Alan Boyle  /  MSNBC.com
Radiation watchdog Walter Wagner holds his Geiger counter against riser tiles at a San Francisco apartment building.
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msnbc.com

Walter Wagner can see the radioactivity as he walks the streets of San Francisco: He stretches out his Geiger counter to a decorative tile on the facade of an apartment building — and sure enough, gets a chorus of clicks. Those sounds are what motivate the self-appointed sleuth’s campaign to root out radiation sources most people don’t know exist: the vintage uranium-glazed tiles in their kitchens and bathrooms, stairways and schools.

Wagner, a former radiation safety officer, has taken on the ticking tiles as his latest cause, contending that health authorities should search for uranium usage in settings ranging from school hallways to bathroom shower stalls.

“Would you get into your shower if you knew that not only hot water was coming out at you every day, but you were also getting beta radiation every time you stepped into your shower?” Wagner asked.

To document the radiation levels, he’s been taking readings and knocking on doors in the Bay Area as well as Hawaii and Utah. He’s due to present his research in July at the Health Physics Society’s annual meeting in San Diego.

It’s debatable how much of a risk the tiles are: To Wagner, it’s a major health risk on a potentially global scale. But other health physicists, such as Paul Frame of the Oak Ridge Institute for Science and Education, say the tiles are not that big of a deal.

“A typical health physicist like me might say, OK, if you had your druthers, you wouldn’t use uranium in the tile, and to keep everybody happy you’d tear it out,” said Frame, who along with a colleague literally wrote the book on household radiation. “But we don’t think of it as a significant health risk, and there are other things that you would worry about more as a health risk.”

Why uranium?
People who don’t happen to be typical health physicists might wonder why anyone would ever put uranium in tile glaze to begin with. The answer goes back to well before the atomic age.

Starting in the 19th century, uranium oxide was used as a coloring agent for ceramics, porcelain and glass. Depending on the precise chemistry and firing temperature, glazes containing uranium could yield reds, oranges, greens, browns and even black.

Uranium glazes became widely used in the United States in the 1920s and 1930s, in part because uranium yellowcake was a cheap by-product of the radium production process. In 1942, the U.S. government took control of the country’s uranium mines for the war effort, but uranium glazes made a comeback in the ’50s and ’60s.

Perhaps the best-known examples of “hot” household items are plates, cups, pitchers and other glazed dinnerware that was marketed under the Fiestaware brand. Present-day china is uranium-free, but vintage, ever-so-slightly radioactive Fiestaware is still a popular collectible.

Uranium-glazed items have historically been exempt from nuclear regulations because they weren’t considered a significant hazard. But most of the calculations on radiation exposure have been made on the basis of dinnerware usage, not the tiles. And it’s at about this point that Wagner parts ways with the mainstream.

Image: Fiestaware
A hand-held Geiger counter picks up readings of radioactivity from an orange-glazed Fiestaware dish. Uranium oxide was used as a coloring agent for ceramics in the mid-20th century, except during World War II and the early postwar era.
Tilting at atomic windmills?
Being out of the mainstream isn’t an unusual role for Wagner. Some might even consider him a modern-day Don Quixote, tilting at atomic windmills. Over the years, Wagner has called attention to radioactivity in cigarette smoke and speculation that a powerful particle collider could spark the end of the world.

His career includes stints as a space science researcher, a schoolteacher and a radiation safety officer at San Francisco’s Veterans Administration Medical Center. Currently, he’s the head of a California wellness institute as well as a Hawaii botanical garden. And since March, he’s become a door-to-door salesman for radiation safety.

Wagner’s interest in the tiles started last year, when he expanded his longtime interest in radioactive collectibles to the decorative tiles sometimes found on vintage tabletops. He soon found out that such tiles were widely used on stairsteps — and that sometimes builders adapted floor and bathroom tiles to such decorative purposes.

In March, he began driving around San Francisco’s Sunset District and Marina District, developing an eye for uranium-glazed tiles and occasionally knocking on doors to see if the residents would let him test their interior tilework. He gained access to four houses that way, and in one house, the bathroom showed evidence of radioactive tiles. (The absentee owner has since warned him away.)

One Saturday, he drove around to three local schools and found ticking exterior tiles at each location. At Francis Scott Key Elementary School, for example, the bottom of the building and an entryway were lined with green specialty tiles that set off Wagner’s Geiger counter.

Tempest over tiles
Wagner later provided school officials with reports about what he called a “major health problem in the older schools across the country” — and that set off a tempest over the tiles.

“We consider safety to be the first priority with our students,” said Lorna Ho, special assistant to the superintendent of the San Francisco Unified School District. “We contacted the state immediately once this issue was brought to our attention.”

Image: Checking tiles
Walter Wagner checks the radioactivity of green-glazed tiles lining an entryway at Francis Scott Key School in San Francisco. Children have been told not to sit on the tiled stoop.
The California Department of Health Services tested the school tiles, and Ho said the preliminary data showed that “there wasn’t any indication of imminent risk.”

A spokesman for the department, Robert Miller, said no information could be released until the investigation was complete. That’s a bit of a sore point for the school district.

“We don’t want to take any chances until the state presents its formal recommendations,” Ho said. “Frankly, it’s been mildly frustrating. ... We can’t authorize ripping out a whole wall until we have some data or we have something official explaining why we’re taking that action.”

In the meantime, she said, the schools are taking “some precautions and trying to do as much as they can to prevent children from sitting on particular items.”

Changes have clearly been made, at least at Francis Scott Key School: In a May 6 report on uranium-glazed tiles, San Francisco’s KTVU-TV aired video footage showing children sitting on the school’s entryway tiles. A week later, however, principal David Wong told MSNBC.com that students have been instructed not to sit on the tiles “because it’s just not proper.” After-school monitors make sure the children obey the instructions, he said.

During a brief visit to the school, Wagner and a reporter saw that tipped-over benches, paint cans and boxes of books had been set along the entryway’s green-tiled interior walls. That was a change, Wagner said, perhaps aimed at keeping children from leaning against the tiles.

Is there a risk?
Health physicists say determining the risk associated with a low-level radiation source can be tricky, since assumptions have to be made about how people come in contact with that source.

Wagner comes up with a high figure, contending that a child sitting on the entryway tiles could receive 50,000 millirads as a shallow dose to the skin in the course of six years, derived by estimating 20 millirads per hour of exposure, two hours a day, 200 days per year. Other studies from the scant literature on uranium-glazed ceramics yield shallow-dose figures ranging from 0.1 to 24 millirads per hour.

All those figures have to be adjusted further to figure out the “whole-body” dose that is most widely used in radiation standards. Taking the example of a uranium-glazed, 10-inch-diameter dinner plate, the Nuclear Regulatory Commission estimates shallow-dose exposure at 24 millirads per hour. But the whole-body dose from handling a full set of the dinnerware is estimated at just 6 millirem per year. Actually using the plates for eating and drinking brings the estimate up to 40 millirem per year — which is still well below standards for radiation exposure.

For the tiles, the mainstream estimates are even lower: Although the state health department’s investigation isn’t finished, a source familiar with the testing told MSNBC.com on condition of anonymity that the radiation emissions from the tiles appeared to be less than a fourth of the level associated with uranium-glazed dishware.

Hearing that led even Wagner to acknowledge, “It’s at the lower limit of what could be a health concern.”

Wagner said he was far more concerned about the potential for exposure from tiles in kitchens and bathrooms.

“Fifteen minutes a day, a few days a year is one thing,” he said. “Fifteen hours a day, 365 days a year, is a far greater exposure potential. So we’re just looking at the tip of the iceberg.”

Even though Frame may take issue with Wagner’s risk assessment, he agrees with Wagner that every reasonable step should be taken to minimize radiation exposure from all sources.

“The operating philosophy that would be pertinent in health physics would be the ‘ALARA’ concept,” Frame said. “The idea is that it is not sufficient to just meet the limits, but you would have to keep exposures ‘As Low As Reasonably Achievable.’ This is in the regulations.”

Wagner argued that it would be reasonable to remove the offending tiles, or sandblast the tiles to remove the glaze. He said he would press for inspections of schools, as well as a legal requirement that properties be certified as “uranium-free” when they are sold.

Frame, however, said he “sure wouldn’t be recommending to people that you should rip the stuff off the wall if it doesn’t pose a risk.”

“Everything is measurably radioactive,” he noted. “There’s a question of where we are going to draw the line. What we’re talking about here is a financial issue, and a political issue about how the people involved in it feel. If it makes you feel uncomfortable, go ahead and deal with it — not necessarily as a public health issue, but to make people happy.”

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