BPS (Bisphenol S) is being touted as a “safer” replacement for BPA, which was linked to early puberty and a rise in breast and prostate cancers. It is often found in plastic products ranging from water bottles to food storage containers to toys. However, researchers at UCLA have demonstrated that BPS speeds up embryonic development and disrupts the reproductive system. Nancy Wayne, a reproductive endocrinologist and professor of physiology at the David Geffen School of Medicine at UCLA states “Our study shows that making plastic products with BPA alternatives does not necessarily leave them safer”. The UCLA researchers used a zebrafish model, choosing this, because their transparent embryos make it possible to witness cell growth as it occurs. The zebrafish were exposed to low levels of BPA and BPS, approximately the same levels as found in polluted river waters. Within 25 hours, the fishes’ physiology was found to be altered at the embryonic stage. This lead to accelerated egg hatching time, and thus to the fish version of premature birth.
The team also tracked the fishes’ development of reproductive endocrine brain cells, which control puberty and fertility. They found an increase of up to 40 percent in the number of endocrine neurons, suggesting that BPA overstimulates the reproductive system and the genes that control reproduction later in life. These effects were observed in both the BPS and BPA-free products. Overstimulation of the neurons could then potentially lead to premature puberty and disruption of the reproductive system.
The researchers were also surprised to find that both BPA and BPS acted partly through an estrogen system and partly through a thyroid hormone system to produce their effects. This means that they appear to mimic the actions of thyroid hormone, as well as mimicking the effects of estrogen. “Most people think of BPA as mimicking the effects of estrogen. But our work shows that it also mimics the actions of thyroid hormone,” said Wayne. “Because of thyroid hormone’s important influence on brain development during gestation, our work holds important implications for general embryonic and fetal development, including in humans.”
