I was in Guam when I heard that on June 11, 1979, John Wayne died of cancer. 
John Wayne, along with other cast members and crew, filmed the movie “The Conqueror” near a nuclear testing site in the Utah desert. This decision had lasting consequences due to the proximity to the infamous Nevada Test Site, where approximately 100 nuclear bombs of various yields were detonated throughout the 1950s.
Tragically, out of the 220 people involved in the production of “The Conqueror,” 92 died of cancer, including Wayne, Hayward, and Armendáriz. The barren hills around St. George, where the film was shot, were likely contaminated with deadly nuclear dust from the nearby nuclear tests. . Although authorities at the time deemed the filming site safe, modern research indicates that the soil in some areas remained dangerously contaminated until 2007.