Hi, Doc! My wife follows this TikTok video series on makeup and she saw one about radioactive makeup. What?? Did people used to have their faces melt off or something?
Apparently it really was a thing – I’ve got to admit I hadn’t heard of putting radioactivity in makeup, but a quick search came up with a French company that sold a makeup line called Tho-Radia (as well as a British company called Radior), who advertised adding thorium and/or radium to their products. I’ve written about the Golden Age of Radium and the use of radium in patent medicines in earlier posts; they can give you an idea of the spirit of the times, when radium was seen as a near-magical cure or treatment for whatever ailed a person; radium also found a use in glow-in-the-dark products and much more. But not only that – in the 1920s and the next few decades saying or implying that something contained radium was a mark of honor. In the words of radiation safety scientist and historian Paul Frame, “Radium was used to connote quality…today, I have a platinum credit card and back then it would have been a radium card.” So one question here is whether Tho-Radia actually contained either thorium or radium (let alone both), or if they just implied it for those (hard though it might be to believe today) positive connotations.
Coincidentally, I was contacted by a colleague who’d been contacted by Erin Parsons, asking if he might know someone able to make measurements on some of the antique Tho-Radia makeup she’d managed find. I did some research and spent a few weeks making measurements of Erin’s makeup. Here’s a short summary of what I was able to find online and the measurements I made.
The Oak Ridge Associated Universities (ORAU) Museum of Radiation and Radioactivity website has a page on Tho-Radia, as does Wikipedia. These include some fascinating historical information as well as some rare facts about the amount of radium and thorium they contained. Apparently the highest radium concentration was about 0.223 millionths of a gram (µg) of radium bromide and 0.5 grams of thorium chloride in every 100-gram sample of Thor-Radia crème. If I got the calculations right, this comes out to about 0.136 microCuries (µCi) of radium (Ra-226) and 341 µCi of thorium (Th-232) in every gram of Tho-Radium cream and considerably less than this in the face powder. The reason for adding thorium and radium was to promote “microcurietherapy,” a takeoff on the “curietherapy” that was being used to treat cancer.
From here I had to do some guessing – it’s easy to calculate the radiation dose rate from a lump of makeup weighing one gram and containing those amounts of radioactivity – but when applied, the amount of skin covered by that one gram of makeup matters. If one gram covers only, say, a few square cm then the radioactivity will be much more concentrated and will give a higher radiation dose than if each gram of makeup is applied to 100 square cm.
Using the latter assumption (that a single gram would be applied to 100 square cm) I used a software application called Varskin that calculated the radiation dose to the skin would be about 225 mr/hr from the thorium and 15.6 µr/hr from the radium. The annual radiation exposure limit to the skin is 50 rem (50,000 mrem) so it would take over 200 hours to reach an annual exposure limit. As for skin burns…they’re not likely to happen because, unless the makeup were to be worn continually for month after month after month, the body would repair most of the DNA damage that had occurred. That being said, I’d recommend against wearing it continuously for an extended period of time because even small amounts of damage can accumulate over time.
So – that covers the safety – now let’s see if there’s actually radium or thorium in the products! I took a few radiation detectors over to Erin’s office/museum (a Geiger counter and a scintillation detector that can measure the energy of radiation striking it. With each of them I first measured normal background levels, then scanned both the lipstick and the face powder. The Geiger counter didn’t measure anything above background on the makeup, but that didn’t surprise me – GM tubes aren’t very sensitive and if it had picked up anything I’d have had some concerns about Erin’s having tried the makeup.
With the scintillation counter…I couldn’t tell. As the count progressed I could see some of the gamma peaks I’m used to seeing from natural background radiation – the gamma energy “fingerprint” characteristic of natural potassium (K-40 at 1460 keV), natural uranium (several gamma peaks, including 186 keV for Ra-226 and U-235 as well as several other gammas from the uranium decay series), and natural thorium (multiple progeny nuclides). These spectra are shown in the plots below.
Because the crystal in my scintillation detector is fairly small (only 1 cm x 1 cm x 1 cm) I collected data for about 7 days for both counts (background and makeup). The important spectrum here is the one showing the difference between the two counts – the gray dots on the final plot.
This looks as though there are some peaks that coincide with some of the expected gamma peaks from Ra-226 and Th-232, but the statistical significance isn’t high enough to state definitively that I detected radioactivity in the makeup. So there might – or might not – be radioactivity in the makeup I counted. That being said, here are a few possibilities:
- There might be radioactivity present, but in quantities too low for me to detect with equipment I’m able to afford. If this is the case, counting on more-sophisticated gear might do the trick. Unfortunately, I don’t have access to the sort of gear that would be needed and, as it costs a few hundred thousand dollars, I’m not going to buy some just to write this post.
- There might not be any radioactivity in the makeup – according to one of the web pages I cited earlier, the company stopped adding radium or thorium to its makeup in 1937, when French regulations were tightened up.
For a quick summary – there might or might not be radioactivity in the makeup I analyzed but, even if the makeup is radioactive, it doesn’t pose a health risk to anyone who wore (or wears) it.