The Quick Answer

  • Insulated stainless steel tumblers (like Stanley and Yeti) rely on a vacuum seal at the base of the cup, which is routinely sealed with a pellet of Lead solder. While the lead is covered by a steel cap and never touches the water, if that bottom cap drops off or is damaged, the severe neurotoxin is exposed to your child's hands. We recommend switching to lead-free fused bottles like HydroFlask or Owala for absolute peace of mind.
Editor's NoteTriggered by massive social media virality regarding Stanley cup lead swab testing.

Why is there Lead in a modern cup?

It comes down to cheap manufacturing. Creating a double-walled vacuum insulation requires sealing the air-hole at the bottom. Using a pellet of lead solder is cheap, melts at a low temperature, and seals perfectly.

Brands defend this by stating the lead is trapped securely under a stainless steel shield. The problem arises with toddlers: they hurl cups onto the pavement. If that bottom shield dents or pops off, the lead pellet is exposed on the bottom of the cup, where a child can easily touch it and then put their fingers in their mouth.

Section Summary

  • Lead solder is used to seal the vacuum wall in many popular tumblers.
  • Damage to the cup exposes the lead to the child's hands.

The Bottom Line

  • A vanity cup is not worth the anxiety of lead exposure. Buy from brands that explicitly market their welding process as 100% Lead-Free.

What We Recommend

Evidence-based alternatives that address the concerns above.

1

HydroFlask Kids

They entirely eliminated lead solder from their manufacturing process several years ago.

2

Owala

Guaranteed lead-free vacuum sealing.

1 more tips

Create a free account to see more buying advice

Sign Up Free

Frequently Asked Questions

Common questions about safety alerts answered by our research team.

QDo at-home lead swabs work?

They are notoriously prone to false positives/negatives on metal surfaces. The most reliable data comes from XRF spectrometer testing.

R

Renee, R3 Founder

Environmental Toxins Analyst

Renee is the founder of R3 and a lead researcher in environmental toxins. She specializes in translating complex toxicology reports into actionable advice for families.

LinkedInX (Twitter)Editorial Standards