Lead: 60,600 ppm · Cadmium: 2,940 ppm · Arsenic: not measured
60,600 ppm lead, roughly 6x the CPSC 90 ppm children's limit. At this concentration, even fired ceramic glaze carries leaching risk under acidic food conditions. No food contact under any circumstances. FluoroSpec will glow. NOTE: 2,940 ppm cadmium also detected, a separate and serious concern for colored glazes.
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: independent consumer-safety researcher (factual data; verdict by EverythingLead)
Original source: https://tamararubin.com/2018/06/vintage-libbey-high-ball-christmas-glass-60600-ppm-lead/
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.