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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The calculated BCF values of the hydrolysis products of the 'Reaction mass of hexadecyl isocyanate and octadecyl isocyanate' were considered to assess the bioaccumulation potential of the substance, as isocyanates are know to rapidly hydrolyse in water under the formation of the corresponding amine as well as solid polyurea compounds. The calculated BCF values for hexadecylamine and octadecylamine were 539 and 1512 L/kg, respectively. As a worst case scenario the BCF value of 1512 L/kg was chosen to assess the bioaccumulation potential of the substance.

Key value for chemical safety assessment

BCF (aquatic species):
1 512 L/kg ww

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 BCF values were 915.5 and 302.9 L/kg, respectively. The calculations of the BCF 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.

The calculated BCF value for octadecylamine was 1512 L/kg. This value is below the bioaccumulation criterion of > 2000 set in Annex XIII to REACH Regulation (EC) No 1907/2006. Therefore, the substance does not fulfil the B-criterion.

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