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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

The substance does not meet the criteria for persistent, bioaccumulation and toxicity (PBT) or the criteria for Very Persistent and Very Bioaccumulative (vPvB) in accordance with Annex XIII of 1907/2006/EC.

Conclusion for the P criterion

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

However, significant and substantial abiotic degradation by means of hydrolysis has been confirmed for both TDI substances. TDI is rapidly hydrolysed in aqueous solution, with a half-life of less than one minute (Yakabe, 1999).

The half-life obtained for TDI is much lower than the P(vP) criterion of t1/2> 40 (60) days. Therefore, TDI is not considered to be persistent in the environment and is identified as not potentially P.

Conclusion for the B criterion

Considering that the experimental log Kow of 2,4-TDI is 3.43 and a full bioaccumulation test with 2,4-TDI indicated that the bioaccumulation potential is low TDI is classified as not potentially bioaccumulating and is therefore identified as not potentially B.

Due to the fast hydrolysis, exposure of the environment to the substance is unlikely or very low. The theoretical hydrolysis product, TDA, measured only under special circumstances has, based on predicted BCF of < 50, no or a low bioaccumulation potential.

Conclusion for the T criterion

Both TDI substances are not classified as carcinogenic, mutagenic and reprotoxic according to Annex I of 67/548/EEC. Based on the effect concentrations determined in the aquatic toxicity tests with TDI, TDI does not fulfill the T criteria. The L(E)C50value for fish, Daphnia and algae are determined as > 0.1 mg/L and the NOEC value > 0.01 mg/l, therefore both TDI substances are indicated as not potentially T.

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