Drinking water, even bottled mineral water, contains harmful pesticides. So why isn’t more being done to protect resources against pollution?

TFA is a largely overlooked and underestimated chemical. It rarely features in public discourse, unlike other substances, yet this toxic chemical is prevalent in water systems across Europe, even being detected in bottled natural mineral waters. Though it is slowly gaining recognition as a high-risk pollutant in drinking water, the tide may not be shifting quickly enough.

Despite its presence in groundwater it seems TFA has evaded regulation and scrutiny for several decades. But now, a team of scientists is sharing their research – which has shed light on the real extent of water contamination – in the hopes of enacting change and preventing an unmanageable environmental and public health issue.

What is TFA and why are we concerned?

TFA, or trifluoroacetic acid, is an ultra short chain chemical in the per and polyfluoroalkyl substances (PFAS) family; forever chemicals, so called for their persistence and accumulation in the environment. Although TFA is a standalone chemical compound, it is also a degradation product of other substances, including being emitted by almost all PFAS pesticides, and also the F-gases used in cooling systems. As these parent compounds break down, the TFA derivative remains in the environment – and due to its chemical stability and high solubility in water, it is able to infiltrate water supplies where it accumulates over time.

The PAN Europe team grew deeply concerned about the multifaceted threat that was going unchecked. They saw widespread usage of pesticides that degrade into a substance that was a known metabolite, and for which there was insufficient evidence of its toxicity and therefore potential outdated rules on its use and acceptable thresholds. Because while it is below the legal threshold at the moment, this threshold may not be enough as it will only accumulate in the environment over time. Added to this loomed the possibility that it may become more popular; as the pesticide industry realised the dangers of long-chain PFAS (such as PFOA), they saw more users turning to shorter chain chemicals because they were deemed less toxic, a claim PAN Europe says is entirely unevidenced.

Risks posed by TFA were poorly understood and certainly not being taken seriously. So Angeliki Lysimachou, head of science and policy, and Salomé Roynel, policy officer on pesticide risk assessment at PAN Europe, analysed EU official monitoring data on residues of PFAS pesticides in European fruit and vegetables over a decade of 2011-2021, and reported increasing quantities of PFAS-active substances in the food products. Intrigued by the results published, it caught the attention of Helmut Burtscher-Schaden, a biochemist who had spent more than 20 years working for Austria’s environmental NGO Global 2000 – a member organisation of PAN Europe. Burtscher-Schaden suggested that the next step should be to carry out water testing.

“I did not know anything about trifluoroacetic acid as a degradation product of pesticides until February this year, even though the issue of chemical contamination of water has repeatedly occupied my attention,” says Burtscher-Schaden, who was surprised at how little-known the subject area was, even among those in the pesticides and environment fields.

The process of water pollution testing

With Burtscher-Schaden onboard the cross-organisation, cross-country team mobilised a network of scientists and NGO partners of PAN Europe from across Europe. He drew up guidelines for the process of taking and submitting tap water samples, and sent centrifugal tubes to each site team. All were returned to Global 2000 to examine in a laboratory in Germany, highly reputed for water analysis. The team collected samples of tap water from 11 European countries and found that 94% of those tested contained TFA, with a minimum limit of detection at 20 nanograms per litre.

With TFA clearly in many locations, next they applied the same method to a range of bottled natural mineral waters to see if the chemical had made its way into very deep, high quality water resources. “We analysed mineral water because we wanted to know if this is a problem that has reached protected groundwater sources. There is a very clear legal obligation here, as you can only get a certificate to market a product as mineral water when the groundwater body is protected,” explained Burtscher-Schaden. “But actually, we found TFA in 12 of the 19 mineral water brands analysed.”

So have those mineral water companies flouted the law? Well no, because while certification requires mineral waters to be natural, unprocessed and free from pollution, that does not specify testing for TFA. “We found many mineral waters were above 0.1 micrograms per litre, which is the legal threshold for pesticides in normal groundwater, so it is not acceptable in mineral water,” he added. “Therefore, with this data, those brands will have problems selling their water as mineral water – and this is also not their fault. It's the fault of the system that has allowed the water to be contaminated in this way.”

When speaking with the mineral water companies about their results, Roynel confirmed their responses as, “We didn’t look into TFA”, and they have been advising the firms on conducting further analysis and water quality checks.

With this information, the team could now challenge one of the core pillars of silence around the topic. Because although pesticides must be strictly controlled, their derivatives are not, unless proven “relevant”. “Pesticides are designed to be toxic, so they must not be detected in water, especially drinking groundwater, above 0.1 micrograms per litre. But when it comes to regulatory toxicology and assessment, metabolites have to be proven to be toxicologically relevant through studies, for such a threshold to apply” says Lysimachou.

However, once again, they found that background research and studies on vegetation and mammals were lacking in number and not acted upon. She argued that a 2021 rabbit study conducted by Bayer demonstrated “serious malformations in the eyes of the rabbits, which is exactly what we had seen with PFOA years ago, so it seems they have a common mechanism of action. So, like other PFAS TFA is toxicologically relevant and it should fall under the high level of protection category”. This rabbit study led European authorities to proceed with the classification of TFA as toxic for reproduction 1B (substances that may harm fertility, and unborn and breastfed children).

Regulatory limits and gaps in evidence

Central to the TFA problem and one of the most contentious issues is the lack of research carried out to prove its impact one way or another, and subsequently, the inadequacy of safety limits. This is partly because polyfluoro chemicals are a very large group of compounds therefore analysing each of them would take many years, so the EU opted for a blanket ban without toxicity data for each individual substance. But collectively, the team believes that between industry efforts to portray TFA as a harmless substance, and authorities failing to demand dedicated research, there has been a significant oversight going on since the 1990s, and TFA’s toxicity has been, at best, downplayed.

For instance, in 2014, the European Food Safety Authority (EFSA) established a tolerable daily intake of 15 micrograms per kilogram of body weight for TFA. Subsequent assessments by German and Dutch authorities proposed slightly lower limits, but Lysimachou argues that they had “no information to say it’s not toxic because there were no studies and they knew it would increase in water”. Burtscher-Schaden says this absence of research into carcinogenicity, genotoxicity and reproductive toxicity – a battery of animal studies that’s necessary to approve a pesticide-active substance – represents a major failure of the regulatory system. Due to this, TFA was classified as a non-relevant metabolite, thereby escaping the stricter regulatory scrutiny typically applied to pesticide-active substances.

“Because its toxicity was underestimated no legal implication was put in place. But also there were no legal implications in terms of monitoring, so you couldn't track this massive pollution coming and then tackle it when it was still quite low. So that's why we called it invisible,” Roynel added. “There was no real incentive in tracking its presence in the environment and no awareness or willingness on the regulators’ sides to check its toxicity and review the science regularly.” As Lysimachou says, effectively “they turned a blind eye to it”.

Is there a TFA solution?

“We’re not asking for the water companies to clean up TFA. What we’re asking is to stop pollution at source,” says Lysimachou. Stopping the source, the team says, is the most effective way of preventing a disaster. Also because of its small size and structure, demanding that water companies clean up sites from TFA is not technically feasible with current methods, and would result in degrading water quality, and simply pushing the cost on to taxpayers by circumventing the polluter pays principle.

Burtscher-Schaden reinforced this point, adding that while the most protective assessment of TFA by the Dutch authorities suggests that current water contamination levels may not yet require immediate cleanup, this could change if contamination continues unchecked. “If you wait too long, there will be a need [to clean the water]. But that would require an extremely complex overhaul of water treatment, as established methods like ozone treatment or filtration through activated carbon cannot remove TFA from the water,” he warned, and of course this would be timely, more costly, and result in compromised drinking water stripped of all desirable minerals. The team’s focus, therefore, is firmly set on prevention – of stopping TFA pollution at its source to avoid complex remediation efforts in the future and ultimately protect our water resources.

More broadly, to mitigate the risks posed by TFA, PAN Europe and Global 2000 are advocating for immediate policy changes, including an outright ban of PFAS pesticides. This, Lysimachou emphasised, doesn’t even require new legislation but stronger enforcement of existing laws. “In our opinion it’s clear in pesticide regulation that if the science indicates that the requirements for authorisation [...] turn out to be wrong assumptions, then you have the duty to withdraw that authorisation,” she says This approach would compel member states to take action based on current scientific knowledge, rather than delaying work while waiting for new regulations to be implemented. Moreover, the team argues that member states should act in accordance with EU pesticide regulation, which mandates the withdrawal of substances found to be harmful to human health or the environment. This could be achieved by applying the precautionary principle more stringently.

Of course, pesticides are not the only source of TFA, though they are significant. Roynel highlighted the need to address other sources, particularly the chemicals used in urban cooling systems, saying “if we want to phase out TFA, you also have to look into F-gases and therefore you need implementation of this universal restriction of PFAS in Europe so that F-gases are banned”. This holistic approach would help to tackle TFA pollution at source, reducing the burden on water treatment systems and preventing further contamination.

Looking ahead, they aim to ensure that the upcoming negotiations on the EU Water Framework Directive prioritise the protection of drinking water from contaminants such as TFA. “TFA is a really clear example of how the system has loopholes,” Lysimachou remarked, adding that the issue highlights the dangers of treating chemicals on a substance-by-substance basis rather than addressing the underlying problems with how these substances are used and regulated. This will be an important aspect of the upcoming Directive negotiations, particularly in light of recent developments that suggest a potential weakening of legal protections. Burtscher-Schaden concluded: “We hope that our reports, together with the mineral water testing results, will get some awareness, especially among the negotiators.”