No one in their right mind would choose to film a big movie at a working nuclear test site nowadays. Herman Joseph Muller, an American geneticist, established in 1927 that extended exposure to radiation may have devastating effects on human health, and by the early 1950s, it was well understood that nuclear explosions create huge volumes of extremely radioactive and potentially fatal fallout. Despite this, the creators of the 1956 film The Conqueror chose to shoot the picture near the rural Utah town of St. George, which is only a hundred miles from the infamous Nevada Test Site.

When the federal authorities said it was safe to film, the cast and crew descended on the town, filling every hotel and motel. Locals were also cast as extras. They had no clue that neighboring Snow Canyon, one of the primary filming sites, had turned into a radioactive hotspot. The year before shooting, eleven atomic bombs were detonated, sending toxic air downwind to Utah.

Despite the fact that producer Howard Hughes was aware of the consequences, the government assured him that there was no risk to public health. After 13 weeks of grueling location filming, Hughes had 60 tons of earth trucked in from St. George to Hollywood so that the studio shots would match the site footage — further subjecting the actors and crew to radioactive contamination.

Almost half of the film’s cast and crew, including Wayne, Susan Hayward, Agnes Moorehead, and director Powell, died of cancer in the years after its release.

Over 100 atomic bombs were tested at the Nevada National Security Site between 1951 and 1962, with 11 of them being tested in 1953 alone as part of Operation Upshot-Knothole, which was an effort to discover a technique to fire nuclear explosives from a grounded cannon rather than dropping them from an airplane.

Wayne, Hayward, and Armendáriz were among the 92 persons who died of cancer after working on the creation of The Conqueror. Even though abnormal amounts of radiation were identified when the region was analyzed, officials categorized the filming site as safe from the detrimental effects of radioactive fallout at the time.

Years later, as cast and crew members began to get cancer, the link was traced back to the set of The Conqueror. Powell died of lymphoma in 1963. Hayward died in 1975 as a result of brain cancer. Wayne died of stomach cancer in 1979, however he claimed it was caused by his long-term smoking habits. When Pedro Armendáriz was diagnosed with terminal renal cancer, he took his own life. Lee Van Cleef died of cancer of the throat. Out of a total of 220 cast and crew members, 91 had developed cancer, and 46 had died from lung cancer, throat cancer, and other types of cancer. That is a staggering figure.

According to recent study, the soil in several places near St. George remained severely polluted until 2007. As a result, the fact that over half of the cast and crew died of cancer was most likely not a coincidence, but rather the effect of chronic radiation exposure.

In 1980, Dr. Robert C. Pendleton, head of radiological health at the University of Utah, told People that he believed the radiation in the region was directly responsible for all of the cancer fatalities on the set.

“With these numbers, this case could qualify as an epidemic,” Pendleton said. “The connection between fallout radiation and cancer in individual cases has been practically impossible to prove conclusively. But in a group this size you’d expect only 30-some cancers to develop. With 91, I think the tie-in to their exposure on the set of The Conqueror would hold up even in a court of law.”