Carcinogens

Should we be concerned about BPA?

Carcinogens have always existed; some are manmade, and others occur naturally within our environment. A very simple definition of a carcinogen is that it is a substance, agent or organism that has the potential to cause or create the environment for cancer. Based on that definition I would classify human behavior as a carcinogen, but who am I? Human activities have introduced new carcinogens as we have evolved, or devolved, however you choose to view the process. Not all exposure to carcinogens results in cancer, which begs the question, what should we try to avoid and how far should we go to avoid it?

For example, we know and have known that smoking is not beneficial to our health and quitting smoking is one of the best decisions one could make. My mother did not heed that warning and subsequently passed away from lung cancer at 73. I have had other relatives who were lifelong smokers who did not share her fate. This would imply that there are other factors involved and that simply being exposed to a carcinogen (or a virus, some people need to hear this) does not necessarily mean that we will perish off the face of the earth in its presence. In this writing I will dive into BPA and try to determine its “threat level” to our species.

What is bisphenol A?

Bisphenol A, also known as BPA, is an organic compound made from fossil fuel sources. BPA is also classified as an industrial chemical that is used to make resins and clear plastic (polycarbonate plastics) going as far back as the 1950’s. We will get more into the history of BPA in a moment. Polycarbonate plastics are widely used today as they are cheap to make, very strong and flexible. [i]

You will find polycarbonate plastics, made with BPA, in baby bottles, reusable plastic bottles, food containers, tableware and storage containers to name a few. Polycarbonate plastic is also the go to for prescription eye wear as these lenses are far more durable, lighter and more scratch resistant than the “old school” glass lenses. Not only is BPA used to make polycarbonate, but it is also used to make epoxy resins which line the inside of metal food cans, bottle tops and even water supply lines. It is likely that the plumbing in your home today has benefited from the existence of BPA. Old cast iron plumbing is known to corrode and deteriorate much more rapidly than PVC, which contains BPA. [ii]

According to the Food and Drug Administration, BPA is safe to use. The FDA first approved BPA in the early 1960’s and since has reviewed its safety following several petitions that were filed questioning the use and safety of the product. In the fall of 2008, the FDA issued a draft confirming the initial approval. Again in 2014, FDA experts specializing in toxicology, analytical chemistry, endocrinology, epidemiology and other fields completed a four-year review of over 300 scientific studies. This review, according to the FDA, did not find any information that would prompt a revision of the FDA’s position on the safety of BPA. [iii]

Background of use

Aleksandr Dianin, a Russian chemist, first synthesized BPA in 1891. He was able to do this by combining phenol with acetone while in the presence of an acid catalyst. BPA was the result of this reaction. By the 1950’s, scientists were able to produce a clear hard resin, now known as polycarbonate, by adding phosgene (carbonyl chloride) to BPA. As previously mentioned, polycarbonate became widely used in the manufacture of plastics, so much so that by the early 21^st century, global BPA production was estimated at 6 billion pounds annually. [iv]

Along the way, BPA has had other uses as well. One of the more interesting applications was as a pharmaceutical hormone. A British researcher at the University of London, by the name of Edward Dodds, was one of the first to identify the estrogenic properties of BPA during the 1930’s. He referred to the chemical compounds that he was testing as the “mother substance.” Diethylstilbestrol, DES, was one of the compounds that he was able to produce with the help of BPA. DES was utilized in the 1940’s for several female related issues that included menstruation, menopause, nausea during pregnancy and even for preventing miscarriages. DES was prescribed to millions of pregnant women over a 30-year period. The drug was eventually banned by the FDA in 1979 due to the potential link to reproductive cancers in girls born to mothers taking DES. [v]

How are people exposed to BPA?

According to the National Institute of Environmental Health Sciences, exposure to BPA is so widespread that detectable levels of BPA have been found in 93% of over 2500 urine samples from people 6 years and older. [vi] That same source claims that the main route of exposure comes from diet as BPA leaches into food from food storage containers, food packaging and water bottles. Now I have written at length about this in a previous paper and was not able to validate that claim, then or now. The article also states that dust, air and water are among other possible sources of exposure.

Exposure to BPA can also occur occupationally. Most of the studies have focused on cashiers handling point of sale thermal receipt paper coated with BPA. I was not able to find the results of those studies and it appears as though they have not been published. There was the 2013-2014 NIOSH BPA exposure study which included six U.S. based companies that either made BPA, BPA based resins or made and used BPA filled waxes. A total of 78 workers participated in this study. The study showed that the workers had BPA levels 70 times higher than the general population. What is not clear, based on that research, is if those elevated levels were associated with any negative health effects. [vii]

Evidence of harm – both for and against

Unlike the FDA, the EPA is concerned about BPA based on animal studies showing that it is estrogenic and could pose developmental and/or reproductive risks. Specifically, they have questions about BPA’s impact on children’s health and the environment, however, they find this issue outside of their jurisdiction and defer to the FDA to make the decision. The EPA does not intend to initiate any regulatory action regarding BPA. Nor do they provide any evidence to support their stance on the issue. [viii]

The Consortium Linking Academic and Regulatory Insights on BPA toxicity, Clarity-BPA, which was a two-year long toxicology study sponsored by the NTP and NIEHS, concluded that BPA did not elicit adverse effects at levels of 25,000 micrograms/kg bw/day. The NTP followed that up with their own 2-year study using levels twice that and concluded that there was no convincing evidence of BPA induced carcinogenesis in rats or mice. [ix]

A systematic review of 29 epidemiology studies and 27 experimental animal studies performed in 2022 aimed to evaluate the potential carcinogenicity of BPA in humans. This review was very supportive of the use of BPA and brought up some very good points. The authors noted that while epidemiology studies may have many limitations that increase the risk of biased results, they do a good job in providing clear and consistent evidence for an association between BPA and any type of cancer.

This review highlighted that there was no clear association between BPA and cancer in humans, and the animal studies failed to show one as well. Not only that, but they could not identify any mechanism of action that would be relevant to humans. The authors concluded by calling the evidence for a causal relationship between BPA and cancer inadequate. [x] In summary, according to this research, BPA does not cause and is not associated with cancer in humans.

One of the major reasons for this conclusion was that the studies did not adjust for any cofounding factors or only adjusted for sociodemographic factors such as age and sex. This makes sense, in that we can’t know based on these studies because cofounding factors were not accounted for consistently. We may all drink from plastic or find ourselves exposed to BPA, but we don’t all eat the same and we all have different lifestyles.

The breast cancer prevention partners do not share the same view on BPA that I just discussed. They have classified BPA as a reproductive toxicant and link BPA to breast and prostate cancer due to its hormone disrupting potential. And that is not all. According to this article, BPA is the root of all evil and is responsible for the following: decreased libido, premature puberty, obesity, diabetes, fatty liver, heart attacks and immune disorders. There were more listed, but, for the sake of time, let’s stop there. I was intrigued and anticipated some strong research to back these statements up. No such luck. The authors did not provide any scientific research to back these claims. One source took me back to the European Environment Agency (most of the negative things about BPA took me back to these individuals throughout my research for this writing) where they had many resources cited, none of which had anything to do with BPA. Interestingly enough, there was a climate change section. [xi]

A 2022 study in the National Library of Medicine suggested that recent research points to BPA effecting the environment around a tumor and may promote breast cancer growth. It can do this by inducing estrogen receptor signaling in breast cancer cells. So, BPA, as discussed earlier, may not cause cancer, but does it create an environment where cancer can progress? This review shared a similar fate as one previously discussed as it was not able to determine a mechanism of action by which this process could occur in humans. The authors noted that more research is necessary to determine the impacts of BPA exposure regarding human health and to better understand BPA’s role in cancer progression to metastatic cancer. [xii]

Dose required for harm

There is a tolerable daily intake established for BPA that we will discuss in a moment. But first, there is some debate as to whether BPA was ever evaluated for safety. The Environmental Working Group suggests that BPA was “grandfathered” into the 1976 Toxic Substances Contral Act, which was the first law to regulate industrial chemicals. Meaning that it was presumed safe by the EPA with no evaluation of the evidence. I was not able to substantiate that information, but I do think that it is worth noting as we discuss the TDI’s. [xiii]

The TDI for BPA is 4 micrograms/kg bw/day and this number also represents a built-in safety margin of 150 micrograms. [xiv] This same source estimates that a person weighing 60kg has a lifelong safe daily intake of 240 micrograms per day. This equates to roughly 1450 cans of beverages every day to reach the level of BPA considered safe for a daily lifelong intake. Another source goes a little farther to reinforce the safety of BPA by stating that a consumer would have to ingest more than 1,300 pounds of food and beverages in contact with polycarbonate plastic every day for an entire lifetime to exceed the safe level of BPA set by U.S. government agencies in 2018. [xv]

With exposure up to 25-50,000 micrograms a day having been deemed safe, as mentioned earlier in this writing, and as low as 4 micrograms per day being prescribed as the TDI, it is very difficult to determine if anyone really knows what the dose required for harm is for BPA. Add to it that the harm has not been established here either.

Litigation re bisphenol A

One would think that with all the claims about how dangerous BPA is there would be a plethora of lawsuits. That is not the case. In fact, I was able to locate more websites of attorney’s willing to represent people than I did lawsuits over BPA. The two that I was able to find involved not properly labeling products containing BPA. I was not able to locate a lawsuit that involved harm caused by BPA directly.

Conclusions and recommendations

Based on the research that I was able to locate, I consider BPA’s threat level to humans to be low. For me to view BPA as a serious threat there would need to be a mechanism of action for BPA to cause cancer in humans. This was discussed in two separate studies in this paper where no mechanism of action could be found, or it lacked relevance to humans. Furthermore, BPA does not even have a strong association with cancer in human or animal studies.

As I came to that conclusion, I could not help but think that this BPA issue is a distraction. Perhaps it is tied in some way to the green new deal/climate change agenda. An issue created to garner public attention and then utilized to motivate a particular political party’s base to get out and vote. I cannot say for sure, but what I do know is that there are far more valuable ways for people to invest their time than spending it on trying to avoid BPA. Instead of going out to the store and finding that BPA free bottle, go for a walk. Join a gym, try group exercise or yoga. Get moving and spend more time on things that matter, like meal preparation and other lifestyle changes that can have a real impact on one’s quality of life.

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[i]Bio-based replacements to fossil fuel plastics. Phys.org. Published 2021. Accessed September 15, 2024. https://phys.org/news/2021-01-bio-based-fossil-fuel-plastics.html

[ii]Bisphenol A. Ny.gov. Published 2011. https://www.health.ny.gov/environmental/chemicals/bisphenol_a/

[iii]Nutrition C for FS and A. Bisphenol A (BPA). FDA. Published online October 19, 2023. https://www.fda.gov/food/food-packaging-other-substances-come-contact-food-information-consumers/bisphenol-bpa

[iv]Cimmino I, Fiory F, Perruolo G, et al. “Potential Mechanisms of Bisphenol A (BPA) Contributing to Human Disease.” International Journal of Molecular Sciences. 2020;21(16):5761.

[v]Vogel SA. “The Politics of Plastics: The Making and Unmaking of Bisphenol A “Safety.” American Journal of Public Health. 2009;99(S3):S559-S566.

[vi]National Institute of Environmental Health Sciences. Bisphenol A (BPA). National Institute of Environmental Health Sciences. Published August 31, 2023. https://www.niehs.nih.gov/health/topics/agents/sya-bpa

[vii]Occupational Exposure to Bisphenol A (BPA) in U.S. Manufacturing Companies | Blogs | CDC. https://blogs.cdc.gov/niosh-science-blog/2017/01/05/bpa/

[viii]US EPA O. Risk Management for Bisphenol A (BPA). US EPA. Published September 21, 2015. https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/risk-management-bisphenol-bpa

[ix]Camacho L, Lewis SM, Vanlandingham MM, et al. “A two-year toxicology study of bisphenol A (BPA) in Sprague-Dawley rats: CLARITY-BPA core study results.” Food and Chemical Toxicology. 2019;132:110728.

[x]Prueitt RL, Hixon ML, Fan T, et al. “Systematic review of the potential carcinogenicity of bisphenol A in humans.” Regulatory Toxicology and Pharmacology. 2023;142:105414-105414.

[xi]Yee A. “How much exposure to BPA is safe?” Breast Cancer Prevention Partners (BCPP). Published April 25, 2024. Accessed September 15, 2024. https://www.bcpp.org/how-much-exposure-to-bpa-is-safe/

[xii]Kwon Y. “Potential Pro-Tumorigenic Effect of Bisphenol A in Breast Cancer via Altering the Tumor Microenvironment.” Cancers. 2022;14(12):3021.

[xiii]Timeline: BPA from Invention to Phase-Out. EWG. Published 2015. https://www.ewg.org/research/timeline-bpa-invention-phase-out

[xiv]Bisphenol is coming soon. Bisphenol-a-europe.org. Published 2024. Accessed September 15, 2024. https://bisphenol-a-europe.org/wp-content/uploads/2017/04/How-much-BPA-does-a-typical-person-take-in-through-a-normal-diet.

[xv]BPA in Common Products | Facts About BPA. Facts About BPA. Published March 28, 2024. Accessed September 15, 2024. https://www.factsaboutbpa.org/bpa-overview/products-bpa/?