A study published today in the journal Nature Communications says a class of commonly used agricultural fungicides appear to produce gene expression changes similar to those in people with autism and neurodegenerative conditions, including Alzheimer’s disease and Huntington’s disease.
Mark Zylka, PhD, senior author of the study, and his team exposed mouse neurons to approximately 300 different chemicals. Then the researchers sequenced RNA from these neurons to find out which genes were misregulated when compared to untreated neurons. This work created hundreds of data sets of gene expression. Zylka’s team used computer programs to deduce which chemicals caused gene expression changes that were similar to each other.
“Based on RNA sequencing, we describe six groups of chemicals,” Zylka said. “We found that chemicals within each group altered expression in a common manner. One of these groups of chemicals altered the levels of many of the same genes that are altered in the brains of people with autism or Alzheimer’s disease.”
Chemicals in this group included the pesticides rotenone, pyridaben, and fenpyroximate, and a new class of fungicides that includes pyraclostrobin, trifloxystrobin, fenamidone, and famoxadone. Azoxystrobin, fluoxastrobin, and kresoxim-methyl are also in this fungicide class.
“We cannot say that these chemicals cause these conditions in people,” Zylka cautioned. “Many additional studies will be needed to determine if any of these chemicals represent real risks to the human brain.”
In addition to changing the way that genes expressed themselves in the brain, the researchers found that these chemicals also created neuroinflammation by producing free radicals.
Zylka stated “The real tough question is: if you eat fruits, vegetables or cereals that contain these chemicals, do they get into your blood stream and at what concentration? That information doesn’t exist.”
Zylka noted that conventionally grown leafy green vegetables such as lettuce, spinach, and kale have the highest levels of these fungicides. But due to each chemical’s effectiveness at reducing fungal blights and rust, crop yields have increased and farmers are expanding their use of these chemicals to include many additional types of food crops.
Zylka’s team hopes their research will encourage other scientists and regulatory agencies to take a closer look at these fungicides and follow up with epidemiological studies.
“Virtually nothing is known about how these chemicals impact the developing or adult brain,” Zylka said. “Yet these chemicals are being used at increasing levels on many of the foods we eat.”