Hexamethylene diisocyanate, oligomerisation product, blocked with 2-butanone oxime

Endpoint summary

Additional information

Justification for the non-equivalence of the test material to the submission substance identity:

HDI trimer MEKO blocked is always produced and marketed as dissolved in solvent. Thus, the substance is reasonably expected to be handled and used in a form of a mixture of the registered substance in the solvent. The environment is anticipated to be exposed rather to the mixture than to the pure substance. Thus, the testing strategy was designed to take this route of exposure into account and

it has been concluded that testing the mixture was more relevant than testing the registered substance as such.

To conclude, ecotoxicological studies were performed on the mixture and as a consequence for endpoint study records, the test material is ticked as ‘no’ when requesting if equivalent to submission substance identity.

Available ecotoxicological information:

Four study reports record experimental results on ecotoxicological properties of the registered substance in the solvent. Among them, three references deal with aquatic organisms, the other one with microorganisms. An overview of the ecotoxicological dataset is provided in the table below.

Section	Guideline	Species	Basis for effect	Endpoint	Effect concentration (mg/L)	Reference
Short-term toxicity to fish	Similar to OECD 203	Danio rerio	Mortality	96h-LC50	141.4 (nom.)	Bayer, 1988
Short-term toxicity to aquatic invertebrates	OECD 202	Daphnia magna	Mobility	48h-EC50	> 1.61 (meas. Initial)	Weyers, 2007
Toxicity to aquatic algae	OECD 201	Desmodesmus subspicatus	Growth rate and biomass	72h-EC50	> 8.1 (nom.)	Weyers, 2007
Toxicity to microorganisms	OECD 209	Not identified	Respiration	3h-EC50	> 10000 (nom.)	Bayer, 1988

Conclusion

Based on the available results, the registered substance does not exhibit acute toxicity effects at its solubility limit to the three trophic levels and the microorganisms.