has been shown to be readily biodegradable with 65.1% of biodegradation at day 28 according to OECD testing guideline 301F.

Based on the values obtained for the test item at Day 28 (24 and 43%), at Days 60-63 (54 and 66%, respectively) and according to the two results of biodegradability available (inherently and readily biodegradable) for two analogues, the test item was considered to be inherently biodegradable and fulfilling specific criteria.

In addition, the biodegradation potential of all relevant main constituents of the test substance was assessed using an in-silico approach, the BOD QSAR Model “LMC OASIS CATALOGIC 301C”. This model also identifies the biotic degradation products of the test substance. The in silico approach was chosen as the most appropriate method to assess the degradation products considering that the parent substance is a complex UVCB consisting of several major constituents. For all assessed constituents, primary half-life values ranged from 3.60 to 6.27 days and ultimate half-life values ranged from 29.59 to 30.75 days, indicating that none of those constituents nor their degradaton products are likely to fulfill the P criterion.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information