The state of Minnesota’s Department of Health (MDH) has initiated a toxicity review of trifluoroacetate (TFA), a by-product of certain f-gases, including the commonly used HFO-1234yf. It is one of the first such governmental reviews to take place in the U.S.
The MDH conducts a review of information on a chemical’s toxicity “to determine if a health-based guidance value for groundwater, air or other environmental media can be developed or updated,” says the agency on its website.
Trifluoroacetate is a negatively charged ion (or anion) created when trifluoroacetic acid (also abbreviated TFA) is absorbed in rain in the atmosphere, following the breakdown of fugitive f-gases. Trifluoroacetate salts, like sodium trifluoroacetate, can be formed on the ground. In any case, the toxicity of trifluoroacetate and trifluoroacetic acid would be virtually the same in small concentrations. (In this article TFA will henceforth refers to trifluoroacetic acid.)
TFA and its salts fall under Minnesota’s definition of PFAS (per- and polyfluoroalkyl substances), or forever chemicals, and are considered to be among the most widespread PFAS in the environment.
On April 9 MDH added trifluoroacetate to a list of several “chemicals under review,” as part of the Drinking Water Contaminants of Emerging Concern (CEC) program. Chemicals remain on this list at least 30 days from the date they are added. During that time, MDH invites interested parties to share via its email health.risk@state.mn.us information on toxicity studies related to these chemicals. Upon completion of review or re-evaluation, chemicals may be added to the Human Health-based Water Guidance Values Table.
Supported by Minnesota’s Clean Water Fund, the MDH’s CEC Initiative prioritizes chemicals that have been “found or are likely to be found in Minnesota drinking water and have little or no information available about human health risk,” says the MDH website. It covers contaminants and potential contaminants in groundwater, surface water or soil.
Given the ubiquity of pollutants like trifluoroacetate, the CEC Initiative shares findings about CECs with individuals and groups inside and outside of state government, says the MDH.
Two reviews
According to MDH, its reviews of chemicals consist of:
- An exposure review, documenting the typical uses of the chemical and where releases are likely to occur in coordination with the Minnesota Pollution Control Agency (MPCA), the Minnesota Department of Agriculture (MDA) and other parties with access to relevant information).
- A toxicological review, providing the most current information on the adverse health effects from exposure to the chemical.
Last year, the MDH completed a review of the two most widely known toxic PFAS, PFOA (perfluorooctanoate) and PFOS (perfluorooctaine sulfonate). TFA, an ultrashort-chain PFAS with two carbon atoms, is comparable in structure to eight-carbon PFOA.
Globally, there have been competing contentions about the potential toxicity of TFA. In its 2020 Assessment Report, the UN Environment Programme says TFA is “unlikely to cause adverse effects in terrestrial and aquatic organisms.” But TFA’s presence in human blood, studies of its effect on rats and rabbits and its continuous and growing presence in the environment have raised concerns about its long-term health impact.
A recent study characterized TFA as a “planetary boundary threat” given its presence in water bodies and soil around the world. In addition to f-gases, other precursors of TFA include pesticides, pharmaceuticals and other PFAS.
While the U.S. has not assessed the toxicity of TFA or set drinking water limits for it, some European countries have. For example, the German Environment Agency (Umweltbundesamt or UBA) has set a human health-based guideline value of 60mcg/L for TFA in drinking water and a “precautionary measure” of 10mcg/L. The Netherlands and Denmark also have precautionary thresholds for TFA in drinking water – 2.2mcg/L and 9mcg/L, respectively. In February, the Belgian village of Villers-le-Gambon announced that it was temporarily closing a mineral-water spring due to high levels of TFA.
Another recent study found that the cost of removing PFAS from the environment in Europe, including “emerging” PFAS like TFA, would be €100 billion ($108 billion) per year.
Amara’s Law
Minnesota, which passed one of the most aggressive PFAS laws in the U.S. in 2023, has been engaged in rulemaking to establish a process to determine whether PFAS refrigerants and other products are “essential” to avoid prohibition in 2032.
Known as “Amara’s Law,” the 2023 PFAS legislation was named in honor of Amara Strande, a young woman who advocated for the bill and spoke at the Minnesota Legislature in March 2023, a month before dying from cancer linked to PFAS exposure.
Parts of the law have already started to take effect. In 2032 bans on non-essential uses of PFAS in other new products, such as certain refrigerants and pesticides, will take place unless the use of the PFAS in the product is determined to be an essential and thus a “currently unavoidable use.”
Maine is another state that has taken a similarly proactive approach to PFAS, with plans to ban the sale of certain refrigerants, foams and aerosol propellants as well as cooling, heating, ventilation, air-conditioning and refrigeration equipment that contain “intentionally added PFAS” beginning in 2040. The California State Legislature has introduced a bill that would eventually prohibit the sale and distribution of products that contain intentionally added PFAS, including most f-gas uses, in 2033.
Minnesota, Maine, California and at least 20 other states define PFAS as “substances that include any member of the class of fluorinated organic chemicals containing at least one fully fluorinated carbon atom.” This definition, endorsed by more than 150 scientists, covers certain f-gases, including HFCs and HFOs, as well as TFA. The U.S. Environmental Protection Agency (EPA) has followed a definition of PFAS that excludes f-gases and TFA.
