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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

No data are available on degradation rates in surface water and sediment; therefore, the substance is regarded as P/vP from a precautionary point of view.


Degradation products were predicted using a QSAR model. 5 of 16 relevant degradation products are readily biodegradable.

Key value for chemical safety assessment

Additional information

QSAR-disclaimer:


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.


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 of the substance, (Q)SAR results were used for the prediction of potential degradation products. 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.


Therefore, experimental simulation testing on sediment and surface water is not provided.


Assessment:


The ready biodegradability of the substance was assessed using a QSAR model CATALOGIC Kinetic OECD 301C v.11.16. The substance was within the applicability domains of the model. The substance was predicted to be not readily biodegradable (7% in 28 d, not readily biodegradable).


Additionally, the analogous compound Di-(2-ethylhexyl)amine (CAS 106-20-7) turned out to be moderately biodegradable (not readily biodegradable) in a ready test according to OECD TG 301B.


According to Regulation (EC) 1907/2006, Annex IX, Section 9.2.1.2, column 2, a simulation study on ultimate degradation in surface water does not need to be conducted if the substance is highly insoluble in water. The substance is poorly soluble (WS < 0.002 mg/L (see IUCLID Ch. 4.8). Therefore, no simulation testing on ultimate degradation in surface water will be performed.


In Annex XI, Section 3, it is laid down that testing in accordance with Annex IX and Annex X may be omitted, based on the exposure scenario(s) developed in the Chemical Safety Report (“Substance-Tailored Exposure-Driven Testing”). In accordance with Annex XI Section 3, it can be demonstrated in the risk assessment that the manufacture and the use of the substance do not pose an unacceptable risk for all environmental compartments as the risk characterization ratios (RCRs) of the chemical safety assessment are below 1 for all compartments (see Chemical Safety Report Ch. 10). Therefore, no sediment simulation testing will be performed.


No futher experimental simulation testing on sediment has been performed although the substance is not readily biodegradable. For the persistence assessment, the substance itself is assessed to be P/vP from a precautionary point of view. Potentially forming degradation products have been predicted using a valid QSAR model (CATALOGIC v.5.14.1.5 BOD 28 days MITI (OECD 301C) v.11.16). The substance is within the applicability domain of the model. The model predicted 33 degradation products, of which 16 can be regarded as relevant based on their predicted quantity (see the coresponded endpoint study record). These relevant degradation products were evaluated with regard to their biodegradability and bioaccumulation potential based on QSAR data. Five substances were readily biodegradable. Significant accumulation is not to be expected for all relevant biodegradation products. Thus they are neither PBT, nor vPvB.