Reassessment of Fluazinam’s Neurotoxicity Yields Contrasting Results
Researchers who revisited a pivotal study on the neurotoxicity of the fungicide fluazinam have reported substantially different findings from the original, prompting calls from campaigners for the pesticide’s market withdrawal.
In 2005, a study commissioned by ISK, the manufacturer of fluazinam, investigated the chemical’s effects on brain development in the offspring of pregnant rats. The study concluded that there were no statistically significant adverse effects on brain development.
Following a safety evaluation, fluazinam was approved for use in the European Union (EU) in 2008. The pesticide, classified as a PFAS fungicide, is utilized to combat various soil-borne fungal pathogens affecting crops such as potatoes and apples. In 2024 alone, approximately 340 tonnes were sold in Germany.
The 2005 study was not submitted as part of the evidence for the pesticide’s approval but was referenced in subsequent discussions, according to .
In a recent pre-peer-reviewed paper, Stockholm University researchers applied the same statistical methods as the original study and arrived at a different conclusion. They identified six instances where exposure to fluazinam caused statistically significant impacts on brain development in rats.
Key findings included reductions in brain weight and width in the offspring exposed to the pesticide.
“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,” the authors stated.
The researchers explained to that the results reported in the 2005 study could not be accurately derived from the raw data using the methods described in that report. They characterized the original conclusions regarding adult offspring brain effects as “entirely unreasonable and not supported by the results that should have been reported.”
Antoine Bailleux, professor of EU law and legal theory at UCLouvain in Belgium, commented that failing to report statistically significant developmental neurotoxicity would constitute a violation of EU pesticide regulations.
Dr Angeliki Lysimachou, head of science and policy at the campaign group Pesticide Action Network (PAN), criticized the withholding of the study from regulators and its inadequate scrutiny upon eventual submission. She described this as a breach of legal obligations and scientific integrity, calling for an urgent investigation, accountability, and the immediate removal of fluazinam from the market.
The study authors argue that due to the pesticide’s effects on brain development, establishing a safe exposure level is impossible, and thus fluazinam should not have been approved in 2008.
Hans Peter Arp, an environmental chemist at the Norwegian Geotechnical Institute who reviewed the study for , concurred that the pesticide should not have been approved based on these findings.
Fluazinam is currently under evaluation for re-approval in the EU. Post-Brexit, it remains on the UK’s approved active substance register, authorized for use until 2029.
Bailleux stated that fluazinam’s approval should not be renewed without further investigation.
Nick Mole, policy manager at PAN UK, urged the UK Health and Safety Executive to “immediately revoke its authorisation.”
The study authors warn that continued use of fluazinam since 2008 may have led to “unnecessary and potentially harmful human exposure.” The pesticide has been detected in the South Tirol region of Italy, where it is applied to apple orchards.
Dr Axel Mie, lead author of the study, noted that while animal studies cannot be directly extrapolated to humans, the evidence of harm to rat brain development necessitates assuming similar risks for humans.
Christina Rudén, professor of regulatory toxicology and ecotoxicology at Stockholm University and co-author of the study, criticized the EU’s pesticide approval system for relying on a conflict of interest, as manufacturers are responsible for producing safety data.
The EU is currently facing proposals to weaken pesticide safeguards by introducing time-unlimited approvals.
Lysimachou emphasized the need for stronger enforcement, transparency, and independent scrutiny of industry science in Europe, stating:
“These findings send exactly the opposite message: Europe needs stronger enforcement, greater transparency, and more independent scrutiny of industry science. When credible evidence points to risks for children’s neurological development, public health must come before commercial interests.”
Regulatory Responses and Ongoing Reviews
The European Food Safety Authority (EFSA) confirmed that the Austrian Agency for Health and Food Safety (AGES) has been requested to review the statistical analysis and underlying data related to fluazinam’s approval.
A spokesperson for EFSA stated:
“This review is independent and follows established EU procedures. EFSA does not act alone: conclusions are reached collectively with member states through the peer review process. Once AGES has completed its assessment, the findings will be scrutinised in the context of the ongoing risk assessment of fluazinam. We expect to publish our conclusions on the safety of fluazinam, agreed and drawn up together with all EU member states, by the first quarter of 2027.”
An AGES spokesperson indicated that the concerns raised by the study would undergo “further assessments in order to provide a sound basis for the decision about the renewal of the approval of fluazinam.”
ISK, the manufacturer, responded by stating:
“We are aware of the claims regarding the 2005 study and, as we have not received the underlying analysis, are unable to provide further commentary. The study of this active substance forms part of the regulatory assessment and has been reviewed by competent authorities in accordance with applicable procedures. We trust established regulatory processes and emphasise that any related claims should be carefully scrutinised and substantiated.”
Huntingdon Life Sciences has not responded to requests for comment.
This report was produced in collaboration with Bayerischer Rundfunk (BR/ARD) in Germany, FF Südtirol in Italy, and Sveriges Television (SVT) in Sweden.
