Trifluoroacetic acid / TFA
The molecule that fell as rain.
Trifluoroacetic acid can begin as another chemical, form in the atmosphere, fall with rain, enter water, and emerge years later as a regulatory object.
CAS 76-05-1EC 200-929-3Ultrashort-chain PFAS
FOLLOW THE EVIDENCE ↓THE REGULATORY LIFE OF ONE MOLECULE
TFA is interesting because its identity stays fixed while the way institutions encounter it keeps changing: model output, rain, runoff, analytical target, evidence question, legal substance.
01 / 06EUROPE15 JUN 2026
MODELLED SCIENCE
It began as something else.
TFA can form when fluorinated gases degrade in the atmosphere. A 2026 study modelled HFO-1234yf, a replacement refrigerant, as a larger contributor to European TFA generation and deposition than HFC-134a.
HFO-1234yfCAS 754-12-1Replacement refrigerant modelled as an atmospheric TFA precursor
HFC-134aCAS 811-97-2Older refrigerant used as the model comparator
HFO-1234yfMODELLED AS THE DOMINANT EUROPEAN CONTRIBUTOR OF THE TWO GASES
This is a model of formation and deposition using emissions data. It is not a map of measured TFA at every location.
02 / 06ATMOSPHERE → WATER2026 MODEL
MODELLED DEPOSITION
Then the molecule became weather.
In the same atmospheric model, wet deposition was the main route back to the surface. TFA moved out of the air through rain and into the water cycle.
88–92%OF TOTAL TFA DEPOSITION WAS WET DEPOSITION IN THE MODEL
The percentage describes deposition within this model. It is not a global observation or a health threshold.
03 / 06SKUTERUD, NORWAYMAR 2025–MAR 2026
FIELD STUDY
A field made the movement measurable.
NIBIO followed TFA in 23 stream samples from one agricultural catchment. The largest losses coincided with major autumn runoff events.
1,083 ng/LMEAN TFA CONCENTRATION ACROSS 23 STREAM SAMPLES
3.3 kgESTIMATED TFA LOSS FROM THE CATCHMENT OVER ONE YEAR
This is one catchment. The result is site-specific, and source attribution should not be generalised to agricultural systems everywhere.
04 / 06UNITED STATESJAN–JUL 2026
OFFICIAL METHOD + PROPOSED MONITORING
The molecule acquired an official method.
EPA Method 563 covers TFA and six other ultrashort organofluorine compounds in drinking water. EPA also proposed TFA for nationwide UCMR 6 monitoring between 2028 and 2030.
18 ng/LSINGLE-LABORATORY LCMRL REPORTED FOR TFA IN METHOD 563
200 ng/LPROPOSED UCMR 6 MINIMUM REPORTING LEVEL FOR TFA
Analytical reporting and confirmation levels describe what a method can measure. They are not health-based limits.
05 / 06WHO / EUROPEAN UNION2026 → 2027
ASSESSMENT REVIEW + ADOPTED EXPERT OPINION
Evidence became a regulatory question.
WHO prioritised TFA among 18 PFAS for evidence collection ahead of planned 2027 normative-value evaluations. In Europe, ECHA records an adopted Risk Assessment Committee opinion in the harmonised classification process.
18 PFASPRIORITISED BY WHO FOR TOXICOLOGY AND WATER-CYCLE EVIDENCE
2027TARGET YEAR FOR WHO NORMATIVE-VALUE EVALUATIONS
WHO has not yet established the planned values. An adopted RAC opinion is an expert milestone; the European Commission still decides whether and how to update the legal classification.
06 / 06FRANCEFROM 01 SEP 2026
BINDING LAW
In France, TFA entered binding law.
Decree No. 2026-545 names TFA in the substances covered by France's PFAS water-pollution charge and applies to discharges from September 2026.
2 kg/yearCOMBINED LISTED-PFAS THRESHOLD FOR THE SELF-MONITORING ROUTE
The charge concerns the combined mass of listed PFAS in discharged water. It is not a general ban on TFA.
HOW TO READ THE EVIDENCE
The status changes. The identity does not.
MODELLEDAtmospheric formation and wet deposition.
MEASUREDOne Norwegian catchment and an official US analytical method.
UNDER REVIEWWHO evidence collection and an adopted ECHA expert opinion.
BINDINGFrance's PFAS water-pollution charge from September 2026.
This visual experiment follows public evidence. It does not claim that one observed molecule completed this exact journey, and it is not compliance advice.