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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

bioaccumulation in aquatic species: fish OECD 305 - Key study, reliability K1;

in vitro trout hepatocites - Supporting study, reliability K2;

Key value for chemical safety assessment

BCF (aquatic species):
8 dimensionless

Additional information

Based on the measured concentration in the test media and fish tissues, the steady state bioconcentration factors (BCFSS) at the end of the 36 day uptake phase for whole fish tissue were 8, 7, 2, 1 and 1 for the 0.010, 0.10, 1.0, 10 and 100 μg/L test concentrations, respectively. After 28 days depuration, a decline in measured concentration in the fish tissues when the fish were transferred to clean water to levels close to the limit of quantification (LOQ, 0.1 μg/kg) of the analytical method.

Analytical difficulties were encountered in this study due to the low exposure concentrations and wide dosing range. Due to prospective planning for a scenario of tissue bioaccumulation, the range of the analytical assays necessitated a high upper limit of quantification (ULOQ) level (x10,000 LOQ). This large range and low exposure concentration resulted in significant risk of contamination occurring, either during extraction or at instrument analysis, and in chromatographic difficulties of peak sensitivity at the lowest concentrations monitored.

High oil content of fish tissue and emulsion formation within the extraction procedure versus required extraction recovery of test substance led to robustness issues with chromatographic column resolution and resultant assay sensitivity. Data at the lowest concentration levels was therefore negatively affected as evidenced by the supporting analytical chemistry results.

The results showed that the test substance has a very limited bioaccumulation potential (BCF < 10) between concentrations of 0.010 and 100 μg/L.

Based on the results of the in vitro trout hepatocyte study, it suggest the test substance is not metabolized by fish, the high water solubility and low Koc of the test substance indicate it is unlikely to be a concern for aquatic bioaccumulation. This supports the findings of the test of bioaccumulation in aquatic fish.