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Environmental fate & pathways

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In aqueous solution, the pH of the substance is naturally low and for testing under realistic environmentally conditions either the sodium salt (NaTFA) or pH adjustment were required.

The ready biodegradability was determined in the closed bottle test performed according to slightly modified OECD 301D, EEC 1984 Part C., and ISO Test Guidelines. Secondary activated sludge was inoculated into 10 bottles per serie containing Trifluoroacetic acid, sodium salt, sodium acetate (reference substance) or only the medium (as a control) under aerobic conditions for a prolonged period of 77 days because the pass level was not reached at day 28. The percentages biodegradation of Trifluoroacetic acid, sodium salt in the closed bottle test were 0% for 0, 7, 21, 28 and 77 days and 8% for 14 and 42 days. The result of 8% degradation at day 42 is probably an artefact due to the 40 % coefficient of variation between duplicate values of the control. The percentages biodegradation of sodium acetate in the closed bottle test was 83% at 28 days. The test substance caused no reduction in the endogenous respiration and therefore is considered to be non-inhibitory to the inoculum. Trifluoroacetic acid, sodium salt was not biodegraded in the closed bottle test and should therefore not be classified as readily biodegradable. Based on these results, an

inherent biodegradability test was conducted in compliance with the methods described in OECD test Guideline 302 A and EEC Directive 87/302 with some minors deviations. Because of the great potential for promoting biodegradation under aerobic conditions, the semi-continuous activated sludge (SCAS) test was chosen and Trifluoroacetic acid, sodium salt was exposed to relatively high concentrations of microorganisms maintained by daily addition of primary settled sewage. The test was conducted for a period of 127 days and the non-purgeable organic carbon (NPOC) was determined in the effluent. . The test compound caused no reduction of the biodegradation of the NPOC present in primary settled waste water, therefore Trifluoroacetic acid, sodium salt is considered to be non-inhibitory to the activated sludge. Trifluoroacetic acid, sodium salt was removed approximately 20% from the wastewater in the SCAS test. Biodegradation of Trifluoroacetic acid has to lead to the formation of fluoride that was not detected in the effluent of SCAS units. This result also demonstrates that Trifluoroacetic acid, sodium salt is not biodegraded.

Another test, not performed according to standardised guideline but with an acceptable scientific method, was conducted in order to assess the cometabolic transformation of Trifluoroacetic acid, sodium salt, by microorganisms present in various inocula for a period of 84 days. The biodegradation of this compound in the presence of various co-substrates (acetic acid, peptone, yeast extract and vitamin B12) was determined by measuring the formation of fluoride. The addition of various co-substrates did not initiate a cometabolic transformation of Trifluoroacetic acid, sodium salt. which was not biodegraded in the batch cultures.

Two other non standardized tests investigated further the biodegradability of TFA. Even if the methodology was scientifically acceptable, the report was not sufficiently documented to assess the reliability of the results. The first study evaluated the ability of aerobic bacteria, previously shown to have a broad range of degradative capabilities, to degrade trifluoroacetic acid (TFA). Nine different bacterial strains were tested in bottle assays for their dehalogenation analysis, using 14C TFA to test for production of 14CO2. This study failed to show degradation of TFA by all strains. The second test was conducted to assess its biodegradability in an engineered anaerobic reactor in a long-term (90 weeks) study . Trifluoroacetic acid was found to be cometabolically degradable in an anaerobic environment.

In conclusion, trifluoroacetic acid is not readily biodegradated in water and no biodegradation and cometabolic transformation by any of the microorganisms tested was observed under aerobic conditions. A not assignable study show that cometabolic degradation in anaerobic conditions can happen.

Biodegradation testing in soil and sediment was not conducted for TFA (according to column 2 of Annex IX of REACH), because direct and indirect exposure of soil and sediment is unlikely based on its low adsorption potential (log Kow = 0.79 and 6.8 < log Koc< 15 L/kg at 25°C).