Are Brazil nuts radioactive? Can I get radiation poisoning from my Fiestaware® plates? Are kitty litter and lawn fertilizer really made from uranium? If I used a shoe-fitting fluoroscope in a shoe store years ago are my feet okay?
These are the kinds of questions that lead many people to the treasure trove of information found in the ORAU Health Physics History Museum section of the ORAU website.
Thanks to decades of work by ORAU health physicists, led by Senior Health Physics Trainer Paul Frame, ORAU has compiled a large collection of items from the radiation era as well as the understanding of how these items affect our culture and our health. Through a combination of personal investigations and compiling the best research available by Frame and his associates, the ORAU Health Physics History Museum provides both reassurance of the safety of many radioactive products as well as the story behind the radioactive reputation that leads to these questions.
Is my Fiestaware safe to use?
If you find yourself eating your Brazil nuts from a Fiestaware dish, are you in danger of radiation poisoning? If your Fiestaware was manufactured in the 1930s by the Homer Laughlin China Co., it was colored with a uranium oxide glaze. As such, it is in fact slightly radioactive, and a Geiger counter will click increasingly as you place it near a Fiestaware plate or bowl. ORAU health physicist Roger Halsey explained that while original Fiestaware does contain radioactive uranium, the levels of radiation emitted are very low.
“You don’t want to use pre-World War II Fiesta red every day, but the radiation emitted by a piece is much less than the radiation you are normally exposed to by other things in your environment,” Halsey said.
Any Fiestaware made after the 1950s has no uranium content in the glaze. In fact, most of the “hot” dishes are now the property of collectors only. The ORAU Radiation History Museum has several place settings in its collection.
Are Brazil nuts radioactive?
Brazil nuts are a popular tree nut found in many varieties of mixed nut snacks and are often eaten by themselves or as an ingredient in other dishes. But are they radioactive? Brazil nuts do contain concentrations of the radioactive element radium (Ra-226 and Ra-228) that can be 1,000 times higher than those found in other foods. The nuts are the seeds of Bertholletia excelsa, a large tree found across South America, not just Brazil. The trees have vast root systems that are responsible for the accumulation of radium as well as barium. Studies conducted in the 1960s determined that most of the radium in Brazil nuts is not retained in the body, but passes safely through the digestive tract.
Does the shoe fit?
Decades ago, a trip to the shoe store often meant a chance to see how the bones of your feet fit inside of the shoes you were planning to purchase. The device that made this possible, the shoe-fitting fluoroscope, used X-rays to give shoe shoppers a glimpse inside their new footwear. The fluoroscopes came in several models, many of which could increase or decrease the level of radiation based on the size of the wearer. The fluoroscope would send a continuous beam of X-rays for typically 20 seconds, allowing you to see through a viewfinder exactly where your toes fit inside your shoes.
People who used a fluoroscope to look at their feet, or those of their children and grandchildren, have a lot of curiosity about the dangers these devices posed to the people who used them. The good news is that the typical shopper who used a fluoroscope once or twice a year at most were exposed to very little radiation. The same, unfortunately, could not be said for the shoe shop employees who operated the machines every day. Injuries related to fluoroscopes ranged from dermatitis of the hand to severe burns requiring amputation of a leg. Health concerns were among the leading reasons for state governments to begin banning their use in the late 1950s.
“By 1960, these events, plus pressure from insurance companies, had led to the demise of the shoe-fitting fluoroscope, at least in the United States,” according to Frame. “In the end, the shoe stores were probably just as glad to be rid of the things. At least one survey had indicated that the machines were perceived by shoe salesmen as a sales gimmick rather than a useful tool.”
What about kitty litter and lawn fertilizer?
Two other consumer products that are still in heavy, everyday use are also the subject of a large number of web searches because they are known to have radioactive properties—cat litter and lawn fertilizer. Most cat litter is manufactured using clay for absorbency, and that clay contains naturally occurring elements that emit low levels of radiation.
“The exposure rate at six inches above a box of cat litter would be approximately 0.1 micro roentgen per hour (uR/hr) above background,” Frame said. “Since cats don’t spend a lot of time in the litter box, the radiation exposure is probably minimal.”
While these emission levels are very low, if you get enough cat litter in one place it begins to add up. “Shipments of cat litter have been known to trip radiation monitors,” Frame said.
As for fertilizer, the typical bag of fertilizer contains at least one quarterphosphorous. The phosphorous content is derived from phosphate rock, which can be associated with uranium, and to a lesser extent thorium deposits. As a result, the fertilizer’s phosphorous content can contain small amounts of uranium. These levels when combined on a large pallet of fertilizer bags can create enough radioactivity to trip a Geiger counter. The uranium content in the raw materials used to make fertilizer emits only 22–140 picocuries per gram. The final product has even less (10 to 50 percent less) radioactivity.
So are there any dangers? The two possible areas of concern would be external exposure to fertilizer before it is spread and internal exposure from consuming food that is grown using fertilizer. Weekend warriors applying fertilizer to their lawns only encounter barely measurable amounts of radiation. The sun overhead would be a far stronger source of radiation. But workers in the phosphate industry can have gamma radiation exposures that range from 30 to 300 mrem per year. Inhaling phosphate dust might result in a dose equivalent to the lungs as high as 5 rem per year. As for the food raised using fertilizer, the National Council on Radiation Protection and Measurements has estimated that exposures to an average member of the U.S. population might be on the order of 1 to 2 mrem per year.
People over age 65 are likely to remember this item from shopping for shoes with their mothers. Kids, parents and shoe salesmen could see the bones of their feet.
To find out more about ORAU's Health Physics Historical Instrumentation collection, or if you are interested in making a donation, please contact Dr. Paul Frame or by phone at 865.576.3388.