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By Chief medical editor
NBC News
updated 3/16/2011 4:18:58 PM ET 2011-03-16T20:18:58

As we watch the nuclear crisis escalate in Japan, many of us have questions on radiation sickness — what are the symptoms and what are the long-term health effects? And should those of us in the U.S. be taking any extra precautions? NBC's chief medical editor Dr. Nancy Snyderman explains.

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Q: What are the main symptoms of radiation sickness?
Radiation sickness (acute radiation syndrome, or ARS) occurs when the body is exposed to a high dose of penetrating radiation within a short period of time. The first symptoms of ARS typically are fatigue, hair loss, nausea, vomiting and diarrhea, as well as skin changes such as swelling, redness, itching and radiation burns. Symptoms may present within a few minutes to days after the exposure, and may come and go. This seriously ill stage may last from a few hours up to several months.

Q: How much radiation does there have to be, and how long do you have to be exposed, to cause health problems?
Most studies on radiation and cancer risk have looked at people exposed to very high doses of radiation. Consequently, it is harder to measure the much smaller increase in cancer risk that might come from much lower levels of radiation exposure. Some scientists and regulatory agencies believe that even small doses of ionizing radiation may increase cancer risk, although by a very small amount. The rule of thumb is that the risk of cancer from radiation exposure increases as the dose of radiation increases. Since everyone’s body is different, there is no definitive threshold dose at which you can be totally safe.

What do you want to know about radiation? Dr. Nancy answer your questions

Q: Is soap and water really enough to get radiation off you?
Any person with contamination on their clothing or body should remove their clothes and shower. Soap and water can go a long way toward minimizing absorption through the skin and keeping local contamination from spreading.

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Q: What are the long-term health consequences of radiation exposure?
Cancer is the most common long-term consequence of radiation exposure. Your bone marrow and your thyroid gland are especially sensitive to radiation. Research shows that some cancers types are more strongly linked to radiation exposure. These cancer types include leukemia, thyroid cancer, multiple myeloma, in addition to skin, lung, stomach and breast cancer.

Young children are very vulnerable to the long-term effect of radiation because their cells are actively dividing as part of normal growth and development. Fetuses are also particularly susceptible to the effects of radiation, and mutations can occur if the radiation exposure happens during the early pregnancy. History shows us that genetic mutations can occur in adults exposed to nuclear radiation. These mutations can sometimes be passed from parent to child.

How much radiation is dangerous?

Q: If the Japanese power plant continues to spew radiation and the wind blows it out to sea, how concerned should we be in the U.S. for our own safety?
A: Not concerned because the amount of radiation is low and any residual will be dissipated by the jet stream before it hits the coast of California.

Story: Demand for potassium iodide spikes; nukepills.com is there

Q: Iodine tablets are selling out in America; should we be stocking up? Are there any other steps we should take in the U.S.?
A: There is absolutely no need to panic and right now and there are no special steps that experts are recommending. After a nuclear event, local public health or emergency management officials will tell the public if they should be taking potassium iodide or if other protective actions are needed. Remember, iodine prophylaxis is not one size fits all. If you have a seafood or shellfish allergy, a thyroid condition or certain skin disorders, you should not take potassium iodide before consulting with your doctor.

Dr. Nancy Snyderman will continue to address your questions as they come up. In the meantime, here are some explanations provided by government agencies.

Q: What is the difference between radiation exposure and radioactive contamination?
A: A person exposed to radiation is not necessarily contaminated with radioactive material. A person who has been exposed to radiation has had radioactive waves or particles penetrate the body, like having an x-ray. For a person to be contaminated, radioactive material must be on or inside of his or her body. A contaminated person is exposed to radiation released by the radioactive material on or inside the body. An uncontaminated person can be exposed by being too close to radioactive material or a contaminated person, place, or thing.

Radiation exposure occurs when a person is near a radiation source. Persons exposed to a radiation source do not become radioactive. For example, an x-ray machine is a source of radiation exposure. However, you do not become radioactive when you have an
x-ray taken.

Radioactive contamination results when loose particles of radioactive material settle on surfaces, skin, or clothing. Internal contamination may result if these loose particles are inhaled, ingested, or lodged in an open wound. Contaminated people are radioactive and should be decontaminated as quickly as possible. However, the level of radioactive contamination is unlikely to cause a health risk to another individual.

Source: NY Department of Health: Radiological Terrorism Rapid Response Card and CDC: Radiation Emergencies

Q: How do we know radiation causes cancer?
When people first began working with radioactive materials, scientists began to notice patterns in the illnesses they experienced. People working with radioactive materials and x-rays developed particular types of uncommon medical conditions. For example, scientists recognized as early at 1910 that radiation caused skin cancer. Scientists began to keep track of the health effects, and soon set up careful scientific studies of groups of people who had been exposed.

Among the best known long-term studies are those of Japanese atomic bomb blast survivors, other populations exposed to nuclear testing fallout (for example, natives of the Marshall Islands), and uranium miners.

Source: EPA: Radiation Protection

Q: How is radiation measured? Some people on TV are talking about millirems; others refer to milliSieverts? What's the difference?

A: Japan measures radiation dose in the metric system unit of Sieverts (Sv). The press in Japan has reported doses in milliSieverts (mSv).  A milliSievert is one thousandth of a Sievert (1000 mSv = 1 Sv). The United States’ unit of a measurement for radiation dose is the rem (Roentgen Equivalent Man). In the U.S., doses are most commonly reported in millirem (mrem). A millirem is one thousandth of a rem (1000 mrem = 1 rem).

Converting Sieverts to rems is easy. One sievert equals 100 rem. (1 Sv = 100 rem).  One milliSievert equals one hundred millrems (1 mSv = 100 millrems).

The EPA has a really interesting calculator that allow you to calculate your own dose from daily living: http://www.epa.gov/radiation/understand/calculate.html

Source: EPA: Radiation Protection

Q: Who is in charge of protecting Americans from radiation exposure?
A: State and local authorities maintain off-site emergency response plans, which are closely coordinated with the plant's on-site emergency response plan. They also conduct off-site radiological emergency preparedness exercises at each commercial nuclear power station every two years.

U.S. Nuclear Regulatory Commission (NRC) issues licenses and policies governing safe operation of nuclear reactors and the commercial use of radioactive materials. NRC also performs inspections and oversees emergency response programs for licensees.

U.S. Environmental Protection Agency (EPA) In 1989 under the Clean Air Act, EPA published standards limiting radionuclide emissions from all federal and industrial facilities. EPA also sets environmental standards for offsite radiation due to the disposal of spent nuclear fuel and high-level radioactive waste.

Department of Homeland Security (DHS), Federal Emergency Management Agency (FEMA) FEMA evaluates both the state and local off-site emergency response plans and the off-site radiological emergency preparedness exercises that are conducted at each commercial nuclear power station every two years.

U.S. Department of Energy (DOE) is responsible for the development and implementation of the disposal system for spent nuclear fuel from the nation’s nuclear power plants. This activity is totally funded by a tax paid by the users of nuclear-generated electricity.

Source: EPA: Nuclear Power Plants

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Video: What to know about radiation poisoning

  1. Transcript of: What to know about radiation poisoning

    MATT LAUER, co-host: What are the immediate health risks from radiation ? And what, if anything, should people in the US do? On the West Coast fear has led to runs on iodine pills. Dr. Nancy Snyderman is NBC 's chief medical editor. Nancy , good morning to you.

    Dr. NANCY SNYDERMAN reporting: Hi, Matt.

    LAUER: Talk about iodine in a second.

    SNYDERMAN: Sure.

    LAUER: If we're looking at the affected area in Japan , I think the simplest way to put it, what you and I have been talking about, is people in this area may...

    SNYDERMAN: Right.

    LAUER: ...may be getting what we would consider a normal one year's worth of radiation in just a couple of days .

    SNYDERMAN: And not only one year's worth, but these microbursts that talk about, you know, there are various ways to measure radiation exposure . And it almost gets a little too wonkish. But for those 50 people who are there, we know they're getting microbursts over and over, and increased...

    LAUER: And what about the people in that 12-mile area and 19-mile area?

    SNYDERMAN: Well, levels of radiation much like what happened to Lester . So the radiation that's in the air will settle down on the earth, and I think the long-term concern is it gets in the soil, then it gets in the grass, the cows eat it, it ends up in your milk. That's how people in Chernobyl had that huge spike of thyroid cancer . They drank the milk from contaminated cows.

    LAUER: When you hear the recommendation from the Japanese government that people in that affected area should stay indoors...

    SNYDERMAN: Right.

    LAUER: ...does that even come close to protecting them?

    SNYDERMAN: Yes! It does, as a matter of fact.

    LAUER: Shut the window and that's it?

    SNYDERMAN: Yes. Duct tape can be your friend in a situation like this. Close the doors, duct tape windows and let the radiation fall to the ground and get dissipated. And for people on the West Coast of the United States , a lot of the jet stream and air is going to take care of this. You know, there haven't been huge, huge amounts of radiation . There have been these micropops, and a lot of those -- a lot of that radiation will get dissipated just by the air.

    LAUER: So anecdotally we're hearing that there has been a run on iodine pills...

    SNYDERMAN: A run?

    LAUER: ...on the West Coast ...

    SNYDERMAN: A run? Gone.

    LAUER: ...of the United States . And there's some confusing information coming out.

    SNYDERMAN: Yeah.

    LAUER: Yesterday surgeon general, Regina Benjamin , told a reporter she thought it was appropriate to get iodine because we have to be prepared. A spokesperson later clarified saying she didn't mean to suggest people should go out and buy the pills. You were strong about this in an interview last night.

    SNYDERMAN: I was strong, and Regina texted me last night and said 'thanks for clarifying.' She wasn't saying everyone should get it. This is a classic kind of thyroid medication you can get that has iodine in it. And it says on the back, "use as directed by public health officials in case of a nuclear accident." Now, this blocks the bad radiation from getting into your thyroid gland. But let me warn people, doesn't block cesium, doesn't block anything else from the rest of the organs. So the most important thing is, this is not to be taken right now. This is in case you are going to be going into an irradiated area. And I want to remind people, for those people who are in harm's way in Japan , the immediate signs are nausea, vomiting, exhaustion, hair falling out. What we worry about are the issues five, 10, 15, 20 years down the line.

    LAUER: OK. Long term.

    SNYDERMAN: Or we might see a bump in cancer.

    LAUER: And those people will be tested for a very long time.

    SNYDERMAN: Yes. We are going to be watching these people for a very long time.

    LAUER: All right, Nancy ...

    SNYDERMAN: But Americans, just pray for the Japanese, and we should all take a deep breath here and relax.

    LAUER: Relax a little bit.

    SNYDERMAN: Yeah.

    LAUER: All right, Nancy , thank you very much .


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