this is the fallout section

Radiation causes ionizations in the molecules of living cells. These ionizations result in the removal of electrons from the atoms, forming ions or charged atoms. The ions formed then can go on to react with other atoms in the cell, causing damage. An example of this would be if a gamma ray passes through a cell, the water molecules near the DNA might be ionized and the ions might react with the DNA causing it to break.

At low doses, such as what we receive every day from background radiation, the cells repair the damage rapidly. At higher doses (up to 1 Sv), the cells might not be able to repair the damage, and the cells may either be changed permanently or die. Most cells that die are of little consequence, the body can just replace them. Cells changed permanently may go on to produce abnormal cells when they divide. In the right circumstance, these cells may become cancerous. This is the origin of our increased risk in cancer, as a result of radiation exposure.

At even higher doses, the cells cannot be replaced fast enough and tissues fail to function. An example of this would be "radiation sickness." This is a condition that results after high acute doses to the whole body (>2 Gy), the body's immune system is damaged and cannot fight off infection and disease. Several hours after exposure nausea and vomiting occur. This leads to nausea, diarrhea and general weakness. With higher whole body doses (>10 Gy), the intestinal lining is damaged to the point that it cannot perform its functions of intake of water and nutrients, and protecting the body against infection. At whole body doses near 7 Gy, if no medical attention is given, about 50% of the people are expected to die within 60 days of the exposure, due mostly from infections.

If someone receives a whole body dose more than 20 Gy, they will suffer vascular damage of vital blood providing systems for nervous tissue, such as the brain. It is likely at doses this high, 100% of the people will die, from a combination of all the reasons associated with lower doses and the vascular damage.

There a large difference between whole body dose, and doses to only part of the body. Most cases we will consider will be for doses to the whole body.

For more information on Acute radiation doses and its effects, check here

What needs to be remembered is that very few people have ever received doses more than 2 Gy. With the current safety measures in place, it is not expected that anyone will receive greater than 0.05 Gy in one year where these sicknesses are for sudden doses delivered all at once. Radiation risk estimates, therefore, are based on the increased rates of cancer, not on death directly from the radiation.

Non-Ionizing radiation does not cause damage the same way that ionizing radiation does. It tends to cause chemical changes (UV) or heating (Visible light, Microwaves) and other molecular changes (EMF). Further information on EMF that may be of interest.

Roentgen (R)

The Roentgen is a unit used to measure a quantity called exposure. This can only be used to describe an amount of gamma and X-rays, and only in air. One Roentgen is equal depositing to 2.58 x 10-4 coulombs per kg of dry air. It is a measure of the ionizations of the molecules in a mass of air. The main advantage of this unit is that it is easy to measure directly, but it is limited because it is only for deposition in air, and only for gamma and x rays.

RAD (Radiation Absorbed Dose)

The RAD is a unit used to measure a quantity called absorbed dose. This relates to the amount of energy actually absorbed in some material, and is used for any of radiation and any material. One RAD is defined as the absorption of 100 ergs per gram of material. The unit RAD can be used for any of radiation, but it does not describe the biological effects of the different radiations.

Radiation

Radiation is energy in transit in the form of high speed particles and electromagnetic waves. We encounter electromagnetic waves every day. They make up our visible light, radio and television waves, ultra violet (UV), and microwaves with a spectrum of energies. These examples of electromagnetic waves do not cause ionizations of atoms because they do not carry enough energy to separate molecules or remove electrons from atoms.

Ionizing radiation

Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become charged or ionized. Examples are gamma rays and neutrons. Radiation is measured in many ways, and commonly expressed in units of RAD.

Non-ionizing radiation

Non-ionizing radiation is radiation without enough energy to remove tightly bound electrons from their orbits around atoms. Examples are microwaves and visible light.

Radioactive Fallout - General Information

A number of factors, such as weather conditions and the strength of the weapon, affected the distribution of radioactive fallout from nuclear weapons tests. "The earlier, low-yield fission weapons deposited much of their debris in the general area around the test sites, whereas the high-yield thermonuclear weapons tested later produced radioactive fallout on a global scale," according to Appendix B of the National Council on Radiation Protection and Measurements Report 94. "For the tests in Nevada, the yield was only about 0.5 percent of the global total. However, while much of the exposure has been quite uniformly distributed on a hemispheric basis, there is still some interest in the doses delivered locally from testing in Nevada."

Radioactive Fallout - Global and National Effects

The United Nation Scientific Committee on the Effects of Atomic Radiation periodically publishes a report to the General Assembly on the sources, effects, and risks of ionizing radiation. The 1988 report (UNSCEAR 88) summarized conclusions reached in previous UNSCEAR reports regarding radiation doses received from nuclear explosions. "In the first four UNSCEAR Reports (1958-1966), the Committee described in detail the meteorological processes that deplete the stratospheric inventory of radioactive debris. For man, the highest exposure was found to be due to long-lived radioactive material that causes radiation exposures over many years. The dominant radionuclides were strontium-90 (half-life:28 years), cesium-137 (30 years) and carbon-14 (5700 years). Some gamma-emitting radionuclides from tropospheric fallout, e.g., zirconium-95 and ruthenium-106, could also contribute significantly through exposure from the ground deposition."

People in some areas of the United States received external and internal radiation exposure from short-lived radioactive materials for a few days or weeks following the weapons tests until the radioactive materials had decayed to levels indistinguishable from normal background radiation. One short-lived radioactive material of interest for internal exposure was iodine-131. A recently published National Institute of Health (NIH) document described the deposition of radioactive iodine across the United States from nuclear weapons testing.

David V. Becker, M.D.
Professor,
Department of Radiology

The effect of radiation on the thyroid gland

Our current research program is divided into several areas. A major part of the activities has to do with the examination, development and refinement of methods of radioiodine treatement of thyroid cancer and hyperthyroidism. Innovative procedures have been devised that allow therapeutic radioiodine administration to be based upon the delivered radiation dose to thyroid gland and to functioning thyroid cancers. Radioiodine kinetic measurements are made and turnover rates calculated in order to permit estimation of projected tissue and organ delivered radiation dose as well as evaluation of the dose actually received. For thyroid cancer patients, estimations of whole body and bone marrow radiation dose are also made as the limiting factor for large therapeutic administrations of radioiodine. Such information is correlated with the patient's initial response as well as long term outcome.

Other thyroid cancer studies being done collaboratively entail an evaluation of the use of recombinant TSH in the treatment of thyroid cancer in the hopes that this agent will allow the elimination of the extended period of thyroid hormone withdrawal and resultant hypothyroidism currently required to produce the elevated TSH necessary to induce uptake in metastases for treatment.

Radiation effects on the thyroid have been a major interest. Dr. Becker is Chairman of the National Cancer Institute's working group on the effects of fallout on the population around Chernobyl. This invovles a number of epidemiologic studies in collaboration with Byelarussian and Ukrainian scientists to determine the effect of fallout radiation upon children and adults in fallout and control areas along with extensive efforts to reconstruct delivered radiation doses. To date there has been a significant number (over 250) of thyroid cancers detected in young children in Byelarus and an extensive epidemiologic study cosponsored by the National Cancer Institute, the United States Department of Energy, the Nuclear Regulatory Commission and the Ministry of Health of Byelarus is currently underway.

A number of collaborative radionuclide imaging studies are under way with a variety of protocols for evaluation of the usefulness of various monoclonal antibodies labeled with different radionuclides as both diagnostic and therapeutic agents. These are all done collaboratively with various investigators in the Medical center as well as with a variety of commercial pharmaceutical sources of these agents.

Interest continues in attempts to determine the etiology of feline hyperthyroidism, a new disease which is now the most common endocrinologic disorder in cats. Studies to date with various collaborators have concluded that the disorder is not autoimmune in origin as is Graves' hyperthyroidism but analogous to toxic nodular goiter in man. Epidemiologic studies of distribution and demographic factors are under way.

Radiation levels in the fenced, ground zero area are low. On an average the levels are only 10 times greater than the region's natural background radiation. A one-hour visit to the inner fenced area will result in a whole body exposure of one-half to one milliroentgen.

To put this in perspective, a U.S. adult receives an average exposure of 90 milliroentgens every year from natural and medical sources. For instance, the Department of Energy says we receive between 35 and 50 milliroentgens every year from the sun and from 20 to 35 milliroentgens every year from our food. Living in a brick house adds 50 milliroentgens of exposure every year compared to living in a frame house. Finally, flying coast to coast in a jet airliner gives an exposure of between three and five milliroentgens on each trip.

Although radiation levels are low, some feel any extra exposure should be avoided. The decision is yours. It should be noted that small children and pregnant women are potentially more at risk than the rest of the population and are generally considered groups who should only receive exposure in conjunction with medical diagnosis and treatment. Again, the choice is yours.

Typical radiation exposures for Americans Per The National Council on Radiation Protection

On hour at ground zero = 1/2 mrem
Cosmic rays from space = 40 mrem at sea level per year
Radioactive minerals in rocks and soil = 55 mrems per year
Radioactivity from air, water, and food = anywhere from 20 to 400 mrem per year
About 22 mrem per chest X-ray and 900 mrem for whole-mouth dental X- rays
Smoking one pack of cigarettes a day for one year = 40 mrem
Miscellaneous such as watch dials and smoke detectors = 2 mrem per year

For more information, contact the White Sands Missile Range Public Affairs Office at (505) 678-1134/1700.

Doses from various sources

Limits for Exposures Exposure Range
Occupational Dose limit (US - NRC) 50 mSv/year
Occupational Exposure Limits for Minors 5 mSv/year
Occupational Exposure Limits for Fetus 5 mSv
Public dose limits due to licensed activities (NRC) 1 mSv/year
Occupational Limits (eye) 150 mSv/year
Occupational Limits (skin) 500 mSv/year
Occupational Limits (extremities) 500 mSv/year
Source of Exposure
Average Dose to US public from All sources 3.6 mSv/year
Average Dose to US Public From Natural Sources 3.0 mSv/year
Average Dose to US Public From Medical Sources 530 microSv/year
Average dose to US Public from Weapons Fallout < 10 microSv/year
Average Dose to US Public From Nuclear Power < 1 microSv/year
Coal Burning Power Plant 1.65 microSv/year
X-rays from old TV set (1 inch) 5 microSv/hour
Airplane ride (39,000 ft.) 5 microSv/hour
Nuclear Power Plant (normal operation at plant boundary) 6 microSv/year
Natural gas in home 90 microSv/year
Average Natural Background 0.008 mR/hour 0.006-0.015 mR/hour
Average US Cosmic Radiation 270 microSv/year
Average US Terrestrial Radiation 280 microSv/year
Terrestrial background (Atlantic coast) 160 microSv/year
Terrestrial background (Rocky Mountains) 400 microSv/year
Cosmic Radiation (Sea level) 260 microSv/year
Cosmic Radiation (Denver) 500 microSv/year
Background Radiation Total (East, West, Central US) 460 microSv/year 350-750 microSv/year
Background Radiation Total (Colorado Plateau) 900 microSv/year 750-1400 microSv/year
Background Radiation Total (Atlantic and Gulf in US) 230 microSv/year 150-350 microSv/year
Radionuclides in the body (i.e., potassium) 390 microSv/year
Building materials (concrete) 30 microSv/year
Drinking Water 50 microSv/year
Pocket watch (radium dial) 60 microSv/year
Eyeglasses (containing thorium) 60 - 110 microSv/year
Coast to coast Airplane roundtrip 50 microSv
Chest x-ray 80 microSv 50 - 200 microSv
Extemities x-ray 10 microSv
Dental x-ray 100 microSv
Head/neck x-ray 200 microSv
Cervical Spine x-ray 220 microSv
Lumbar spinal x-rays 1.30 mSv
Pelvis x-ray 440 microSv
Hip x-ray 830 microSv
Shoe Fitting Fluroscope (not in use now) 1.70 mSv
Upper GI series 2.45 mSv
Lower GI series 4.05 mSv
Diagnostic thyroid exam (to the thyroid) 0.5 Gy
Diagnostic thyroid exam (to the Whole Body) 0.35 mGy
CT (head and body) 11 mSv
Therapeutic thyroid treatment (dose to the thyroid) 50-100 Gy
Therapeutic thyroid treatment (dose to the whole body) 7 cSv 5-15 cGy
Earliest Onset of Radiation Sickness 0.75 Gy
Onset of hematopoietic syndrome 3 Gy 1 to 8 Gy
Onset of gastrointestinal syndrome 10 Gy 5 - 12 Gy
Onset of cerebrovacular syndrome 100 Gy >500 Gy
Thershold for cataracts (dose to the eye) 2 Gy
Expected 50% death without medical attention 4 Gy 3 to 5 Gy
Doubling dose for genetic effects 1 Gy
Doubling dose for cancer 5 Gy (8% per Sv, natural level at 20%)
Dose for increase cancer risk of 1 in a 1,000 1.250 cSv (8% per Sv)
Consideration of theraputic abortion threshold (dose in utero) 10 cSv
SL1 Reactor Accident highest dose to survivor 27 cSv
Three Mile Island (dose at plant duration of the accident) 0.80 mSv