Trifluoroacetic acid

Endpoint summary

Additional information

MONITORING DATA

Several monitoring studies of good quality report widespreaded TFA concentrations in several environmental matrix including air, freshwaters and marine waters all around the world and tend to establish its sources. Four studies, two in peer reviewed journals and two study reports presented results relevant for the European area. Three other published studies report TFA concentrations in North America and in China that support the European data's.

Concentrations

Analytical techniques for TFA have relied primarily on GC-based methods and involved derivatization. Each of these methods has been successfully employed in the analysis of TFA in environmentally diverse matrices and at various concentrations. For example, TFA has been measured in samples of rainwater(< 0.2-850 ng/L), surface waters (<0.2-280 ng/L), fog condensate (2154 ng/L), drinking water (<0.2-450 ng/L) and air (<3.3-3230 ng/L).

TFA concentration have been determined regularly in air, precipitation, and surface waters in Bayreuth from March 1995 until Septembre 1996. In addition, isolated samples have been taken at various locations in Germany, Europe and on other continents during the same period. The average concentration of TFA in air samples taken near Bayreuth is 50 pg/m3, in rain water 100 ng/L, and in river water 140 ng/L. Waters from ground sources contain TFA in concentrations similar to those of precipitation in Germany while in mineral waters concentrations are markedly lower (in three waters older than 200 years, TFA did not exceed blank levels). In water samples from other continents (South Africa, Australia, Brasil, Israel, Siberia) concentrations ranged from 20 to 500 ng/l and in two samples, TFA could not be detected. Ocean waters contained 40 ng/L (Baltic Sea), 90 ng/L (North Sea), 160 ng/L (South Atlantic, Cape of Good Hope), and 250 ng/L (North Atlantic, French Coast). In one study, TFA levels in Atlantic and Antarctic Ocean waters were almost all about 200 ng/L rank and independent of depth. In another study, the reported values for ocean waters ranged from < 10 ng/L in the Pacific Ocean to greater than 150 ng/L in the Atlantic Ocean. Sampling at low depth (up to 700 -800 m) exhibited variable TFA concentrations but below this depth, in water having 14C ages exceeding 1000 years, the TFA concentrations were constant (150 ng/L). TFA concentrations in Mediterranean Sea were between 0.5 and 50 ng/L.

Supporting data were obtained in 1994-1996 from several locations in California and Nevada. Fog and rain samples contained 31 -3779 ng/L TFA. Snow samples taken in more remote areas had 51-584 ng/L. Surface water varied from 55 ng/L - 41 µg/L depending on type and location. Washout of TFA from the lower atmosphere was observed in both rain and fog samples.

Haloacetic acid (HAA) concentrations were measured in air samples from a semi-rural and a highly urbanized site in southern Ontario throughout 2000 to investigate their sources and gas-particle partitioning behavior. Total HAA concentrations (i.e., gas + particles) ranged between < 0.025 and 19 ng/m3 for individual HAAs (TFA, DFA, MFA and TCA) at both sites. A simple deposition model indicated that precipitation concentrations can be successfully predicted by the Henry's law constant. Results from nine provinces and autonomous regions in China indicate that the concentrations of TFA through the period from 2000 to 2001 in nine rainfalls and three snowfalls ranged from 25 to 220 ng/L, in the inland surface water samples ranged from 4.7 to 221 ng/L, in groundwater samples was 10 ng/L and in coastal water samples ranged from 4.2 to 190.1 ng/L.

Sources

Known sources of TFA include the termolysis of perfluorinated chemicals, the atmospheric oxidation of hydrochlorofluorocarbons and hydrofluorocarbons and fluorotelomer alcohols. Industrial and consumer applications are the primary source of emissions of the higher perfluoro acids while TFA results primarily from both the atmospheric degradation of CFC replacements and from the degradation of fluoropolymers in high temperature applications. For some authors, TFA has only recently entered the environment and arises from anthropogenic sources. The pattern of high TFA concentration values observed in industrialized countries of Europe, coupled with very low concentrations near blank values found in remote regions suggests that a significant part of TFA is produced from precursor molecules with lifetimes of less than two weeks. A much uniform distribution would occur if the precursor molecules were HCFC's, HFC's, HBFC's having lifetimes ranging from 1 -20 years. TFA measurements taken in Germany, Switzerland and Israël suggest that the level of TFA found in rainwater and/or in fresh and salt waters bodies are at least of 10 greater than predicted based on known sources and that TFA-release has started to take place some decades ago. All this information suggests that there are unknown sources of TFA.

However, in an other study investigating possible natural sources of TFA, profiles were taken over three vents in the Pacific and Mediterranean Oceans and the results suggest that some deep-sea vents may be natural sources of TFA. Further, the determination of TFA in ocean waters of known age was performed and TFA levels in Atlantic and Antarctic Ocean water were almost all about 200 ng/L, independent of depth. Therefore, TFA is present in the global environment in quantities exceeding what can be explained by industrial processes and/or chemicals hitherto considered, and is far more than may be expected from a few years of HFC production. This assumption is supported by the magnitude of TFA levels measured in North America indicating that formation in the environment from HCFC and HFC degradation is occurring more rapidly than expected, or that alternate sources of TFA exist. However, whether anthropogenic processes sush as combustion of fossil fuels have contributed to the present-day levels, or whether natural geogenic or biogenic processes are also involved remains to be clarified.

FIELD STUDIES

Three field studies published in peer review journals and of good quality are also available for TFA. One study invastigated the degradation of TFA in field aquatic microcosms and laboratory sediment water systems from Canada. Trifluoroacetic acid was extremely persistent and showed no degradation during one-year field studies and 2880h in laboratory microsoms. In the two others studies TFA was added experimentally to upland and wetland forest. More than 70% of the added TFA was exported from the upland forest in drainage water while the reminder was retained in the surface organic soil (10-20%) and vegetation (5-20%). In contrast, probably <5% of the added TFA flowed out of the forest wetland in drainage water. Considerable TFA was retained in the forest wetland soil (20 -60%) and vegetation (20-50%).