Consumer Products and Radiation
Many consumer items contain radiation, either as a function of their operation or as a naturally occurring material that’s included as part of the product. Consumer products containing radiation can be used safely and do not pose a health risk. However, it is helpful for consumers to know about these sources of radiation so they handle these items properly and make informed choices before they buy.
The Nuclear Regulatory Commission (NRC) recently updated its consumer product policy statement to reflect the current approach to radiation protection for these products. A recent NRC blog provides further explanation of the new policy statement. Below is an alphabetical list of some of the more common consumer products that contain radioactive materials.
Antique Radioactive Cures
A wide range of radioactive products were sold as cure-alls, primarily from the 1920’s to the 1950’s. Radium-containing pills, pads, solutions, toothpastes, and devices designed to add radon to drinking water were once commonplace. Some of these devices are relatively harmless, but others contain potentially hazardous levels of radium.
Older camera lenses from the 1950’s to 1970’s often used coatings of thorium-232 to alter the index of refraction.
Cat litter made from bentonite clay can contain trace amounts of uranium, thorium, and potassium that occur naturally in the clay. These levels do not pose a risk to cats or their owners, although special care should be taken when handling used litter from animals being treated for cancer using radioactive isotopes.
Ceramic materials such as tiles or pottery often contain elevated levels of naturally occurring uranium, thorium, or potassium. Some pre-1960 tiles, pottery, and ceramics—especially those with an orange-red glaze such as Fiestaware®--are radioactive due to the uranium in the glaze. Green, yellow, and black ceramics can also contain radioactive materials.
While cigarettes are not an obvious source of radiation exposure, they contain small amounts of radioactive materials. Tobacco leaves contain radioactive material, particularly lead-210 and polonium-210. The radionuclide content of tobacco leaves depends heavily on soil conditions and fertilizer use. Radioactive particles lodge in the bronchial epithelium in the lungs and over time can provide a large dose of radiation. Radioactivity may actually be a contributing factor in lung cancer among smokers.
Commercial fertilizers are available in over 100 different blends that contain varying concentrations of nitrogen, phosphorus, and potassium. Potassium is naturally radioactive, and phosphate ore can contain elevated levels of uranium and its decay products, including radium. The concentration of radium-226 varies depending on the fertilizer blend and the source of the phosphate ore. Processing of the phosphate ore further concentrates these naturally occurring radioactive materials. The phosphate fertilizers that contain radium and its decay products (including lead-210 and polonium 210) may build up in the soils if used year after year.
Fluorescent Light Bulbs
Some compact fluorescent lights (CFLs) use small quantities of promethium-147, krypton-85, or tritium within a sealed starter or glow switch to warm up the electrode in the light’s ballast. The small piece of wire in each bulb contains less than 1 microcurie of radioactive material and is below regulatory limits established for general public use. CFLs with electronic ballasts do not use radioactive material in their starters.
Food contains small amounts of naturally occurring radioactive materials. Topping the list are Brazil nuts, which contain high levels of radium-226 and potassium-40. Bananas containing enough radioactive potassium-40 have occasionally set off alarms at border crossings and ports. Other common foods that contain small amounts of radioactivity include root crops such as carrots, potatoes, and peanut butter. Beer, red meat, and lima beans also make the list. Low-sodium and no-sodium salt substitutes often contain enough potassium-40 to double the background count rate of a survey meter.
Early 19th century European glass makers sometimes added small amounts of uranium to glass to give it a yellow or greenish color. Because of its color, this type of glass was called vaseline or canary glass. Collectors like vaseline glass for the attractive green glow the uranium gives off when exposed to a black light.
Antique glassware containing radioactive materials continues to emit low levels of radiation for many years, so it is advisable to avoid displaying these antiques in areas where people spend a lot of time. Vaseline glass should not be used to hold food or drink.
Starting around 1970, the intentional use of radioactive coloring agents in commercial glazes and glasses in the U.S. decreased dramatically. A few U.S. companies still make decorative vaseline glass, and other countries produce glasses containing radioactive coloring agents.
Granite Countertops and Other Building Products
Common building products such as brick, cement, granite, and glazed tiles may contain radioactive materials. Nearly all rocks, stone, soils, and minerals contain trace concentrations of naturally occurring radioactive materials such as radium, thorium, and uranium.
Because granite bearing trace amounts of uranium can release radon into the air, granite countertops emit radiation and radon gas. Although the amount released can vary considerably from one type of granite to another, the radon concentrations in most kitchens tested are much less than the Environmental Protection Agency (EPA) guideline of 4 picocuries/liter. While the radioactive material in the granite can produce a reading on a sensitive radiation-detection device, the radiation produced is well below levels that would cause harm.
Some camping lanterns use mantles that contain thorium-232. The mantles are produced by dipping a meshed fabric into a solution of thorium nitrate. When fuel is burned inside the mantle, it heats the thorium and produces light. Many companies have discontinued their use of thorium mantles and replaced them with non-radioactive equivalents. Thorium-containing mantles are radioactive enough to be used as check sources for radiation survey meters.
Negative Ion Technology
Negative ion technology embeds negative ions in personal products and is currently being advertised as a means to maintain health, balance energy, and improve well-being. This technology is used in certain silicone wristbands, quantum or scalar-energy pendants, and kinesthesiology tape. The minerals that produce these negative ions often include naturally occurring radioactive substances such as uranium and thorium. While the long-term health impact from exposure to radiation at the levels contained in these personal products has been found to be negligible, the radiation detected in some of these products has been higher than background level and in some cases high enough to require licensing. Because the minerals used in these products contain varying levels of radioactivity, it can be difficult for the consumer to know exactly how radioactive these items are.
Most home smoke detectors contain low-activity americium-241. Alpha particles emitted by the americium ionize the air to create a steady current. When smoke particles enter the unit, they reduce the current and set off the alarm. Alpha particles cannot travel but a few inches in air, and the gamma rays emitted by americium are fairly weak. The americium isotope is enclosed inside the detector, so it doesn’t pose a risk unless it is broken open. Instructions for the proper installation, handling, and disposal of smoke detectors are included in the packaging and can reduce the chance of inadvertent exposure.
Watches and Clocks
Some watches and clocks contain a small quantity of hydrogen-3 (tritium) or promethium-147 as a light source. Some older (pre-1970) watches and clocks used radium-226 to illuminate the dials and numbers. It is not advisable to open or disassemble these older timepieces, as some of the radium could flake off and be accidentally ingested or inhaled.
Sources include the Health Physics Society, the Environmental Protection Agency, and the Oak Ridge Associated Universities.