Formation of trifluoroacetic acid from the atmospheric degradation of hydrofluorocarbon 134a: a human health concern?

The wide presence of fluorinated compounds in common chemical products and the environment: a review

The C-F bonds, due to their many unique features, have been incorporated into numerous compounds in countless products and applications. These fluorinated compounds eventually are disposed of and released into the environment through different pathways. In this review, we analyzed the occurrence of these fluorinated compounds in seven types of products (i.e., refrigerants/propellants, aqueous film-forming foam, cosmetics, food packaging, agrochemicals, pharmaceuticals, coating materials) and discussed their fate in the environment. This is followed by describing the quantity of fluorinated compounds from each source based on available data. Total on- and off-site disposal or other releases of 536 fluorinated compounds in 2021 were analyzed using the data sourced from the U.S. EPA Toxics Release Inventory (TRI). Among the chemicals examined, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were the primary contributors in terms of total mass. Upon examining the seven sources of fluorinated compounds, it became evident that additional contributors are also responsible for the presence of organofluorine compounds in the environment. Although various toxic degradation products of fluorinated compounds could form in the environment, trifluoroacetic acid (TFA) was specifically highlighted in this review given the fact that it is a common dead-end degradation product of > 1 million chemicals. This paper ended with a discussion of several questions raised from this study. The path forward was elaborated as well for the purpose of protecting the environment and human health.

Mammalian toxicity of trifluoroacetate and assessment of human health risks due to environmental exposures

While trifluoroacetic acid has limited technical uses, the highly water-soluble trifluoroacetate (TFA) is reported to be present in water bodies at low concentrations. Most of the TFA in the environment is discussed to arise from natural processes, but also with the contribution from decomposition of environmental chemicals. The presence of TFA may result in human exposures. For hazard and risk assessment, the mammalian toxicity of TFA and human exposures are reviewed to assess the margin of exposures (MoE). The potential of TFA to induce acute toxicity is very low and oral repeated dose studies in rats have identified the liver as the target organ with mild liver hypertrophy as the lead effect. Biomarker analyses indicate that TFA is a weak peroxisome proliferator in rats. TFA administered to rats did not induce adverse effects in an extended one-generation study and in a developmental toxicity study or induce genotoxic responses. Based on recent levels of TFA in water and diet, MoEs for human exposures to TFA are well above 100 and do not indicate health risks.

Targeted and Suspect Screening of Per- and Polyfluoroalkyl Substances in Cosmetics and Personal Care Products

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals reported in cosmetics and personal care products as ingredients, possible impurities in the raw material manufacturing process, or degradation products. The purpose of this study was to further delineate contributions of these varying PFAS sources to these products. Thirty-eight cosmetics and personal care products were selected and analyzed for polyfluoroalkyl phosphates (PAPs), perfluoroalkyl carboxylic acids (PFCAs), fluorotelomer sulfonic acids (FTSAs), and perfluoroalkyl sulfonic acids (PFSAs) using targeted liquid chromatography tandem mass spectrometry (LC-MS/MS). A subset of products was also subjected to suspect screening using LC-high resolution mass spectrometry (HRMS) for >200 compounds. Results of LC-MS/MS and LC-HRMS indicated a predominant and ubiquitous presence of PAPs (detection frequency 99.7%, mean and median ΣPAPs 1 080 000 and 299 ng/g). Total median PFCA and PFSA concentrations were 3 and 38 times lower, respectively. There were significant correlations (Spearman's correlation coefficients = 0.60-0.81, p < 0.05) between 6:2 PAPs and their biotransformation products. Low levels of other PFAS classes were detected, including those previously measured in wastewater and human blood (e.g., hydrido-PFCAs), and five compounds associated with aqueous film-forming foams. Overall, these data highlight that cosmetics and personal care products can contain a breadth of PFAS at extremely high levels, leading to human and environmental exposure.

The concept of essential use for determining when uses of PFASs can be phased out

Because of the extreme persistence of per- and polyfluoroalkyl substances (PFASs) and their associated risks, the Madrid Statement argues for stopping their use where they are deemed not essential or when safer alternatives exist. To determine when uses of PFASs have an essential function in modern society, and when they do not, is not an easy task. Here, we: (1) develop the concept of "essential use" based on an existing approach described in the Montreal Protocol, (2) apply the concept to various uses of PFASs to determine the feasibility of elimination or substitution of PFASs in each use category, and (3) outline the challenges for phasing out uses of PFASs in society. In brief, we developed three distinct categories to describe the different levels of essentiality of individual uses. A phase-out of many uses of PFASs can be implemented because they are not necessary for the betterment of society in terms of health and safety, or because functional alternatives are currently available that can be substituted into these products or applications. Some specific uses of PFASs would be considered essential because they provide for vital functions and are currently without established alternatives. However, this essentiality should not be considered as permanent; rather, constant efforts are needed to search for alternatives. We provide a description of several ongoing uses of PFASs and discuss whether these uses are essential or non-essential according to the three essentiality categories. It is not possible to describe each use case of PFASs in detail in this single article. For follow-up work, we suggest further refining the assessment of the use cases of PFASs covered here, where necessary, and expanding the application of this concept to all other uses of PFASs. The concept of essential use can also be applied in the management of other chemicals, or groups of chemicals, of concern.

Transport and fate of trifluoroacetate in upland forest and wetland ecosystems

Although trifluoroacetate (TFA), a breakdown product of chlorofluorocarbon replacements, is being dispersed widely within the biosphere, its ecological fate is largely unknown. TFA was added experimentally to an upland, northern hardwood forest and to a small forest wetland ecosystem within the Hubbard Brook Experimental Forest in New Hampshire. Inputs of TFA were not transported conservatively through these ecosystems; instead, significant amounts of TFA were retained within the vegetation and soil compartments. More TFA was retained by the wetland ecosystem than by the upland forest ecosystem. Using simulation modeling, TFA concentrations were predicted for soil and drainage water until the year 2040.