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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Parent compound:

To assess the biodegradation potential of modified Isophoronediamine (MIPDA, CAS 93940-97-7), a GLP-study was conducted according to OECD guideline 301F (ready biodegradability test). Municipal non-adapted activated sludge was used as inoculum (BASF AG, 2005, report no. 26G0405/053156). After 28 days, the O2-consumption and DOC removal were below 10%. Therefore, the substance is considered to be poorly biodegradable (not readily biodegradable according to OECD criteria).

Further experimental data are not available.

The result is supported by the model CATALOGIC 301C v11.15 (OASIS Catalogic v5.13.1). The model predicted that the substance would be degraded to 23% after 28 d based on oxygen consumption (BASF SE, 2019). The substance was not completely within the applicability domain (100% parametric domain, 95% structural domain; 100% metabolic domain). However, the model was used mainly to predict potential metabolites of MIPDA.

Metabolites:

CATALOGIC 301C v11.15 (OASIS Catalogic v5.13.1) predicted 129 metabolites, identifying 50 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). Five 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 56% 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.

While the majority of the predicted metabolites are potentially P/vP, the log Kow values are all below 3 and indicate that their bioaccumulation potential is negligible (not B/vB). Hence, MIPDA is considered to be of no concern in terms of PBT and vPvB assessment.

Key value for chemical safety assessment

Additional information

Water:

In accordance with Regulation (EC) No 1907/2006, Annex IX, Section 9.2 and 9.2.1.2, Column 2, the simulation test on ultimate degradation in surface water does not need to be conducted as the chemical safety assessment according to Annex I indicates that there is no need to investigate further the degradation of the substance and its degradation products. The risk characterization ratios (RCRs) of the chemical safety assessment are below 1, indicating that the risks are acceptable. In addition, for the substance (MIPDA, CAS 93940-97-7) only industrial uses with adequate risk mitigating measures are foreseen. Environmental exposure through widespread uses by professionals and consumers is excluded. Therefore, no biodegradation studies in surface water will be provided.

Sediment:

In accordance with Regulation (EC) No 1907/2006, Annex IX, Section 9.2 and 9.2.1.4, Column 2, the simulation test on ultimate degradation in sediment does not need to be conducted as the chemical safety assessment according to Annex I indicates that there is no need to investigate further the degradation of the substance and its degradation products. The risk characterization ratios (RCRs) of the chemical safety assessment are below 1, indicating that the risks are acceptable. For the substance (MIPDA, CAS 93940-97-7) only industrial uses with adequate risk mitigating measures are foreseen. In addition, environmental exposure through widespread uses by professionals and consumers is excluded.  Further, the substance does not have the potential to bioaccumulate nor is it considered as a PBT/vPvB substance. In addition, the risk assessment results in Risk Characterization Ratios below 1. Hence, sediment is not expected to be a compartment of concern. Therefore, no biodegradation studies in sediment will be provided.