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Bisphenol A (BPA) is a chemical commonly found in plastics, including food packaging. It has the potential to disrupt cellular function. Are we exposed to enough BPA to cause harm? And should we be concerned about products labeled ‘BPA-free’? Let’s just say...it’s not a simple answer.
What is BPA?
Remember when Nalgene bottles were the must-have item? Back in the early 2000s, we didn’t have jet packs, but we had durable, hard plastic water bottles made from the same material found in bulletproof glass. They didn’t crack when dropped, and they didn’t give off a plastic taste to your water. It felt like we were living in the future. And the future seemed great.
These bottles were made from a strong plastic called polycarbonate, which is specifically polycarbonate derived from bisphenol A. Here’s what BPA looks like:
To make polycarbonate plastic, you'll need bisphenol A (BPA), phosgene (which provides the carbonate part), and other chemicals that will bond them into a repeating chain structure: BPA-carbonate-BPA-carbonate-BPA-carbonate. Plastics, or polymers, are essentially chains like this. For example, polyethylene is a chain of ethylene molecules, polystyrene is a chain of styrene molecules, and so on. The structure of polycarbonate BPA plastic looks like this (with repetition indicated by brackets):
Nothing is permanent, even the toughest plastics. Over time, polymers start to degrade, and small fragments can break free from their chain structure. While the BPA within the chains isn’t harmful on its own, people are concerned about the free BPA molecules that escape. Heat accelerates this breakdown, so items that are microwaved or exposed to sunlight are more likely to release the BPA that people are worried about.
The main concern stems from BPA’s shape—it closely resembles estradiol, a type of estrogen. This resemblance is so striking that BPA can actually bind to estrogen receptors within our cells' nuclei. These receptors influence how our cells interpret DNA instructions, and excessive estrogen at inappropriate times or places can disrupt embryonic development or promote tumor growth.
Is BPA Harmful?
If someone offered you a glass of estrogen, you’d likely decline. But drinking water from a polycarbonate bottle is far from the same thing. For one, very little BPA leaches from the bottle into your water. Additionally, BPA binds to estrogen receptors 10,000 times weaker than estrogen itself.
The real issue isn't whether BPA mimics estrogen—we know it does. The concern is whether the BPA that leaches from water bottles (as well as canned food liners and thermal paper used in store receipts) is in sufficient quantity to cause harm. Some scientists and environmental organizations believe it is, while others, especially those with ties to the plastics industry, argue that it isn't.
Here's a quick rundown of the opinions from various organizations:
The World Health Organization concluded in 2010 that the evidence ranged from 'no health concerns' in some instances to insufficient data in others.
The US Food and Drug Administration stated in 2014 that 'an adequate margin of safety exists for BPA at current levels of exposure from food contact uses' (such as can liners and packaging) and that 'BPA is safe at current levels found in foods.'
The European Food Safety Authority asserted in January 2015 that there is 'no health concern for any age group from dietary exposure and low health concern from aggregated exposure.'
The Endocrine Society declared in a 2015 review that recent research 'eliminates any doubt that [endocrine disruptors like BPA] are contributing to increased chronic disease burdens related to obesity, diabetes mellitus, reproduction, thyroid, cancers, and neuroendocrine and neurodevelopmental functions.'
These conclusions are overshadowed by significant controversy. While there’s no conclusive evidence proving BPA is harmful, it's difficult to know who to trust when the most reputable studies are funded by industry, and the so-called 'independent' studies are small and can't be replicated.
Mother Jones discovered that one company was concealing its own test results, and the Environmental Working Group has accused the US government of placing too much trust in industry-sponsored studies. Sadly, study results often align with the interests of their funders. This bias can stem from unconscious factors or intentional decisions in how studies are designed and reported. For instance, critics argue that the rats used in many BPA studies don’t respond to estrogen strongly.
This is just one criticism raised in a 2005 paper in Environmental Health Perspectives, which argues that BPA is toxic at low doses—a fact overlooked by decades of research. Most substances follow a clear dose-response relationship: the more alcohol you consume, the more intoxicated you become. To claim that BPA is dangerous at low levels, researchers must assert that BPA doesn’t follow this general pattern. Statistician Patrick McKnight reviewed this argument for Sense About Statistics, finding the research on low-dose effects to be disorganized. While low doses could be harmful, the existing evidence doesn’t provide strong support, requiring more research.
This conclusion is shared by nearly every study, whether supportive or opposing: we simply don’t have enough research on BPA. Or more precisely, there’s been ample research, but it often doesn’t address the key questions. For example, there’s been minimal research on the impact of BPA on actual human beings. Most studies focus on cells in a lab setting or on effects in rats and fish.
Despite our limited understanding of BPA, we know even less about the chemicals used in 'BPA-free' plastics. One common BPA alternative is bisphenol S, which also appears to act as an endocrine disruptor. A study examining over 500 plastic products, published in Environmental Health Perspectives, conducted by a lab with a contentious reputation in the plastics industry, found that “almost all” of the tested plastic products exhibited estrogenic activity, including those labeled “BPA-free.”
The Environmental Protection Agency evaluated several potential alternatives to BPA in thermal paper (commonly used for cash register receipts) and concluded that there are “no clearly safer alternatives.” In their comprehensive comparison chart, only BPA had most of its hazard ratings filled out; the rest of the entries were marked with footnoted estimates.
If You Want to Avoid BPA
I’m not trying to panic anyone. You probably don’t need to completely avoid BPA. It's likely that low doses won’t pose a significant risk, but we don’t have enough conclusive evidence to be certain. There's no harm in choosing alternatives to plastics, particularly if you prefer their aesthetic or practical benefits.
If you’re avoiding BPA-containing plastics as a precaution, it’s a good idea to avoid other plastics as well. After all, new chemicals don’t undergo the same level of scrutiny before being introduced to the market. So when a product says “BPA-free,” it simply means it lacks a chemical that has been studied, and instead contains a newer, untested chemical. It could be safer, or it could be worse. Here are some strategies you might consider to reduce exposure to potential endocrine disruptors:
Opt for non-plastic options like glass or stainless steel. While usually more costly, these materials are available for items such as food containers and water bottles. Take advantage of the mason jar trend while you can!
Avoid microwaving plastic containers or exposing them to heat and sunlight. Even if you store food in plastic, consider transferring it to a different container for microwaving, and wash plastic by hand rather than using the dishwasher.
Stay away from canned foods because the lining of cans often contains BPA. Fresh or frozen alternatives don’t carry the same concern. Tetra Paks, which resemble juice boxes, use a plastic not yet linked to estrogenic activity.
Resist licking receipts. It may sound funny, but you’re not a six-month-old. At that age, my kids found receipts irresistible. Simply handling a receipt with dry hands won’t significantly affect the BPA levels in your body, so if that’s all you do with them, you’re likely fine.
Some individuals go to extreme measures to eliminate plastics from their lives. If that seems excessive, consider incorporating these habits occasionally. For instance, I prefer storing leftovers in glass containers at home, though I still rely on plastic when packing my lunch for the day. These precautions might seem outdated in fifty years, but for now, they feel like the right choice.
Illustration by Tara Jacoby.
