It is impossible to correctly reach the results in the 2005 report
Stockholm University researchers found six instances of statistically significant brain damage in rat offspring exposed to fluazinam, contradicting the original 2005 manufacturer study. The pesticide was approved by EU in 2008 despite concerning data that was withheld from regulators, raising questions about scientific integrity and regulatory oversight.
- Stockholm University researchers found six statistically significant impacts on brain development in rats exposed to fluazinam, contradicting the 2005 manufacturer study
- Fluazinam was approved by the EU in 2008; 340 tonnes sold in Germany in 2024
- The pesticide has been detected at children's playgrounds in South Tirol, Italy
- EU decision on fluazinam's safety expected by first quarter of 2027
New research contradicts a 2005 manufacturer study, finding fluazinam fungicide causes significant brain development effects in rats. Campaigners demand immediate withdrawal of the EU-approved pesticide.
A fungicide approved across Europe in 2008 may have been cleared on the basis of flawed science, according to researchers who have now re-examined the original safety data and reached conclusions that contradict the manufacturer's findings. The substance in question is fluazinam, a pesticide used to control fungal diseases in potatoes and apples. In Germany alone, 340 tonnes were sold in 2024.
The story begins with a 2005 study. Huntingdon Life Sciences, working on behalf of ISK—the company that makes fluazinam—conducted research on pregnant rats to determine whether the pesticide affected brain development in their offspring. The conclusion was reassuring: no statistically significant effects were found. Three years later, in 2008, the European Union granted approval for the pesticide based partly on this safety assessment. What was not widely known at the time was that this particular 2005 study had not been formally submitted as part of the approval evidence, though it was referenced in subsequent discussions.
Now, researchers at Stockholm University have reanalyzed the same raw data using the same statistical methods specified in the original report. What they found tells a different story. They identified six instances where exposure to fluazinam produced statistically significant impacts on brain development in the rats' offspring—specifically, decreases in brain weight and width. The Stockholm team concluded that such effects on brain morphology, given their potentially lifelong consequences, qualify as severe. They went further, stating that it is mathematically impossible to arrive at the original 2005 conclusions using the methods and data that were documented. The original authors' conclusions, they wrote, are "entirely unreasonable and not supported by the results that should have been reported."
The implications are serious. If the 2005 study had correctly reported these findings, European regulators would have faced a different picture when deciding whether to approve fluazinam. Antoine Bailleux, a professor of EU law at UCLouvain in Belgium, argues that failing to report statistical significance in developmental neurotoxicity studies violates EU pesticide regulations. Angeliki Lysimachou, head of science and policy at Pesticide Action Network Europe, describes the situation as a breach of both legal obligations and scientific integrity—data withheld from regulators and warning signs missed even when the study eventually reached authorities.
The Stockholm researchers argue that because fluazinam affects brain development in rats, it must be assumed the same could occur in humans. They conclude that no safe level of exposure can be established and therefore the pesticide should never have been approved in 2008. Hans Peter Arp, an environmental chemist at the Norwegian Geotechnical Institute, reviewed the new study and agrees: based on these findings, fluazinam should not have been approved. The study authors note that continued use since 2008 may have resulted in "unnecessary and potentially harmful human exposure." The concern extends to children: fluazinam has been detected at playgrounds in South Tirol, Italy, where the pesticide is used on nearby apple farms.
Fluazinam is currently being evaluated for re-approval in the EU. In the UK, where it was carried over into the approved substances register after Brexit, it remains authorized until 2029. Campaigners are calling for immediate action. Nick Mole, a policy manager at Pesticide Action Network UK, says the Health and Safety Executive should revoke its authorization. Bailleux argues the pesticide should not be renewed without further investigation. The European Food Safety Authority has asked Austria's health and food safety agency to review the statistical analysis and underlying data. A decision on fluazinam's safety is expected by the first quarter of 2027.
ISK, the manufacturer, said it has not received the underlying analysis from the Stockholm study and therefore cannot comment further. The company emphasized that the original 2005 study was reviewed by competent authorities in accordance with established procedures and that it trusts regulatory processes. Huntingdon Life Sciences did not respond to requests for comment. What happens next depends on whether regulators treat this new evidence as reason enough to pull a pesticide that has been in use for nearly two decades—or whether the approval system, as critics contend, remains too dependent on industry-generated data and too slow to act when that data is challenged.
Citas Notables
In our opinion, considering the potentially lifelong consequences of brain development deficits, an effect of a chemical on brain weight, width and morphometrics qualifies as severe.— Stockholm University study authors
When it finally reached the authorities, the warning signs were still missed. This is a breach of both legal obligations and scientific integrity that demands an urgent investigation and the immediate withdrawal of fluazinam from the market.— Dr Angeliki Lysimachou, Pesticide Action Network Europe
La Conversación del Hearth Otra perspectiva de la historia
So the original study said the pesticide was safe, and now someone has looked at the same data and found the opposite. How is that possible?
The 2005 researchers concluded there were no statistically significant effects on brain development. But when Stockholm University reanalyzed the raw data using the same methods, they found six instances of significant effects—smaller brains, narrower brains. It's not that the data changed. It's that the conclusions drawn from it were wrong.
Could this be a matter of interpretation? Different scientists reading the same numbers differently?
That's what makes it troubling. The Stockholm team says it's mathematically impossible to reach the original conclusions using the methods and data that were documented. They're not saying it's a judgment call. They're saying the original report is unreasonable.
And this study was used to approve the pesticide across Europe?
Not directly. The 2005 study wasn't formally submitted as approval evidence, but it was referenced in discussions. The pesticide was approved in 2008 anyway. Now, eighteen years later, we're learning the safety data may have been misinterpreted.
What does this mean for people who've been exposed to it?
That's the hard question. The researchers say continued use since 2008 may have caused unnecessary and potentially harmful exposure. They found the pesticide at children's playgrounds in Italy. We don't know yet what that means for human health—animal studies don't directly translate—but the researchers say if it damages rat brains, we have to assume it could damage human brains too.
So what happens now?
The EU is reviewing it. A decision is expected by early 2027. But campaigners are saying that's not fast enough—they want it withdrawn immediately. The UK has it approved until 2029. It's a test of whether regulators will act on credible evidence that contradicts old approvals.