Are Pesticides And Fungicides Triggering Autism?

Just in time to kick off April's month of autism awareness and acceptance campaigns, new research is shedding a negative light on certain pesticides and especially a new class of fungicides. This new research examines changes in the gene expression of mice that are similar to those found in individuals with autism, Alzheimer's disease, and some other neurological conditions. The new research, published in Nature Communications, calls for further investigation into the scientists' findings of a possible autism-triggering mechanism of fungicides.

Senior author Dr. Mark Zylka, associate professor of cell biology and physiology at the University of North Carolina School of Medicine, and his colleagues exposed the brain cells of mice to around 300 different chemicals to see if any of them triggered changes in gene expressions similar to those of people with autism.

Using RNA sequencing on the mouse neurons, they pinpointed which genes were affected by exposure to the chemicals. A series of computer programs helped the research team establish which chemicals triggered changes in gene expression that could indicate that the chemicals might be able to trigger gene changes associated with those of people with autism.

Through this research, the scientists found six groups of chemicals that changes the gene expression in this way. The chemicals included pesticides and fungicides. One new class of fungicides is especially interesting, according to a press release.

The fungicides, known as strobilurins, were introduced into the U.S. food supply in the late 1990s, according to Medical News Today, just before statistics show a massive increase in the rate of autism. Fungicides in this class include pyraclostrobin, trifloxystrobin, fenamidone, famoxadone, azoxystrobin, fluoxastrobin, and kresoxim-methyl.

The researchers also examined the trends of the use of particular fungicides on particular foods. Azoxystrobin was found in greatest concentrations on cilantro and leafy greens. Famoxadone was found mostly on lettuce and other leafy greens. Fenamidone was mostly used on spinach and lettuce. Farmers began using fluoxastrobin mostly in cherry and normal tomatoes around 2006. Pyraclostrobin is mostly found on spinach, but was also used on dandelion greens!

"We found that chemicals within each group altered expression in a common manner," Zylka explained. "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."The chemicals reduced the expression of genes that play an important role in neuron communication. Reduction of this gene expression can interfere with brain functioning. The fungicides also increased expression of genes that are believed to trigger nervous system inflammation, such as is seen in autism and neurodegenerative disorders. The fungicides also boosted the production of free radicals, which cause cell damage and interfere with microtubules within neurons.

"Disrupting microtubules affects the function of synapses in mature neurons and can impair the movement of cells as the brain develops," Zylka said. "We know that deficits in neuron migration can lead to neurodevelopmental abnormalities. We have not yet evaluated whether these chemicals impair brain development in animal models or people."

The fungicide class has been predominantly used, according to the researchers, on leafy green vegetables like spinach, lettuce, and kale. The team notes, though, that these fungicides are being added to other food crops at an increasing rate as well. Zylka points out that earlier research into the fungicide trifloxystrobin has shown that it can disrupt the motor function of rats for up to several days, and even a low dose of the fungicide picoxystrobin has been linked to impaired motor functioning. While animal testing can't necessarily affirm the same effect in humans, Dr. Jeannie T. Lee, professor of genetics at Harvard Medical School and Massachusetts General Hospital, is calling this a wake-up call to regulatory agencies and the medical community.

"The work is timely and has wide-ranging implications not only for diseases like autism, Parkinson's and cancer, but also for the health of future generations. I suspect that a number of these chemicals will turn out to have effects on transgenerational inheritance."
Meanwhile, the researchers say that these chemicals need to be investigated more fully for any possible triggering-effect in relation to autism.

"Virtually nothing is known about how these chemicals impact the developing or adult brain," Zylka commented. "Yet these chemicals are being used at increasing levels on many of the foods we eat."

The new research into the possible link between autism and fungicides can be read without a subscription online.

[Image via Pixabay]