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Environmental fate & pathways

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Three reliable experimental data from standard studies were available for the biodegradation of the test substance. One closed bottle test showing up to 43% of biodegradation after 140 days of a prolonged experimental phase (Ginkel, 1993) and two CO2 evolution tests showing after 28 days, 27.8% of biodegradation (Coenen, 1991) and 64% of biodegradation (Mead, 2000). From the two last studies there was evidence of low bioavailability due to the poor solubility of the substance. Accordingly, Mead (2000) designed the study following recommended guidance on poorly soluble materials using silica gel to enhance bioavailability of the substance. Finally, it is concluded the substance can be considered as ready biodegradable but failing the 10-day window criterion, criterion although this may be related to bioavailabiltiy issues rather than inherent biodegradable properties of this substance.

The substance exerts a very high hydrophobicity (log Kow of 8) so bioaccumaulation may be expected. Moreover, in anin vitrobiotransformation study metabolism by hepatocytes was not observed although it is not clear whether this was due to the bioavailability of th substance and non-bioaccumulation cannot be concluded from this study. Estimations using well-known QSARs (BCFBAF v3.00) conclude on the non-bioaccumulative property of the substance according to Melyan et al. (1995) or Arnot-Gobas (2008) biotransformation rates in Fish. A BCF study on fish is currently a technical challengedue to the extremely low water solubility of the substance which cannot yet be measured at its aqueous solubility limit.

The substance is expected to adsorb strongly to sediment and soils with a Koc = 1.70x105as determined in a reliable standard test using the HPLC method (Vos, 2010).According to estimation from a level III fugacity model , the distribution of the substance will be 0.042% in the air compartment, 12.3% in the water compartment, 63.6% in the soil and 24.1% in the sediment for a overall persistent time of 1038 h.