Edison’s experiments required an assistant to place his hands repeatedly on top of a box, where they were exposed to X-rays. When he sustained burns on one hand, the assistant simply switched to using the other. But the burns wouldn’t heal. Eventually surgeons amputated the assistant’s left arm and four fingers from his right hand. When cancer spread up his right arm, the doctors took that, too. The disease traveled to his chest, and in October 1904 he died, the first known victim of man-made radiation. Even
