Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

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, environmental fate studies were performed on the mixture and as a consequence for endpoint study records, the test material is not ticked when requesting if equivalent to submission substance identity.

Summary of available data

Considering the type of substance (UVCB) and according to manufactures experience, the registered substance is to be considered as difficult to analyse. In addition, the test material (being the mixture of the registered substance in the solvent) exhibits low water solubility (less than 100 mg/L). The test material has to be considered as a difficult mixture to be tested particularly for achieving exposure concentration and preparing representative media.

In a hydrolysis study (OECD TG 111), a half-life of 139 d for pH 7 at 25 °C in water was calculated for the registered substance (HDI Trimer MEKO-blocked) from experimental data obtained at 50, 65 and 80°C. Considering the nature of the substance (UVCB), it was not possible to identify the hydrolysis product. Therefore, the registered substance is to be considered as stable to hydrolysis based on the available half-life.

In a standard screening biodegradation test (manometric respirometry method), the percentage of biodegradation of test material was determined at 3, 4, 7 and 9% based on BOD after 6, 12, 20 and 28 days of exposure, respectively. Thus, the test material does not meet the readily biodegradable criterion. Therefore, the registered substance has to be considered as not readily biodegradable.

The adsorption coefficient (Koc) of the registered substance (HDI Trimer MEKO-blocked) was determined by High Performance Liquid Chromatography (HPLC). The experiment was conducted in accordance with the OECD Guideline 121 and in compliance with the OECD-GLP standard. A key value of log Koc values has been determined to 3.0. Therefore the registered substance is to be considered of low mobility.