VOA常速英语:Japan's Nuclear Crisis Stokes Fears of Radiation Exposure

How do potassium iodide tablets help protect against radiation exposure?

“The whole idea with potassium iodide is to provide non-radioactive, cold, stable iodine to the thyroid in the body. If the thyroid gland has been saturated with this cold, stable, harmless iodine, then if the body happens to take in by breathing or by eating or drinking any radioactive iodine, it won’t be taken up in the thyroid. It will be excreted. We know from past experiences like Chernobyl, the radiation exposure to the thyroid gland can lead to thyroid cancer. So we want to prevent exposure at all costs, first by making sure we are monitoring for radioactivity, particularly radioactive iodine in the food and the milk. That’s where most of the radioactive iodine intake is going to come from as opposed to breathing it in the air.”

The situation in Japan is causing anxiety throughout Asia and the world. It has caused a “run” on soy sauce in China, where some think the salt in soy sauce could protect them from exposure to radiation.

“It’s not something I would recommend that they do. Presumably, what people are looking for is the iodine that happens to be in the soy sauce because it contains high levels of salt. And salt in most countries has iodine. But, you know, you might have to consume an awful lot of that to get the amount of iodide that you need.”

What are the health consequences of a high exposure to radiation?

“When we start getting in to the acute levels of radiation exposure, perhaps 1,000 millisierverts is where that begins. These acute effects can lead to death. Actually, about 4,000 millisierverts would be about a 50 percent risk of death.”

Are the Japanese workers trying to put out the fires at the nuclear plants exposed to that high level of dose?

“There is no reason for them to be exposed to that high of a level. However, they could have hundreds of millisierverts that they are exposed to. For volunteer doses, that means in order to save the life of a comrade or colleague at a power plant in case of some accident, it would not be untoward to have that volunteer to be exposed to as much as 250 or 500 millisierverts.”

What are some of the symptoms of radiation poisoning?

“The acute radiation syndrome phase would begin with nausea, vomiting, diarrhea. And that could occur within hours, perhaps it might take days before that begins to occur. The greater the dose that the person is exposed to, the more likely those kinds of symptoms are going to appear earlier.”  

There are a lot of fears about radioactive plumes of smoke.  How far could that spread?

“It can spread very far. Normally here in the U.S., the Nuclear Regulatory Commission uses a 10 mile [16 km] protection zone to keep people out of that because of the concern that the plume can be so concentrated within 10 miles of a plant that the fallout from that could be harmful. The 50 mile [80 km] zone that the Nuclear Regulatory Commission recommends in some cases, like they are doing in Japan right now, is to make sure that people are not exposed to any high levels of radioactivity in a plume as well as not exposed to anything in the soil or  the food, the water, that could be contaminated. So the idea is outside that 50 mile protection zone, then you are safe to eat, and drink and be outdoors.”