Benzenediamine, ar-methyl-, polymer with 2-methyloxirane and oxirane

Biodegradation in water: screening tests

Description of key information

The test item is not readily biodegradable, according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

In order to assess the readily biodegradability of the substance a GLP study conducted according to OECD Guideline 301F is available. The degradation of the test item was determined to be 27% (O2 consumption, after 28 days, Currenta, rep.no.: 2008/0142/15, 2009). Thus, the substance is not considered to be readily biodegradable, according to OECD criteria. Furthermore, there is an inherent biodegradation study (OECD 302C) available for the substance. This GLP study assessed inherent biodegradability within 27 days, giving a degradation of 42% for Benzenediamine, ar-methyl-, polymer with 2-methyloxirane and oxirane (BOD degradation, Currenta, rep. no.: 2008/0142/14, 2009). In conclusion, the substance is considered inherently biodegradable, not fulfilling specific criteria

The substance is an UVCB substance. In accordance with Annex IX, Section 9.3.2 and Section 9.2.1.2 the assessment of bioaccumulation or bioconcentration and biodegradation of each constituent and impurity present in concentrations at or above 0.1% (w/w) must be performed. Since the substance is a polymer with ethoxylated and propoxylated components no purity (% w/w) can be stated. Therefore, the three representative chemical structures with three representative sizes (large, medium and small) were determined:

Constituent 1 (CC(O)CNc1ccc(C)cc1NCCO), small size
Constituent 2 (CC(CN(CCOCC(C)O)c1ccc(C)cc1N(CCOCC(C)O)CCOCC(C)OCC(C)O)OCC(C)O), medium size
Constituent 3 (CC(CN(CCOCC(C)OCC(C)O)c1ccc(C)cc1N(CCOCC(C)OCC(C)O)CC(C)OCC(C)OCC(C)O)OCC(C)OCC(C)O), large size

Therefore, in order to assess the biodegradation potential of the substance (CAS 67800-94-6) a weight-of-evidence approach with the representative constituents was performed. Due to the lack of the experimental data for the constituents, the assessment of biodegradation is based on two QSAR models of CATALOGIC and one QSAR model of BIOWIN.

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.
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 table below lists the applied (Q)SAR models, the estimated biodegradation rates and basic information on the applicability domain (AD) for the compound. Detailed information on the model’s results and the AD are given in the endpoint study records of IUCLID Chapter 5.2.1. The selected models comply with the OECD principles for (Q)SAR models.

The following table provides results for the constituents of the substance:

Model	Constituent 1	Constituent 2	Constituent 3
BIOWIN v4.10 (EPI Suite v4.11)	Not Readily	Not Readily	Not Readily
Kinetic (301F) v11.15 (OASIS Catalogic v5.13.156)	12% BOD	14% BOD	14% BOD
28 Days MITI (301C) v13.16 (OASIS Catalogic v5.13.156)	3% BOD	34% BOD	21% BOD

 

Considering all models applied representative structures of the registration item are estimated to be not readily biodegradable. According to the BIOWIN estimation model only the first structure was estimated to be within the applicability domain of the model. With regard to Catalogic, the fragments of the three substructures are largely within the structural domain (>80%), no incorrect fragments have been identified and only a minor part of fragments (<20%) is unknown to the model.

Hence, based on the available experimental data on the test substance (CAS 67800-94-6) and calculated data from the weight-of-evidence approach with the three representative structures, it is considered that the substance (CAS 67800-94-6) is not readily biodegradable (according to OECD criteria).

 

Metabolites

CATALOGIC 301C v11.15 (OASIS Catalogic v5.13.1) predicted for the representative constituents 1524 metabolites, identifying 441 metabolites as relevant degradation products in terms of PBT/vPvB assessment, with an estimated quantity of ≥ 0.1% (for details see ‘Attached background material’ of the respective Endpoint Study Record).

From the 441 relevant metabolites 16 metabolites was identified for the chemical structure 1, 175 for the chemical structure 2, 250 for the chemical structure 3.

Fifteen of the relevant metabolites were calculated to be readily biodegradable (≥ 60% after 28 days, based on BOD). The other relevant metabolites were estimated to be not readily biodegradable (0 to 40% after 28 days, based on BOD). In conclusion, the majority of the predicted metabolites present in a concentration of ≥ 0.1% (equivalent to>=0.001 mol/mol parent) are estimated to be not readily biodegradable. The degradation products of the substance (CAS 67800-94-6) which are predicted to be not readily biodegradable should be considered as potentially P/vP from a precautionary point of view, until further data become available. However, all metabolites have a log Kow ≤ 3, thereby not fulfilling the screening criteria for bioaccumulation (B/vB) as laid down in Section 3.1 of REACH Annex XIII. In conclusion, all (relevant) predicted metabolites are not expected to significantly accumulate.

CATALOGIC 301F v13.16 (OASIS Catalogic v5.13.1) predicted for the constituents 454 metabolites, identifying 137 metabolites as relevant degradation products in terms of PBT/vPvB assessment, with an estimated quantity of ≥ 0.1% (for details see ‘Attached background material’ of the respective Endpoint Study Record).

From the 137 relevant metabolites 9 metabolites was identified for the chemical structure 1, 51 for the chemical structure 2 and 77 for the third representative chemical.

Eight of the relevant metabolites were calculated to be readily biodegradable (≥ 60% after 28 days, based on BOD) and the rest relevant metabolites were estimated to be nor readily biodegradable. Therefore, the degradation products of the substance (CAS 67800-94-6) should be considered as potentially P/vP. However, all metabolites have a log Kow ≤ 3, thereby not fulfilling the screening criteria for bioaccumulation (B/vB) as laid down in Section 3.1 of REACH Annex XIII. In conclusion, all (relevant) predicted metabolites are not expected to significantly accumulate.

Based on modeled data relevant degradation products present in concentration of ≥ 0.1% (equivalent to quantity setting in OASIS CATALOGIC: ≥0.001 [mol/mol parent]) do neither fulfill the PBT criteria (not PBT) nor the vPvB criteria (not vPvB).

Hence, based on the available experimental data on the substance itself and calculated data from the weight-of-evidence approach with the three representative chemical structures along with the modeled data for the relevant degradation products, it is considered that oTDA-EO-PO (CAC 67800-94-6) is not readily biodegradable, according to OECD criteria. The information obtained from QSAR analyses on the three representative structures demonstrate that all potential breakdown products occurring at relevant levels at or above 0.1% have log KOWs below 4.5, i.e. are not fulfilling the B criterion.

Therefore, Benzenediamine, ar-methyl-, polymer with methyloxirane and oxirane and its degradation products do not raise PBT concerns.