Blue Shift: How the Panic Over BPA Accomplished Nothing

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You can find alarmist warnings about BPA, a demonized chemical, in every nook and cranny on the Internet: it’s an endocrine disruptor, it can give you diabetes, breast cancer, or ADHD, among other things. It has a long and confusing rap sheet, and a lot of this stuff is really scary and people don’t know what to believe.

But please stop and take a deep cleansing breath. All this fear about BPA is overblown. We could get sidetracked by blaming media hype, poor science reporting, or even how scientific research is funded. But while these things are highly relevant, let’s talk about sharks instead.

In two articles about the link between herbicides and cancer, toxicologist David Eastmond and chemist Derek Lowe use a great analogy about sharks to explain the difference between hazard and risk. “Sharks are a hazard. They are fierce predators with sharp teeth, and they most definitely have attacked humans in the past. But for most people, sharks are not much of a risk. ‘Risk’ … refers to your chances of being harmed under real-world conditions, while ‘hazard’ refers to the potential for harm,” Lowe says. So if you’re swimming in a tank full of sharks, your risk is high. If you’re mowing your lawn somewhere in the Midwest, your risk is low. The hazard does not change.

This analogy applies to BPA as well (BPA is the shark in this scenario). It is a hazard—multiple studies have shown that it can harm animals when they’re fed large amounts of the stuff. But is it a risk? At the levels we’re being exposed to, no it is not. In January 2015, a huuuuuuuuge (seriously, it’s 1,000 pages long) risk assessment conducted by the European Food Safety Authority found that “there is no health concern for any age group from dietary exposure and low health concern from aggregated exposure,” according to its panel on BPA. That is, we are not swimming in pools with BPA sharks when we use, say, plastic food-storage containers.

But before we could sort this all out, people got pretty freaked out about BPA. As a result, a lot of companies pulled it out of their products and replaced it with—wait for it—virtually identical materials that appear to have the exact same effects as BPA in large doses. Nothing really changed. For all our stress, nothing is better, and things might even end up being worse—at this point, scientists know a lot more about BPA than they do about the newish alternatives. Also, you might now be out a couple hundred dollars on new glass and aluminum containers. We can hardly blame anyone for responding to this panic, but the way it’s turned out suggests that reacting to headlines without carefully weighing evidence may not be in our best interest in the long run.


Why do we need BPA anyway? Bisphenol-A, as it’s also known, is a compound that’s used as a building block to create long chains called polycarbonates. There are polycarbonates that don’t contain BPA, but companies like (or liked) BPA because it makes plastic that’s both tough and shatter-resistant.

bpa polycarbonate polymer

Illustration: Leigh Boerner and Grant Kindrick

BPA was used to make a lot of polycarbonate hard plastics, like those found in reusable water bottles, cell phones, car parts, and football helmets. Food companies use BPA in the resin that helps seal bacteria out of canned food; it’s also in dental sealant and cash-register receipts.

structure bpa bpf bps

Illustration: Leigh Boerner and Grant Kindrick

Did you notice how much I said “was” above? That’s because a lot of companies have stopped using BPA in plastic products, and started using very similar compounds called BPS and BPF instead. As you may have guessed, these stand for bisphenol-S and bisphenol-F. Per the illustrations above, these are very close analogs, structurewise, of BPA, and there’s some evidence that researchers see the same health effects from BPS and BPF in lab animals as they do with BPA. It stands to reason that BPS and BPF, like BPA, are also probably not dangerous in the amounts we’re exposed to. (In other products, such as thermal paper, BPA replacements are less similar in structure.)

So if a product is labeled “BPA-free,” it may still be using one of these very close analogs. All that this rigmarole has yielded is a new soothing label for brands to slap on their merchandise without really changing anything.


There are, of course, plastic alternatives. As I said above, BPA is not much of a risk at current doses. But if you really want to avoid both BPA and its friends, you could always go with glass or stainless steel. There’s also Tritan, a copolyester hard plastic that’s used in a lot of stuff now, including Camelbak water bottles. What exactly is in it is proprietary (of course, some companies never tell you anything in fear of their secrets being stolen by competitors) but according to Eastman, Tritan is not made from BPA or any of its analogs.

You may have heard there were risks associated with Tritan, but those came from a single source who founded a competing plastics company. In the end, Eastman sued them and won.

If you do choose a plastic alternative, check first if it has a lining because some metal water bottles have an epoxy lining that contains—guess what—BPA.


Science being science, research is still going on about BPA. And even though the European Food Safety Authority says the amount of BPA we’re getting now is fine, hopefully we’ll have an even clearer picture in the future, either on BPA or the newer alternatives. A lot of people out there try to avoid plastic in general just because of these uncertainties. I wish it were not true, but there is always going to be uncertainty; that’s how science is, in part because of how we have to test for possible effects on humans.

It’s unethical to feed people large amounts of BPA and see if it messes them up. So instead scientists have to use animal models, which may or may not be good models for people. They may also test on cells outside of a body, or use observational studies, which are the type that look back later and see if, just for a made-up example, diabetic white men in their 50s have high amounts of BPA in their urine. Leaving out the issue of correlation does not imply causation, observational studies aren’t the best (pdf), just because there can be a lot of factors the experimenters can’t control and it’s sometimes hard to draw clear conclusions. To revisit the sharks, we may never know exactly how big of a shark BPA is, but we still know it’s in the ocean, and we are on the beach.

That being said, health risks from BPA seems to be very, very small (remember: far-away sharks). There are many other things that are a much higher health risk, such as eating poorly, not getting enough exercise, riding in a car (especially if you’re a kid), or swimming in pools with hungry sharks. But if you’re still worried about being bitten, go for the (liningless) stainless steel.

Correction: A previous version of this piece erroneously stated that BPA is a plasticizer. It is in fact a monomer, a type of compound that’s part of the larger polycarboxylate plastic structure. The Sweethome regrets the error.

When a source of light moves toward you, its waves are compressed and pushed to a higher energy. We can’t always see this blue shift, but it’s there.

In the space of Internet science, there’s a lot of bad information floating around. In this biweekly column, Leigh Krietsch Boerner, chemistry PhD and science editor of The Sweethome, will tell you what you need to know on the science of home products, and what’s all around you.

(Top photo by Michael Hession, with illustration by Elizabeth Brown.)

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