PFAS pesticide sales in Denmark have increased despite concerns that one of the substances still authorised for agricultural use may break down into TFA, a highly persistent chemical found in Danish groundwater. The Danish Environmental Protection Agency (Miljøstyrelsen) has now funded new research into five active substances and the government says it could consider bans if the suspected link to drinking-water contamination is confirmed.
Sales of lambda-cyhalothrin have increased since 2015
The main substance under scrutiny is lambda-cyhalothrin, an active ingredient used in insecticides that can still be sold and used in Denmark.
According to the Danish Ministry of Environment (Miljøministeriet), products containing a total of 3,326 kilograms of lambda-cyhalothrin were sold in 2024, the latest year for which figures are available. Sales have increased since 2015.
The Danish Environmental Protection Agency says it has reasonable grounds to suspect that lambda-cyhalothrin and four other PFAS-related active substances still authorised in Denmark can degrade into trifluoroacetic acid, or TFA.
TFA is an ultra-short-chain PFAS compound. It is not itself applied as a pesticide, but can form when some fluorinated substances break down in soil and the wider environment.
The issue has become particularly important in Denmark because TFA was detected in 902 drinking-water wells between 2021 and 2024, representing about 40 percent of the wells tested, according to the Environment Ministry. The Danish authorities currently assess the concentrations detected in drinking water as not posing a danger to human health.
Denmark funds research into five PFAS pesticides
The Environmental Protection Agency allocated DKK 1.8 million (about €241,000) in June to the Geological Survey of Denmark and Greenland (GEUS) for a research project examining whether the five substances produce enough TFA to threaten groundwater and drinking-water supplies.
The findings will help determine whether there are grounds to withdraw authorisations for products containing the active substances.
Denmark already took similar action in 2025, when the Environmental Protection Agency withdrew 33 pesticide products after studies showed that the substances could break down into TFA at levels exceeding regulatory thresholds.
Under pesticide rules, Danish authorities need evidence showing that an active substance degrades into TFA and that this occurs above the applicable limits before an authorisation can be withdrawn on that basis.
Environment Minister (Miljøminister) Maria Reumert Gjerding said the government was prepared to act if the new research confirms the suspected risk.
“If the research shows what we fear, namely that these substances form the forever chemical TFA to such an extent that it threatens our groundwater and drinking water, then we will ban products containing lambda-cyhalothrin,” she said in the ministry’s statement.
The minister has also asked officials to assess whether action against pesticides containing the five active substances could be taken under the EU precautionary principle while the research is still under way.
How EU pesticide rules affect a possible Danish ban
Pesticides in Denmark are regulated within a broader European Union framework. Under Regulation (EC) No 1107/2009, active substances are approved at EU level, while individual plant protection products are authorised by national authorities under the conditions established by the regulation.
The legislation is explicitly based on the precautionary principle. It states that EU countries are not prevented from applying that principle where scientific uncertainty remains over risks that plant protection products may pose to human or animal health or the environment.
At European level, scrutiny of TFA has also intensified. The European Chemicals Agency (ECHA) says its Risk Assessment Committee (RAC) adopted an opinion on the harmonised classification of TFA in June 2026. The process followed a proposal from Germany seeking, among other classifications, to classify TFA as toxic to reproduction, category 1B.
The RAC opinion is part of the EU’s classification process under chemicals legislation. A harmonised classification ultimately requires a decision by the European Commission and EU countries before it is incorporated into the relevant EU rules.
This process is separate from pesticide authorisation, but the scientific assessment of TFA adds to the regulatory debate over substances that can release the chemical into the environment.
Drinking water is becoming a wider political issue
The case also fits into a broader Danish debate over pesticide use and groundwater protection.
The government programme presented on 3 June 2026 includes plans for a national pesticide ban in vulnerable groundwater-forming areas, including restrictions involving sewage sludge and contaminated soil. Negotiations on the proposal began shortly after the government took office and are expected to continue after the summer.
For lambda-cyhalothrin and the other four substances now under investigation, the immediate decision will depend on whether researchers can establish a sufficiently strong link between their use and TFA contamination.
The Danish investigation therefore sits at the intersection of national drinking-water protection and EU chemicals and pesticide rules. Its results could determine whether Denmark moves from suspicion to restrictions on another group of PFAS-related agricultural products.
