The construction of a Stanley tumbler involves a lead-based solder, but this material does not come into contact with the beverage and is hidden under a disc on the bottom of the tumbler. The cup is safe to drink from; but if the disc falls off and exposes the solder, you should get a replacement.
Do Stanley cups contain lead or pose a risk of lead poisoning?!
I will be throwing away my kid’s Stanley Cups! https://t.co/tKG9gqBtX2
— Rob Schneider (@RobSchneider) January 25, 2024
It was a shock to many, especially given Stanley's viral product status. According to a story from CNBC, the Stanley Quencher water bottle took the company from around $70 million per year to $700 million a year. It was even the star of a "Saturday Night Live" sketch. So the rumors about lead were a major problem.
The story originated with Tamara Rubin, a lead safety advocate known online as the Lead Safe Mama. In March 2023, she published a report on her website and a video on TikTok allegedly showing lead in the Stanley tumbler.
Rubin used an X-ray fluorescence device to test for lead and other harmful heavy metals and found what she claimed to be a dangerous concentration of lead under a cap on the bottom of the cup.
While investigating unrelated claims about lead in vintage cookware in 2019, Snopes reviewed the method and equipment Rubin uses to test different commercial products for lead. It is scientifically valid — Rubin's tests did legitimately detect lead in the Stanley tumbler.
Rubin explained to Snopes in a phone interview that she intended to alert consumers to the presence of lead in the bottle, but that some users became concerned about whether they had been drinking water contaminated with lead the entire time. As far as Snopes and Rubin could tell, that was not true.
The bottles made by Stanley (as well as similar bottles made by other companies) hold the temperatures of liquids so well by using an insulating vacuum between the bottles' exterior and interior layers of metal. According to Stanley's FAQ page, a pump sucks out all the air between the layers through a small hole to create that vacuum. Before the cup hits store shelves, the hole is sealed using a small amount of solder.
According to the tests conducted by Rubin, that small dot of solder material was about 25% lead. In other words, yes, it's true that Stanley cups contain lead. A company spokesperson confirmed as such to NBC News. However, because the small dot of lead-based solder is not on the inside of the bottle, you can still drink water from the bottle without fear of lead contamination.
As a protective measure, the Stanley tumbler features a small disc on the bottom of the cup covering the solder point. As long as this cover is still attached, there is no risk of lead poisoning. If that cap comes off, however, it's time to get a new water bottle (According to the FAQ page, the detached cap is covered under the company's lifetime warranty, too).
The danger posed by the lead is only present if that cap comes off. Rubin said that main concern was "hand-to-mouth activity," like touching the leaded solder point before eating with your hands. She added that although the Stanley tumbler could easily be given to kids as a gift, the product isn't considered "made for children" and therefore isn't subject to any federal regulations about lead concentration in such products. If it was considered "made for children," Rubin said, the Stanley tumbler would not be allowed on shelves.
Rubin added that there are companies that make similar vacuum-sealed water bottles without using lead, and recommended that consumers research their options if they had any concerns.
Rubin also noted in her report that the tumbler is specifically meant for cold water — not for hot or acidic beverages like coffee, because of the nickel content of the stainless steel used. Nickel is another metal that can be seriously harmful if ingested, but it takes a lot of time for the metal to actually contaminate food or water. Both heat (from beverages like hot coffee or tea, for instance) and acids (like those found in citrus fruits and soda) can speed that process up. Sticking to plain water removes that risk.
We also reached out to Stanley for its response to the viral rumor about its product, and will update the story if the company responds.
This was not the first time we have addressed rumors about risks of lead contamination in other common items, like Shein clothes.