Bisphenol S: A Toxic BPA Substitute Found in BPA-Free Products
Manufacturers of plastic products, including water bottles and containers were running scared just a few years ago when an accumulation of research continued to surface regarding the toxicity of a key ingredient in plastics called Bisphenol A (BPA). That enlightened the public to the dangers of BPA products and pressured the industry to make changes and remove BPA-containing items from retailer shelves. The industry responded with Bisphenol S (BPS) which is possibly even more toxic and may also lead to
diabetes, asthma and cancer and altered prostate and neurological development.
BPA is a dangerous chemical linked to health concerns from digestive problems to issues with brain development. It’s was found present in around two billion products in the U.S. that are used on a daily basis. Because it’s the most harmful on developing brains and bodies, children and pregnant women especially need to avoid contact with BPA.
“When it comes to BPA in the environment, the biggest exposure, in my opinion, is from cash register receipts,” says John C. Warner of the Warner Babcock Institute for Green Chemistry (WBI), in Wilmington, Mass. “Once on the fingers, BPA can be transferred to the mouth, onto food, and likely absorbed through the skin.”
Bisphenol A has become the primary focus of consumer advocates for several reasons:
Other plastics--even BPA-free ones--may also be a source of endocrine disrupters. A recent analysis of more than 450 everyday plastic products, from plastic bags to water bottles, found that about 95% of the items tested leached chemicals that triggered a bioassay for estrogenic activity, including most of the products labeled as BPA-free (C&EN, March 14, page 48).
Recent investigation has shown that Bisphenol A isn't the only endocrine disrupting chemical consumers should be worried about. According to an article published today in the US News and World Report, chemical substitute BPS, an endocrine disrupting hormone with traits very similar to BPA, is present in BPA-Free products and is inside paper money, cash register receipts and most plastic consumer products much like its predecessor.
Widespread human exposure to BPS was confirmed in a 2012 analysis of urine samples taken in the U.S., Japan, China and five other Asian countries.
According to a study by University of Texas Medical Branch at Galveston researchers, though, BPS also resembles BPA in a more problematic way. Like BPA, the study found, BPS disrupts cellular responses to the hormone estrogen, changing patterns of cell growth and death and hormone release. Also like BPA, it does so at extremely low levels of exposure.
“Our studies show that BPS is active at femtomolar to picomolar concentrations just like endogenous hormones --that’s in the range of parts per trillion to quadrillion,” said UTMB professor Cheryl Watson, senior author of a paper on the study now online in the advance publications section of Environmental Health Perspectives. “Those are levels likely to be produced by BPS leaching from containers into their contents.”
BPS has some of the same estrogen-mimicking effects of BPA, and that people may now be absorbing 19 times more BPS through their skin than when BPA was used to coat paper.
Watson and graduate student Rene Vinas conducted cell-culture experiments to examine the effects of BPS on a form of signaling that involves estrogen receptors -- the “receivers” of a biochemical message -- acting in the cell’s outer membrane instead of the cell nucleus. Where nuclear signaling involves interaction with DNA to produce proteins and requires hours to days, membrane signaling (also called “non-genomic” signaling) acts through much quicker mechanisms, generating a response in seconds or minutes.
In the case of BPS, there's reason to believe it is just as dangerous to human health, and possibly more so, than BPA, although the research is not nearly as abundant just yet. Writing in the journal Toxicology In Vitro, researchers stated:
"In 2011, the European Commission has restricted the use of Bisphenol A in plastic infant feeding bottles. In a response to this restriction, Bisphenol S is now often used as a component of plastic substitutes for the production of babybottles. One of the major concerns leading to the restriction of Bisphenol A was its weak estrogenic activity. By using two highly standardised transactivation assays, we could demonstrate that the estrogenic activity of Bisphenol A and Bisphenol S is of a comparable potency."
Not only does BPS appear to have similar hormone-mimicking characteristics to BPA, but research suggests it is actually significantly less biodegradable, and more heat-stable and photo-resistant, than BPA. GreenMedInfo reports:
"... while regulators wait for manufacturers who promote their products with "BPA-Free!" stickers at the same moment that they infuse them with BPS to voluntarily reformulate,there isevidence now that BPS may actually have worse effects to environmental and human health, alike..
"... BPS' relative inability to biodegrade indicates: 1) once it is absorbed into the human body, it may accumulate there for longer periods of time. 2) it is more likely to persist in the environment, making external exposures to it, and its many metabolites, much more likely than the faster degrading BPA. In other words, its potential to do harm will worsen along the axis of time, not lessen, which is a common argument made for the purported "safety" of BPA."
In a study meant to simulate "real-world" use, 95 percent of all plastic products tested positive for estrogenic activity, meaning they can still disrupt your hormones even if they carry a BPA-free label. Even more disconcerting is the finding that BPA-free plastics in some cases leached more BPA than the non-BPA free plastics.
Watson and Vinas focused on key biochemical pathways that are normally stimulated when estrogen activates membrane receptors. One, involving a protein known as ERK, is linked to cell growth; another, labeled JNK, is tied to cell death. In addition, they examined the ability of BPS to activate proteins called caspases (also linked to cell death) and promote the release of prolactin, a hormone that stimulates lactation and influences many other functions.
“These pathways form a complicated web of signals, and we’re going to need to study them more closely to fully understand how they work,” Watson said. “On its own, though, this study shows us that very low levels of BPS can disrupt natural estrogen hormone actions in ways similar to what we see with BPA. That’s a real cause for concern.”