FUKUSHIMA, Japan -- Even if the worst nuclear accident in 25 years leads to many developing cancer, we may never find out.
Looking back on those early days of radiation horror, that may sound implausible. But the ordinary rate of cancer is so high, and our understanding of the effects of radiation exposure so limited, that any increase in cases from the Fukushima nuclear plant disaster may be undetectable.
Several experts told The Associated Press that cancers caused by the radiation may be too few to show up in large population studies, like the long-term survey just getting under way in Fukushima. The average lifetime cancer risk is about 40 percent.
That could mean thousands of cancers under the radar in a study of millions of people, or it could be virtually none. Some of the dozen experts interviewed said they believe radiation doses most Japanese people have gotten fall in a "low-dose" range.
The cancer risk may be absent, or just too small to detect, said Dr. Fred Mettler, a radiologist who led an international study of health effects from the 1986 Chernobyl disaster.
The 2 million residents of Fukushima prefecture, targeted in the new 30-year survey, probably got too little radiation to have a noticeable effect on cancer rates, said Seiji Yasumura of the state-run Fukushima Medical University.
"I think he's right," as long as authorities limit children's future exposure to the radiation, said Richard Wakeford, an epidemiologist at the Dalton Nuclear Institute at the University of Manchester in England.
The idea that Fukushima-related cancers may go undetected gives no comfort to Edwin Lyman of the Union of Concerned Scientists. A lot can be done to limit the toll by reducing future exposure to radiation, he said, but that could mean decontamination projects, condemned land and people never returning home. "There's some difficult choices ahead."