A chemical produced when certain newer air-conditioning and refrigeration products break down is raising concerns among scientists after being detected in drinking water, rain and human blood.

Known as trifluoroacetic acid (TFA), the substance belongs to a group of chemicals called per- and polyfluoroalkyl substances (PFAS), often described as 'forever chemicals' because many persist in the environment for exceptionally long periods.

Although some newer refrigerants were introduced to reduce the environmental damage caused by older cooling chemicals, their breakdown products may create additional environmental concerns. Researchers are now examining how widespread TFA exposure has become and what prolonged contact could mean for human health.

TFA Has Been Found in Drinking Water and Blood

A 2025 study published in Environmental Science & Technology examined 119 archived blood serum samples from Wilmington, North Carolina, collected between 2010 and 2016. Researchers detected TFA in 77% of the samples, with a median concentration of 17 nanograms per millilitre.

The team also analysed drinking water samples collected in 2017, finding that TFA and another ultra-short-chain PFAS accounted for 95% of the quantifiable PFAS detected.

The findings suggest that exposure to these chemicals can be reflected in human blood, even when some compounds move through the body relatively quickly. However, the research examined a specific population with a history of contaminated drinking water and does not establish exposure levels across the wider population.

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How Do Cooling Chemicals Produce TFA?

Refrigerants are substances that transfer heat in air conditioners, refrigerators, and vehicle cooling systems. Their formulations have changed over several decades as scientists and regulators sought to address environmental risks.

Older chemicals contributed to ozone layer depletion, prompting international action under the 1987 Montreal Protocol. Hydrofluorocarbons later became common replacements because they did not damage the ozone layer in the same way, although they are potent greenhouse gases.

Newer alternatives, including HFO-1234yf, have a substantially lower global warming potential. However, when this refrigerant escapes into the atmosphere, it can break down into TFA.

The resulting chemical can return to the ground through rainfall and other forms of atmospheric deposition, eventually reaching rivers, lakes, soil, and drinking water.

What Could TFA Mean for Human Health?

Scientists have not established the full health consequences of long-term exposure to TFA. However, concerns are growing as evidence of its environmental persistence and widespread presence accumulates.

A 2024 review published in Environmental Science & Technology warned that continued releases could lead to increasing concentrations in environmental systems. It also highlighted findings from animal studies suggesting possible reproductive and liver toxicity.

In July 2026, the European Food Safety Authority (EFSA) published updated health-based guidance values after assessing evidence from 170 studies and position papers. Its assessment identified effects on development, reproduction and thyroid hormones in animal studies.

EFSA established an acceptable daily intake of 0.014 milligrams per kilogram of body weight per day, down from the previous value of 0.05 milligrams. These are precautionary benchmarks for assessing exposure, not evidence that ordinary contact causes illness.

Should You Be Worried?

The findings deserve attention, but they do not mean that everyone exposed to TFA will develop a health condition. Researchers still need more evidence to establish the risks associated with typical environmental exposure in humans.

Regulators are also beginning to respond. In July 2026, the US Environmental Protection Agency proposed including TFA among 30 unregulated contaminants that public water systems would monitor between 2028 and 2030. The proposal does not establish a legal drinking water limit for the chemical.

For now, the priority is better monitoring, research, and efforts to prevent refrigerant leaks and unnecessary chemical releases. The challenge is finding cooling technologies that protect the climate without creating another long-lasting environmental health problem.

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