After Stanley fans posted home lead test results on social media, the company confirmed the viral insulated tumblers do contain lead. Here’s what experts are saying.

Stanley, the makers of the tumblers that have become a viral sensation, have come under scrutiny this week. Social media users, specifically on TikTok and Instagram, have been sharing videos showing at-home lead test findings, and the results are worrying faithful Stanley sippers.

Dozens of consumers are posting videos claiming that their tumblers tested positive for lead. It's often unclear from the videos which or how many different brands of at-home lead tests these consumers are using, but to be EPA-certified, home lead tests such as D-Lead must produce an accurate result (when used correctly) 95% of the time. At-home lead tests for drinking water are less reliable.

In response to the claims, Stanley issued a statement about lead in its product.

"At Stanley, one of the key features of our products is our vacuum insulation technology, which provides consumers with drinkware that keeps beverages at the ideal temperature," the company wrote on its website, acknowledging that lead is used in the manufacturing process. The statement continues, "Once sealed, this area is covered with a durable stainless steel layer, making it inaccessible to consumers. 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."