Phenol, C14-18-alkyl derivs.

Biodegradation in water: screening tests

Description of key information

The registration substance, and all major relevant components thereof, are considered unlikely to be persistent. 
While under strict conditions of OECD 301B no degradation occurred, substance properties may have confounded assessment in this study. 
Relevant components have been reliably assessed in QSAR models and are predicted to undergo rapid degradation, hence weight of evidence conclusion is some inherent degradation potential for registration substance. 

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, not fulfilling specific criteria

Additional information

In the experimental study, the potential of the test material to undergo biodegradation was investigated in a modified Sturm test conducted in accordance with the standardised guidelines OECD 301B, EU Method C.4-C, ISO 9439 and ISO 10634 under GLP conditions. The study was awarded a reliability score of 2 in accordance with the principles for assessing data quality set forth by Klimisch et al. (1997). Difficulties in the application and dispersion of the substance in the inoculum, despite use of inert carriers, mean that the overall result may not be a reliable indicator of degradation potential despite being conducted properly and to GLP.

Activated sludge from a municipal sewage treatment plant receiving predominantly domestic sewage was exposed to the test material for 28 days, with the last CO2 measurement on day 29. The test material was tested in duplicate at 14.5 mg/L, corresponding to 12 mg TOC/L. Based on the TOC content, the ThCO2 of the test material was calculated to be 3.04 mg CO2/mg. The test material was not sufficiently soluble in water and tended to float on the surface of the test medium. Therefore, the test material was coated on an inert carrier. For each replica, 10 mL Milli-RO water was added to approximately 29 mg test material. After vigorous vortex mixing the resulting suspensions were added to individual test bottles containing 10 g silica. 300 mL Milli-RO water was added to the coated silica and thorough mixing was applied for 15 minutes to ensure homogenous distribution of the test material. The final test media were made up to 2 litres by adding inoculated medium and Milli-RO water. The test solutions were continuously stirred during the test, to ensure optimal contact between the test material and the test organisms. however this contact cannot be confirmed. The relative biodegradation values calculated from the measurements performed during the test period revealed no significant biodegradation of the test material (6 % in both replicates).

As per ECHA requirements for multiconstituent substances or UVCBs, the major relevant components of the registration substance were also assessed via predictive software tools EPIWIN at >0.1%, and the chemistry of the components assessed falls within the applicability domain. Therefore the outputs are deemed reliable and are used alongside the test result for the registration substance in a weight of evidnece assessment. The majority of these components are seen to be likely to degrade and are not likely to be persistent. A summary of the outputs of the EPIWIN models for persistence and for bioaccumulation is attached to this and shows that where a component may demonstrate a potential for one property (mainly bioaccumulation, but in one instance possibly persistence), no component appears to demonstrate potential for both, which adds reassurance to the contention that the overall substance will not be P and B.

Based on a weight of evidence assessment, the registration substance is considered not to be persistent in the environment. We therefore conclude it to be not P or vP.