Answer to Question #12886 Submitted to "Ask the Experts"
Category: Consumer Products — Radioactive Ceramics and Glass
The following question was answered by an expert in the appropriate field:
I am 73 and tour antique stores. I see Fiestaware that give my Geiger counter high readings of nearly 10 microsieverts (µSv) or higher. I saw a report from Oak Ridge Associated Universities (ORAU) stating there is no radon released because the uranium is chemically purified, so there is no radium present to decay to radon. I studied the uranium decay series and see radium and radon decay daughters are indeed present. Being a retired teacher, I am always concerned about safety of customers, and the people who are near or in closed areas with radon. I understand the levels are probably lower than the Environmental Protection Agency action level of 4 picocuries per liter (pCi/L), but is radon present?
First, since you detected some radioactivity with your Geiger counter I agree that this probably is Fiestaware, or a similar product (see the article on the ORAU website). I agree with your confusion, I am not quite sure why chemical purification of uranium would eliminate radon emissions. Regardless, this Fiestaware is safe! You should not be concerned about any levels of uranium decay products or radon that may emanate from these ceramic products. I seriously doubt you would be able to detect any radon emanating from this dish or plate. However, there might be radon from other natural sources, most likely the soil.
Separate from the negligible amounts of radiation from Fiestaware, we all receive , about 3,000 µSv of radiation (at sea level) annually from natural background sources, such as the sky (cosmic radiation), the ground (radioactivity in rocks and soil such as radioactivity from the decay of naturally occurring uranium and thorium), and even from radioactivity within our body. The radiation levels you are detecting are simply negligible; although detectable, they are not harmful.
Fiestaware has been studied quite extensively. Yes, we can detect such low levels, but the emissions are too small to pose any sort of risk. It is highly unlikely, if not impossible, for any individual to receive enough radiation from such a product that could be harmful. The ORAU website has a very detailed discussion of Fiestaware and its history, along with calculations and estimates made by numerous professionals.
I hope my answer is satisfactory.
Orhan H. Suleiman, MS, PhD