Some insulated cups use a lead seal in the base, but it's safe while the cover stays on
Do this instead
- Check the bottom cap now and thenThe lead is only exposed if the cover comes off.
- Replace a cup whose base cover has come offStanley says it covers this under its lifetime warranty.
- Lead-free brands existHydro Flask, Owala and Klean Kanteen say they don't use lead.
The short version
Stanley confirmed in 2024 that its tumblers use a lead pellet to seal the vacuum insulation, hidden under a steel cover on the bottom. Drinks never touch it. Experts say there's no exposure while the cover is in place, but kids can loosen it over time.
The evidence
Stanley says the lead pellet sits under the bottom cover and that other insulated cup makers use similar seals. Experts quoted by NBC News said the risk is practically zero while the cover stays on, since liquid doesn't touch the pellet.[1]
Exposure is possible only if the base cover comes off, which heavy use, fidgeting kids and repeated washing can cause. An exposed pellet can flake when scraped on hard surfaces.[1]
Spot an error or have newer test results? Email corrections@doctorsoni.ca and we'll review it. How we decide verdicts