The Conqueror (1956)
Many people involved in the production knew about the radiation (there's a picture of Wayne himself operating a Geiger counter during the filming), but no one took the threat seriously at the time. Thirty years later, however, half the residents of St. George had contracted cancer, and veterans of the production began to realize they were in trouble. Actor Pedro Armendariz developed cancer of the kidney only four years after the movie was completed, and later shot himself when he learned his condition was terminal.
Howard Hughes was said to have felt "guilty as hell" about the whole affair, Although as far as I can tell it never occurred to anyone to sue him. For various reasons he withdrew The Conqueror from circulation, and for years thereafter the only person who saw it was Hughes himself, who screened it night after night during his paranoid last years."