Substances deployed to safeguard the ozone layer are now associated with an unforeseen ecological impact. Recent research indicates that these compounds have facilitated the global dispersal of substantial quantities of a durable and possibly dangerous forever chemical throughout the world.
A group of atmospheric scientists, spearheaded by experts from Lancaster University, has for the first time quantified the extent of this contamination on a planetary scale. Their detailed assessment reveals that replacement chemicals for chlorofluorocarbons (CFCs), combined with select anesthetic gases, have resulted in approximately 335,500 tonnes of trifluoroacetic acid (TFA) being released from the atmosphere and settling onto the Earth’s surface over the period from 2000 to 2022.
Pollution Levels Set to Keep Climbing
The investigation further cautions that this issue has not yet reached its zenith. Numerous CFC substitute chemicals linger in the atmosphere for many years, enabling TFA to persistently infiltrate the environment well beyond the initial release points. Experts project that the yearly output of TFA from these origins might attain peak values at some point between 2025 and 2100.
These revelations appear in the prestigious journal Geophysical Research Letters. The team employed chemical transport modeling techniques, which simulate the movement, chemical alteration, and ultimate deposition of substances from the atmosphere.
Mechanisms Behind TFA Formation from Refrigerants and Anesthetics
Through this methodology, the scientists determined the processes by which TFA emerges as specific gases degrade in the atmosphere. Key contributors include hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), prevalent in refrigeration units, as well as various inhalation anesthetics.
Even though these F-gases are undergoing phase-out as per the Montreal Protocol and the subsequent Kigali Amendment, their atmospheric concentrations are still on an upward trajectory overall.
TFA is part of the extensive category of per- and polyfluorinated alkyl substances (PFAS), notorious as forever chemicals due to their remarkable resistance to degradation and their ability to endure in ecosystems for extraordinarily extended durations.
Ongoing Debates on Environmental and Health Impacts
Researchers continue to deepen their knowledge of TFA’s prospective consequences. The European Chemicals Agency deems TFA detrimental to aquatic organisms. It has been identified in human bloodstreams and urine samples, prompting the German Federal Office for Chemicals to suggest categorizing it as a potential reproductive toxin for humans.
Certain regulatory authorities maintain that present TFA concentrations in the environment fall below levels anticipated to pose risks to human health. Nevertheless, apprehension is mounting regarding its continuous and possibly permanent accumulation, fueling demands to regard TFA as a threat to planetary boundaries.
“Our research demonstrates that substitutes for CFCs are probably the primary atmospheric contributor to TFA,” stated Lucy Hart, a PhD candidate at Lancaster University and the study’s principal author. “This underscores the extensive hazards that regulators must evaluate when replacing deleterious substances like ozone-depleting CFCs.”
Aligning Simulations with Empirical Observations
To corroborate their projections, the team cross-referenced their modeled TFA generation and deposition figures against actual field data. This encompassed analyses from Arctic ice cores and precipitation samples gathered from diverse global sites.
The simulation incorporated data on emission volumes and sites from an international monitoring system. As these gases react with atmospheric elements, they undergo breakdown, yielding TFA.
Meteorological dynamics were integrated into the models to illustrate TFA’s transport and settling patterns. The compound can be scavenged from clouds via precipitation or directly deposited from the air onto terrestrial and aquatic surfaces.
Arctic Ice Cores Expose Planetary Dispersion
The outcomes indicate that almost every trace of TFA in the Arctic originates from CFC replacement chemicals, despite the area’s remoteness from primary emission hotspots. This revelation emphasizes the extensive global dissemination of TFA contamination.
“Replacement chemicals for CFCs possess extended atmospheric lifespans, permitting transport from emission sites to distant locales like the Arctic, where they degrade into TFA,” explained Lucy Hart. “Research has documented rising TFA concentrations in remote Arctic ice cores, and our findings offer the inaugural definitive proof that nearly all such accumulations stem from these gases.”
Emerging Refrigerants Introduce Future Risks
Beyond polar zones, the research identifies other worrisome contributors. In mid-latitude areas, the models corroborate accumulating indications that HFO-1234yf, a staple in automotive air conditioning, is evolving into a significant and potentially growing generator of atmospheric TFA.
“HFOs represent the newest generation of engineered refrigerants promoted as eco-conscious substitutes for HFCs,” noted Professor Ryan Hossaini from Lancaster University, a co-author on the paper. “Several HFO variants are recognized TFA producers, and their expanding deployment in vehicle air conditioning across Europe and beyond introduces unpredictability to prospective TFA concentrations in our surroundings.”
“Addressing environmental TFA contamination is essential, given its ubiquity, extreme persistence, and escalating levels,” Professor Hossaini emphasized.
Urgent Push for Worldwide Surveillance and Response
“The escalating TFA concentrations from F-gases is remarkable. While HFC deployment is slowly diminishing, this TFA pathway will linger for decades. We urgently require insights into additional TFA origins and a thorough evaluation of its ecological repercussions. This demands a unified global initiative, encompassing broader TFA surveillance in the UK and other nations,” he added.
Professor Cris Halsall, who directs the Lancaster Environment Centre and served as a co-author, highlighted that TFA’s provenance is more diverse than previously assumed.
“Traditionally, we’ve considered TFA mainly as a degradation product from certain fluorinated pesticides, but evidently, this highly enduring environmental chemical derives from a broad spectrum of organofluorine compounds, encompassing refrigerants, solvents, pharmaceuticals, and the PFAS family at large.”
Dr. Stefan Reimann, a co-author whose Swiss-based team meticulously monitors TFA-forming F-gases atmospherically, affirmed the universal pattern.
“Across all areas with TFA data, a uniform trend of rising atmospheric levels and surface depositions is apparent,” he observed.
“This research stands out by integrating, for the first time, all major atmospheric TFA sources with a worldwide perspective. As HFO usage proliferates, TFA buildup in aquatic systems could intensify, rendering sustained monitoring imperative.”
The comprehensive results are outlined in the publication titled ‘Growth in production and environmental deposition of trifluoroacetic acid due to long-lived CFC replacements and anesthetics’.
Collaborators hailed from institutions including Lancaster University, the University of Leeds, the University of Urbino, Australia’s Commonwealth Scientific and Industrial Research Organisation, the Norwegian Institute for Air Research, the University of California San Diego, the University of Bristol, Kyungpook National University in Korea, the Swiss Federal Laboratories for Materials Science and Technology, and Goethe University Frankfurt.
