Another complicating factor, although the report refers to it as a relatively minor consideration, is that the calculations for numbers of cancers that could develop over a lifetime were based on American life-expectancy tables. But Marshallese life expectancy is about eight years shorter than the U.S. population (69.7 years for both sexes combined for the Marshalls, 77.4 years for the United States.)

A 1958 census helped researchers estimate the Marshall Islands population at the time of the Bravo test as around 13,940. If the tests had never occurred, the report says, about 5,600 cancers would have developed among them during their lifetimes.

"Within the lifetime of the cohort, we estimate an additional 530 cancers that might be attributable to fallout radiation. Similar to the case for the baseline cancers (not caused by fallout), about one-half of the radiation-induced fallout are yet to develop or be diagnosed.

"These findings indicate that we expect the exposure to fallout to result in about a 9 percent increase in the total number of cancers," it says. Altogether, including cancer that would have happened without the tests and counting both fatal and nonfatal cancers, the 14,000 people can expect 6,130 cases of cancer.

The report makes these estimates for cancers caused by fallout among Marshallese, over their lifetimes: leukemia, five cases; thyroid cancer, 262 cases; stomach cancer, 15 cases; colon cancer, 157 cases; other cancers, 93 cases. The total is 532 among the nearly 14,000 inhabitants.

The thyroid and colon cancers among Rongelap and Ailinginae islanders are only "crude upper limit" estimates, the study concedes.

Of these 532, cancers that are expected to develop but which had not shown up as of 2004 are: leukemia, fewer than one; thyroid cancer, 99 cases; stomach cancer, 13; colon cancer, up to 116; other cancers, 61. Total not yet developed, according to the report: 289.

The 289 yet to show up represent close to 55 percent of the cancers caused among Marshall Islanders by the U.S. atomic tests in the Pacific.

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E-mail: bau@desnews.com