Project 4.1 was the designation for a medical study conducted by the United States of those residents of the Marshall Islands exposed to radioactive fallout from the March 1 , 1954 '' Castle Bravo '' nuclear test at Bikini Atoll , which had an unexpectedly large yield . Government and mainstream historical sources point to the study being organized on March 6 or March 7 , 1954 , six days after the '' Bravo '' shot
Castle Bravo
Castle Bravo
Project 4.1