Fukushima Watch: Study Suggests up to 1,300 Could Die From Radiation Effects

By Yoree Koh

The radiation toll from last year’s Fukushima Daiichi nuclear accident could eventually result in anywhere from 15 to 1,300 deaths, according to a study by Stanford University scientists. The researchers also calculate that about 24 to 2,500 cases of cancer illnesses could someday be attributed to the accident. Plant workers who were exposed to radiation on-site may account for another two to 12 cancer cases.

Even at the higher end of the scale, the study’s results paint a far milder picture compared with the grim health effects seen after the world’s last major nuclear accident, in Chernobyl in 1986. They also fall in line with the earlier consensus of other scientists. Chernobyl resulted in 5,000 to 6,000 cases of thyroid illness, mostly among children, according to some experts. A global group created to study the health effects of Chernobyl expects a total of 4,000 fatal cancers among those most highly exposed.

But the ultimate tally could still be higher than the results suggest.

“The whole 15 to 1,300 range is probably in reality, in my personal opinion, a conservative number. I certainly wouldn’t go lower than that,” Mark Z. Jacobson, co-author of the study and an environmental engineer at Stanford, told JRT in an interview.

In the study, which was published in the journal Energy & Environmental Science this week, the scientists’ best estimate within the range was that the radiation would eventually be responsible for 130 deaths and 180 cancer cases.

Mr. Jacobson described those figures as “very conservative,” especially once non-cancer related illnesses such as cardiovascular and respiratory ailments are considered. “In fact there is a huge health effect from particles, but we didn’t even calculate those effects,” said Mr. Jacobson, who has researched the health impact of other environmental pollutants prior to this study.

The wide-ranging figures in the study — the first one to quantify the global health impact of the devastating nuclear accident — underscore the difficulties in calculating radiological health effects. Numerous uncertain factors complicate matters. The biggest trouble is the dearth of real data available to show the relationship between nuclear accidents and physical health. Previous epidemiological studies were used to inform the researchers about how to crunch the data had limitations. Some were only theoretical while others, including analyses of Nagasaki and Hiroshima, contained uncertainties, Mr. Jacobson said.

The study steered clear of attempting to answer one of the biggest post-Fukushima unknowns — the effect of extended exposure to low-level radiation. Instead, it focused on the impact of radiation exposure for a short period of time over a lifetime. About 27% of the health effects expected in Japan will occur sometime in the next 50 years, the study said.

The Stanford study ran simulations that predicted the dispersion and transformation of radioactive emissions around the world for one month beginning March 12, the day after the devastating tsunami, based on estimates of how much radioactivity was released. Using a three-dimensional global atmospheric model, they mapped out the spread and concentration of the radioactive nuclides — iodine-131, cesium-137 and cesium-134. The predictions overlapped for the most part when compared against actual measurements of airborne and ground level radioactive contamination.

They then calculated the health effects of each dose of radiation on the global population based on a linear no-threshold model, a controversial approach that assumes that any amount of extra radiation exposure increases cancer risk. The map ultimately showed one of the main reasons why the health effects are likely to be minimal compared with Chernobyl: About 80% of the radioactivity was blown towards the ocean whereas, in the case of Chernobyl, most of the radioactivity settled over land and the amount released was far greater.

Mr. Jacobson said the human toll would be much more devastating if a similar accident happens at a nuclear plant in western Japan because the large-scale winds would push the radioactivity over land.

The paper also stated that the swift evacuation procedures may have resulted in 22% fewer deaths and cancer cases. But at the same time it noted that “the lives saved due to evacuation may be an overestimate since reports indicate that policymakers failed to evacuate people away from the plume immediately following the accident.”

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