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Environmental fate & pathways

Biodegradation in water: screening tests

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Link to relevant study record(s)

Description of key information

A test on ready biodegradability was conducted according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). After 28 days  tert-Butylamin, the hydrolysis product of tert-butyl isocyante, showed 0 % degradation. Therefore, tert-Butylamin, and thus tert-butyl isocyante too,  is not readily biodegradable (MITI, 2001).

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

read-across to the corresponding amine

Read-Across-Justification:

Isocyanates are known to rapidly hydrolyse under the formation of the corresponding amine as well as solid polyurea compounds *. However, the insoluble inert polyurea is not assumed to cause environmental hazards due to the reduced uptake of high molecular mass compounds, whereas the amine is assumed to be the ecotoxicological relevant species. Concluding, tests per-formed using the corresponding amine can equally be used to assess the ecotoxicological hazards of isocyanates assuming the complete transfer of the isocyanate into the corresponding amine while neglecting the formation of a certain fraction ecotoxicological not active polyurea com-pounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment.

* Test Lab (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aque-ous Test Solutions. Project No: 200300181.

Test Lab (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095.