How Common Fungicides May Harm the Human Brain
The lettuce in your salad may contain more than just vitamins
In our modern world, fungicides have become an indispensable tool for securing global food supply, with sales accounting for more than 40% of all pesticide sales in the European Union. Yet, emerging research suggests these agricultural chemicals—specifically designed to kill fungi—may pose unexpected risks to the human brain.
A growing body of scientific evidence indicates that chronic exposure to certain fungicides, even at low levels, could be linked to neurological diseases and disorders including Parkinson's disease, autism, and Alzheimer's.
Fungicides represent over 40% of pesticide sales in the EU, yet their neurological risks are often overlooked.
Relative neurological risk levels of common fungicide classes based on current research:
Groundbreaking research published in Critical Reviews in Toxicology in 2024 delivered a startling conclusion: exposure to fungicides, particularly those containing manganese ethylene bis-dithiocarbamate (maneb and mancozeb), is linked to the development of neurological diseases and disorders in humans 1 .
This systematic review—the first of its kind—analyzed scientific literature across multiple databases and found concerning associations between fungicide exposure and Parkinson's disease, neurodevelopmental issues, cognitive disorders, depression, and even amyotrophic lateral sclerosis (ALS) 1 .
The review revealed that while insecticides have traditionally received the most scrutiny for human toxicity, fungicides represent an overlooked threat.
This is particularly concerning given their prophylactic application pattern—they're often applied up to 10 times per growing season to prevent, rather than treat, fungal infections 8 .
Fungicides don't stay neatly contained in agricultural fields. These chemicals enter aquatic ecosystems through runoff, drift, and drainage, and have been detected in surface water bodies in agricultural catchments throughout entire growing seasons 8 .
One study found propiconazole, a common triazole fungicide, in rivers connected to drinking water treatment plants at mean concentrations of 4,493.1 ng/L 7 .
Fungicides have been detected in a wide range of foodstuffs, with conventionally grown leafy green vegetables such as lettuce, spinach, and kale typically containing the highest levels .
| Fungicide Class | Example Compounds | Primary Applications | Detection in Environment |
|---|---|---|---|
| Triazoles | Tebuconazole, Propiconazole | Fruits, vegetables, cereals | Surface water, drinking water sources |
| Strobilurins | Pyraclostrobin, Trifloxystrobin | Grapes, apples, wheat | Food residues, surface water |
| Dithiocarbamates | Maneb, Mancozeb | Various crops | Limited monitoring data |
| Chloronitriles | Chlorothalonil | Turfgrasses, vegetables | Frequently detected in water |
Fungicides are designed to target fundamental biological processes in fungi. The problem, as scientists have discovered, is that many of these processes have parallels in human cells. Triazole fungicides, for instance, work by inhibiting cytochrome P-450 enzymes in fungi—but they can also interfere with similar enzymes in humans, disrupting cellular function in unintended ways 3 .
Research on human SH-SY5Y neuroblastoma cells (a model for studying Parkinson's disease) revealed that triazole fungicides impair mitochondrial function 7 .
When exposed to propiconazole and tebuconazole, these neuronal cells showed significant reduction in ATP production (the energy currency of cells) and increased oxidative stress—both hallmarks of cellular damage that can lead to neuron death 7 .
Researchers at the UNC School of Medicine found that several fungicides produce gene expression changes similar to those seen in people with autism and neurodegenerative conditions like Alzheimer's and Huntington's disease .
The results showed that strobilurin fungicides reduced expression of genes involved in synaptic transmission—the connections crucial for communication between neurons .
| Condition | Type of Evidence | Fungicides Implicated |
|---|---|---|
| Parkinson's Disease | Epidemiological studies, animal models | Maneb, Mancozeb |
| Autism Spectrum Disorders | Gene expression studies | Pyraclostrobin, Trifloxystrobin |
| Alzheimer's Disease | Gene expression studies | Fenamidone, Famoxadone |
| Neurodevelopmental Issues | Human cohort studies | Multiple triazole fungicides |
| Cognitive Disorders | Systematic review | Manganese-based fungicides |
One pivotal study conducted by researchers at the UNC School of Medicine provides compelling experimental evidence for how fungicides might influence neurological disorders .
The analysis revealed six distinct groups of chemicals based on their gene expression impacts. Most concerningly, one group—which included strobilurin fungicides such as pyraclostrobin and trifloxystrobin—altered the levels of many genes that are similarly misregulated in the brains of people with autism or Alzheimer's disease .
Specifically, these fungicides:
The senior author of the study, Dr. Mark Zylka, emphasized the significance while noting the need for further research: "We cannot say that these chemicals cause these conditions in people. Many additional studies will be needed to determine if any of these chemicals represent real risks to the human brain" .
Understanding how fungicides affect the brain requires sophisticated laboratory techniques and tools. Here are some of the essential components of the neurological toxicology toolkit:
| Tool/Technique | Function | Application in Fungicide Research |
|---|---|---|
| SH-SY5Y Neuroblastoma Cells | Human-derived cell line used as a model for neurons | Studying mitochondrial dysfunction and lipid changes 7 |
| RNA Sequencing | Comprehensive analysis of gene expression | Identifying misregulated genes in neurons exposed to fungicides |
| Time-Kill Curve Assays | Measure microbial survival under chemical exposure | Evaluating antifungal persistence in fungal pathogens 9 |
| Cell Viability Assays | Determine proportion of living cells after exposure | Quantifying ATP production and metabolic activity in neurons 7 |
| Lipidomics | Comprehensive study of cellular lipid profiles | Understanding how fungicides disrupt cell membrane composition 7 |
With growing evidence of potential harm, experts are calling for a more cautious approach to fungicide use. The authors of the 2024 systematic review recommend further multicentric clinical trials and prospective studies to better understand the neurological risks 1 .
Meanwhile, infectious disease experts are raising alarms about how agricultural fungicide use is driving resistance to medical antifungal treatments, calling for a coordinated global "One Health" approach that considers the interconnectedness of human, animal, and environmental health 2 .
All fruits and vegetables should be washed thoroughly before consumption.
Particularly for leafy greens which tend to have higher residue levels.
Agricultural practices that reduce pesticide dependency.
More comprehensive pesticide testing and regulation.
As the scientific evidence continues to accumulate, it becomes increasingly clear that we must balance agricultural needs with neurological health.
The solution, as many researchers suggest, lies in prevention—developing safer agricultural practices and reducing our reliance on potentially harmful chemicals 5 .
The hidden neurological threat of fungicides represents yet another chapter in our understanding of how environmental chemicals can shape brain health across the lifespan. By bringing this issue to light, we take the first step toward protecting both our food supply and our most precious organ—the human brain.