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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Data waiving:
exposure considerations
Justification for data waiving:
the study does not need to be conducted because direct and indirect exposure of soil is unlikely
other:
Transformation products:
not specified

Description of key information

The biodegradation testing in soil has been judged to be not necessary in accordance with column 2 of REACH Annex IX and X 9.2 and also in accordance with section 3 of REACH Annex XI. 

Key value for chemical safety assessment

Additional information

The study on biodegradation in soil has been judged to be not necessary in accordance to column 2 of REACH Annex IX and X 9.2 and also in accordance with section 3 of REACH Annex XI. In accordance with column 2 of REACH Annex IX and X, further biotic degradation testing is not proposed because the results of the chemical safety assessment do not indicate any need to investigate further the biodegradability of the substance and its degradation products. 

Additionally, as no biodegradation (0%) was observed in a study on ready biodegradability it is not expected that a significant degradation would occur in a simulation test. The test substance is considered as non-biodegradable in the surface water, sediment, and soil compartment. Moreover, biodegradation is irrelevant as primary degradation step because immediate hydrolysis takes place forming amines and CO2 and further resulting in polyurea molecules. For the hydrolysis product isophorone diamine it is calculated in a Mackay Level I model that, the main target compartment for isophorone diamine will be the hydrosphere (99.8 %), followed by sediment and soil (0.08 % each). Additionally, 42 % isophorone diamine degraded within a period of 31 days in a simulation study which is comparable to OECD guideline 303. The resulting polyurea molecules are considered persistent in the environment, however due to their high molecular weight they are also considered as not bioavailable and non-toxic to organisms.

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