Radiation

Radiation was energy produced by materials and by physical interactions, such as the contact of matter with anti-matter.

Biological effects
Radiation was often harmful or fatal to most life and could cause mutations. In many life forms, it induced radiation sickness. (TV: "The Survivors") Some organisms could withstand large amounts of radiation, such as the Foamasi. (TV: The Leisure Hive) Time Lords could absorb, withstand and expel great doses of certain types of radiation; the Tenth Doctor said he used to play with roentgen bricks in the nursery. (TV: Smith and Jones) Others could absorb and regenerate with it, such as the Kastrians (TV: The Hand of Fear) and the Daleks on Skaro, whose evolution led to them becoming dependent on a constant supply of radiation. (TV: The Daleks) Nevertheless, radiation could still prove harmful to the Daleks. When "Rusty" was damaged, a crack in his power supply began leaking trionic radiation that began killing him and affected his mind, turning him into a "good Dalek." When the Twelfth Doctor stopped the radiation leak, Rusty immediately returned to normal. (TV: Into the Dalek)

An Exxilon fuel pod was left in ancient Earth Incan civilisation, causing mutations in the populace and leading to Huitzilin gaining great powers. (PROSE: The Left-Handed Hummingbird) The Solonians used thaesium radiation to cause the "mutations" that were part of their life cycle. (TV: The Mutants) The Cybermen showed a weakness to radiation, which Ben Jackson and the team at the base Snowcap used to their advantage when the Cybermen invaded Earth in 1986. The radiation in the chamber of the Z-Bomb instantly affected them so they could not ensure the bomb was dismantled before their home planet Mondas was destroyed. (TV: The Tenth Planet)

On Wengrol, radiation from the star Mortain caused mutations in the genetically modified Yend. (PROSE: The Sons of the Crab)

The effects of radiation could be combated by ingesting an anti-radiation pill. (TV: Destiny of the Daleks, PROSE: Plague of the Cybermen)

Radiation could be used as a therapy against other kind of illness, such as the infective Lazar's disease. (TV: Terminus)

Sociological effects
The Thousand Year War between the Thals and the Kaleds initially saw nuclear weapons used. The fallout from this caused disfigurement on both sides, with those effected being cast out to preserve racial purity. (TV: Genesis of the Daleks)

The war between the Argolins and the Foamasi saw the former become sterile. This dictated the field of scientific study the Argolins attempted to save their species. The Tachyon Recreation Generator was a product of their research. (TV: The Leisure Hive)

Radioactive locations

 * On the planet Janus Prime, radiation made the sand glow blue. It also destroyed a human body's lipids, making skin sticky to the touch and changing to a jelly-like texture. Upon death, the body lost cohesion and collapsed into a porridge-like substance. (PROSE: The Janus Conjunction)
 * On Dulkis, the Dulcians irradiated an island to see the effects. When the Dominators landed there, they absorbed the radiation from the island into a storage tank, allowing them free access to the area. (TV: The Dominators)
 * Romana and the Fourth Doctor suffered from radiation on Skaro. Romana, to escape the Daleks, faked dying from radiation. (TV: Destiny of the Daleks)
 * Argolis had a radioactive atmosphere from a nuclear war with the Foamasi. (TV: The Leisure Hive)
 * Messaline had a relatively high level of radiation; this was eradicated by terraforming. (TV: The Doctor's Daughter)
 * Oseidon had the highest radiation level in the galaxy of Mutter's Spiral. (TV: The Android Invasion)
 * The Petrified Forest of Skaro had a high radiation level from a past nuclear war between the Thals and the ancestors of the Daleks. (TV: The Daleks)
 * The Third Doctor regenerated due to radiation exposure on Metebelis III. (TV: Planet of the Spiders)
 * The Tenth Doctor regenerated due to radiation exposure caused by taking Wilfred Mott's place in a radiation containment chamber. (TV: The End of Time)
 * Because of an ongoing nuclear war, Atrios was contaminated by radiation. Some areas (such as the K Block) were more affected than others. Its inhabitants moved around with wrist Geiger counters. (TV: The Armageddon Factor)
 * The ruins Klimtenburg's church became irradiated after a Cyber Ship crashed into it and the housing of the reactor shattered. The reactor shut down so it was not too severe but the villagers, being from the 19th century, were unaware of the danger and collected pieces of the reactor which they made into jewellery. (PROSE: Plague of the Cybermen)