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Japan’s Radioactive Leak: What Are the Long-Term Consequences?

Fukushima nuclear power plant.

Environmental and nuclear scientists in the U.S. are watching apparent leakage discovered at the Fukushima Daiichi nuclear reactor site this week with a concerned eye, for both health effects and impact on the environment.

Japanese safety officials are maintaining that the newly found contamination — highly radioactive water in tunnels outside the plant, plutonium in nearby soil samples and spikes in levels of radioactive iodine in seawater — pose no new risks to the public.

Radioactive iodine 131 was found in ground water near No.1 reactor of Fukushima Daiichi complex, plant operator Tokyo Electric Power Co. said this week. “Radioactive materials in the air could have come down to the earth’s surface and they could have seeped into the ground due to rainfall,” said a company spokesman, according to news agencies.

But experts say the long-term consequences are still unknown and warn the contaminated water pooling in and around the plant is dangerous for workers immediately.

“Conditions for the workers have deteriorated a lot,” said Arjun Makhijani, president of the Institute for Energy and Environmental Research. “[They] are appallingly dangerous. That is why they are limiting work to 15 minutes at a time.”

Workers at the damaged Fukushima nuclear plant. Photo via TEPCO.

The radioactivity levels of the leaking water found at the plant were reportedly more than 1,000 milli-Sieverts per hour, enough to give a worker acute symptoms in an hour, according to Edwin Lyman, senior global security scientist at the Union of Concerned Scientists. Outside the site, environmental contamination is also a growing issue, he said.

“There has already been an enormous amount of radioactivity released from this plant into the air, and that will deposit on seawater and surface water supplies,” Lyman told reporters. “It’s hard to imagine that there won’t be some significant contamination that will have to be dealt with.”

Residents within 12 miles of the nuclear plant have been evacuated and Fukushima prefecture is continuing to uphold a warning for infants consuming tap water. Food is being tested regularly by the government and restrictions have been placed on the sale of leafy vegetables and milk. Elevated levels of radionuclides have now been found in food in six prefectures.

The International Atomic Energy Agency also reported Wednesday it found radiation in one village outside the evacuation zone at twice the recommended threshold for evacuation, though it did not specifically advocate expanding the zone.

And on Wednesday, the U.S. government reiterated its travel warning on Japan, including its recommendation that U.S. citizens within 50 miles of the Fukushima plant evacuate the area or take shelter indoors. The State Department added that U.S. citizens should defer non-essential travel to regions including Tokyo, Yokohama and several other prefectures.

The levels of radioactivity found in the region around the plant are already “well above background levels”– the natural levels of radiation measured at a location — and “high enough to be of concern,” said James Smith, an adjunct professor of environmental health at Emory and the former associate director of the radiation division at the Centers for Disease Control.

Smith said the most immediate concern is another pulse of radioactivity into the environment, from an event like another fire at the reactors, that could boost levels even higher.

Jacquelyn Yanch, professor of nuclear engineering at the Massachusetts Institute of Technology, said background levels vary quite a bit around the world, and that the levels seen now in Japan are comparable to the natural levels seen in some parts of China, India and Brazil.

“The radiation levels to the public [in Japan] are relatively low, they are certainly higher than background, but people live at these levels around the world,” Yanch said. “We don’t have any data that show that living in these areas increases your chance of getting cancer or shortens your life.”

Officials are maintaining the 12 mile zone is sufficient, though they are recommending people within 18 miles stay inside their homes. The government said Wednesday that contaminants seen in the seawater will dilute quickly and are not a risk.

Just how the seawater contamination will affect the livelihoods of the many people that rely on Japan’s fisheries remains unclear. Close monitoring will be crucial, said Timothy Mousseau, a radioecologist and biology professor at the University of South Carolina.

“There is the potential for bioaccumulation for some of these radionuclides through the food chain,” he said, which occurs when chemicals collect in the tissue of organisms, such as fish, increasing the concentration of that chemical.

The two contaminants scientists are watching most closely in this crisis are Iodine 131, which dissipates quickly and has a half life of eight days, and cesium-137, which has a half-life of about 30 years.

“At Chernobyl it was the iodine 131 that provided the highest doses to people who lived in the local region around the plant,” said Smith. Iodine 131 can get into milk supplies and goes straight to the thyroid if ingested, he said, putting children at especially high risk of thyroid cancer.

Cesium-137 on the other hand attaches itself to vegetation and soil and can remain part of the environment for decades.


Iodine 131 has been detected in 12 prefectures so far and cesium 137 has been found in nine, but still at low levels outside the evacuation radius.

While some residents were caught violating the evacuation zone this week in order to collect belongings from their homes, still others aren’t waiting to see if the situation at the reactor can be controlled and are beginning to voluntarily evacuate from zones further from the plant.

View all of our Japan coverage.

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