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In the absence of experimental data, a BCF was calculated based on the measured log Kow using a QSAR model and the equation set out in the Technical Guidance Document. The BCFs were calculated to be 925 and 3548 respectively, using a log Kow value of 5.

The screening criterion for bioaccumulation in the PBT assessment is that a substance with a log Kow of =4.5 is not B or vB. 2,4,4-trimethylpentene has a measured log Kow of 5.0 and therefore based only on the log Kow, 2,4,4-trimethylpentene meets the B/vB screening criteria. However, the BCF calculated on the basis of the log Kow is 925 (EPISuite v.4.0) and on the TGD recommended QSAR for BCF the calculated BCF is 3548 (Veith et al. 1979). The predictions from the models clearly indicate that while 2,4,4-trimethylpentene can be considered a potential B, it would not be a vB.