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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

General discussion of environmental fate and pathways:

 The direct and indirect exposure of the aquatic compartment is unlikely because HDI Trimer asymmetric hydrolysis completely in water. A complete hydrolysis of the isocyanate groups in the test substance took place during the hydrolysis preliminary test at ambient conditions. For this reason, an experimental study is not useful, and calculated values were used. However, the calculated logKoc and Henry's law constant values from asym. HDI Trimer were used for the calculation of PNEC concentration for sediment and soil.

Detailed conlusions

Phototransformation in air:

In the atmosphere a half-life of 11.7 h for HDI oligomers, iminooxadiazindione is estimated due to indirect photolysis reaction with hydroxyl radicals and the corresponding triamine of the main component HDI Trimer asymmetric (Iminooxadiazindione, n=3) has a half-life of 3 h.

Biodegradation (in water, screening test):

Within 28 days only 2 % of the test substance was degraded (Closed Bottle Test).

In a 'Modified MITI (II) Test' with adapted inoculum no degradation of HDI Trimer asym. could be obtained within 28 days. Therefore the test item is also considered to be "Not Inherently Biodegradable"

Bioaccumulation:

A potential for bioaccumulation of asym. HDI Trimer is not expected due to the rapid hydrolysis. Therefore the BCF-values were calculated. Bioconcentration factors (BCF) of 706 L/Kg for the main component of asym. HDI Trimer (read-across) and 10.11 L/Kg for the corresponding triamine of asym. HDI trimer were obtained.

Adsorption / desorption:

 The calculated Log Koc value of the main component HDI Trimer asym (Iminooxadiazindione n=3) is 5.4-7.2 and for the corresponding triamine is 3.0-5.0.

Transport and distribution:

The calculated Henry's law constant of 1.25 * 10-9Pa m3/mol (read-across from HDI-Trimer) indicates that the compound has a low potential for volatilization from surface waters.