How do museums deal with radioactive artifacts?
The question first popped in to my head when I was standing at the entrance of the Mütter Museum in Philadelphia, looking at a device built by Pierre Curie in the 1880s to measure radioactivity.
Given that the device—a piezoelectric quartz electrometer—had spent decades measuring radioactivity, I guessed it probably was or had been radioactive itself.
Then it occured to me that the devices used by Pierre and Marie Curie aren’t the only kind of radioactive artifacts found in museum collections.
German chemist Martin Heinrich Klaproth discovered uranium in 1789, and by 1830 the radioactive element was being used heavily as a yellow-green colorant in all sorts of glassware (before people even knew what radioactivity was).
By the early 20th century, uranium oxide was used to color the incredibly popular orange-red ceramic Fiesta tableware favored by Andy Warhol and many others. And radium-226 was used to paint watches, aircraft gauges, door knobs, religious icons, light switches and even chamber pots so that they glowed in the dark.
Radioactivity also became a health fad. Look no further than the “Lifetime Radium-Vitalizer Water Jar,” from the 1920s, which added radiation to water by means of a chunk of uranium ore at the bottom of the vessel.
In addition to quack health products, radioactive artifacts are sometimes natural history museum minerals as well as relics and equipment from the Manhattan project and all subsequent nuclear testing.
Since we are all exposed to low-levels of radiation daily–heck, our own bones emit radiation to those around us–the issue is whether a particular artifact emits enough radiation to present a health hazard to museum staff and the public.
“Whenever a new artifact comes into the museum, the first thing I do is run a Geiger counter over it,” said Anna Dhody, the Mütter Museum’s curator, when I called to ask about Pierre Curie’s electrometer. You often don’t know the precise life trajectory of an artifact, she explained, and it’s wise to be precautious, particularly with donations.
Pierre Curie’s electrometer had been professionally decontaminated by a nuclear physicist, Dhody said, but she couldn’t provide more details because it had happened before her tenure at the museum.
She suggested I call up the National Atomic Testing Museum (NATM), whose whole modus operandi is to deal with artifacts related to the more than 1000 nuclear tests that took place from 1951 onwards at the Nevada Test Site, about 68 miles outside Las Vegas.
“You don’t want to fool around with radioactive artifacts,” Karen Green, the NATM’s curator told me.
She told me that the artifacts in the NATM, such as radiation containment chambers (“hot cells“) and oscilloscopes, have been decontaminated by government scientists using high tech clean rooms where radioactive dust can be mechanically scrubbed off and chemically removed from equipment and then isolated. Waste water and cleaning equipment are also decontaminated.
Procedures vary according to the specific radioactive elements contaminating the artifact (such as uranium, cesium or plutonium, for example), and the type of radioactivity coming off the artifact (such as alpha, beta or gamma decay).
Even though her artifacts are professionally decontaminated, “that doesn’t mean I haven’t taken the Geiger counter into the collection and just gone up and down the rows a few times,” Green says.
So the take home message to museum staff: Buy a good Geiger counter or scintillator and if you detect radioactivity, talk to a professional.
Museums can then assess whether the artifact is too radioactive to be on display and should be carefully stored, whether it needs decontamination or whether radiation levels are low enough to present the piece to the public, possibly in a protective, transparent lead-glass case.
According to the United States Nuclear Regulatory Commission, the average person receives an annual radiation dose of about 350 millirem from natural and human sources, but it’s also relatively common to receive more, usually from medical procedures. The USNRC suggests capping off any additional radiation at 100 millirem per year.
Because the pretty green uranium glass is rather ubiquitous, the USNRC has done a radiation exposure assessment for the glassware.
If a glass is simply sitting on a shelf in your house, your annual radiation dose is 0.2 millirem. If you drink regularly from the glass, the exposure goes up to 2 millirem.
Overall, pretty low.
In 2001, Donna Strahan, a conservator at the Metropolitan and a lecturer at the University of Delaware did a study of over 400 glass, enamel and ceramic objects from museum and private collections that use uranium as a colorant.
Her conclusion: “Little health risk from uranium-containing objects was found unless many objects were stored in a small area or if acidic or alkaline foods were stored in them and consumed in quantity.”
In 2002, a nuclear scientist named Eric Norman, now at the University of California, Berkeley, studied the all the various brightly colored Fiestaware china for radiation and only found the orange dishes and the yellow teapot to be detectably hot.
Even so, “none of the observed radioactivity levels are very high and should not be cause for alarm,” Norman writes in this report. “Nevertheless, I would not want to routinely eat salad off the orange plate or drink tea from the yellow teapot,” he adds.
As for radium watches and other devices… that’s the subject of an upcoming post…
And before I forget: If you believe the only hazardous artifacts are the radioactive ones, think again. I’ve described how museum staff face high levels of arsenic in natural history collections. But there’s also guns and ammunition in war museums, poison-coated spears from ethnology museums and mercury coatings on the back of old mirrors–to name just a few of the perils faced by those who peruse old objects.