Page 4: The United States’ Nuclear Testing Programme

Daigo Fukuryū Maru (Lucky Dragon Number 5) in the early 1950s, shortly before the detonation of Castle Bravo.

Immediate and long-term effects of fallout

A few hours after the explosion, fallout from the explosion began sprinkling over a Japanese fishing boat, Lucky Dragon Number 5.  The fallout consisted of coral rock, soil, and other debris sucked up in the fireball and made intensively radioactive by the nuclear reaction. The boat was some 145 km downwind of the explosion point at the time. Rongelap atoll, which was about 170 km downwind, was also showered with radioactive particles.

Many of Lucky Dragon’s crew became ill and one crew member died.  A number of the 64 inhabitants of Rongelap experienced immediate radiation sickness including vomiting, skin damage and hair loss. By the time they were evacuated from the area two days after the detonation of Castle Bravo, some of the islanders had received 175 rads (See Chart 2) from gamma radiation and 160 rads from I-131 (See Chart 1).

In Bravo for the Marshallese: Regaining Control in a Post-nuclear, Post-colonial World, the anthropologist Holly Barker describes an epidemic of birth defects, cancer, mental retardation, and suicides, in addition to the thyroid disorders, among the local population.
The March 1, 1954 Bravo hydrogen bomb crater. Photo © Matt Harris www.bikiniatoll.com

Long-term health consequences

Radioiodine levels were measured in the urine of adults from Rongelap and a neighbouring atoll, Ailinginae, by the Los Alamos Scientific Laboratory two weeks after their exposure to Bravo fallout. The Atomic Archive explains how I-131 built up rapidly to serious concentration in the thyroid glands of the victims, particularly young Rongelapese children. A report entitled Radiation Effects in the Marshall Islands compiled by the Clinical Endocrinology Branch, National Institute of Health, Maryland, and the Medical Department, Brookhaven National Laboratory, New York, USA, states that: “Early radiation effects were observed in many of the 64 inhabitants of Rongelap and the 18 on nearby Sifo Island. During the second and third decades after the accident, most of the Rongelap children and many adults developed thyroid nodules, some of which proved to be malignant.”

In Bravo for the Marshallese: Regaining Control in a Post-nuclear, Post-colonial World, the anthropologist Holly Barker describes an epidemic of birth defects, cancer, mental retardation, and suicides, in addition to the thyroid disorders, among the local population. High numbers of miscarriages and stillbirths were noted in some women who had been exposed to the fallout.

Cancers attributed to nuclear fallout

Ionizing radiation, which refers to several types of particles and rays given off by radioactive materials, is one of the few scientifically proven carcinogens in human beings. The time that may elapse between radiation exposure and cancer development can be anything between 10 and 40 years.

A report on the Estimation of the Baseline Number of Cancers Among Marshallese and the Number of Cancers Attributable to Exposure to Fallout from Nuclear Weapons Testing Conducted in the Marshall Islands was published in September 2004. The report was prepared by the Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, and the Department of Health and Human Service, USA, and stated that:

“We estimate that the nuclear testing program in the Marshall Islands will cause about 500 additional cancer cases among Marshallese exposed during the years 1946-1958, about a 9% increase over the number of cancers expected in the absence of exposure to regional fallout. More than 85% of those radiation-related cases would likely occur among those exposed in 1954 on the atolls of Rongelap, Ailinginae, Ailuk, Mejit, Likiep, Wotho, Wotje, and possibly Ujelang. Doses to the thyroid, colon and stomach of persons on Rongelap, Alinginae, and (to a lesser extent) Utrik at the time of the BRAVO test in 1954 were extremely high. Based on this analysis, a high proportion of cancers of those organs that develop among members of those population groups are likely to be radiation-related. About 40% of the thyroid cancers and more than one-half of cancers to the other organs (at all atolls) are yet to develop or to be diagnosed.”