With radiation levels high in Japan, radiation exposure is explained

What radiation exposure really means.
Written by Boonsri Dickinson, Contributing Editor

It's possible that Japan's nuclear crisis might be as bad as Chernobyl was. The radiation released in the Chernobyl accident was equivalent to several hundred Hiroshima bombs.

Just reading about the nuclear crisis in Japan makes my stomach hurt. But this had me thinking about radiation exposure of radioactive iodine and cesium.That's not even counting the radiation in the spent fuel pool, which contains old rods with radioactive materials (plutonium, strontium and cesium).

The risk depends on the distance, dose and amount of exposure — and the effects of radiation are cumulative. Radioactive iodine breaks down pretty quickly, much faster than cesium.

How much is too much? Too much radiation can disrupt cells and cause death. Exposure to a lot of radiation can lead to thyroid cancer, bone cancer and leukemia.

The heroic workers trying to save the reactors have the greatest risk of developing cancer. In one hour, the workers are getting exposed to radiation levels that a person would be exposed to in a year. People who live near the Fukushima Nuclear Power Plant have evacuated.

But it's not a localized problem.

Now, airlines and travelers are avoiding Tokyo, after a small spike in radiation was measured. It's about 10 times higher than normal there. Residents are advised to stay indoors to minimize exposure.

The radioactive materials spewing from the nuclear reactors in Japan could travel in the air, be inhaled by the people, or make its way into the food supply and drinking water.

And those on the other side of the pond are left wondering, what if the plume from the radiation gets into the jet stream and makes it all the way to California and the rest of the United States? After all, it has happened before and will probably happen again.

The radiation after the 1986 Chernobyl disaster was dispersed all the way throughout the Northern Hemisphere in just three weeks!

There's a chance, the cloud will shroud Tokyo and then float over the Pacific, and will make its way over to Canada and the United States and the rest of the world. (If you want real-time info, radiation levels are now being crowd-sourced through Radiationnetwork.com). However, the Nuclear Regulatory Commission claims the United States is so far away, that we shouldn't be exposed to any harmful levels of radioactivity. Japan is 5,000 miles from the west coast.

According to Reuters, meteorologists predict it would take about six days to the United States, but by then, it would be dissipated into the atmosphere. Still, California is monitoring the situation: the state has radioactivity monitory systems in place to check the air, water and food supply.

Experts claim that the radioactive material seems to be dissipating into the atmosphere, instead of forming a huge cloud like it did in the Chernobyl accident.

Radiation naturally exists. Brazil nuts and bananas have more radiation than other foods. Location matters too: People living in Colorado are exposed to more cosmic radiation than people living along the beach. Consumer products like tobacco and exit signs also emit radiation.

Half of a person's exposure is natural, the other half isn't (and this artificial source comes mainly from diagnostic medical procedures).

Our exposure to radiation is measured in a unit called a microsievert. The radiation levels near Fukushima plant's No. 2 reactor were about 73 microsieverts before a blast, but then it got to be as high as 11,900 microsieverts.

Airport scanners can deliver a radiation dose up to 20 times more than previously thought - and this could increase a person's risk of developing skin cancer. Getting on an airplane from New York to Los Angeles will exposure you to 30-40 microsieverts.

If you're on a plane and it flies near or through a lightning storm, you could be exposed to levels of radiation equivalent to 400 chest X-rays.

That said, one chest X-ray is about 100 microsieverts. But that's nothing compared to a year's worth of exposure to natural radiation, which is 3,000 microsieverts.

Radiation exposure is a fuzzy area, but the associations between radiation exposure and the development of cancer are clear when studied in populations with high levels of ionizing radiation, such as patients involved of therapeutic medical procedures and Japanese atomic bomb survivors. The higher the dose of radiation, the sooner the effects of radiation show up... and the higher probability of death.

The workers at Chernobyl were exposed a large dose, and suffered from acute radiation sickness - some died within three months of the radiation injuries. Radiation sickness, or acute radiation syndrome, can damage tissue and cause the bone marrow to stop making new blood cells...and can possibility lead to death. Symptoms include vomiting, bloody diarrhea, rash, poor wound healing, crippling of the immune system and fatigue and weakness.

Some people are taking potassium iodide pills to keep the body from absorbing radioactive iodine. The Japanese government has given out 230,000 units of iodine to residents near the Fukushima plant, as a precaution.

Photo: U.S. Nuclear Regulatory Commission and NRC

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