Science fiction and horror movies have taught generations of people about the hazards of radiation. Aside from the giant monsters (who may or may not go on to wreck Tokyo), exposure to high levels of radioactive items can cause a host of alarming symptoms that usually end with a lingering, horrible death. Lower doses may not poison you, but every last picocurie (pCi) you’re exposed to measurably increases your lifetime risk of getting cancer. In other words, there is no “safe” amount of ionizing radiation, and every increase, however small, fractionally worsens your odds of becoming the world’s oldest person.
Knowing that it can be alarming to think about all of the radiation we’re exposed to on a daily basis. Roughly half of the radiation in the environment is considered “background,” and it comes from sources such as the Sun and cosmic rays, which are continuously bombarding the Earth and can’t really be stopped. The other 50 percent of radiation you’re getting comes from terrestrial sources, and some of them might be closer than you think.
1. Granite Countertops
The term “granite counters” in a home listing adds maybe 5 percent to the asking price of a house. Granite is hard, smooth, and very attractive when polished to a mirrorlike finish, so it’s no surprise that people like to have lots of it around when they’re setting up housekeeping. Every year, millions of tons of the stuff get quarried, cut, and shipped out to homeowners who’ve decided to add a touch of class to their kitchens.
Granite is, however, just a rock that comes out of the ground, and that means it’s made out of minerals. Some of those minerals contain trace amounts of radioactive substances they picked up on the long climb out of the Earth’s mantle and into the crust. Some of the more common radioactive elements found in granite are uranium and thorium, both of which emit alpha particles. A few loose alphas are nothing to worry about – they don’t have the energy to penetrate the skin – but alpha emitters can be lethal if they get into your lungs or your bloodstream, which is an excellent reason always to wear a respirator when grinding, cutting, or polishing stone.
2. Old Clocks (and New Clocks Too)
Did you ever own a watch with glow-in-the-dark hands? How about an alarm clock with green tips and a faintly glowing face? As cool as those were, they were also kind of hot with radiation. Old timepieces managed their faint green glow with little daubs of radium tincture mixed into the paint. Radium does this trick by capturing visible-light photons from sunlight, or whatever other source is around. The incoming photons bump radium’s electrons into higher orbits than they had before, effectively storing energy like a battery. Later, when it’s dark, those electrons start falling back down to lower orbits around the radium nucleus, emitting a photon as they go, which gives the substance its faint glow.
Unfortunately, a photon of light isn’t all that the paint emits. Most radium-226 drops an alpha particle when it decays in this way, but there are a few eccentric atoms in any sample that follow a different decay chain. On this path – which happens perfectly randomly and cannot be predicted or stopped – the Radon breaks down into radon, which is 2.7 million times more radioactive than uranium and absolutely will be mentioned again and again in this list. Old radium clocks have been phased out over the years, though radium-226 has a half-life of over 1,600 years, so it’s not going anywhere except the landfill and the ocean. Newer glowing dyes use a radioactive isotope of hydrogen (tritium) or promethium, which have half-lives of 12 and three years, respectively. That’s not necessarily an improvement, as a shorter half-life usually means an isotope is more radioactive in the short term, as it decays faster.
3. Pre-1960s Ceramics
It’s quite fashionable for people under 40 these days to collect vintage china and earthenware. That may lead to another popular trend when these young adults are over 60: chemotherapy. Many of the dyes used in ceramic glazes from before the 1960s, and in glassware from before the ’70s, is hot with radioactive elements that people from the past either did not know about or didn’t take seriously until humanity really should have known better.
Earthenware vessels with orange, yellow, and thick red glazes sometimes contain a subtle, volatile mix of uranium, thorium, and potassium-40, all of which emit alpha and beta radiation. Think of alpha radiation as something you can stop with a sheet of paper. A layer of aluminum foil can stop beta radiation. Gamma radiation (which is further down the list, watch for it) can punch through up to eight feet of concrete without stopping. The fact that green and yellow-green glassware from the Victorian Period to the 1970s “only” emits alpha particles from its uranium content isn’t comforting, though. Remember, there aren’t any little men in your stomach who can hold up sheets of paper to protect you if you drink out of these vessels. If you have any of this stuff and are wondering if it’s irradiating you, try looking at it under a blacklight in a darkened room. If it glows, you might want to put it in a case and stop handling it.
4. Smoke Detectors
Smoke detectors are one of those things, like fire extinguishers and life insurance, that responsible adults are just supposed to own. And it’s true – they do help keep you safe from the immediate danger of a house fire. They don’t do this for free, however, and the long-term problems caused by their radioactive components may be more serious for our distant descendants than a house fire would be now.
Many smoke detectors, especially older models, contain small amounts of a radioactive isotope called americium-241. For all kinds of complicated physics-based reasons, this stuff’s weak stream of alpha particles is helpful for detecting smoke particles in the air, which is the point of a smoke detector, after all. It’s still radioactive, and if the detector housing gets damaged (in a fire, say), the americium can be released. Americium-241 has a half-life of 432.2 years, so only about 75 percent of the stuff we’ve made so far will be gone in 1,000 years. Worse, americium-241 decays into neptunium-237, which has a half-life of 2.14 million years. Five million years ago, our ancestors had chimpanzee-sized brains and didn’t use fire. Five million years from now, roughly a quarter of the radioactive neptunium we’ve produced as waste will still be out there… somewhere.
5. Cat Litter
Dealing with any pet waste is no fun. Even cats, which have a reputation for being among the cleaner household pets you can own, still leave a mess in their litter boxes, which have to be scooped daily to keep odors and infection risk under control. As if that wasn’t bad enough, the litter you’re probably using is also likely irradiating your house.
Most cat litter is made from a mix of organic and inorganic compounds, including several types of clay. Most clay is an amalgam of various minerals, including uranium, thorium, and potassium-40. A typical litter box isn’t very dangerous, though in a strange twist it can become significantly more radioactive if your cat is being treated for cancer. Many of the radioisotopes used in cancer treatments are excreted via urine and feces, and that can add significantly to the latent radioactivity of the cat’s box.
Speaking of feces, many commercially available brands of plant fertilizer have radioactive components that can rest in the soil for years, and which may be taken up inside plant tissues, including various edible parts that might wind up on your table.
The source of this radiation can be traced back to the phosphates in the fertilizer. That is the base of the fertilizer’s chemistry, and so it can’t be gotten rid of, but depending on the source it may be contaminated with radium-226. Fertilizer usually gets its phosphorous from large deposits originally laid down as bird guano. In places where birds have been breeding – and making a mess – for tens of thousands of years, this phosphorous builds up into layers that can be hundreds of feet deep. When it gets mined, radium-bearing rocks often come with it, and extracting all of the radioactive isotopes usually costs more than it’s worth. So take comfort; that radioactive phosphorous you’re spreading around the garden could be a little safer, but it’s too expensive for the fertilizer company to care.
7. Old TVs
It turns out your mom was right about sitting too close to the television. TV sets from the bad old days before LEDs make their picture with a stream of electrons emitted by cathode ray tubes. These tubes emit their electrons by warming up and radiating at a specific part of the EM spectrum. One side effect? They get hot enough to emit X-rays as well.
X-rays are a type of ionizing radiation that sits right inside the dangerous sweet spot for harmful emissions. Alpha and beta particles are super easy to produce, so they’re everywhere, but they usually don’t cause real harm because of the low energy they carry. Gamma rays are absurdly powerful and therefore dangerous, but it takes a lot of energy to produce a single gamma photon, so those sources are thankfully rare. X-rays, on the other hand, are powerful enough to do real harm, but not so powerful that they’re hard to produce. If you insist on watching that 40-year-old TV in the basement, you can avoid the worst of the X-rays by sitting at least three feet back from the screen… just like Mom told you to do.
8. The Food You Eat
An awful lot of the food you eat is detectably radioactive, and some of it comes from surprising sources. Tomatoes, corn, and other garden vegetables may have alpha emitters in them from taking up the aforementioned phosphate-based fertilizers, but even commercially grown products set the Geiger counters clicking.
Brazil nuts are at the top of the list here, with maybe 1,000 times the radioactivity found in other foods. It seems to be an odd result of how the Brazil nut tree grows; its roots selectively take up radioactive potassium and phosphorous from the ground and concentrate them in the nuts. Bananas contain enough potassium-40 to trip the radiation detector in the airport, while even humble, unassuming beer is very weakly radioactive from the barley and hops used in its brewing. As a rule, you can expect a little bit of alpha radiation from anything with potassium in it, which unfortunately is almost every nutritious food you eat.
9. The Air In Your Basement
Radon is one of those weird public health panics that broke out in the ’70s, got tons of press for a while, and then dropped off of our threat-radars. That is odd because radon gas is a huge danger that most people don’t even think about. Radon is produced when uranium in the ground decays, and small bubbles of it gradually seep upward into the soil and are released into the air. When this happens under the spot where your house was built, radon can build up in your basement and eventually reach life-threatening levels.
The numbers here are as genuinely scary as the evening news tries to make everything sound. The EPA estimates that perhaps one out of every 15 homes in North America has at least some radon seepage, while other sources of radon contribute even more gas to more carefully situated homes. Those granite counters, for example, leak small amounts of radon in addition to their natural uranium-based emissions, as do the depression glass vessels and the glazed earthenware. Radon can seep out of recycled metals, if the recycler had carelessly mixed metal sources and incorporated some forms of medical waste in the alloy, and even a walk in the park can expose you to some radon if the ground there was ever used as a landfill, as it was in the infamous Love Canal disaster. Radon is currently pegged as the second-leading cause of lung cancer in the developed world; only smoking is more dangerous.
10. Your Own Body
Remember how food sources that contain necessary nutrients like potassium and phosphorous are always a little radioactive? Well, your body is a big pile of meat that has lots of phosphorous in it. Some of that phosphorous are radioactive, as are some of your body’s isotopes of potassium, calcium, and iodine. We all have a small amount of uranium in our systems, taken up from the environment no matter how careful we are, and then there are those trace amounts of tritium and thorium you can’t avoid.
All of this is pretty normal and nothing our ancestors couldn’t cope with, so it’s probably nothing to worry about. One thing that is new, however, and something none of our ancestors ever had to evolve to handle, is plutonium. Plutonium is highly radioactive, and so it has a shorter half-life than most naturally occurring radioactive substances. All of the plutonium in the early solar system decayed within a few million years and never got taken up by Earth’s natural systems. The first plutonium on Earth was produced in 1942, as part of the Manhattan Project, and it’s been the devil to handle ever since.
In April 1964, the SNAP-9a satellite disintegrated over the Southern Hemisphere. When the nuclear fuel component broke up, it released almost exactly one kilogram of plutonium into the upper atmosphere, which was then carried around the world on high-altitude wind currents. Over the years that followed, atomized bits of plutonium were taken up by basically every living thing. You have a few atoms of that plutonium in your body right now, quietly emitting small amounts of radiation, and so does everybody else. We don’t know what the effect of this will be if any, but the incident was serious enough to motivate NASA to develop advanced solar panel technology at last, so it wasn’t a complete waste. Try not to think about the plutonium; there’s probably nothing you can do about it.