March 1 - Bikini's weather outlook downgraded to "unfavorable" and Joint Task Force 7 directs several ships to move 20 miles to the south to remove them from the expected fallout zone. Despite weather reports showing that winds are blowing in the direction of inhabited islands, the March 1 Bravo hydrogen bomb test is detonated at Bikini. At 15 megatons, it is 1,000 times the strength of the Hiroshima bomb. Within hours a gritty, white ash is enveloping islanders on Rongelap and Ailinginae Atolls. A few hours later, American weathermen are exposed to the snowstorm of fallout on Rongerik, and still later the people of Utrik and other islands experience the fallout "mist". Those exposed experience nausea, vomiting and itching skin and eyes. March 3 Rongelap islanders are evacuated 48 hours later, and Utrik is evacuated 72 hours after Bravo. Both groups are taken to Kwajalein for observation. Skin burns on the heavily exposed people begin to develop, and later their hair falls out. The U.S. Atomic Energy Commission issues a statement to the press calling Bravo a "routine atomic test", and stating that some Americans and Marshallese were "unexpectedly exposed to some radioactivity. There were no burns. All were reported well."

3月1日 ビキニの天候は「不適切」な状態に変わり、統合タスクフォース7は、数隻の船舶に対して南方20マイルへ移動を指示し、予想放射性降下物ゾーンから離脱させようとした。住民のいる島に向かって風が吹くという天気予報にもかかわらず、3月1日、ブラボー水爆がビキニ環礁で爆発した。広島爆弾の1000倍の15メガトンの威力だった。数時間のうちに、ロンゲラップ環礁とアイリンギナ環礁の島民を、ざらついた白い雲が覆った。数時間後、米国の期初観測要員が、ロンゲリックで放射性降下物の吹雪に被曝した。さらに後に、ウチリック環礁などの島民が、放射性降下物の霧に被曝した。被曝した人々は、吐気・嘔吐・皮膚や眼のかゆみなどを経験した。ブラボー爆発の48時間後の3月3日に、ロンゲラップ島民たちが、72時間後にウチリック島民が避難した。両島民ともに、観察のためクワジェリンに移送された。重度に被曝した人々の火傷が次第に悪化し始め、その後、髪が抜け落ちていった。米国原子力委員会は「ブラボーは通常の核実験である、少数の米国人とマーシャル諸島の住民が、想定外にある程度の放射線被曝をした。火傷はない。全員、良好な状態である」との声明を出した。

March 7 - Project 4.1, "Study of Response of Human Beings Exposed to Significant Beta and Gamma Radiation due to Fallout from High Yield Weapons," establishes a secret medical group to monitor and evaluate the Rongelap and Utrik people.

3月7日 プロジェクト4.1「高出力兵器からの放射性降下物による、強いベータ線およびガンマ線に被曝した人間の反応についての研究」が、ロンゲラップ島民及びウチリック島民の観察と評価を実施する、秘密医療グループを編成した。

April - A Project 4.1 memo recommends that the exposed Rongelap people should have "no exposure for (the) rest of (their) natural lives." April 29 Department of Defense report states that the "only other populated atoll which received fallout of any consequence at all was Ailuk...It was calculated that a dose...would reach approximately 20 roentgens. Balancing the effort required to move the 400 inhabitants against the fact that such a dose would not be a medical problem it was decided not to evacuate the atoll."

4月 被曝したロンゲラップ島民は、生涯にわたり、これ以上の被曝を避けることを推奨するプロジェクト4.1のメモが作られた。4月29日の国防省の報告書によれば、何らかの影響が出る放射性降下物の降った、住民のいる島は アイルック環礁である。被曝量は20レントゲンと推定される。400人の島民を退避させることを考えれば、医学的症状が出るほどの被曝ではないので、環礁からの退避を行わないと決定した」

May - Utrik Islanders allowed to return home because, according to U.S. officials, "Their island was only slightly contaminated and considered safe for habitation."

5月 ウチリック島民に帰還許可。米国当局によれば「ウチリック環礁は少し汚染されただけであり、居住に問題ない」

[ "Exhibit photographs courtesy of: United Nations, U.S. National Archives, Mr. Jonathan Weisgall, Brookhaven National Laboratory, U.S. Department of Energy, Holly Barker ]

Project4.1の報告書の一つは前書きで、Operation Castleには生医学の実験計画はなかったため、急遽調査チームを編成したとある。
Operation CASTLE did not include a biomedical program. The participants in Project 4.1 were drawn from various laboratories and were totally unprepared for a field program when the joint DOD, AEC Medical Research Team was organized after the operation had begun.
Since little detailed information was available about dose and initial symptomatology, the research team was organized to include the following talents for the constitution of the emergency medical team: internal medicine, hematology, radiation technology and radiobiology. In the selection of personnel the emphasis was placed on past experience in biomedical research in the field with atomic weapons. In addition, provisions were made for a swecnd echelon of specialized personnel in case they were needed. Accordingly, a preventive medicine unit of the Commander in-Chief, Pacific Fleet, was alerted for possible bacteriologic studies; blood bank personnel, and additional clinicians and nurses were notified incase conditions justified their services in the Kwajaken area. Rear Admiral Bartholomew Hogan, MC, USN, Pacific Fleet Medical Officer, immediately made any needed medical facilities of the Pacific Fleet availabe.

線量と初期症状については詳細な情報はほとんどないため、内科・血液学・放射線技術・放射線生物学の専門家を含むよう、緊急医療チームを編成した。 要員の選定では、核兵器に関する生医学研究の過去の経験に重点を置いた。さらに、必要な場合に備えて、専門職員の迅速な動員のための規定が作成された。したがって、太平洋艦隊司令官の予防保全ユニットには、細菌学的研究の可能性があることが警告された。血液バンク要員・追加の臨床医および看護師には、クワジェリン地区での任務があることが通知された。 海軍海兵隊太平洋艦隊軍医バーソロミュー・ホーガン少将は、ただちに必要かつ利用可能な太平洋艦隊の医療施設を要した。

[ Cronkite et al: "Study of Response of Human Beings Accidentally Exposed to Significant Fallout Radiation" (1954) ]

軍事技術史学者Barton C. Hacker, PhDも「Project4.1」という研究計画の名称が、後に「原子力委員会が意図的に被曝させた」という非難を招いたと記している。
In March 1954, the AEC had quickly decided that learning how the Marshallese victims of Castle Bravo responded to their accidental exposure could be of immense medical and military value. Immediate action centered on seeing them evacuated and decontaminated, then cared for medically. But studies of their exposures and aftereffects also began. That effort became project 4.1 in the Castle experimental program. This unfortunate choice of terminology may help explain later charges that the AEC had deliberately exposed the Marshallese to observe the effects. Like the American radium dial painters of the 1920s and the Japanese of Hiroshima and Nagasaki in 1945, the Marshallese of 1954 inadvertently were to provide otherwise unobtainable data on the human consequences of high radiation exposures. Findings from project 4.1 soon began to appear in print.


[ Barton C. Hacker: "Elements of Controversy: The Atomic Energy Commission and Radiation Safety in Nuclear Weapons Testing, 1947-1974" (1994), p.226

「意図的に被曝させた」との非難の例として、1972年にミクロネシア代表Ataji Balosの発言が機密解除されている。
"I am now convinced US knowingly and consciously allowed people of Rongelap and Utirik to be exposed to 1954 fallout. This was done to Rongelapese and Utirickes so that US could use them as human guinea pigs n development of its medical capabilities to treat its citizens who might be exposed to radiation in event of war with an enemy country. This is a crime unmatched in peacetime. The US chose to make guinea pigs out of our people because they are not white but some brown natives in some remote pacific islands. Medical treatment that Rongelapese and Utirikese have been receiving is also highly questionable. The object of their (AEC medical teams) visits appears to be collection of medical data instead of restoration of health to h-bomb victimes who have developed all kinds of diseases and abnormalities. ..."


[ Quote is from unclassified telegram DISTAD Palau to SECSTATE Wash. DC, 27 Jan 72, Document 48025, CIC ]

メインストリームの歴史では否定されているが、その後も、「意図的に被曝させた」との非難は消えていない。たとえば、Adam Jonas Horowitzの2011年の映像作品"Nuclear Savage"も、「intentional radiation poisoning at the hands of the American government (米国政府による意図的放射線被曝)」というトーンで作らている。