Bisphenol A, and Zebrafish: or How to Scare Pregnant Women

Bisphenol A (BPA) is a controversial compound which has led to consumer bans of baby bottles as well as caused concern over canned food. However, government regulators all over the world, continue to state that at normal levels of exposure, BPA is safe. Recently, a study from the University of Calgary has been making the rounds on social media, claiming a link between BPA and hyperactivity disorder. The paper claims that pregnant women should avoid BPA coated register receipts. Is this cause for concern or hype with no substance?

What is Bisphenol A?

BPA is a carbon-based synthetic compound which can be found in canned food, plastics, and receipts. Polycarbonates which contain BPA are preferred due to their lightweight and durability compared to other materials, such as glass. In canned foods, they are used to prevent the food from coming into contact with the metal surface of the can. With any food product, repeated contact with a surface will cause leaching of that material into what you consume. BPA can also be absorbed through the skin from the use of creams and the handling of receipts.

Concern over BPA stems from its ability to mimic the effects of natural estrogen, which led scientists to research the possible effects of BPA on the endocrine system. The first study to show a possible link between BPA and endocrine disorders was completed in 1997, by exposing rats to low doses of BPA. More studies were soon to follow. These research findings alarmed parents and put pressure on governments to determine whether the levels of BPA we are exposed to are harmful.

The Banning of BPA in Baby Bottles

In 2008, The Government of Canada banned the use and sale of BPA in baby bottles given the concern raised by the growing number of animal studies. The specific concern was that babies, which are smaller and less developed, were at a greater risk from BPA than adults. There was no scientific evidence that this was indeed the case, but given pressure from constituents, the government decided to take precautionary measures. The government release explained that, “The scientists concluded in this assessment that bisphenol A exposure to newborns and infants is below levels that cause effects; however, due to the uncertainty raised in some studies relating to the potential effects of low levels of bisphenol A, the Government of Canada is taking action to enhance the protection of infants and young children”.

The problem with precautionary measures such as this, is that bans tend to stigmatize products that are otherwise safe. This has happened in the case of silicone breast implants in the United States, which the US Food and Drug Administration (FDA) banned prematurely in 1992. As documented by Barry Glassner in his book, The Culture of Fear, this ban resulted in a cultural panic and devastating litigation against silicone breast manufacturers. However, health problems were not supported by the epidemiological studies which showed that there was no health difference between women with implants and those without. The same thing occurred in the case of thimerosal containing vaccines. In the book, Autism’s False Prophets, Dr. Paul Offit explains how in 1999, Dr. Neal Halsey, a pediatrician from Johns Hopkins Medical School, pushed to remove thimerosal from vaccines. Dr. Halsey’s concern was over the the fact that thimerosal was an organomercury compound, however, epidemiological studies showed thimerosal to be safe. In his dealings with the FDA and Centers for Disease Control and Prevention (CDC), Dr. Halsey was able to convince them to suggest delaying the hepatitis B vaccine. This back-and-forth between the CDC and FDA created a confusion that harmed, more than it helped. Not only did it harm those who were unnecessarily exposed to hepatitis B, but instilled distrust when it came to government regulatory action towards vaccines.

Banning BPA by itself is not risk-free. Dr. Steven Novella, a clinical neurologist and managing editor at Science-Based Medicine, worries, “What will take its place, and is that safe? BPA is used because it is cost effective and there are advantages to the durable plastic that is used in many products. What will we lose if we give up this technology?”.

In 2012, the FDA amended its regulations to no longer provide information for the use of BPA in baby bottles. This change was not due to safety concerns with BPA, but that manufactures had stopped on their own accord, the use of polycarbonates in the production of their baby bottles.

What is the Evidence?

Most of the evidence on the health effects of BPA have been done in animal studies or in studies which measure the concentration of BPA in humans. A lot of these studies have been contradictory in their conclusions. Given the short half-life of BPA, it is hard to determine general exposure in humans, therefore, it is hard to do an appropriate epidemiological study of the health effects of BPA.

Animal studies have also been criticized since most expose the animals to BPA in ways that would not reflect normal human exposure. According to Richard M. Sharpe of the University of Edinburgh, approximately 70% of BPA gets inactivated in our digestive system. However, in some studies, animals are injected with BPA, exposing them to higher doses than would be consumed through our canned foods and water bottles. Animal models, though scientifically useful, should not be taken too literally. After all, human beings are not mice. The fact that BPA was found to have health effects in mice, can be a good reason to do further epidemiological research, but one should always have caution before extrapolating too much from these studies.

As it stands right now, the risks are still theoretical. What that means is that BPA is likely to have an endocrine effect, but that at current exposures we are not at risk. On January 21, 2015, the European Food Safety Authority (EFSA), re-evaluated the evidence of BPA and concluded that at current levels of exposure to BPA, there were no consumer health risks. In fact, our exposure to BPA is three-to-five times lower than the “tolerable daily intake” (TDI). Infants and toddlers were exposed to more BPA, given their body size, but the exposure was still lower than the TDI for infants and toddlers. This included all forms of exposure, from canned food and water bottles, to receipts and cosmetics. The EFSA conclusion, of the safety of BPA, is in line with the FDA’s own assessment of the evidence.

…Then Came the Zebrafish

In spite of the evidence, many are still afraid of the potential harm from BPA especially when it comes to infants and fetuses. Which is why a recent article titled, “Attention pregnant shoppers: Study says those cash register receipts could harm your unborn child”, found in the health section of the National Post, is particularly frustrating. Given that society is already hyper conscious about what pregnant women do or do not do to their bodies, we don’t need more ways of shaming peoples life choices. This toned up rhetoric does little to inform mothers about the safety of their children and the fault lies not only with the National Post, but also with the researchers.

University of Calgary researchers published a paper called, “Low-dose exposure to bisphenol A replacement bisphenol S induces precocious hypothalamic neurogenesis in embryonic zebrafish”. In this paper they make very stark proclamations involving the use of BPA’s, explaining that their results, “support the removal of all bisphenols from consumer merchandise”. What evidence do they provide to make these claims? The scientists placed zebrafish embryos during their second semester of gestation in a water solution which contained BPA and then watched as they matured. They noticed that the zebrafish embryos in the BPA contaminated water exhibited increased locomotor activity, which they claim represents hyperactivity in human beings.

Not only are zebrafish bad models for human related disease, but human fetuses do not gestate in pools of water. It is not likely that exposure to BPA in the womb would be analogous to the types of exposure received by zebrafish embryos. So why raise concern about receipts specifically? The scientists claim, that since the BPA exposure of the zebrafish embryos was lower than the TDI of infants and toddlers, that this represents a concern for even the small dose of BPA we absorb through skin contact of receipts coated with BPA. Even the famous Canadian chemist Dr. Joe Schwarcz ain’t buying this one, and frankly neither should you.

So, why all of this rhetoric for a finding which seems to be a stretch at best? I don’t know. One way to increase research funding is to stoke public interest and there is no better way to do that than to scare them. Scientists are also not immune to their own biases, and could be against BPA for more ideological reasons. Reasons which could cloud their research findings, or make them see more than what is given by the data. What the exact motivation was for these scientists is just speculation, but in the end it doesn’t really matter. One study is never enough, and given the preponderance of evidence to the contrary, it is safe to say that at current levels of exposure to BPA our babies will be just fine.

Conclusion

The moral of this story is that both the media and scientists are good at over-hyping research findings, and both can profit off the “sky is falling” narrative. Whether or not BPA is safe, or the extent to which BPA is safe, is a complicated story. We would better serve society if we didn’t scare people by over-selling and over-extrapolating our research findings. Over the years, as the steady grind of research has been developed, there seems to be no evidence that at our current rate of exposure to BPA is doing any harm. One study on zebrafish is probably not going to change all that.

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