Radiation poisoning

Radiation sickness was an illness caused by excess radiation. When the First Doctor, Susan Foreman and Ian Chesterton discovered, through the use of a Geiger counter, that there was excess radiation on Skaro, they deduced that it was causing radiation sickness. In that particular case, the effects of the disease included a jungle being turned to stone, soil becoming barren, and a feeling of sickness between the three. (TV: "The Survivors")