Answer to Question #3211 Submitted to "Ask the Experts"

Q

I grew up in Middlesex County, New Jersey, an area that once had a thriving terra cotta industry. All sorts of ornamental work and structural tiles were produced. I have discovered (sitting in my grandmother's yard) a number of old tiles which give noticeable readings on my survey meter. I'm roughly recalling about 0.3 to 0.7 mrem/hr at a few inches, less than for a Fiesta® Dinnerware dish. One kind is a mottled yellow-green; another is a clear yellow. We also have about five fiesta-like colored tiles 2" square in our bathroom floor that are radioactive. While I have read many accounts of radioactive glazes in the pottery ware industry, I know of nothing written about radioactive glazes in the tile industry, except for one paper, barely relevant, from Taiwan. My question is: Has there been any research done on radioactive tile products used in construction? Where might I find any information on this topic? Or, have I found something not previously known or researched?

A

Some research has been conducted on this topic, but not much. The lack of interest is probably due to a number of factors. First, the general feeling is that the exposures to the public from radioactive tiles are probably too low to worry about. Second, the level of radioactivity in ceramic tiles varies tremendously. This means that the measurements made in one study would not necessarily apply to other situations. Third, the potential exposures from the radioactivity would depend to a large extent on an individual's proximity to the tiles as well as the length of the exposure period. In other words, there would be a great deal of guesswork required to interpret the measurements generated in a given study.

Even so, I have heard of some situations where the ceramic tiles in a building have been removed because the exposure rates were perceived to be too high. This would be a judgment call made on a case-by-case basis.

I assume that the following is the reference that you describe as barely relevant: http://www.irpa.net/irpa10/cdrom/00181.pdf.

You could also go to the Health Physics Journal website and perform a search of the Journal abstracts using the word "tiles." With luck, you might find a few relevant articles that way. While on that link use the "Search Contents" option on the left side of the page.

This is not to say that nobody is concerned about this issue. You can read about one individual's crusade (for lack of a better word) on the Internet.

Paul Frame, CHP, PhD