The Straight Dope: Did John Wayne die of cancer caused by a radioactive movie set?

"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."

Mom has wondered from time to time whether or not Grandpa's leukemia had anything to do with his filming venues. She has mentioned a filming location, fallout, and the names of a few actors who died of cancer after working there. But I could never remember the place names. This link which my girlfriend provided seems to point to the right places.