Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis([1,1'-biphenyl]-4-yl)-2,5-dihydro-

Biodegradation in water: screening tests

Description of key information

The nano and the bulk form of the test substanse are not biodegradable as shown in the ready biodegradability test.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Additional information

Biodegradation studies are availabe on the nano (RCC Ltd. 2008) and the bulk form (RCC NOTOX B.V. 1993).

The nano form was tested in a guideline study according to OECD 301B. It was was not biodegradable (<20%) under the test conditions within 28 days. In the toxicity control, containing both the nano form and the reference item sodium benzoate, no inhibitory effect on the biodegradation of the reference item was determined. Thus, the test substance had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 20 mg/L. In the procedure controls, average biodegradation of the reference item was 89% by Exposure Day 14, thus confirming suitability of the activated sludge (>60% degradation by Exposure Day 14). By the end of the test (Exposure Day 28), average biodegradation was 99%. Therefore, the nano form ist not readily biodegradable according OECD criteria.
The study using the bulk form  was also performed according to OECD guideline 301B. The relative degradation values calculated from the measurements performed during the test period revealed no significant degradation of the substance at both concentrations (< 6% within 28 days). Since the substance was hardly soluble in water, the lack of microbial degradation was a consequence of the limited availability of the substance for micro-organisms.

Furthermore, a QSAR calculation has been conducted (Sun Chemical 2022):
In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort. 

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided. 

For the assessment  (Q)SAR results were used for aerobic biodegradability in water. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment. 

The results of the QSAR calculation support the findings of the biodegradation studies according to OECD guideline 301B. All calculated metabolites are not readily biodegradable according OECD criteria. Therefore, the test substance and its metabolites is defined as P/vP. Nevertheless, it could be shown, that all relevant metabolites in concentration > 0.1% are not bioaccumulative according PBT criteria and the test substance and its metabolites do not to be classified as PBT and vPvB.