The effects of radiation on the human body vary, depending on the radiation dosage and whether exposure is slow and protracted or significant and instantaneous. Radiation affects cells in the human body that actively divide (e.g., hair, intestine, bone marrow, reproductive organs). The most frequent kind of radiation exposure is exposure to small body areas. Damage in localized tissue and blood vessels in the exposed areas can disturb organ functioning. Higher doses cause gangrene or death of localized tissue.
A large, rapid radiation dose causes cell death, and effects are immediately apparent – within hours, days, or weeks. With prolonged exposure, cells can do some repair over the exposure period. Protracted exposure is generally better tolerated, even when the total dose is high. (It is impossible to measure how much radiation a person has been exposed to over an extended period). Radiation doses low enough to avoid cell damage can still induce cellular changes that may be clinically detected sometime in the future and could be passed on through defective genes. With radiation exposure due to internally deposited radiation, effects are delayed, and degeneration or destruction of the irradiated tissue may not be as severe. Cancer initiation is possible, depending on the affected organ and the nature of the radioactive element (its half-life, radiation characteristics, and biochemical behavior).
High whole-body doses of radiation produce a characteristic pattern of injury.
Acute Radiation Syndrome (See Extremely High Doses and High Doses above): Acute radiation syndrome is a condition brought on by exposure to radiation, whether in a single high dose or over time (although it is impossible to determine how much radiation a person has absorbed over a long period). In the case of a high dose over a short period, symptoms will be more noticeable immediately. Acute radiation syndrome, which includes the most severe symptoms of radiation exposure, necessitates prompt medical intervention. Survival without medical care is unlikely.
Initially, patients feel exhaustion, loss of appetite, nausea, vomiting, and diarrhea for a day or two. If the radiation dose is exceptionally high, there may also be symptoms such as fever and respiratory issues. Symptoms disappear for several days or weeks, and the sickness becomes severe.
Radiation suppresses the formation of blood cells, leading to bleeding and anemia as the number of red blood cells declines and the inability of wounds to heal as blood clotting components are depleted. A lower white blood cell count hampers the body’s immune system, leading to more illnesses.
Additionally, electrolytes, fluids, and the intestinal lining may be lost. In more extreme situations, brain fluid buildup can result in central nervous system syndrome, which presents with nausea, vomiting, and diarrhea symptoms.
Hair loss, lens clouding in the eyes, and temporary male sterility are possible further symptoms. Damage to hair-root cells results in thinner, more fragile hairs that eventually fall out and cause hair loss.
Late Effects: Many organs, especially the bone marrow, kidneys, lungs, and eye lens, have decreased function and degenerative changes due to radiation exposure that manifest later on. These changes are mainly brought on by blood vessel damage.
A significantly higher incidence of leukemia, thyroid, lung, and breast cancers (relative to the average number among those exposed to doses of less than 100 rads) is the most severe late impact of radiation exposure.
Subsequent to cataracts and hair loss, radiation exposure can increase the risk of infertility and congenital disorders. Those who receive fewer radiation doses are also more likely to develop leukemia, lung cancer, radiation-induced anemia, and bone cancer. The method of radiation exposure affects the type of cancer. For instance, radioactive dust exposure among uranium mine employees was associated with a high risk of lung cancer. Watch painters lick radioactive paintbrushes in the early 20th century, increasing bone cancer risk and radiation-induced anemia. The incidence of leukemia among Hiroshima survivors exposed to 100 rads or more is very high.
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