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The aquatic toxicity of NExBTL renewable diesel was tested using three aquatic organisms from different trophic levels (fish, crustancea and algae). Due to the poor water solubility of the substance, the organisms were exposed to a Water Accommodated Fraction (WAF) of the test substance which is a commonly accepted procedure for regulatory studies on poorly soluble substances. The loading rates used in these studies were 1000 mg/l for fish and 100 mg/l for crustancea and algae. In the experimental toxicity tests, no adverse effects were observed. In an acute test with sediment-dwelling amphipod, the LC50 value was 1200 mg/kg dry weight (d. w.), NOEC was 373 mg/kg d. w. and LOEC was 1165 mg/kg d. w.

Due to high lipophilicity of the substance (with log Kow 8.4), 98.2 % of it will migrate to sediment if it is continuously released in water at a constant rate (estimated using EQC Equilibrium Criterion Model 2.02). After a single spill, more than 99.9 % of the substance will be found in sediment at the equilibrium (calculated based on Koc = 3.78x103from Sabljic A et al, 1995). Furthermore, the substance was found to be readily biodegradable in a test carried out according OECD Guideline 301B (Ready biodegradability; CO2 Evolution Test). Therefore, the water phase will serve as a significant exposure route only in acute exposures. In chronic exposures, the concentration of the substance in water phase will be very low and the possible target organisms will be those living in sediment-water surface. Thus, chronic toxicity or bioconcentration testing using fish is not relevant.

REFERENCE:

Sabljic A, Güsten H, Verhaar H and Hermens J, 1995, QSAR modelling of soil sorption. Improvements and systematics of log Koc vs. log Kow correlations, Chemosphere 31, 4489-4514.

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