Nukewatch Quarterly Spring 2022
By Setsuko Shimomoto
Editor’s note: The Castle Bravo thermonuclear bomb test was accidentally the largest nuclear weapon detonation ever made by the United States. The 15-megaton blast was three times the five megatons that was planned, due to errors made by its designers from the Los Alamos National Lab. The bomb’s colossal fallout radioactively contaminated thousands of Pacific Island inhabitants, poisoned hundreds of fishermen who were working in the area of the Marshall Islands, and dispersed radioactive particles around the world.
Note from Mari Inoue of Manhattan Project for a Nuclear-Free Future: Below is a transcript of testimony by Ms. Setsuko Shimomoto, originally from Muroto, a fishing village in Kochi, Japan. In the 1950s, Setsuko’s father was a fisherman who was exposed to the radioactive fallout from the U.S. nuclear weapon testing near the Marshall Islands. It is estimated that more than 10,000 Japanese fishermen and 990 fishing boats were affected by the  Castle Bravo series of tests in the Pacific, but their voices and struggles were deliberately suppressed and erased from history. Setsuko is one of the plaintiffs in two court cases in Japan seeking recognition and workers’ compensation on behalf of her late father who died from cancer. In February, one of the cases was heard in local court in Tokyo and another hearing is scheduled for May.
Setsuko Shimomoto: “In March 1954, when my father was a fisherman on a tuna fishing boat, he was exposed to radioactive fallout from U.S. hydrogen bomb testing. Deep sea fishing was thriving. Many small, 100-ton fishing boats sailed near the Marshall Islands, where 67 atmospheric nuclear tests were conducted. Some fishermen were told to keep quiet about the radiation; others were not informed. In 1955, the U.S. agreed to pay $2 million in damages to Japan. Many tuna fishermen were ignored, except for those of the Daigo Fukuryu Maru (Lucky Dragon No. 5). The incidents were trivialized as the single incident of the Daigo Fukuryu Maru. Accordingly, Japan waived its right to seek damages from the U.S. without the consent of the affected.
“In 2014 after over 30 years of research by Mr. Masatoshi Yamashita, an advisor at Hata Seminar high school program in Muroto, and others, Japan’s Ministry of Health released the list of 990 fishing boats that discarded irradiated tuna and documents that recorded the radiation dose of these boats. Researchers of Hiroshima University also tested the teeth and blood of those fishermen and scientifically proved that these fishermen were indeed exposed to radiation. In 2020, we filed two lawsuits, after previous lawsuits had been dismissed; one for workers’ compensation, the other against the government for neglecting the fishermen without providing them relief.
“Why did we take action against the government more than 60 years after the incident?
“The catalyst was meeting the mother of Setsuya Fujii who was exposed to radiation in Nagasaki and the Pacific. Setsuya became ill and killed himself by drowning at the age of 27. Many fishermen have died of illnesses that were undoubtedly caused by radiation exposure. Masayasu Taniwaki was affected while on a training boat and passed away at the age of 20, only seven months after exposure. My father had an operation for stomach cancer at the age of 60 and died of bile duct cancer at 78. Mr. Minami, who was on the same boat as my father, died of liver cancer 13 years after exposure. He was 46.
“The government that failed to recognize the radiation exposure of those fishermen also promotes nuclear energy. Despite the nuclear disaster in Fukushima, the government continues its efforts to restart nuclear power plants. The Ikata Nuclear Power Plant was restarted in December 2021. Japan has also decided to dump radioactive water from Fukushima Dai-ichi into the ocean. Japan is following the lead of the U.S. in downplaying the effect of radiation. Despite being victimized by atomic bombing during the war and having victims of nuclear testing, Japan refuses to sign the Treaty on the Prohibition of Nuclear Weapons.”
— Transcript translated by Yukiyo Kawano of Oregon Physicians for Social Responsibility, and edited for space by Kelly Lundeen. See Ms. Shimomoto’s full testimony at: