It has many cause and effects like 
1.It cannot be controlled in any way as the rays emitted by them are Radioactive rays.
2.It can harm other Living Organism near by them.
3.It can also harmful disease like Infections,Cancers of many types.
4.It also Poisoned the soil or makes it very Infertile.
5.It cannot be Degraded.
nuclears bombs are very dangerous.

if a nuclear bombs blasts , then it will effect our lives for millions of years.

if the radioactive rays of the nuclear bomb is smelled by a pregnant woman then , her baby will be born as an handicapped.

through this example , u can understand that how dangerous are nuclear bombs.