contaminate (v)
He will also be interested in investing in young people, including the inaguration of Fulbright university in Vietnam, dealing with legacy of war including removing unexplored bombs, returning remains of soldiers and remediating sites contaminated by dioxin, according to a media briefing by the U.S. embassy last week.
to make something less pure or make it poisonous:Much of the coast has been contaminated by nuclear waste.The food which had been contaminated was destroyed.