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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The BCF was calculated to be 94.7 L/kg (regression-based estimate) and 6.54 L/kg (Arnot-Gobas method), respectively [with BCFBAF v3.01 (EPIWIN software by US-EPA)].

Key value for chemical safety assessment

BCF (aquatic species):
94.7 L/kg ww

Additional information

The prediction for the bioconcentration factor (BCF) of the substance tributyl citrate was done by the computer program BCFBAF v3.01 (EPIWIN software) made available by US-EPA. Furthermore the whole body primary biotransformation rate estimation for fish was calculated with the notation that the bio half-life normalized to 10 g fish at 15 °C. It is possible to predict the apparent metabolism half-life in fish for three different trophic levels (lower, mid and upper). Using the regression-based estimate (traditional method) a BCF of 94.7 L/kg wet-wt (LogBCF = 1.98) was calculated for tributyl citrate. Using the Arnot-Gobas method, which is based on mechanistic first principles, an aquatic BCF of 6.54 L/kg wet- wt (LogBCF = 0.82) is the result. Both values have been calculated based on an experimental LogPow of 3.5 [low potential for bioaccumulation according to Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP), as value is < 4]. Further, the whole body primary biotransformation rate estimate for fish results in a half-life of 0.00137 days, whereby the bio half-life is normalized to 10 g fish at 15 °C. The rate constant (kM) for 10 g fish is 50/day, whereby the predicted value exceeds theoretical whole body maximum value. This is taken into account to predict the apparent metabolism half-life in fish of tributyl citrate. With the Arnot-Gobas method it is possible to differentiate between three trophic levels. For the lower trophic level the BCF results in 9.263 L/kg wet-wt, for a mid trophic level the result is 8.55 L/kg wet-wt and for the higher trophic level 6.544 L/kg wet-wt. Based on the results, a low potential for bioconcentration is to be expected (according to CLP Regulation 1272/2008 substances with a BCF ≥ 500 have a potential for bioconcentration in aquatic organisms).