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Environmental fate & pathways

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No biodegradation (0% degradation within 28 days) was observed in a manometric respiratory test performed with domestic, non-adapted activated sludge according to Directive 92/69/EEC, C.4-D (Bayer AG, 2000). Biodegradation of the substance itself is irrelevant as primary degradation step because the substance hydrlolyzes immediately. As no degradation occurred in the test on ready biodegradability it is not expected that a significant degradation would occur in a simulation test (surface water, sediment and soil). The test substance is considered as non-biodegradable in surface water, sediment and soil.

The registered substance is not found to be readily biodegradable but exhibits a dissipation time in water less than the cut-off value of 12 h and is therefore considered as hydrolytically unstable. Upon contact with water the diisocyanate groups of IPDI react by forming amines and CO2. The amines (i.e. isophorone diamine) react further with unreacted diisocyanate groups of IPDI resulting in oligo- and subsequently polyurea components. Hence isopohorone diamine and polyurea are regarded as hydrolysis products and need also be addressed.

Isophorone diamine is not readily biodegradable (8 % degradation within 28 days), but a simulation test (equivalent to OECD 303) indicated that 42 % of the test item degraded within a period of 31 days. Polyurea is an inert material and is practically resistant to biodegradation or other external influences.