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Environmental fate & pathways

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The bioaccumulation factor (BCF) for fish was calculated using QSAR based software approaches. The QSAR model used by Episuite (Epiweb 4.0) is based on correlations between BCF and chemical hydrophobicity (as modelled by log KOW).The Caesar BCF model is based on a dataset of 473 compounds with experimentally determined BCF values. The final model is a Neural Network based on 8 molecular descriptors.

For the test substance, a log KOW of 4.78 was determined experimentally. Using this value, Episuite [BCFBAF (v3.00)] calculated a BCF value of 662 L/kg body weight (BCFBAF 2010). In contrast, using the Caesar QSAR model software a BCF value 28 L/kg body weight was obtained (Caesar 2010).

In conclusion, the two QSAR approaches provided striking differences in the calculated BCF values associated with low to moderate bioaccumulation properties.