Dr. Cyclops (1940) on Netflix

Plot summary

Alexander Thorkel works in a primitive laboratory in the Peruvian jungle, attempting to shrink humanity and so lessen its impact on the environment. His eyesight is too poor for him to examine a specimen himself, so he summons a team of biologists from America. One of the biologists identifies iron crystal contamination, and Thorkel thanks them and asks them to leave. Annoyed, the visitors camp in his stockade and find the area rich in pitchblende, the ore of uranium and radium. Thorkel reveals that radiation drawn down a deep shaft from a radium deposit shrinks living creatures.