Project 4.1 was a secret U.S. medical study launched after the 1954 Castle Bravo hydrogen bomb test at Bikini Atoll unexpectedly spread radioactive fallout over Rongelap, Utirik, and Ailinginae Atolls in the Marshall Islands. Instead of immediate evacuation, 239 Marshallese and 28 Americans were monitored for radiation effects. The 15-megaton blast caused acute radiation sickness—nausea, […]