Cryotherapy is gaining in popularity across the world, and it has recently made a foray into U.S. markets. Cryotherapy involves subjecting a patient’s body to extremely cold temperatures, way below that of any place found on the planet Earth. According to a report from the New York Times, however, the treatment is facing new scrutiny after a woman in Nevada perished after being subject to abnormally low temperatures.

A person steps into an upright cylinder, and a platform raises their head up above the surface. A cold gas rushes into the chamber at roughly negative 300 degrees Fahrenheit.

Cyrotherapy supporters claim that the treatment can provide miraculous health benefits including pain reduction, improved recovery time from injuries, and improvement to mood. Centers are opening up across the country at a rapid pace, and some even claim that the therapy can prevent osteoporosis, alleviate asthma, improve sexual drive and even induce weight loss. It has received celebrity endorsements from notable NBA athletes Shaquille O’Neal and LeBron James.

The technicians that perform the procedure, cryotherapists, assert that the practice is completely safe and that cold temperatures have been applied to injuries for millennia. Ice baths are a common practice in athletics, and minor bruises and bumps are almost always treated with an ice pack.

The FDA, however, has made no approval of cryotherapy and has not recognized any medical benefits. The devices are completely unregulated, and the recent death of 24-year-old Chelsea Ake-Salvacion has raised suspicion about proponents’ claims of safety.

According to Deborah Kotz, a spokeswoman for the Food and Drug Administration, the agency is worried about cryogenic devices that have not yet met any sort of regulatory standard for safety.

A Texas woman, Alix Gunn, is suing a cryotherapy center that allegedly froze her arm, left third degree burns, and resulted in serious disfigurement. According to Gunn’s attorney, the woman was given wet gloves prior to the cold gas immersion, which resulted in severe frostbite. CryoUSA responded that Ms. Gunn signed a waiver releasing the company of liability, and that she did not take proper precautions before entering the chamber.

Ms. Gunn’s story isn’t the only one like it. American Olympian sprinter Justin Gatlin got a nasty case of frostbite on his feet after wearing damp socks in a cryotherapy chamber in 2011. While cryotherapy centers across the country remain unregulated, people are growing increasingly concerned about the safety of applying such cold temperatures to human tissues.