Stanley tumblers — or Stanley cups as they’re more frequently referred to by consumers — have managed to create an entire culture for themselves online, with influencers showing off how they’ve accessorized the insulated water bottles with knick-knacks ranging from attachable snack plates and custom-shaped ice cubes to decorative charms, and even miniature Stanley cups that perch atop the straw. 

But success on the internet usually brings about more scrutiny and the now-iconic tumbler is not immune. Over the past year, content creators on Instagram and TikTok have started calling attention to claims that Stanley uses lead to make its popular product. Two different class action lawsuits have been filed against the brand’s parent company, Pacific Market International, in January and February of this year, for failing to adequately disclose the application of lead in some of its water bottles. Stanley has responded to the uproar about lead in its cups, insisting that they are safe to use. But after all the back and forth between social media accounts, there still seems to be confusion about whether or not the tumblers contain lead, and if we should still be drinking from them — so let’s clear up any misinformation.

Do Stanley cups have lead?

The answer to this question calls for a major “yes, but—” moment. Simply put, Stanley cups do have a small lead pellet in their base, which helps create vacuum-sealed insulation, enabling them to hold temperature steady for a long period of time. The problem is that many people stop reading after they learn that. 

As Stanley states on its website, a layer of stainless steel covers this small amount of lead, and neither the person using the water bottle nor the liquid within ever comes into contact with the lead. The Seattle-based brand also details that “its products meet all U.S. regulatory requirements, including CA Proposition 65. Stanley tests for and validates compliance on all products through FDA-accredited 3rd party labs that verify our products follow strict guidelines, including BPA/BPS, PFOS, and phthalate regulatory requirements, among others.”

Martin Bucknavage, a senior food safety extension associate and team leader for the Industrial Food Safety and Quality Team at Penn State, confirmed that Stanley cups, indeed, can be considered safe, elaborating that “the lead is not at all exposed to the food in an intact container. The stainless steel internal cup is the only component that comes in contact with the food, and this internal stainless steel cup component separates the beverage from the small lead piece used within the wall that connects the outer cup to the inner cup. The only way the lead would be exposed is if the cup broke apart, and even then, someone would have to use the cup in this defective state.”

Are Stanley cups safe to drink from?

Both Stanley and Bucknavage point out that the only way you could come into contact with lead is if your tumbler is damaged, exposing the interior of the bottom of the cup. Considering how durable the product is, this would be extremely difficult to do — in the event that you do somehow break open part of your water bottle, just throw it away and definitely don’t drink from it.

It’s not uncommon for other insulated water bottle manufacturers to use lead in the process of sealing their tumblers — one of the most popular competitors of Stanley, Yeti, confirms in its FAQ that it uses the same lead pellet system for sealing their vacuum insulation. Yeti also extensively explains the testing that their products undergo to ensure that they are entirely lead-safe for consumers. 

This drives home one of Buckanavage’s other notes, as he emphasized that “In the end, a well-known company such as Stanley is in the business to make containers that are safe for use.  It would be [unthinkable] for them to produce a product that was unsafe, especially to design and seal it up [in a way that caused] the potential to have lead leach into the product.”

Audiences are increasingly more conscious and curious about what contaminants could be in their food — especially following reports of issues like lead in cinnamon, and arsenic in apple sauce — so rest assured that even from a monetary perspective, it benefits Stanley to ensure people can safely drink from their cups, because of course they want us to keep buying them.

What are the symptoms of lead toxicity?

If you have somehow consumed water from a broken Stanley water bottle, or you’re worried about other exposure to lead, the best resource to learn accurate information about lead toxicity is the Centers for Disease Control and Prevention (CDC). It’s important to know that almost everyone is exposed to lead through their daily environment. The CDC’s page on blood lead level guidance notes that “The Council of State and Territorial Epidemiologists’ (CSTE) blood lead reference value is 3.5 micrograms per decilitre.” Their site also states clearly that there is no recognized level of blood lead levels for children that is considered safe.

Children are more likely to suffer symptoms of lead toxicity at a lower level of exposure, and according to the CDC lead “inhibits the bodies of growing children from absorbing iron, zinc and calcium, minerals essential to proper brain and nerve development.” Symptoms of this may include, but are not limited to, developmental delays, problems with learning, or difficulty paying attention.

Adults are less likely to experience lead poisoning than children, but can also suffer neurological effects like lack of concentration, irritability, mood changes. The signs of lead poisoning vary drastically, depending on the age of who is exposed and what their level of exposure is. If you’re concerned, the best thing to do in the short term is consult either the CDC or Mayo Clinic’s resources on possible symptoms and sources of exposure, and then consult your primary healthcare provider as soon as you can.

Luckily, if you’re drinking water from a Stanley cup — like I am right now — you won’t have to worry about any of the above. So keep calm, and keep on using that insulated tumbler.