8 Everyday Things That Are Surprisingly Radioactive

Bananas are packed with potassium, which is great for you — and a small fraction of all potassium in nature is a radioactive form called potassium-40. That means every banana gives off a whisper of radiation, which is why physicists half-jokingly measure small doses in “banana equivalent doses.”

Before you swear off smoothies: you’d have to eat something like ten million bananas at once to reach a dangerous dose, and your body simply flushes out excess potassium anyway. Eat the banana. Your muscles want the potassium far more than the trace radiation could ever bother you.

Brazil nuts are the most radioactive food you’re likely to eat — often hundreds of times more so than a banana. The trees have enormous root systems that pull naturally occurring radium up out of the soil and concentrate it in the nut.

Even so, we’re talking about a genuinely trivial amount. Nutritionists happily recommend Brazil nuts as one of the best sources of selenium on the planet. A couple a day is a health tip, not a hazard.

That handsome granite slab in a lot of kitchens formed deep underground, and granite naturally contains traces of uranium and thorium. As those slowly decay, some stone releases a faint trickle of radon gas along with a bit of background radiation.

The vast majority of granite countertops emit far too little to matter. The EPA’s practical advice isn’t about your counters at all — it’s to test your home for radon, because the gas seeping up from the ground beneath a house is the part actually worth checking.

From the 1930s into the early 1970s, the cheerful red-orange glaze on Fiesta dinnerware got its color from uranium oxide. Collectors nicknamed it “radioactive red,” and a Geiger counter held to a genuine vintage plate will chatter away happily.

Displayed on a shelf, these dishes are fine. The one sensible caution is not to eat acidic food off vintage uranium glaze day after day, since a little uranium can leach out. Admire them; maybe don’t use them for your morning grapefruit.

Before modern glow-in-the-dark paint, watch and clock hands were coated with radium so they’d shine all night. The eerie thing is that many still glow faintly a century later, because radium’s half-life is around 1,600 years.

An old watch sitting in a drawer poses very little risk to you. The real tragedy was the “Radium Girls” — factory workers who licked their brushes to a point and swallowed the paint, a grim chapter that helped launch modern workplace safety law.

Most household smoke alarms are the “ionization” type, and they work thanks to a minuscule amount of a radioactive element called americium-241. It ionizes the air inside a small chamber, and when smoke drifts in and disrupts that flow, the alarm sounds.

The source is sealed and gives off almost nothing outside the device. This is radiation quietly saving lives on your ceiling — a case where a radioactive material is doing one of the most protective jobs in your home.

Clumping cat litter is usually made from clay minerals like bentonite, dug straight out of the earth. Like a lot of natural clay and soil, it carries trace amounts of uranium, thorium, and their decay products.

A big bag of litter can register slightly above background radiation, enough that it has occasionally tripped sensitive detectors at ports and landfills. For your cat and for you, though, it’s completely harmless — just clay being clay.

Here’s the exception to our reassuring theme. Tobacco plants take up a radioactive element called polonium-210 from fertilizer and soil, and it collects in the sticky leaves. When you smoke, tiny radioactive particles lodge in the lungs and sit there delivering a dose.

Unlike everything else on this list, this genuinely adds up over years and is one more reason smoking is so harmful. It’s the rare case where the radioactivity in an everyday product really is worth avoiding — by not smoking.

You are, right now, mildly radioactive. Your body is full of potassium-40 (the same isotope as in bananas) and a bit of carbon-14, and together they cause thousands of tiny radioactive decays inside you every second of your life.

You even give a faint dose to anyone you share a bed with — utterly harmless, and a fun fact to deploy at the right moment. Being slightly radioactive is simply part of being alive on a planet made of the same star-stuff as everything else.