Cryotherapy treatments are unregulated by the U.S. Food and Drug Administration. In fact, regulation of any kind is virtually nonexistent across the nation.

Cryosauna manufacturers say the practice originated in Japan in the late 1970s. Cryospas started getting popular in the U.S. around 2010.

The procedure's been featured on The Dr. Oz Show, with the chambers making their way into the locker rooms of professional and university sports teams like the Dallas Mavericks and Texas Christian University Horned Frogs.

Lack of regulation for the procedure drew national alarm last month. Chelsea Patricia Ake-Salvacion, a 24-year-old cryotherapy technician in Henderson, Nev., died in a cryospa machine Oct. 19, after using it alone after hours at the business where she worked, RejuvenIce.

The coroner's office for Clark County, Nev., ruled that Ake-Salvacion died from a lack of oxygen—not from the unit's frigid temperatures. As the chamber fills with liquid nitrogen vapor to cool it, ambient air in the chamber gets displaced, along with the oxygen in it.

"When in use, oxygen levels inside the chamber can drop to less than 5 percent," the coroner's Nov. 10 statement says. "Breathing air with this low level of oxygen can quickly result in unconsciousness and then death." (Regular air is 21 percent oxygen.)

Ake-Salvacion's is the first recorded death during cryotherapy.

The investigation into her death led the state of Nevada to shut down all RejuvenIce locations within its borders, but only on a technicality: According to multiple Las Vegas media reports, the business lacked workers' compensation insurance.

Since her death, the call has grown for government regulators to take a closer look at whole-body cryotherapy.

That includes Oregon, where two cryotherapy centers operate.

For the state to regulate whole-body cryotherapy, the Legislature would have to issue rules for the Oregon Health Authority to enforce.

State Sen. Laurie Monnes Anderson (D-Gresham), who chairs the Senate's Health Care and Human Services Committee, tells WW that new regulation for cryotherapy is unlikely before 2017.

"We definitely want to look into it and see if this is something that Oregon should be regulating, or not regulating, or banning," Monnes Anderson says. "One death is too many."

Richard Sprauer owns Active Cryotherapy in Portland's Sylvan neighborhood, where Lizzy Acker tried a treatment. He says cryotherapy is safe, and welcomes regulation.

"I can understand them wanting to regulate it, of course," Sprauer says. "I would like to see it carefully tended because it is something to be careful with."