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Description of key information

The calculated Koc values of the hydrolysis products of the 'Reaction mass of hexadecyl isocyanate and octadecyl isocyanate' were considered to assess the behaviour of the substance in the environment. For hexadecylamine the estimated Koc is 42250 L/kg (logKow method) and 59350 L/kg (MCI method). For octadecylamine the estimated Koc is 147200 L/kg (logKow method) and 197100 L/kg (MCI method).

Key value for chemical safety assessment

Koc at 20 °C:
197 100

Additional information

There is no reliable data available for the test substance itself. But as results are present for both main constituents of the reaction mass (65% and 35%), this data is taken into account for further assessment as read-across approach. It is assumed that due to the similarity of the chemical structures of both main constituents the ecotoxicological hazards of the reaction mass can be described with data of one or both main components as a realistic approach.

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 performed 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 compounds. An underestimation of environmental hazards is thus avoided supporting a conservative and thus protective hazard assessment.

* Bayer Industry Services (2004). 4-chlorophenyl-isocyanate: Investigation on Stability in Aqueous Test Solutions. Project No: 200300181. Leverkusen, Germany.

* Bayer Industry Services (2003). Isopropylisocyante: Investigation on Stability in Aqueous Test Solutions. Project No: 200300095. Leverkusen, Germany.

The reaction mass of hexadecyl isocyanate and octadecyl isocyanate, as defined in section 1, consists of 35 % of hexadecyl isocyanate and 65 % of octadecyl isocyanate. The calculated logKoc values were 5.51 (MCI-method)/ 7.07 (logKow-method), and 6.03 (MCI-method)/ 7.93 (logKoc-method), respectively. The calculations of the logKoc values were based on the chemical structure of the isocyanates and can have little or no relevance to the environmental partition process as the substances hydrolyse rapidly. Therefore, the corresponding amines should be used for further assessment. As a worst case scenario the Koc of 197100 L/kg estimated for octadecylamine was taken for assessment. A Koc of 197100 L/kg (logKoc 5.29) indicates a very strong sorption to soil and sediment, and a negligible migration potential to groundwater.