BPA Chemical Affects Brain Development in Zebrafish

Bisphenol A, a chemical known as BPA that's commonly used in consumer products, reportedly affects brain development in young zebrafish, causing concern that it can also negatively impact human brains still developing in the womb, according to new research.

While it would seem that zebrafish and humans are drastically different, and therefore their responses to environmental stimuli are different too, in actuality about 80 percent of the genes found in people have a counterpart in zebrafish (Danio rerio). Not to mention that both organisms share similar developmental processes, so it may be that bisphenol is dangerous to us as well.

Public concern had caused manufacturers to modify their products and replace BPA with a chemical called bisphenol S (BPS), which is often labeled as "BPA-free" and presumed to be safer. However, according to a new report in the journal Proceedings of the National Academy of Sciences, exposure to both BPA and BPS changed the timing of when neurons were formed in the brains of zebrafish, leading to hyperactive behavior.

"These findings are important because they support that the prenatal period is a particularly sensitive stage, and reveals previously unexplored avenues of research into how early exposure to chemicals may alter brain development," Cassandra Kinch, a PhD student at the University of Calgary, who was involved in the research, said in a press release.

"In the second trimester," explained lead author Deborah Kurrasch, "brain cells become the specialized neurons that make up our brain. What we show is that the zebrafish exposed to BPA or BPS were getting twice as many neurons born too soon and about half as many neurons born later, so that will lead to problems in how the neurons connect and form circuits."

Specifically, the researchers discovered that the number of neurons generated, while young zebrafish brains were still developing, increased by 180 percent compared with fish unexposed to these harmful chemicals. Additional experiments also found that BPS increased the number of neurons by 240 percent. The end result was fish that exhibited heightened hyperactivity later in life.

"I was actually very surprised at our results. This was a very, very, very low dose, so I didn't think using a dose this low could have any effect," Kurrasch said.

So what does this mean for humans who are regularly exposed to products containing either BPA or BPS on a daily basis? Further research is needed to see if the chemicals cause similar effects in humans, however until then Kurrash notes that pregnant women should try to limit their exposure to items containing bisphenols.

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