Cancer from radiation

The incidence of stochastic effects can only be treated in a probabilistic manner. Consider cancer first. In the United States the normal incidence of cancer (not necessarily fatal) in the adult population is 25 percent. The estimate for radiation-induced cancer is (1.5-4.5) x 10 per manSv [(I.5-4.5) x lO " per manrem]. To understand this estimate better, consider an example. In a group of 10,000 adult Americans, about 2500 cases of cancer will be detected (not necessarily fatal). If this group of 10,000 persons receives 0.01 Sv (1 rem) of radiation collectively, the estimated number of cancers due to this radiation dose is 1.5-4.5. Therefore, the total number of cancers expected to be detected will be between 2501.5 and 2504.5. The incidence of fatal cancer in the United States is 16.4 percent. The risk of deadly cancer from radiation is estimated to be (0.7-2.26) X 10 per manSv [(0.7-2.26) X lO " per manrem]. 

Health effects other than cancer from radiation exposure are not likely when the dose to the unborn baby is very low. 

The accident at the Three Mile Island (TMI) plant in Pennsylvania in 1979 led to many safety and environmental improvements (4—6). No harm from radiation resulted to TMI workers, to the pubHc, or to the environment (7,8), although the accident caused the loss of a 2 x 10 investment. The accident at the Chernobyl plant in the Ukraine in 1986, on the other hand, caused the deaths of 31 workers from high doses of radiation, increased the chance of cancer later in life for thousands of people, and led to radioactive contamination of large areas. This latter accident was unique to Soviet-sponsored nuclear power. The Soviet-designed Chemobyl-type reactors did not have the intrinsic protection against a mnaway power excursion that is requited in the test of the world, not was there a containment building (9—11). 

Around the beginning of this century, cancer and illness was associated with excessive use of X-rays. Watch dial painters got mouth cancer from radium in the paint. It soon was realized that radiation has health effects. The measures of energy deposition concepts introduced... 

Archer, V.J., Oncology Overview, Selected Abstracts on Risk of Cancer from Exposure to Low Level Ionizing Radiation, PB84-922906, International Cancer Research Data Bank Program, National Cancer Institute, U.S. Department of Health and Human Services, Salt Lake City, Utah, (August 1984) ... 

Fig- 13. Relationship between incidence of lung cancer and radiation dose to lung from inhaled beta-gamma emitting radionuclides in experimental animals (Bair et al., 1974). 

After the nuclear explosion at Chernobyl in 1986, Anatoly and other professors and physicians created a foundation, For the Children of Chernobyl. Their goal was to send children abroad for the summers for a reprieve from radiation exposure which impairs their immune systems and has resulted in unprecedented levels of thyroid cancer in children and adults. The first host country to respond to their call for help was India. Before long, the foundation was sending 30,000 children every summer to host families and programs in many countries, including Germany, England, Japan, the U.S., Spain, Italy and France. 

Ultraviolet radiation Invisible rays that are part of the energy that comes from the sun. UV radiation can damage the skin and cause melanoma and other types of skin cancer. UV radiation that reaches the earth s surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of UV radiation. [NIH]... 

Radiation therapy contributes to the cure of 23% of all cancer patients [alone (12%) or in combination with surgery (6%) or chemotherapy/immunotherapy (5%)]. Thus about half of the cancer patients who are cured benefit from radiation therapy at least for part of their treatment this proportion illustrates the important role of radiation therapy in cancer management. 

Radioisotopes are also used in radiation therapy to treat cancer. The goal in radiation therapy is to kill malignant cells, while protecting healthy tissue from radiation effects. Radioisotopes such as yttrium-90, a beta emitter, may be placed directly in the tumor. Alternatively, the diseased tissue may be subjected to beams of gamma radiation. Cobalt-60 used in radiation therapy is prepared by a series of transmutations ... 

My research eventually convinced me (and a great many others) that radon in homes is very much less harmful than the widely publicized estimates that were based on extrapolating from the number of excess cancers seen in uranium miners who had very high radon exposures. Those estimates were (and are) based on the assumption that the cancer risk from radiation is proportional to the dose, the so-called linear-no threshold theory (LNT). 

In 1986, a meltdown occurred at this nuclear power plant in Chernobyl, Ukraine. Because there was no containment building, large amounts of radioactive material were released into the environment. Three people died outright, and dozens more died from radiation sickness within a few weeks. Thousands who were exposed to high levels of radiation stand an increased risk of cancer. Today, 10,000 square kilometers of land remain contaminated with high levels of radiation. 

ICRP (1991) has acknowledged that the modifications of the probability of a fatal response are necessarily judgmental and somewhat arbitrary, particularly the weight to be given to nonfatal cancers relative to fatal responses in assessing total detriment. Nonetheless, the following approach to assessing total detriment from radiation exposure for purposes of radiation protection was developed. 

SC 64-22 Design of Effective Effluent and Environmental Monitoring Programs SC 64-23 Cesium in the Environment SC 72 Radiation Protection in Mammography SC 85 Risk of Lung Cancer from Radon SC 87 Radioactive and Mixed Waste... 

Stather, J.W., Wrixon, A.D. Simmonds, J.R. (1984) The risks of leukaemia and other cancers in Seascale from radiation exposure. National Radiological Protection Board Report R-171, HMSO, London. 

Under LNT, the risks of developing cancer from occupational radiation exposure are about the same as the risks of any other occupational illness or injury—about 1 in 10,000. By comparison, the background cancer death rate is about 1,600 in 10,000 (16%), and about 1 person in 7,000 dies each year in traffic accidents (more than 40,000 in the year 2000). For the vast majority of radiation workers, the drive to work is far more hazardous than their occupational radiation exposure, even using the LNT model. 

Ozone exists naturally in the upper atmosphere of the earth. The ozone layer is especially important because it absorbs ultraviolet light and thus acts as a screen to prevent this radiation, which can cause skin cancer, from penetrating to the earth s surface. When an ozone molecule absorbs this energy, it splits into an oxygen molecule and an oxygen atom ... 

No evidence linking oral exposure to uranium to human cancer has been found. Although natural, depleted, or enriched uranium and uranium compounds have not been evaluated in rodent cancer bioassays by any route by the NTP (BEIR 1980, 1988, 1990 Hahn 1989 Sanders 1986 UNSCEAR 1982,1986,1988), there is potential for the carcinogenicity of uranium, since it emits primarily alpha radiation. Nevertheless, no evidence has been found to associate human exposure to uranium compounds and carcinogenesis. The National Academy of Sciences has determined that bone sarcoma is the most likely cancer from oral exposure to uranium however, their report noted that this cancer has not been observed in exposed humans and concluded that exposure to natural uranium may have no measurable effect (BEIR IV). 

The mineral structure of bone also incorporates metals and metalloids that resemble calcium, including lead and a variety of elements some isotopes of which emit alpha radiation, including strontium-90, uranium-235, and plutonium-239. Bone acts as an important storage depot for these elements and the high local concentration in bone is responsible for the high risk of bone marrow effects and of bone cancers from a-emitting radionuclides. 

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