Do Stanley cups pose a lead danger? Here’s what to know about the trendy tumblers

Stanley cups, the trendy tumblers whose sales have skyrocketed in recent years, have been the beneficiary of social media success.

Customers have waited in long lines to buy the cups, and a limited edition pink version sparked mayhem as customers tried to snatch them up at Target stores in early January.

But more recent social media videos alleging the popular cups contain lead and endanger consumers have flooded Facebook, Instagram, X and TikTok. Many featured people using lead home-testing kits on the cups.

We found at least a dozen Facebook posts sharing the same screenshot from a post in which a person claims to have used lead home test swabs in a Stanley cup, and on cups from its competitors, Yeti and Rtic. One Jan. 29 post was shared more than 600 times.

"I rubbed it on the inside of the cup where the drink is," the person wrote. "Every single Stanley I owned tested positive for lead." The other cups did not, the post said.

The post was flagged as part of Meta’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

Lead is a metal that is toxic to people, particularly young children. It can cause developmental delays and other adverse effects, health officials say.

The Consumer Product Safety Commission has not recalled any Stanley cups and said lead home-testing kits are unreliable. An expert also said the home tests generally are used to detect lead on painted surfaces.

(Facebook screenshot)

Stanley said on its website that it uses lead in manufacturing its cups, but not in any part consumers touch or drink from.

Stanley said it uses "an industry standard pellet to seal the vacuum insulation at the base" of the cups. The sealing material contains some lead, but the area is covered with a durable stainless steel layer, making it inaccessible to consumers, Stanley said.

"Rest assured that no lead is present on the surface of any Stanley product that comes into contact with the consumer nor the contents of the product," Stanley said.

If the cups’ bases break and expose the seal, customers can contact Stanley to take advantage of the products’ lifetime warranty. 

Stanley, after initial publication of this article, referred us to the company’s website about how lead is used in its cups. A spokesperson told NBC News the company is working on alternative materials to use in the sealing process.

The Consumer Product Safety Commission has not issued a recall for Stanley cups, a search of the agency’s website shows. The agency previously has recalled other companies’ children’s drinking cups over lead exposure concerns, spokesperson Patty Davis said.

"We have recalled children’s cups in the past where the lead solder bead became accessible due to the bottom coming off, or the lead solder bead was just covered by paint, which is not considered a barrier to make it inaccessible," Davis said.

The agency issued recalls for several brands of children’s drinking cups in November for that reason. 

A U.S. Food and Drug Administration spokesperson told PolitiFact the agency has not received any reports of lead poisoning from Stanley cups. 

Jack Caravanos, a New York University clinical professor of environmental public health sciences who studies lead poisoning, said after seeing social media videos about the Stanley cups he tested several of the cups himself.

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Caravanos used what he called a "state of the art" X-ray fluorescent monitor that can detect lead and other metals in solid or semisolid materials. He also used an at-home test kit with swabs that change color if lead is detected. He used both the monitor and the kit to test the cups’ outside areas, including the top portions consumers drink from.

"I did not find anything on the outside that contained lead in any detectable quantity," Caravanos said.

"So, the cups that people are buying today are absolutely lead-free on the outside and (there's) really no practical way for you to ingest that lead material," he said.

Caravanos said it would be impossible for the lead used at the base of the cup to leak into the cup’s interior, which holds the beverage. He described the thermoses as a "bottle within a bottle, and the space between the inside and the outside is a vacuum."

"There's no way that lead can go through the stainless steel into the drinking part of the cup," he said.

It’s  unclear what testing kits people in the social media posts are using on the Stanley cups. Some videos show people swabbing the inside of the cups; others show them swabbing the base of the cup with the protective cover removed. Some videos have shown positive tests; others have shown negative results.

The U.S. Environmental Protection Agency has recognized three test kits that it says can accurately determine whether lead-based paint is present on a surface, although one is no longer being produced by its maker, 3M Co. Those tests are for use on walls, windows and other building surfaces to detect lead-based paint, not consumer products, an EPA spokesperson said. 

There are other home testing kits available, some of which say they can test for lead on any surface. The EPA does not recognize or evaluate lead test kits for consumer products, a spokesperson said.

However, the Consumer Products Safety Commission does not recommend testing for lead with home kits.

"They are not reliable and can have false positives and false negatives," Davis said.

Caravanos said the home tests generally are used to detect lead on painted surfaces.

"They're really intended for paint or glaze, we don't usually use them on metals," he said.

Should consumers be concerned about lead exposure from these cups?

Caravanos said when testing the cups he tried and failed to pop off the cap covering the lead at the cup’s bottom, and his friend suggested they would need to use a drill to remove it.

"If I have to do all that to get to the lead, it's really unlikely a human can expose themselves to that material," he said.

Even if the base broke and exposed the lead, it would be unlikely to be ingested, Caravanos said, but it could contaminate other surfaces, perhaps leaking into water if you’re washing the cup in a sink or a dishwasher.

"The chances that you’re drinking something that gets contaminated like that are pretty low," said Caravanos, who added that lead should not be used in any consumer product.

Social media posts say the inside of popular Stanley cups are testing positive for lead. 

The cups contain lead in material that’s used to vacuum seal the cups’ base. Unless the cup is damaged, that lead does not come into contact with the inside of the cups or any part the consumer would handle, the company and an expert said. 

The Consumer Product Safety Commission has not recalled any Stanley cups as of this article’s publication and says home testing kits for lead are unreliable. The tests generally are used to detect lead on painted surfaces, an agency official said.

A lead expert who tested the cups told PolitiFact he detected no lead on the cup’s exterior or lid and that it would be impossible for lead in the base to reach the cup’s interior.

We rate these claims False.

Update, Feb. 5: This story was updated after publication to include comments from the U.S. Food and Drug Administration, the Environmental Protection Agency and Stanley.