Yasushi Nishiwaki is known as a Japanese scientist who informed the world of the suffering of the Bikini incident in 1954 and the danger of radioactive fallout. This paper seeks to explain, with the help of newly discovered documents, his early research on the Bikini fallout and his subsequent trip to Europe in order to warn about its dangers. During that trip he encountered Joseph Rotblat, a meeting which eventually resulted in the Russell‒Einstein Manifesto in 1955. The paper also discusses his attitude toward nuclear power, showing that his view on nuclear power was informed by a risk-benefit perspective that few Japanese scientists of his time shared. Nishiwaki was consistent throughout his life in stressing the need of preparedness for a nuclear disaster of any kind, whether it was an attack or an accident.

In the history of the 1950s fallout controversy, associated with the first hydrogen bomb tests, scholars often focus on the plight of the Japanese crew of the Fukuryū Maru, or as it was called in English-language newspapers, the Lucky Dragon. Doing so silences the Japanese who tried to show that fallout was not simply about one ship, one part of the ocean, or even one generation of humans. In this essay we show how Japanese perspectives influenced several American scientists to think differently about the implications of nuclear tests for humans and the natural environment. We propose three fundamental conceptual points about fallout that already were present in Japanese scientific discourse in the mid-1950s. One was spatial; one was temporal; one was legal. The Japanese ideas, from a range of scientists, informed the views of American scientists during the fallout controversy of the 1950s, not just providing data but shaping both scientific and political discourse in the West.

This paper takes Yoshio Hiyama as an example to explain how Japanese biologists confronted radioactive contamination revealed during the Fukuryū Maru incident in 1954. It argues that Hiyama sought to reconcile a twofold dualism through research and advice. The first part of dualism was scientific, as radioactive fallout had a potential not only as a harmful pollutant but also as a useful tracer. The other part was political due to Japan's conflicting status as a partner of the United States while being a victim of its nuclear weapons. Hiyama sought to manage this matrix of science and politics, defusing the tuna scare that rocked U.S.-Japan relations while making the case for a nuclear test ban which the Japanese government embraced as a politically less destabilizing goal. By bringing antinuclear sentiments to a soft landing, Hiyama midwifed the birth of Japan as an anti-nuclear weapons nation with all its contradictions.

In those days when Yasushi Nishiwaki visited the Soviet Union, Soviet scientists stood at the crossroads in understanding radiation effects on the living body: their perspective was changing from that of a mere follower of Western studies to that of a radical critic. Looking for a disregarded context in which research on radiation effects emerged as a major topic in Soviet science, this paper aims to explain the indigenous needs for such research in the Soviet Union as well as its early development by shedding light on radiation casualties at a nuclear development center, Chelyabinsk-40 (later, -65) and hazard studies conducted there in the early years. This paper shows that, even before the fierce debate began in UNSCEAR in the summer of 1958, there had already been an internal drive within the Soviet Union for expanding research on radiation effects on humans and other organisms.