XRF readings:
Lead: not measured · Cadmium: not measured · Arsenic: not measured
Verdict: Not Lead Safe
There is no safe amount of lead. This number is a starting point, not a verdict on your safety. What matters is whether the lead can actually reach a person. Think of tacks: a box of them in a drawer is fine, the same tacks loose on the kitchen floor are not. Lead locked in a stable fired glaze is mostly in the drawer. The same ppm in something a child can mouth, chew, or swallow, like paint dust, play sand, or a worn or chipped surface, is on the floor. Food is its own category: if the lead is in something you eat or drink there is no "might reach you," you are guaranteed to take the dose. Dose is what counts: 1 gram of a 90 ppm material is about 90 micrograms of lead, roughly 40 times the 2.2 micrograms per day the FDA uses as a child reference level. A reading that looks low can still matter in the wrong form, and a high reading on intact glaze may never reach anyone. Do not trust the number alone. Test the actual item, and when in doubt keep it away from kids and food.
What XRF actually measures (and what it doesn't)
XRF detects elemental lead presence on the surface. It does not
measure whether that lead migrates into food. Those are different
questions. Lead bound in fired ceramic glaze is chemically locked in the
vitreous matrix and, in independent leach testing on items up to ~3,000 ppm,
showed no detectable migration. Lead in surface paint, decals, or worn glaze
behaves very differently and is a meaningful exposure risk.
What this XRF reading actually means →
Test your own dishes with FluoroSpec →
Source data: EverythingLead
Original source: https://everythinglead.org/index.php/Vintage_Holly_Glass_Mugs
Test method: XRF (Niton XL 5 Plus, 1.5 sigma)
License: Factual XRF measurements are not copyrightable
(Feist v. Rural Tel., 499 U.S. 340). Verdict and methodology CC-BY-SA 4.0.
