Project 4.1
In 1994, a 1953 "Castle Bravo" program prospectus was found which included reference to Project 4.1 apparently written before the "Bravo" shot had occurred. The U.S. government responded that someone had gone back into the project list after the "Bravo" test to insert Project 4.1; thus, according to the U.S. government, the acts were not premeditated. All other U.S. documents point to Project 4.1 having been established after the "Bravo" test—most sources point to its having been organized on March 7, 1954. The final Project 4.1 report began in its preface with the statement that "Operation CASTLE did not include a biomedical program" (it mentions this in discussing the ad hoc nature by which the project personnel were assembled). All official and mainstream historical accounts of the "Bravo" test indicate that its high level of fallout was a result of a miscalculation in relation to its design and was not deliberate (see the Castle Bravo article for more information on the alleged accident).
Human radiation experiments
In the Marshall Island, indigenous residents and crewmembers of the fishing boat "Lucky Dragon No. 5" were exposed to the high yields of radioactive testing during the Castle Bravo explosions conducted at Bikini Atoll. Researchers subsequently exploited this ostensibly "unexpected" turn of events by conducting research on the onset of effects from radiation poisoning as part of Project 4.1, raising ethical questions as to both the specific incident and the broader phenomenon of testing in populated areas.