Toxicity of Trifluoroacetate to Aquatic Organisms

Abstract

As a result of the atmospheric degradation of several hydrofluorocarbons and hydrochlorofluorocarbons, trifluoroacetate (TFA) will be formed. Through precipitation, TFA will enter aquatic ecosystems. To evaluate the impact on the aquatic environment, an aquatic toxicity testing program was carried out with sodium trifluoroacetate (NaTFA). During acute toxicity tests, no effects of NaTFA on water fleas (Daphnia magna) and zebra fish (Danio rerio) were found at a concentration of 1,200 mg/L. A 7-d study with duckweed (Lemna gibba G3) revealed a NOEC of 300 mg/L. On the basis of the results of five toxicity tests with Selenastrum capricornutum, we determined a NOEC of 0.12 mg/L. However, algal toxicity tests with NaTFA and Chlorella vulgaris, Scenedesmus subspicatus, Chlamydomonas reinhardtii, Dunaliella tertiolecta, Euglena gracilis, Phaeodactylum tricornutum, Navicula pelliculosa, Skeletonema costatum, Anabaena flos-aquae, and Microcystis aeruginosa resulted in EC50 values that were all higher than 100 mg/L. The toxicity of TFA to S. capricornutum could be due to metabolic defluorination to monofluoroacetate (MFA), which is known to inhibit the citric acid cycle. A toxicity test with MFA and S. capricornutum revealed it to be about three orders of magnitude more toxic than TFA. However, a bioactivation study revealed that defluorination of TFA was less than 4%. On the other hand, S. capricornutum exposed to a toxic concentration of NaTFA showed a recovery of growth when citric acid was added, suggesting that TFA (or a metabolite of TFA) interferes with the citric acid cycle. A recovery of the growth of S. capricornutum was also found when TFA was removed from the test solutions. Therefore, TFA should be considered algistatic and not algicidic for S. capricornutum. On the basis of the combined results of the laboratory tests and a previously reported semi-field study, we can consider a TFA concentration of 0.10 mg/L as safe for the aquatic ecosystem.

Characterization and evaluation of the hydrolytic stability of trifluoroacetylated cellulose fibers

“…It is important to underline that even in the case of high surface modification, the quantities of trifluoroacetic acid released during hydrolysis in these applications would be minimal and harmless, once rapidly converted into one of its salts [29].…”

Thermolysis of fluoropolymers as a potential source of halogenated organic acids in the environment

“…Following the introduction of hydrochloro¯uorocarbon (HCFCs) and hydro¯uorocarbon (HFCs) gases as replacements for the ozone-destroying chloro¯uorocarbons (CFCs), it has been discovered that HCFCs/HFCs can degrade in the atmosphere to produce tri¯uoroacetic acid 1 , a compound with no known loss mechanisms in the environment 2,3 , and higher concentrations in natural waters 4 have been shown to be mildly phytotoxic 5 . Present environmental levels of tri¯uooracetic acid are not accounted by HCFC/HFC degradation alone 8±10 .…”

Cleaving Carbon-Carbon Bonds by the Release of Trifluoroacetate to Remodel Molecules and Assemble Fluorinated Structures

“…24 monofluoroacetate and difluoroacetate are highly toxic, the inert nature of trifluoroacetate prevents any defluorination, and it is remarkably resistant to metabolism in microorganisms, 25 plants, animals, environmental decomposition, or photochemical breakdown. 26 Indeed, trifluoroacetate is nontoxic to aquatic organisms and algae, 27 microorganisms, 25 plants, animals, and humans. 26 Therefore, a chemical process that generates trifluoroacetate does not pose significant environmental or health risks.…”