Radio active Pollution-Sources/causes

1. Nuclear accidents from nuclear power plants. Examples -

Chernobyl, Fukushima, Thee mile Iceland 

2. Use of nuclear weapons for mass destruction as in Hiroshima and Nagasaki.

3. Use of radio isotopes for detectors and other industrial activities. Radio isotopes are used in smoke detectors, watches, clocks, non stick cookware, cosmetics, sterilization etc.

4. Mining radio active mineral ores like radium and uranium cause pollution.

5. Tests using radiation therapy like X-ray.