The Science of DioxinApril 22, 2016 | |
Study Asserts That New Class of Fungicides Plays Role in Autism and Neurodegenerative Diseases
Scientists at the UNC School of Medicine are reporting that a class of commonly used fungicides produces gene expression changes similar to those in people with autism and neurodegenerative conditions, including Alzheimer’s disease and Huntington’s disease.
The study, published in the journal Nature Communications, describes what the authors claim is a new way to home in on chemicals “that have the potential to affect brain functions.”
Mark Zylka, Ph.D., the senior author of the study and an associate professor of cell biology and physiology at UNC, 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 mis-regulated when compared to untreated neurons. According to the researchers, this work created hundreds of data sets of “gene expression.”
Dr. Zylka’s team then used computer programs to deduce which chemicals caused gene expression changes that were similar to each other.
The researchers said that these chemicals reduced the expression of genes involved in synaptic transmission – the connections important for communication between neurons – and that they caused an elevated expression of genes associated with inflammation in the nervous system. According to the researchers, this so-called “neuroinflammation” is commonly seen in autism and neurodegenerative conditions.
The researchers also found that these chemicals stimulated the production of free radicals and also disrupted neuron microtubules.
“Based on RNA sequencing, we describe six groups of chemicals,” Dr. 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,” he added.
According to Dr. Zylka, chemicals in this group included the pesticides rotenone, pyridaben, and fenpyroximate and a new class of fungicides that included pyraclostrobin, trifloxystrobin, fenamidone, and famoxadone. Azoxystrobin, fluoxastrobin, and kresoxim-methyl also were in this fungicide class.
“We cannot say that these chemicals cause these conditions in people,” Dr. Zylka cautioned. “Many additional studies will be needed to determine if any of these chemicals represent real risks to the human brain.”
Dr. Zylka added, “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.”
Dr. Zylka concluded that his team hoped its research would encourage other scientists and regulatory agencies to take a closer look at these fungicides and to follow up with epidemiological studies.
In addition to Dr. Zylka, Brandon Pearson, Ph.D., and Jeremy Simon, Ph.D., were co-first authors on the study. Additional authors included Eric McCoy, Ph.D., Giulia Fragola, Ph.D., and Gabriela Salazar.
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Paper Asserts €1.5 Billion Annual Cost to Endocrine Disrupting Chemicals in the EU
A new paper published in the Journal of Clinical Endocrinology & Metabolism contends that the economic costs of female reproductive disorders attributable to endocrine disrupting chemical exposures in the European Union is nearly €1.5 billion annually.
Patricia A. Hunt, Sheela Sathyanarayana, Paul A. Fowler, and Leonardo Trasande are the authors of the paper, “Female Reproductive Disorders, Diseases, and Costs of Exposure to Endocrine Disrupting Chemicals in the European Union.”
The researchers said that they estimated the “economic costs of female reproductive disorders attributable to endocrine disrupting chemical exposures.” According to the researchers, these exposures “may contribute substantially to fibroids and endometriosis, costing nearly €1.5 billion annually.”
The researchers said that the “most robust” data related to endocrine-disrupting chemicals (“EDCs”) for female reproductive disorders existed for diphenyldichloroethene-attributable fibroids and phthalate-attributable endometriosis in Europe. In both cases, the researchers said, the “strength of epidemiological evidence was rated as low and the toxicological evidence as moderate,” with an assigned probability of causation of 20 percent to 39 percent. They added that, across the EU, attributable cases were estimated to be 56,700 and 145,000 women, respectively, “with total combined economic and health care costs potentially reaching €163 million and €1.25 billion.”
The paper concluded that EDCs (diphenyldichloroethene and phthalates) “may contribute substantially” to the most common reproductive disorders in women, endometriosis and fibroids, costing nearly €1.5 billion annually in the European Union. In the authors’ view, these public health costs “should be considered as the EU contemplates regulatory action on EDCs.”