brunt of nuclear testing under the United States' Pacific Proving Ground program. Now known officially as the Republic of the Marshall Islands, it was a United Nations Trust Territory administered by the United States from 1944 to 1979, years during which the United States tested 66 nuclear weapons in the Marshall Islands. One of these many tests, the March 1, 1954, explosion of Castle Bravo, a U.S. thermonuclear device, was responsible for most of the radiation the Marshall Islanders were exposed to. The fallout-related doses of this single test are believed to be the highest recorded in the history of worldwide nuclear testing. Many of the Marshall Islands which were part of the Pacific Proving Grounds remain contaminated by nuclear fallout, and many of those downwinders who were living on the islands at the time of testing have suffered from a highly increased incidence of several types of cancers and birth defects. Effects of radiation on female downwinders The primary long-term health hazard associated with exposure to ionizing radiation as a result of nuclear fallout is an increased risk for cancers of the thyroid, other solid tumor cancers, and leukemia. The relationship between radiation exposure and subsequent cancer risk is considered "the best understood, and certainly the most highly quantified, dose-response relationship for any common environmental human carcinogen", according to report by the National Cancer Institute. Overall, men in the United States develop cancer at a rate 22% higher than that of women. However, women develop cancer from radiation at a rate from 37.5% to 52% higher than that of men. In recent years, studies conducted by both the National Research Council and the EPA have confirmed that compared to men, women are at a significantly higher risk of radiation-induced cancers, such and that women's sensitivity to radiation-induced cancers is much higher than was previously estimated. The increased radiosensitivity of certain organs in women, such as the breast, ovaries, and thyroid is likely the cause of this difference. In the EPA's 1999 Federal Guidance Report #13(FGR 13), Cancer Risk Coefficients for Environmental Exposure to Radionuclides, the authors conclude that women have a 48 percent higher radionuclide-related cancer mortality risk than men. Further evidence of sex-based disparities in radiation-induced cancers was published in the 2006 report by the National Research Council's Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation (known as the BEIR VII report), which