Distronic explosive

Distronic explosives were powerful but unstable weapons, used on many worlds as components of explosive warheads attached to missiles.

The explosives were highly dangerous, even before they were detonated, causing anyone exposed to unshielded distronics to develop distronic toxaemia. In just a short time, this disorder caused fatigue and killed the victim. (TV: Genesis of the Daleks) As distronic explosives decayed, they became unstable and when subsequently exposed to sunlight, were prone to spontaneous detonation. Because of this instability, distronic explosives were at one time banned throughout the galaxy. (COMIC: Smart Bombs)

Towards the end of the Thousand Year War on Skaro, the Thals developed a rocket with a distronic warhead. To load this explosive onto the rocket they used captured prisoners, including Sarah Jane Smith and Sevrin, as expendable slave labour. Rather than die from distronic toxaemia, the workers tried to escape from the Thal Dome. They failed. The rocket was used to destroy the Kaled Dome. (TV: Genesis of the Daleks)

The Tenth Doctor and Rose later met the Smart Bombs, a group of sentient missiles whose warheads were packed with distronic explosive. Because the explosive was unstable in sunlight, the missiles could not venture onto the surface of their planet until another missile exploded, causing a nuclear winter which blocked out the sun, allowing the missiles to go out and play on the surface. (COMIC: Smart Bombs)
 * It is not made clear in Smart Bombs exactly when distronics were banned or in which galaxy.