The makers of the Stanley Cup product that seemed to be on everything Gen Z's Christmas list have responded to claims it contains dangerous amounts of lead.

Lead is used as part of the tumbler’s vacuum insulation and is covered by a stainless steel layer that protects consumers from lead exposure, according to the Stanley cup manufacturer, Pacific Market International.

“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,” a Stanley spokesperson said in an emailed statement to CNN.

“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,” the statement said.

But people on social media are nervous, considering the dangers of any exposure to lead.

The tumblers, which come in a rainbow of colours and hold up to 40 ounces of water while still fitting in a car cup holder, have become a status symbol among youngsters.

Stanley cups are in the hands of beauty bloggers, the cars of parents at school pickup, and even on the Christmas lists of many kids this past year. 

Some caution is warranted, said Jane Houlihan, research director for Healthy Babies, Bright Futures, an alliance of nonprofits, scientists and donors with a stated mission of reducing babies’ exposures to neurotoxic chemicals.

If the base cap of a Stanley cup does come off and exposes the seal the cup is eligible for replacement

“If the cup stays intact, there’s likely no lead exposure risk for consumers. But if that bottom seal comes off, all bets are off,” Houlihan said.

“Lead is so toxic you just can’t take chances with it,” she said in an email.

“If a company has to rely on their product remaining perfectly intact in order for it to be safe, that company has a basic material safety problem that they are passing on to their customers.”

If the base cap of a Stanley cup does come off and exposes the seal, which is rare, the cup is eligible for replacement under the lifetime warranty, according to a statement from Stanley.