Hiroshima Memo: Data on black rain should be analyzed again with outside experts on epidemiology

by Akira Tashiro, Executive Director of the Hiroshima Peace Media Center

Hearing the words “black rain,” many would think of the novel “Black Rain” by Masuji Ibuse. Due in part to the title of this well-known novel, people in Hiroshima tend to associate the atomic bombing with the black rain which fell over the city after the blast.

The rain, which contained a significant amount of soot and dust as a result of fires consuming such things as wooden houses, was highly radioactive. In a display of drawings in one corner of Hiroshima Peace Memorial Museum, one survivor has depicted people’s desperate thirst for water as they try to catch the falling rain in their open mouths or drink from puddles of rainwater.

In another instance, radioactive particles poured down in the form of snow-white powder. In 1954, the Japanese fishing boat known as the Daigo Fukuryu Maru (The Lucky Dragon No. 5) happened to float near the area where the United States was conducting one of its hydrogen bomb tests in the Marshall Islands, an archipelago in the Pacific Ocean. This white powder was radioactive fallout, produced when coral reefs were charred by the bomb’s heat rays and blown into the air. All 23 crew members, who were engaged in tuna fishing some 160 kilometers east of the test site, developed acute symptoms of radiation sickness, including vomiting and diarrhea.

In 1946, one year after the atomic bombings of Hiroshima and Nagasaki, the United States began conducting atmospheric nuclear tests. Although many of the islanders around the test site and soldiers involved in the tests were not subjected to direct nuclear strikes, they suffered from many diseases, including cancer, as a result of radiation exposure caused by the radioactive fallout, the so-called “ashes of death.” The United States then continued its nuclear testing in the atmosphere after the test site was moved to a facility in the state of Nevada in 1951. But downwind of the test site, residents in a broad area of Nevada, Utah, and neighboring states were exposed to radiation either through external exposure to residual radiation or through internal exposure by consuming contaminated foods such as beef, and eventually suffered various illnesses.

Neither the military nor the Atomic Energy Commission (now, the Department of Energy) informed soldiers and residents of the risks of radiation. Under the heightened tensions of the Cold War between the United States and the Soviet Union, the nation’s development of nuclear weapons was given priority in the name of national security.

It would be 1990 before Bill Clinton, then president of the United States, signed new legislation which granted compensation to soldiers, downwinders, and uranium miners who were exposed to radiation and had developed particular diseases, including leukemia and lung cancer. But this compensation, which could also be received by relatives of the deceased, would not be forthcoming until the end of the Cold War and the amount (75,000 dollars to a soldier, for example) was not easy to obtain due to a cumbersome procedure.

While searching the Internet, Koya Honda, a Nagasaki doctor found a report on a study carried out on the black rain. The report, entitled “An Examination of A-bomb Survivors Exposed to Fallout Rain and a Comparison to a Similar Control Population,” was released by the Oak Ridge National Laboratory (ORNL) in 1972. Based on data involving A-bomb survivors that was compiled by the Atomic Bomb Casualty Commission (ABCC), the two researchers who wrote this report, one Japanese and one American, compared people who were caught in the black rain in areas 1,600 meters or farther from the hypocenter, where the initial dose of radiation exposure was relatively low, with people in similar conditions but not caught in the rain. The report reveals a much higher incidence of radiation sickness, including such symptoms as hair loss, diarrhea, and fever, among those who experienced the black rain.

There is one troubling aspect to this report, however. In the abstract which begins the paper, it says: “This paper is an examination of readily available information and represents an attempt to establish conclusions which would either promote or discourage more detailed analyses of the effects of radiation fallout on an otherwise lightly exposed population.” This statement gives the impression of asking authorities for their assent, while the report has already clearly revealed the consequences of the black rain.

The Oak Ridge National Laboratory worked in close coordination with the Atomic Bomb Casualty Commission in conducting research into the effects of radiation on the human body. At the same time, the laboratory has been one of the main facilities engaged in nuclear weapons research and development since the time of the Manhattan Project during World War II.

Until it became the Radiation Effects Research Foundation (RERF) in 1975, run jointly by Japan and the United States, ABCC continued its research at the discretion of the U.S. government. This was a time when the United States was competing with the Soviet Union in the arena of nuclear weapons development. It would come as no surprise if the Oak Ridge National Laboratory or the U.S. Atomic Energy Commission, which holds jurisdiction over the laboratory, had advised ABCC not to pursue such research, thinking it advisable to keep an “inconvenient truth” secret from the public.

The valuable data on the effects of radiation on Hiroshima and Nagasaki survivors is held by RERF. This data, though, is not the exclusive possession of RERF, nor is it an exclusive possession of Japan or the United States.

Through discussion about the report with Dr. Honda, it has turned out that basic data exists on 13,000 people in connection to the black rain. Why not take this opportunity to analyze the data once again with an epidemiologist from outside and other experts? Such an effort would also express the proper appreciation to the A-bomb survivors who provided this valuable information.

With the accident at the Fukushima No. 1 (Daiichi) nuclear power plant involving a core meltdown, there is growing concern among the residents of Fukushima Prefecture, as well as other places, over the effects of radiation on the human body. Accurate knowledge involving the radioactive fallout from the black rain would contribute to improving measures to protect against radiation and easing anxiety among the public.

(Originally published on December 5, 2011)