Hyperonic radiation is a type of radiation that is lethal to most humanoids. This type of radiation also renders transporters inoperable and randomizes phaser fire (although Lt. Cmdr. Data adapted a phaser using his own circuitry to be able to fire in such an environment).
The atmosphere of the planet Tau Cygna V had an abundance of hyperonic radiation that killed one-third of the crew of the SS Artemis when it crash-landed on the planet in 2274. The survivors adapted to the radiation and thrived to build a colony of over 15,000. (TNG: "The Ensigns of Command")