Radiation exposure causing

Thousands of studies of radiation and its risks have been conducted. Yet there is no conclusive evidence that low levels of radiation exposure cause either cancer or birth defects. The nuclear iadustry operates oa the coaservative ALARA approval, assumiag that any exposure iavolves some risk. 

There is no evidence to date of any increase in the incidence of any malignancies other than thyroid carcinoma or of any hereditary effects attributable to radiation exposure caused by the Chernobyl accident. This conclusion, surprising for some observers, is in accordance with the relatively small whole body doses incurred by the populations exposed to the radioactive material released. The lifetime doses expected to be incurred by these populations are also small. In fact, the risks of radiation-induced malignancies and hereditary effects are extremely small at low radiation doses and, as the normal incidences of these effects in people are relatively high, it is not surprising that no effects could be detected. 

Gastrointestinal (Gl) syndrome can result after acute exposure to 10 Gy or less. The radiation exposure causes destruction of the epithelial lining of the GI tract, and Gl syndrome is characterized by lethargy, diarrhea, dehydration, degeneration of bowel epithelium, and death in 10-14 days (NCRP, 1989). The other syndrome associated with acute exposure is hematopoietic syndrome, which may present days to weeks after total body radiation exposure ranging from 2.5 to 5 Gy. The hematopoietic syndrome is characterized by granulocytopenia, thrombocytopenia, hemorrhage, infection, and electrolyte imbalance. Even lower doses (1-5 Gy) can cause hematopoietic syndrome, which results in what... 

The Chernobyl nuclear accident in 1986 resulted in the largest radiation exposure in recent history. The radioactive materials released contained high levels of radioactive iodine (particularly, with a half-life of 8 days), an element that accumulates in the thyroid gland as a component of thyroid hormone. Following the explosion, people were exposed to deadly radioactive materials estimated to be 100 times greater than that associated with the detonation of the atomic bomb over Hiroshima. In Belarus, thyroid cancer in children under 18 increased from an incidence of 0.03-0.05 cases per 100,000 (1986-1988 data) to more than 10 times that level (5-8 cases per 100,000) in the period 1993-2002. Increases in thyroid cancer also were noted in Ukraine, with rates going from 0.02 per 100,000 (1986-1988 data) to 5-10 times that level (1-2.2 per 100,000) over the period from 1993-2002 (Reiners et al., 2013). There is little doubt that Chernobyl radiation exposure caused thyroid cancer among children in the affected area. 

Most of the data on radiation health effects have come from medical monitoring of Japanese atomic bomb survivors. For survivors who received radiation exposures up to 0.10 Sv, the iacidence of cancer is no greater than ia the geaeral populatioa of Japanese citizens. For the approximately 1000 survivors who received the highest radiation doses, ie, >2 Sv, there have been 162 cases of cancer. About 70 cases would have been expected ia that populatioa from aatural causes. Of the approximately 76,000 survivors, as of 1995 there have beea a total of about 6,000 cases of cancer, only about 340 more cases than would be expected ia a group of 76,000 Japanese citizens who received only background radiation exposure (59). 

Radiation Dosimetry. Radioactive materials cause damage to tissue by the deposition of energy via their radioactive emissions. Thus, when they are internally deposited, all emissions are important. When external, only those emissions that are capable of penetrating the outer layer of skin pose an exposure threat. The biological effects of radiation exposure and dose are generally credited to the formation of free radicals in tissue as a result of the ionization produced (17). 

The nuclear explosions that devastated Hiroshima and Nagasaki killed 100,000 to 200,000 people instantaneously. Probably an equal number died later, victims of the radiation released in those explosions. Millions of people were exposed to the radioactivity released by the accident at the Chernobyl nuclear power plant. The full health effects of that accident may never be known, but 31 people died of radiation sickness within a few weeks of the accident, and more than 2000 people have developed thyroid cancer through exposure to radioactive iodine released in the accident. Even low levels of radiation can cause health problems. For this reason, workers in facilities that use radioisotopes monitor their exposure to radiation continually, and they must be rotated to other duties if their total exposure exceeds prescribed levels. 

Exposure to UVB radiation has a profound effect on the corneal endothelium. Following exposure to UV radiation, the cornea swells, the extent and duration of which is directly related to the magnitude and duration of the exposure (Riley etal., 1987). At very high in vivo exposures, these authors reported a decrease in ascorbate concentration and an increase in protein content, which they suggested resulted from a breakdown of the blood-aqueous barrier. They concluded that UV radiation may cause or promote changes in the endothelium associated with ageing. 

It has been noted previously that radiation exposure of a positive resist causes chain scission in its structure. As a result, its molecular weight decreases. According to Ku and Scala (3), the decrease in the number average molecular weight resulting from such irradiation is given by the expression ... 

Mancuso, T.F., Stewart, A., and Kneale, G., Radiation exposures of Hanford workers dying from cancer and other causes, Health Physics, 33, 369-385, 1977. 

The hazards of technetium are the same as for all radioactive elements. Excessive exposure to radiation can cause many kinds of tissue damage—from sunburn to radiation poisoning to death. 

Some radiation is helpful and necessary, as in the case of sunlight, which allows us to see the world. The nonionizing radiation of the sun warms us, but too much ultraviolet radiation can cause sunburn or cancer depending on our individual sensitivity. There is clearly a dose - response relationship between exposure and effect, with individual sensitivity playing an important role. Microwave and radiofrequency radiation are incredibly useful in heating and transmitting information. 

Exposure to radiation may cause cancer. Studies on experimental animals show it induces tumors. 

Exposure to Cf radiation can cause cancer. Similar to other radioactive elements, californium can accumulate in the skeletal system, causing damage to the red cell forming mechanism. 

As with other radioactive substances, exposure to its ionizing radiation can cause cancer. When ingested it tends to accumulate in the liver, kidney, and spleen causing radiation damage from the alpha particles. All operations and handling must be carried out in leak-proof boxes by mechanical means behind thick neutron shields. 

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