Here’s a page from AEG Test (archive), a company which sells radiation detectors, talking about the safety of uranium glass. Right from the get-go it feels like LLM slop. “As a passionate collector of uranium glass,” the unattributed author begins, “I’ve often been asked: ‘Does handling these glowing antiques pose a health risk?’” It continues into SEO-friendly short paragraphs, each with a big header and bullet points. Here’s one:

Uranium glass emits low levels of alpha and beta radiation, detectable with a Geiger counter. However, most pieces register less than 10 microsieverts per hour (μSv/h), which is:

• Far below the 1,000 μSv annual limit recommended for public exposure.
• Comparable to natural background radiation from rocks, soil, or even bananas (which contain potassium-40, a mildly radioactive isotope).

First, uranium glass emits gamma rays too, not just alpha and beta particles. More importantly, these numbers are hot nonsense.

First, the Sievert is a measure of dose, not source intensity; saying a piece emits 10 µSv/hour is like saying a heat lamp emits five degrees of warming per minute. It depends on how close you are to the lamp, how much of you is facing it, whether you’re shielded by clothing, and so on. The dose from a uranium glass cup depends on whether you’re chipping off bits and eating them, cuddling it every night, or keeping it in a display case.

10 μSv/hour is 87,600 μSv/year. How is that “far below” 1,000 μSv/year? If you’ve got a uranium glass candy dish on your desk that delivers 10 µSv/hour to your body, and you keep that up for eight hours a day, you’re looking at 29,200 µSv (29.2 mSv) per year. That’s over the DHS emergency guidelines for public relocation, and about half of the NRC dose limit for radiation workers.

The other comparisons are also bonkers: 10 μSv/hour is not comparable to typical background radiation: in the US, that’s roughly 3,100 μSv/year, or 0.35 μSv/hour. Nor is it on par with a banana: the banana equivalent dose is very roughly 0.1 μSv. Nobody is eating 100 bananas an hour.

The best source I know for uranium glass safety (and which, now that we’re drowning in LLM slop, is surprisingly hard to actually track down) is the Nuclear Regulatory Commission’s NUREG-1717. The section on glassware begins on page 499 of the PDF, labeled 3-217. You should read their methods for estimating dosages, as exposure is highly dependent on uranium density, exposure vector, acidity, distance, etc. The NRC estimated a negligible 1.8 × 10^-5 mSv/year (0.018 μSv/year) from drinking glass leachate, up to 0.02 mSv/year (20 μSv/year) from external exposure to drinking glasses (e.g. washing dishes, being in the same room, etc.), and 0.002 mSv/year (2 μSv/year) from occasional handling, admiring, and generally being around four pieces of decorative glassware scattered through a home. These exposures are almost certainly fine.

Please stop asking large language models to tell you or others about radiation safety. Ask a physicist or regulator instead.