The wildly popular Stanley Quencher cups are trending yet again, this time over a proposed class action lawsuit that accuses the makers of the cup, Pacific Market International, of false advertising.

Separate lawsuits were initially brought forward by Stanley cup owners in California and Nevada. Both women say they purchased their cups at big box retail stores and were unaware of the potential dangers they say the cups posed. Among those dangers was the exposure to lead that was used during the insulation processes when manufacturing the cups.

The lawsuit explained that “PMI marketed its products as safe for use by adults and children despite knowing they contain a toxic material that, if the cup were damaged, could expose consumers (including children) to lead. It thus knowingly misled Californians by failing to disclose a fact that reasonable consumers — especially those in PMI’s safety-conscious target demographics — would want to know before buying a drinking cup, especially considering that similar products are available that do not use lead or pose any lead-related risks.”

The lawsuit goes on to argue that the cup, known for its heavy-duty construction, would be more susceptible to dings and drops. Over time, this harsh use of the cup could cause damage that exposed users to the lead within.

The Stanley Quencher cup grew to be the status symbol tumbler simply overnight. The stainless steel tumbler dominated the consumer landscape this past year. Despite its fierce competition with other status symbol tumblers like the HydroFlask, YETI Rambler, and Owala FreeSip, Stanley’s Quencher saw a 275% increase in 2022. Sales of all sizes of the tumbler were up 751% in the year to date according to company representatives. Fueling the popularity of the tumblers was the brand's shift to an unconventional demographic, Gen Z and Millennial women. The inconspicuous blue-collar cup was rebranded with exclusive models, bright colors, and marketing that resonated with younger generations.

The success of this unapologetically stand-out thermos was short-lived, largely in part by the fickle nature of social media. After consumers became aware of the company’s utilization of lead in its insulation process, some called out the century-old brand for falsely advertising the cup. Consumers say the brand touted itself as being BPA-free and failed to “warn purchasers of the potential presence of lead.”

The concerns about the usage of lead in the Stanley cups first began to circulate after users posted online about at-home lead testing kits they conducted on the inside of their cups. While the results were varying, some users reported that their kits detected the presence of lead on the stainless steel.

In January, the company released a statement affirming that the cups are insulated with a material that contains lead; however, they say the cup is reinforced with a stainless steel covering that protects users from ever coming in contact with lead. The portion of the cup that utilizes this lead material is found on the bottom of the cup. Some users say that this component, found on the bottom of the cup, can pop out, exposing the lead used in insulation. Stanly says this component is fused shut with the base of the cup and is not designed to pop out. In the event the base of the tumbler does pop off, Stanley offers a lifetime warranty that replaces the cup.

Stanley’s statement explained in part, “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. Our manufacturing process currently employs the use of an industry-standard pellet to seal the vacuum insulation at the base of our products; the sealing material includes some lead. Once sealed, this area is covered with a durable stainless steel layer, making it inaccessible to consumers.”

Consumers pushed back in the lawsuit, arguing that had they known lead was used in the manufacturing process, they would not have purchased the cups. “PMI kept customers in the dark so as not to interfere with its bonanza of influencer-driven sales, especially sales to young women,” the lawsuit maintains.

The complaint is seeking compensatory and punitive damages along with a permanent injunction in California that would require Pacific Market International to disclose to customers the cups contain the presence of lead and other toxins if they are present.