The maker of the ultra-popular Stanley cups was sued on Thursday in California state court by four women who say the company misled consumers by failing to disclose that the product contains lead, a toxic substance.
The lawsuit, which seeks class action status, alleges that Stanley brand owner Pacific Market International marketed the reusable cups as safe and durable while knowing that there was lead in the cups’ vacuum seals.
The women, who filed their case in Los Angeles, say they would not have purchased the cups had they known that the cups contained lead, arguing that they could have been exposed to the metal.
“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 said.
Representatives for Pacific Market International did not immediately respond to questions about the lawsuit’s allegations.
John Rushing, a lawyer representing the women, told Reuters that Stanley “could have been honest with customers,” but “chose not to.”
The women seek compensatory and punitive damages, as well as a permanent injunction requiring Stanley to disclose the presence of lead and any other toxins in its products in California.
The company has acknowledged in a statement posted on its website that there is lead present in the seal for the cup’s vacuum insulation, but it said “no lead is present on the surface of any Stanley product that comes into contact with the consumer nor the contents of the product.”
The Stanley cups, formally known as the Stanley Quencher cups, retail for between $35 and $50. Recent sales of the cups, driven largely by social media, propelled the 100-year-old, privately held Stanley brand to a ten-fold increase of $750-million in revenue last year, according to CNBC in December.
Posts about lead in the cups have exploded on social media in recent weeks, with some consumers posting at-home lead tests on their cups on TikTok.