GWEN IFILL: As we reported, the nuclear scare went global today, as Australia, Germany, Russia and other countries urged their citizens to leave Tokyo and northern Japan.
The U.S. Embassy recommended Americans stay outside a 50-mile radius of the nuclear plant or take shelter indoors. By contrast, Japanese officials have announced zones that extend to 20 miles for their civilians. U.S. troops were also told to stay 50 miles away. And crews and equipment that flew over or near the nuclear plant were checked for signs of radiation.
In Washington, the head of the Nuclear Regulatory Commission said emergency workers inside the plant are in grave danger.
GREGORY JACZKO, U.S. Nuclear Regulatory Agency: We believe that around the reactor site that there are high levels of radiation. It would mean it would be very difficult for emergency workers to get near to the reactors. The doses they could experience would potentially be lethal doses in a very short period of time.
GWEN IFILL: There's been much discussion about the radiation and health risks near the plant, the outlying areas and even farther away.
We try to make some sense of it now with Lake Barrett, a nuclear engineer and consultant who directed the cleanup of Three Mile Island for the Nuclear Regulatory Commission, and Norman Kleiman, a professor of environmental health sciences at Columbia University's Mailman School of Public Health in New York. His work focuses on exposure to radiation.
Lake Barrett, you have been involved in something similar to this, even though some time ago now. Give us a sense of what's happening inside that plant right now.
LAKE BARRETT, nuclear engineer: Well, the workers are coping with a very challenging, very difficult situation there at Fukushima.
They have three reactors cores that have been overheated, and the rubble, and is probably partially melting in the cores. I believe those cores are stable at the moment with fire hoses and fire connections they have for the reactors. The most immediate concern is the two spent fuel pools that are in unit four and unit three.
Those apparently have overheated. And there's been hydrogen released. There's been explosions. Some of the buildings have been damaged severely. And they're working very hard to try to contain that radioactivity as we speak.
GWEN IFILL: Norman Kleiman, as we -- we talk about the effects of radiation exposure, what distinction has the U.S. -- can we figure that the U.S. government has drawn between saying there should be a 50-mile radius of safety for U.S. citizens, and the Japanese government, which is suggesting only a 20-mile radius?
NORMAN KLEIMAN, Columbia University: I think that our government is being prudent and careful and conservative in its estimates about radiation exposure, and not wanting to expose any individuals, any U.S. citizens to risk.
I think it's a little difficult, in the absence of concrete data and information, for the U.S. government and for the Japanese government to actually know what the real risks are. They're just trying to be extra conservative and cautious in protecting the health of the populations.
GWEN IFILL: Mr. Kleiman, as they come up with these guidelines, what's the distinction between advising people to stay indoors and advising people to get out altogether?
NORMAN KLEIMAN: There are several ways to protect oneself against ionizing radiation exposure, certainly shielding, so behind a barrier. The concrete, the wood, the brick of buildings affords some protection. Distance affords some protection, which is why the exclusion zone has been increased, and time, the dose rate and the amount of time one is exposed to radiation.
So, these are all factors that need to be calculated. In the absence of knowing precisely what the doses are and what the types of isotopes being released are, it's difficult to give hard data on what a safe level is. I think everyone is being very cautious and very conservative.
GWEN IFILL: It is difficult to figure it out, but the thing that most scientists, Mr. Barrett, seem to agree on is that this has now exceeded the danger that was at Three Mile Island. Is that your sense of it as well?
LAKE BARRETT: Yes, it is.
GWEN IFILL: So, what do people do? What are the risks? How are they manifested for individuals who are either nearby or within the plant, or even across the ocean?
LAKE BARRETT: Well, the people at the plant are trained nuclear professionals working very hard under very difficult conditions. Radiation levels are high. It's -- they have to wear protective suits and respirators as they work. It's very difficult. But they are trained to understand the risks involved with working with radioactive materials.
The -- the immediate people around the site which is most affected have been evacuated. And you will be needing reports of contamination and radiation levels compared to that round. And those will go up quite some distance from the plant. But I believe, if the people follow the directions of the government, I think, from the health point of view, I think they will be at very low risk.
GWEN IFILL: Mr. Kleiman, when we hear about risk and how the risk is manifested, do we know, is this an immediate risk? Do we -- do -- are the people who are there or nearby immediately see signs of radiation poisoning or exposure, or this something that only surfaces eventually?
NORMAN KLEIMAN: Those workers in the plant themselves, if they're exposed to significant levels of radiation, will experience what's called acute radiation syndrome. These are at much higher levels that's been reported since so far, but symptoms such as nausea, gastrointestinal distress, and a change in their bone marrow.
These occur at doses of about 8.8 sieverts to one sievert. That's not been reported so far, but we can presume that there are levels inside the plant, hopefully regions that the plant workers are not in right now, where those levels are present.
For the general population, as distance increases, radiation exposure drops dramatically. And at this point, based on the figures we have been given, it's unlikely that anyone would have any kind of symptoms from radiation exposure outside of the immediate vicinity of the plant.
GWEN IFILL: Mr. Barrett, we are -- tell me if I'm correct, that we were all exposed to some degree to radiation in our daily lives. How's the magnitude in this case different?
LAKE BARRETT: Well, the Earth is a radioactive place. It was radioactive before mankind was on this Earth. So, we are all exposed to natural radiation every day.
We're also exposed to manmade radiation from medical exposures. In this plant in close are extremely high radiation levels that are -- can be deadly if they're not properly managed. Once -- as the doctor had managed, once you get away, yes, there will be increased risk due to some increased radiation from the plant, but I think the levels will be below those that you would commonly find in medical procedures.
Millions of people have medical procedures such as X-rays or diagnostic work done that involves radioactive materials, and it is not a huge health risk. So, I would say this is not a health catastrophe, but it certainly is an industrial catastrophe in the plant.
GWEN IFILL: So, this run, Mr. -- Mr. Kleiman, we have been seeing on iodide pills that are supposed to be some sort of -- ameliorate whatever problem which crops up, is that reasonable?
NORMAN KLEIMAN: Probably not.
Iodide pills protect against a unique kind of cancer that can be caused by radiation, thyroid cancer. And they're only effective if they're taking immediately preceding a radiation exposure, certainly within the first 24 hours preceding an exposure.
There's absolutely no evidence for anyone in the United States or in Hawaii or even in the area surrounding the plant that there have been increased levels of radioactive iodine that are of concern to the general population. So, while it may make feel -- people feel a little more comfortable, psychological benefit, the overall benefit at this point is very low.
GWEN IFILL: Mr. Barrett, do you agree with that? There is some concern on the West Coast that something in this cloud, something in this -- this plume could, as the wind drives it across the Pacific, it could end up here.
LAKE BARRETT: That's virtually a zero-risk type of situation. I don't think that people in California should be concerned one bit about it.
GWEN IFILL: And the people in Tokyo?
LAKE BARRETT: Tokyo is quite a ways away, and I don't think the people in Tokyo should be worried either, unless -- as they follow the instructions that they will get from their government as time goes on.
So, no, I believe the health risks are extremely low. I would consider it safe in Tokyo.
GWEN IFILL: But I do have to ask you this question, because you were involved in the Three Mile Island cleanup. And there are a lot of things we didn't know about for years. Is that going to be the case as well here?
LAKE BARRETT: Well, clearly, what's going on, this is the fog of war in an industrial accident. The people at the plant are actually dealing with it. It is a very difficult thing.
Information flow is terrible to everybody. People are frustrated. They want to know what's going on. But we -- there's no way we can know, when we're not in the plant itself. And even those working in the plant, it is very difficult.
So, we just are going to have to wait, and get our lessons learned on what happened, and make things better, and go forward, and do a lot of cleanup. But I don't believe this is a health catastrophe.
GWEN IFILL: Lake Barrett, Norman Kleiman, thank you for helping us to make sense of it all.
NORMAN KLEIMAN: Thank you.
LAKE BARRETT: Thank you for inviting us.
NORMAN KLEIMAN: Thank you.