Answer to Question #3167 Submitted to "Ask the Experts"

Category: Consumer Products — Radioactive Ceramics and Glass

The following question was answered by an expert in the appropriate field:


During the Depression era, many companies used uranium in their glazes of pottery and glass. What kind of effects would this uranium have if you eat off the dishes?


The simple answer would be none, that is, no effects. Although uranium was used in pottery glazes to impart specific and special colors, there is little likelihood that a person could ingest enough uranium from the pottery glaze to produce any adverse effects. There are a number of reasons why. First and foremost is that there is simply not enough uranium in the glaze; natural uranium is of relatively low toxicity and its chemical toxicity, which is similar to that of lead, far outweighs its radiotoxicity or potential for radiological effects. And the uranium in the glaze is not easily dissolved by foodstuffs and so is not going to be in a form that will be ingested with the food. If the uranium in the glaze were somehow solubilized and were to leach out of the glaze, the color change in the pottery would be quite and quickly apparent. But this, of course, does not happen.

Thus it is perfectly safe to eat from pottery and china bearing uranium glazes; the amount of uranium that one might ingest, even if high-acidity foods are eaten, is trivial. What may be of more concern is the external radiation given off by the uranium and the other members of its decay chain, which produce a measurable radiation field primarily from beta radiation in the vicinity of the pottery. Thus a person using such pottery will receive a small external radiation exposure, with the amount of the exposure dependent upon how close one is to the pottery, how big the piece(s) are, and how many are nearby. But once again, not to worry; unless a person is in close proximity to the pottery with the uranium glaze for long periods of time, and frequently (say daily), the additional radiation exposure from this source should not be of concern and would be a small fraction of the natural background radiation to which that person is already exposed. However, although any potential hazard is negligible, in keeping with the principle of ALARA (as low as reasonably achievable), it is good practice not to use pottery bearing uranium glazes. And, considering the fact that many such pottery pieces are collectibles, one could likely sell one's uranium-glazed pottery and realize enough cash to buy a nice, new set of pottery (or perhaps even fine china) without uranium glazes.

Ron Kathren, CHP
Professor Emeritus
Washington State University

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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