Confusion around lead exposure among owners of Stanley Quencher cups continues to persist, and for good reason.

If you own one of these viral sensations, here is how you can tell if you have been exposed to lead:

Consumer guide Tamara Rubin from Lead Safe Mama, a lead poisoning prevention activist, identified that the sealing dot located on the bottom of the Stanely Quencher tumblers tested positive for high levels of lead, as NBC 5 DFW reported. Rubin conducted the test using X-ray fluorescence technology.

On the bottom of Stanley Quencher tumblers is a small button with a logo that serves to cover the lead sealing dot. The lead is used to help produce the vacuum insulation known for keeping the temperature of the contents consistent.

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As reported last month in The Dallas Express, Stanley has acknowledged the use of lead in the production of its popular products, which have been making big cultural waves.

If you own a Stanley Quencher and the bottom button falls off, cease using it immediately. Contact the company and request a replacement under its lifetime warranty, Rubin advised.

Exposure to lead can cause damage to the brain and nervous system, slow growth and development, and cause learning, hearing, and speech problems, according to the CDC. If you suspect you or your family members may have been exposed to lead, consult with a doctor.

While Stanley is not the only manufacturer to include lead in its products, its recent virality has likely helped draw attention to the cup maker.

However, according to Stanley, worried customers have nothing to fear.

“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 company said, according to NBC 5.