The first human trial of a new type of dirty-bomb-antidote pill, designed to remove harmful radioactive contamination from the body, is starting in the US.

The drug, HOPO 14-1, is thought to work against several materials that might be used in weapons, including uranium.

If it proves safe and effective it could guard against potential harm from nuclear accidents or terrorist attacks.

About 42 volunteers will try different doses, checking for side effects.