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Ecotoxicological information

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Description of key information

The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI). Hence, data of the category substances can be used to cover this endpoint. The read-across category justification document is attached in IUCLID section 13.


 


Two acute studies in terrestrial organisms are available. A short-term toxicity study in earthworms and a study in plants (van der Hoeven et al., 1992b; van der Hoeven et al., 1992a) with the source substance pMDI. The results did not show any adverse effects (LC50 > 1000 mg/kg dw). This low toxicity is consistent with the overall hypothesis that MDI substances hydrolyse quickly when in contact with water to form insoluble polyurea and therefore no MDA is available to soil organisms. It is inevitable that all substances of the category will form such insoluble polyurea and show limited availability to the terrestrial compartment.
Since all category substances have similar behaviour in the (aquatic) environment (rapid hydrolysis, formation of polyurea), it is concluded that none of the substances of the category will exhibit toxicity towards terrestrial organisms in analogy to pMDI as representative and source substance of the category. The read-across and the assessment is considered appropriate in terms of the level of confidence.


For the safety assessment however, a PNECterrestrial has been derived applying the Equilibrium Partitioning Method. A value for the PNECterrestrial of 2.33 mg/kg soil dw is considered for all the MDI substances of the category. Details can be found in the section 6. Ecotoxicological information.


 


To make the endpoint more robust, the registrant will perform additional OECD 222 studies. The data will be generated on the three boundary substances of the category 4,4'-MDI/DPG/HMWP, 4,4'-MDI and pMDI. 


Testing proposals for the OECD 222 studies with these three substances are added to the respective dossiers. A category approach will be used to fulfill the data requirement for the registered substance.


 

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