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Study Reveals How Chemicals in Flame Retardants Interfere with Brain Development

June 15, 2020
Neurons are the basic working unit of the brain, and if there is a disruption in them in children, the effects could last a lifetime.

Many of the items people use in their everyday lives, from baby clothes and Halloween costumes to furniture, are doused with chemical flame retardants designed to make the items safer.

But a new study from Cellular and Molecular Biology Professor Ramendra Saha and his former Ph.D. student Robert Poston indicates that some of those same chemicals correlate to inhibited brain development and function, and notes that they could be particularly harmful to infants and young children in their most developmentally critical years.

“Infants and toddlers have a higher body burden because of their size and the concentration of exposure,” Saha said. “How these problems affect them later in life haven’t been studied but given the body of evidence about behavioral and I.Q. deficits, the effects could carry on into adulthood.”

Not only do the chemicals build up in the body, but Saha, who studies the epigenetic mechanisms of neuronal gene transcription and their role in mental health, said these chemicals are persistent environmental pollutants, meaning they do not biodegrade.

“When neurons are exposed to polybrominated diphenyl ethers (PBDEs), there is an increase in the disruption of the axon guidance in the brain,” Poston said.

Neurons are the basic working units of the brain, transmitting information to other nerve, muscle or gland cells. Axons are the long, threadlike parts of nerve cells along which the impulses are conducted from the neuronal cell body to other cells — they are the primary transmission lines of the nervous system. Axon guidance is the process by which neurons send out axons to reach their correct targets.

During normal brain development, axons follow extremely precise paths in the nervous system, and there is a large body of evidence that indicates disruption of these pathways correlates to negative neurological outcomes, Saha said.

Poston and Saha have been working on this project for about two years, trying to discover the molecular mechanisms of PDBE toxicity and how the mechanisms come together to affect gene expression and the neuronal signaling cascades in the brain.

“It could be that a group of things are happening simultaneously, or it could be a cascade of effects,” Poston said. “If we ever hope to intercept these problems, we need to know how it all works.”

During their research, Poston and Saha were surprised to find that the neural pathway and signaling molecule they thought was the most affected by PDBEs was actually one of many of the chemicals’ targets.

“That opens up many other avenues for exploration,” Saha said.

The topic of PBDEs has been on Saha’s mind since his postdoctoral work at the National Institutes of Health’s Environmental Health Sciences division. He joined UC Merced’s Department of Molecular and Cell Biology and the Health Sciences Research Institute in 2014. He pitched the idea of this line of research to Poston when he came to UC Merced in 2015 from the University of Dayton, Ohio.

Though Poston graduated with his Ph.D. in December, he remains part of Saha’s lab, but will be moving on before long. Saha said he has funding from the NIH Health Sciences division to move the research forward, but he will need another graduate student.

“I hope to be able to find someone as dedicated and efficient as Robert,” Saha said.

The researchers said there are others trying to develop safer flame-retardant materials. Compounds with PDBEs have been largely banned across Europe and are discouraged in the United States, but Poston and Saha said they want people to be aware of PBDEs and the links to developmental issues so they can make informed purchases, especially for newborns.

“We’re potentially exposed to thousands of chemicals and we don’t know all of the effects on the body,” Poston said.

Lorena Anderson

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