Radiation from the Fukushima nuclear plant may cause as many as 1,300 cancer deaths globally, according to a study that showed fallout from Tokyo Electric Power Co.’s crippled reactors may be deadlier than predicted.
The March 2011 nuclear disaster may cause as many as 2,500 cases of cancer, mostly in Japan, Stanford University scientists said. They incorporated emission estimates into 3-D global atmospheric modeling to predict the effects of radiation exposure, which was detected as far away as the U.S. and Europe.
Cancer cases may have been at least 10 times greater if the radiation hadn’t mostly fallen in the sea, said Mark Z. Jacobson, co-author of the first detailed analysis of the event’s global health effects. Identical emissions from a hypothetical accident at California’s Diablo Canyon Power Plant would be 25 percent deadlier because of differing weather patterns, according to the study published yesterday in the journal Energy & Environmental Science.
“There was a lot of luck involved,” said Jacobson, a professor of civil and environmental engineering at Stanford, in a telephone interview. “The effects vary significantly with the meteorological conditions and the only reason this wasn’t a lot worse was because 81 percent of all the emissions were deposited over the ocean.”
The failure of backup power at the Fukushima Dai-Ichi plant, located 135 miles (220 kilometers) north of Tokyo, caused the worst atomic accident since Chernobyl in 1986.
Radiation fallout forced the evacuation of about 160,000 people surrounding the plant. It also left about 132 square kilometers as a no-go zone, some of it uninhabitable for decades. Prolonged exposure to radiation in the air, ground and food can damage DNA, causing leukemia and other cancers.
The best estimates of cancer cases resulting from the Fukushima disaster is 180, and range from 24 to 2,500, yesterday’s study said.
The most likely number of cancer deaths is 130 and estimated to range from 15 to 1,300, the authors said, adding that the ranges reflect uncertainties about emissions and the methods the researchers used to calculate their impact.
“They have demonstrated there are no significant public health effects” from radiation exposure, said Evan Douple, associate chief of research at the Hiroshima Radiation Effects Research Foundation. “Their best estimate of 130 cancer deaths in Japan would be lost in the background wash of the hundreds of thousands of cancer deaths that would be occurring in the million or so people in the population exposed.”
The biggest health effects were psychological, said Douple, whose team is studying the impact from Fukushima. Stress from the earthquake, tsunami and meltdown may cause a range of health effects, including cancer, he said.
About 600 people died because of the evacuation, mostly due to fatigue and exposure among the elderly and chronically ill, the Stanford researchers said, cautioning against drawing conclusions about evacuation policy.
“You still have an obligation to evacuate people according to the worst-case scenario,” Jacobson said in statement.
Those affected by the fallout of radioactive material were overwhelmingly in Japan, according to the researchers’ model. It predicted “extremely small effects” in mainland Asia and North America.
The U.S. would have 0 to 12 cancer deaths and 0 to 30 cases, the researchers said, acknowledging that their methods used were less precise for areas that saw only low radionuclide concentrations.
“These worldwide values are relatively low,” study co-author John Ten Hoeve said in the statement, adding that they should “serve to manage the fear in other countries that the disaster had an extensive global reach.”
In a nuclear accident, radioactive isotopes including iodine-131 and cesium-137, which are normally contained inside the fuel rods, may be released into the atmosphere as gases or particulates if the rods are damaged. These can be inhaled or ingested through contaminated food or water.
Radioactive barium, cesium, iodine and tellurium were detected March 16, 2011, in a radiation plume released by damaged nuclear reactors at Fukushima. A partly dispersed cloud passed by the Tokyo area the same day, Austria’s Meteorological and Geophysics Center reported.
Children are especially susceptible to radiation poisoning from iodine, which can accumulate in the thyroid gland, according to the World Health Organization. Infants can suffer most because their cells are dividing more rapidly and radiation-damaged RNA may be carried in more generations of cells.
Cesium-137 that enters the body is distributed throughout the soft tissues, especially in muscle. Cesium-137 is eliminated faster from the body than other radionuclides, according to the U.S. Environmental Protection Agency.
The Fukushima Dai-Ichi plant may have emitted about 900,000 terabecquerels of the iodine equivalent of radioactive iodine 131 and cesium 137 into the air at the height of the disaster, the utility known as Tepco said in May. The amount is about 2 times more than the 480,000 terabecquerels estimated in February by the Nuclear and Industrial Safety Agency or NISA, the utility said.
The total radiation release at the Chernobyl accident was estimated to be about 5.2 million terabecquerels.