radioactive

radioactive
ra‧di‧o‧ac‧tive /ˌreɪdiəʊˈæktɪv◂ $ -dioʊ-/ adjective
a radioactive substance is dangerous because it contains radiation (=a form of energy that can harm living things):
    the problem of how to dispose of radioactive waste
    a consignment of highly radioactive plutonium