Bisphenol A (BPA): Other than a good if not suggestive acronym, what is it? If you’re someone who has children or reheats leftovers in Tupperware, then you may be familiar with this synthetic material, as it is widely available and in common use today. For most of us, though, we are only vaguely aware of it as something having to do with plastic, and you probably have an inkling that it is harmful to us in some form or fashion, but that the science concerning this mystery acronym is still ongoing.
A TOXIC CHEMISTRY
Bisphenol A was first synthesized by the Russian chemist Alexander Dianin in Saint Petersburg one hundred thirty years ago. It is made by combining the organic hydrocarbon phenol with acetone. (See Figure 1.)
Phenol is a hexagonal-shaped ring molecule, and a close cousin of the hydrocarbon benzene. Benzene is a ring-shaped molecule, where the ring-shaped carbon structure is saturated with hydrogen. What makes phenol different from benzene is that one of the hydrogen molecules has been replaced with an -OH molecule or a hydroxyl group. The hydroxyl group is common to water (the core of acid-base chemistry), alcohol and many other compounds across the organic spectrum. Phenol is a strong acid, extremely toxic to human beings—for example, direct skin contact or exposure to phenol in excess of ten square inches is considered fatal. It is widely used as an industrial reagent and in the production of polycarbonates, epoxies, Bakelite, nylon, detergents, herbicides and a wide variety of pharmaceutical components.
There are two physical properties of phenol to keep in mind, because of the attached hydroxyl group: it is water-soluble and when mixed with other organic liquids it forms an azeotrope. (This is a fancy chemical name for a liquid mixture that boils as a liquid mixture, making it difficult to separate the mixture into individual components through boiling or distillation alone.)
Acetone, the second reagent used in producing BPA, is the binder molecule that sits in the middle and bridges the two phenol molecules together. Most of us interact with acetone on a frequent basis through its two main uses, nail polish remover and paint thinner. Acetone is produced and disposed of in the human body through standard metabolism and is present in kidney-liver functions and the urinary tract. Acetone is a by-product of fermentation and can build up in the human body due to imbalances such as prolonged fasting, alcoholism and diabetes, all of which produce excess levels of acetone. This is commonly known as ketoacidosis and in some cases results in harm to human reproductive organs.
LOTS OF IT AND PROFITABLE
Today BPA is primarily used as a building block to produce two synthetic building materials: polycarbonates (75 percent) and epoxy resins (25 percent). Total global demand for BPA is approximately 6.5 million metric tonnes annually, even though it’s only 0.4 percent of the total petrochemical demand of 1,800 million metric tonnes. Capacity to produce BPA stands at roughly 9 million metric tonnes in 2020, with production facilities concentrated in the U.S. (12.5 percent), Western Europe (22.5 percent), Japan-Korea-Taiwan (25 percent) and China (30 percent). The production of BPA is concentrated in the four regions where most of the world’s petrochemical production capacity is located.
From a corporate interest or engineering perspective, the reasons why we use BPA are clinically real; performance, cost and “safety.” It is lightweight, durable, moldable and thermally stable, with a melt point of about 315 degrees F; it does not oxidize easily (it’s biologically stable); it is affordable; and maybe most important, it is clear or transparent when used alone or in other synthetic materials. The transparency of the material is likely the key advantage over other substitutes in a visual society such as ours. This makes BPA an ideal building block for large water bottles (think water cooler at work), beverage bottles (so you can see what you are drinking), baby bottles (you need to see the milk), electronics packaging (you need to see your gadget) and as a liner to preserve food that you may find in canned goods (no metallic aftertaste).
The issue of affordability is probably understated as to why BPA is so integral to our packaging supply chain. Both phenol and acetone used to manufacture BPA are derivative chemicals, produced as by-products in the manufacture of other synthetic materials, namely the big four consumer plastics. Being a by-product has the distinct economic advantage of constant surplus production, because supply is determined by the big four basic plastics (low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and polypropylene). As you produce more of the big four, the by-products are produced whether you need them or not and the situation for the last thirty to forty years has been oversupply. When you have a material in chronic oversupply, the best option is oftentimes to create new demand outlets.
If global demand is 6.5 million metric tonnes and production capacity stands at nine million metric tonnes, the inference is that the BPA industry needs only to utilize about 70 percent of its capacity to meet global demand. Further, BPA is a solid and environmentally stable material, meaning that it is cheap (in relative terms) to transport around the world, with a variety of implications for centralizing production and keeping regional price differences or arbitrages stable in terms of trade volatility.
Even though BPA is a by-product, the materials used to make BPA (acetone and phenol) are also by-products themselves and in most cases in higher oversupply than the BPA itself. The typical price spread between BPA and the phenol and acetone needed to manufacture BPA is relatively healthy and results in a profitability of two to three billion dollars per year before fixed and variable costs. A healthy business model or vested financial interest is nothing to sneeze at and leaves plenty of capital to fund scientific research, marketing, lobbying and other support industries necessary to preserve that primary source of wealth generation—the price difference between BPA and the raw materials required to manufacture BPA.
It should also be noted that the BPA production industry is fairly concentrated, with only about seven to ten true market participants globally. The big players in the BPA game are Bayer, Dow Chemical, SABIC (Saudi Arabia Basic Chemicals), Dow, Momentive-Hexion Specialty Chemicals, Sinopec (China State Petrochemicals), Mitsubishi (Japan Conglomerate), Mitsui (Japan Conglomerate) and LG Chem (Korea Chaebol). The heavy concentration of the industry and the homogeneity of the product are important in that it suggests that the main risk to industry profitability is a change in public sentiment versus direct competition from a rival company.
HOW BPA DEGRADES
Despite its engineered material stability, like many materials BPA is susceptible to the following degradation mechanisms: leaching, friability and thermal softening.
- Leaching: Put two materials in contact for a long period of time and some molecules of material A are going to pass into material B and vice versa. It may be a very small number of molecules but some leaching will occur, with time in contact being the determining variable—think canned food storage and that metallic aftertaste.
- Friability: Rub a plastic bottle with a nail file for a couple of minutes; notice the light clear flecks on the nail file—those are friable particles.
- Thermal stability: Take a plastic bottle and put it in the dishwater several times; notice how the plastic bottle softens and is deformed. You have now thermally fatigued the plastic bottle.
BPA, like almost all thermal polymers, is subject to all three of these deterioration mechanisms. And because BPA is prevalent in food packaging, it is almost inevitable that some amount of BPA will mix with food or drink and be ingested into the human body, even if the amounts are incredibly small or at the molecular level.
Figure 1: The Chemical Structure of BPA
IS IT SAFE?
So what happens when small amounts of this synthetic material, BPA, are ingested into our bodies? I will give you a hint: It accumulates. The other detail to note (and the rationale for the mini-organic chemistry lesson at the beginning of this article) is that benzene molecules (the hexagonal ring) are very stable and difficult to break down. This is one of the reasons we utilize benzene so ubiquitously in modern chemistry but also the reason why chemicals labelled as carcinogens usually contain benzene.
The second key thing to note about BPA is that the scientific and medical communities have classified it as a xenoestrogen, in that it exhibits estrogen-mimicking behavior in the human biological system. Without having a background or educational degrees in medicine, chemistry or advanced science, these are the key details I note. We interact with it; it enters our bodies in minute quantities; it is chemically stable and difficult to break down; it behaves in our bodies as if it were a hormone; and thus it interacts with our endocrine systems.
BPA has been investigated and evaluated as a synthetic hormone for at least the past eighty years. In the late 1930s, it was evaluated as a synthetic estrogen and found to be approximately 1/37,000th as effective as estradiol, the naturally produced form of estrogen, prescribed as a hormone replacement for women experiencing menopause.
This potential interaction as a synthetic hormone is a primary reason why many consumer advocacy groups have raised issues about the common usage of BPA and why it has been studied extensively for the past twenty years by the various food, health and medical safety organizations across the globe. There are many, many studies by these various organizations that, for the most part, have concluded that “BPA in low levels in the human body is safe,” followed by a dozen or so caveats about the effects of low and high dosages on mice. The studies and websites typically contain statements such as the following: “Overall, the study found ‘minimal effects’ for the BPA-dosed groups of rodents. The report did identify some areas that may merit further research, such as the increase in occurrence of mammary gland tumors at one of the five doses, in one of the groups. But the significance of these findings will be assessed through the peer review process.” Not very reassuring, to say the least.
Many of these studies are publicly available and can be found at websites such as factsaboutbpa.org, but there are a couple of key details to note about these types of informative public health advocacy websites and studies. Not all the time, but more often than not, they are funded by the very industry that produces the product in question. Factsaboutbpa is no exception, as it is funded and produced by the BPA and Polycarbonate Manufacturing Association. It would be odd (or not in their own self-interest) for the entities that profit from the manufacturing of BPA and related compounds to spend hundreds of millions of dollars evaluating their own product to determine that their own product is unsafe and has deleterious effects on humans after prolonged exposure. So odd that you can likely count the occurrences of industry doing this under their own volition on the fingers of one hand.
I am not suggesting that the scientific research done around BPA is faulty or fraudulent, as it is subject to the same rigorous peer review that all research is required to undergo to be labeled as “science.” My concern is one of vested interest, conflicting priorities and the distorted reality that often occurs when science is mixed with corporations and corporate lawyers. What we are seeing in society more and more is a case where the individual is left to decide who has the best science. A natural inclination is to assume that the entity that spends the most money on their science has the best science. What is perhaps more accurate to state is the entity that has the most resources typically produces the most science (quantity) and the best-packaged science (quality) but not always the correct science (truth). I think this case is no exception.
The other underlying issue is that our society and legal system currently do not have a commonly-accepted numerical definition of safety or many other key definitional words that we use all the time to make decisions about our lives. I’m sure there is legal definition of “safe” and “unsafe,” but I’m willing to wager that these definitions are so obfuscated in legalese that they might as well be written in Klingon.
Here is the challenge that we have with BPA and many other synthetic materials that we interact with regularly. We have a lot of clues or circumstantial evidence that BPA is probably not something we want to be ingesting into our bodies in large quantities—call it common sense or intuition. Yet the scientific, health and safety administrations of our respective governments label it “safe.” The formal official published science deems the material as safe for human consumption in small amounts, after producing acceptable test results in laboratory rodents.
There are some important differences in the real world versus the laboratory. First of all, rodents and humans are different species, related but different. All humans are similar but also different, both in our genetics and the other materials we interact with on a daily basis. No two people have the same experiences, except in science fiction, so the other materials that we are mixing in the chemistry experiment of our bodies are going to differ in minute ways as well. No two of us are ingesting the same amount of micro-BPA particles and other things which may or may not interact with BPA.
We know that BPA affects our endocrine systems—which we know through our own experience of life to be delicate, requiring constant balancing and more sensitive early in our lives than later. So we know that the science deems BPA safe, but we also know that we are likely ingesting some amount and that it affects our very sensitive hormone regulation and balancing system.
As a hypothetical thought exercise, consider the following. What if high exposure to BPA affects only one in two hundred of us or 0.5 percent in a negative way after prolonged exposure, and the consequence of this exposure is a hormonal imbalance with knock-on effects that come with too much or too little of one or multiple hormones in our biological system? Would you determine that this material is safe or unsafe? It’s a personal judgment call, right? What if someone was paying you to perform science where the only acceptable conclusion was to call that same material “safe”? Would that influence your judgment?
Fortunately, in the case of BPA, there are some options for those of us who feel that the science is undecided. We can make conscious choices to minimize the usage of BPA, particularly for domestic food storage or any container that you may put through regular thermal cycling (such as the dishwasher). There is a readily available alternative to BPA and other hardened polycarbonates: It’s called glass. Unlike the larger discussion on the use of plastic versus glass that we explored in last issue’s article on plastics, the substitution of BPA for glass in baby bottles and Tupperware is unlikely to materially alter the global greenhouse gas balance, but it could have an important effect on your health.
One tactic that the BPA-producing industry has developed is to create similar but slightly different compounds, namely BPF and BPS. This allows the industry to label a storage or packaging material as “BPA Free” without having to alter the business model materially. Without having looked at those alternatives in depth, I can say confidently and without further study that the science around BPA is likely to be similar for BPF and BPS.
The key thing is to know whether your plastic packaging is a polycarbonate that may contain BPA, BPF or BPS. In this case this is something that we can know with certainty. Look for the triangle symbol on any food or food-containing packaging that you purchase. If the package has this symbol, seek an alternative or think about how you use that specific product and whether or not you want to risk the potential of BPA entering your or your child’s body and accumulating silently. If a given risk is unknown but easily avoidable, isn’t the most sensible course of action to avoid the unknown risk in its entirety?
BPA makes plastic harder and tougher without losing transparency, so plastic bottles and food storage containers are the main sources. Use glass instead of plastic for food storage and avoid beverages sold in plastic bottles; minimize the use of foods in plastic-lined cans. Flexible plastic wrap does not contain BPA.
Cold temperatures reduce the migration of chemicals, so storage of soups, broth, etc. in the freezer is probably OK. Let these foods cool completely before transferring them to plastic containers.
Babies are likely to be particularly sensitive to the hormone-mimicking effects of BPA. Use glass bottles and a stainless steel sippy cup. Do not give babies baby food packaged in plastic.
Most cash register receipts are thermal paper containing BPA! It’s unlikely that the chemical will transfer through your skin, but it could aerosolize if the receipt is crushed or folded. . . so handle receipts with care!
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Winter 2020🖨️ Print post