In a new report on per- and polyfluoroalkyl substances (PFAS), the U.K.’s Health and Safety Executive (HSE) has identified trifluoroacetic acid (TFA), a degradation product of certain f-gas refrigerants, as being “a concern for developmental toxicity” requiring further scrutiny.
HSE is responsible for the registration, evaluation, authorization and restriction of chemicals (REACH) regulation in the U.K. In the report – titled “Analysis of the most appropriate regulatory management options (RMOA)” – HSE collaborated with the U.K. Environment Agency to examine the risks posed by PFAS, also known as “forever chemicals” for their persistence in nature, and develop potential regulatory solutions.
HSE’s report parallels a new review of PFAS launched in February by the EU’s European Chemical Agency (ECHA). Like ECHA, HSE employs a definition of PFAS that includes certain f-gas refrigerants and TFA, which is produced in the atmosphere by the breakdown of refrigerants HFO-1234yf (100%) and HFC-134a (up to 20%). TFA descends to Earth in rainfall, infiltrating land masses and waterways.
While its health effect is not yet certain, “TFA has been identified as a concern for developmental toxicity,” says the report, adding that certain HFCs and HFOs, which are “commercially significant in the U.K.,” may “transform to TFA.” As a result, TFA is regarded as needing “further evaluation and investigation.”
The report says that the greatest volume of PFAS potentially available in the Great Britain market arise from a limited number of groups, including polyfluoroalkyl substances such as refrigerant gases, fire-fighting foams and cleaning agents.
Monitoring undertaken by the U.K. Environment Agency since 2014 suggests some PFAS are detectable in “most groundwater, surface water bodies and biota” in the U.K., the report says. Of these, short-chain PFAS, which include refrigerants and TFA, “are the most mobile, likely to be present in water compartments and have greater potential to bioaccumulate in air-breathing organisms.” Drinking water can provide a ”dominant pathway” for exposure to PFAS.
The report cited a “developmental toxicity study” indicating that TFA and other short-chain PFCAs “might cause rare abnormalities in rabbit offspring.”
According to the HSE News Desk, information on the study was “provided by the registrants of trifluoroacetic acid in their EU REACH registration dossier.” This was made public In the substance’s brief profile published on ECHA’s website in a note on developmental toxicity: “Adverse effect observed LOAEL [lowest-observed-adverse-effect-level] 180 mg/kg bw [body weight]/day (subacute [the systemic effect of repeated doses of materials or their extracts for no less than 24 hours and no greater than 10% of the total lifespan of the test animal], rabbit)”
In the Annex to its RMOA, HSE provide additional information about the nature of the observations in the study, sourcing the ECHA website:
“Sodium trifluoroacetic acid (gavage [the administration of food or drugs by force, especially to an animal, typically through a tube leading down the throat to the stomach]): Increased incidence of abnormalities, predominantly affecting the eyes and multiple cervical / thoracic / lumbar / caudal vertebral and rib abnormalities at 375 and 750 mg/kg/. At 180 mg/kg/day (lowest dose tested), identical malformations involving the eye were observed but at lower incidence which were within the range of historical control data. Since higher incidences of foetuses had these extremely rare eye abnormalities at higher doses a relationship to treatment could not be ruled out. Registrants identified a NOAEL of < 180 mg/kg bw/day, since changes in foetal/pup body weight occurred at this dose.”
“We do not have access to the study report but understand it to have been commissioned by the registrants themselves,” said HSE. HSE did not name the registrants.
The Precautionary Principle
Assessing the potential impact of PFAS, the report notes that PFAS will persist in the environment for long periods of time “with a potential to cause serious and irreversible damage.” However, it acknowledged that “there remains uncertainty on the human health hazards of the majority of PFAS due to a lack of available data and limited understanding of long-term exposure.”
Thus the agency concludes that “it would be appropriate, considering the Precautionary Principle,” to initiate a series of steps, including
- Preparation of Annex XV dossiers to potentially support one or more restrictions of PFAS under U.K. REACH.
- Further evaluation and investigation of substances that have been highlighted to be of concern, including TFA, EEA-NH4, perfluoroalkanes and perfluorocycloalkanes.
- Continued collaborative work across government and with external stakeholders to bring together work on PFAS strategically, including a review of the F-gas regulations to determine whether additional PFAS registered under U.K. REACH should be brought within scope; and development of statutory standards for PFAS in drinking water in England and Wales.
Commenting on the report, Clare Perry, Climate Campaign Leader for the Environmental Investigation Agency (EIA), a London-based NGO, said, “The potential impacts of TFA and other PFAS on human health and the environment are of growing concern and add to the multiple reasons why the cooling industry needs to move rapidly away from fluorochemical refrigerants and invest in sustainable climate- and environmentally friendly natural refrigerants.”
The chemical industry addressed the environmental deposition of TFA in an October 2021 study funded by the Global Forum for Advanced Climate Technologies (globalFACT), which represents f-gas producers Chemours, Honeywell, Arkema and Koura (and equipment manufacturer Daikin). The study concluded that “with the current knowledge of the effects of TFA on humans and ecosystems, the projected emissions through 2040 would not be detrimental.” But the study also acknowledged that “the major uncertainty in the knowledge of the TFA concentrations and their spatial distributions is due to uncertainties in the future projected emissions.”
“The potential impacts of TFA and other PFAS on human health and the environment are of growing concern and add to the multiple reasons why the cooling industry needs to move rapidly away from fluorochemical refrigerants and invest in sustainable climate- and environmentally friendly natural refrigerants.”Clare Perry, Climate Campaign Leader for the Environmental Investigation Agency