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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

Comparing with the Criteria of Annex XIII, an assessment of the PBT status of MDI has been made using all available data. The information available suggests that MDI does not meet the PBT screening criteria as outlined in Annex XIII of Directive 2006/121/EC.

Conclusion for the P criterion

The results from the inherently biodegradation test indicate that PMDI is not biodegradable.

Significant and substantial abiotic degradation by means of hydrolysis has been confirmed for PMDI and its hydrolysis transformation products have been assessed. The half-lives obtained for PMDI are much lower than the P(vP) criterion of t1/2> 40 (60) days. Based on experimental hydrolysis and indirect photolysis half-lives, PMDI is not considered to be persistent in the environment and is identified as not P. Based on the justification in the category approach, it is assumed that all MDI analogues included in the category are not P.

Conclusion for the B criterion

Although MDI has a high measured log Kow value (4.51), a full bioaccumulation test with 4,4’-MDI indicated that the bioaccumulation potential is low. The expected hydrolysis product MDA has, based on its measured log Kow value of 1.55 and predicted BCF of <14 L/kg, no or a low bioaccumulation potential. Due to the fast hydrolysis, exposure of the environment to the substance is unlikely or very low.

Considering the above together with the fast hydrolysis of MDI, there is no potential for significant bioaccumulation possible. Hence, 4,4’-MDI does not fulfil the requirements for the B criterion and is identified as not B. Based on the justification in the category approach, it is assumed that all MDI analogues included in the category are not B.

Conclusion for the T criterion

Based on the effect concentrations determined in the aquatic toxicity tests with PMDI, MDI does not fulfil the T criteria. It was noted that the concentrations tested were far above the estimated water solubility of the MDI substances (i.e. 7.5 mg/L). However, the water solubility limit of MDI is far above the criteria for T and on the basis of aquatic toxicity tests MDI is identified as not T. However, according to Annex I of 67/548/EEC MDI is classified as Xn, R48, which automatically triggers a T. Based on this classification MDI is identified as T.