Blue Shift: How the Panic Over BPA Accomplished Nothing

In two articles about the link between herbicides and cancer, toxicologist David Eastmondand 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.

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 stuffnow, 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.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s