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?
A: 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?
A: 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.
Q: Is soap and water really enough to get radiation off you?
A: 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?
A: 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.
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
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.
Q: How do we know radiation causes cancer?
A: 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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