Israeli scientists claim to reverse aging process

"The biochemical basis for the toxicity of oxygen is the partial reduction of oxygen by one or two electrons to form reactive oxygen species, which are natural by-products of the normal metabolism of oxygen and have important roles in cell signalling."

https://en.wikipedia.org/wiki/Oxygen_toxicity#Mechanism

"Under normal physiological conditions, cells control ROS levels by balancing the generation of ROS with their elimination by scavenging systems. But under oxidative stress conditions, excessive ROS can damage cellular proteins, lipids and DNA, leading to fatal lesions in the cell that contribute to carcinogenesis."

https://en.wikipedia.org/wiki/Reactive_oxygen_species#Damagi...

"The effect’s duration is yet to be determined in the long-term, Efrati said."

I would keep an eye on the potential emergence of new cancers in these folks.