Biological Effects of Ionizing Radiation (BEIR)

Radiation is the transfer of energy from one body to another. Most of the phenomena we associate with that term, such as nuclear power and X-rays, is ionizing radiation, meaning it can strip electrons away from atoms or molecules. When the cells in your body are exposed to ionizing radiation, they often suffer structural damage and might die as a result. Your cells can repair and replace themselves in cases of minor doses of radiation, but when cells die faster than they can be replaced, you may have a life-threatening exposure.

Effects

• Ionizing radiation may alter cells without affecting their activities, or create minor cell structure damage that gets repaired. Even some damage to chromosomes can be repaired. But when cells are heavily altered and cannot repair themselves, they can adversely affect other cells and tissue, or may reproduce abnormally. This is one of the main causes of cancer.

Acute Dose

• The dosage of radiation you get, measured in "rad," affects how much damage gets done to your cells. Acute doses are doses larger than 10 rad within a few hours or a few days. Radiation sickness occurs when a person is exposed to an acute dose of 100 rad or more. Acute doses of 450 rad result in a 50 percent death rate within 60 days without medical help.

Chronic Dose

• A chronic dose of radiation is one received in small amounts over long periods, something that usually happens to workers exposed to radiation on the job. Because the body can repair minor radiation damage, chronic doses often cause less severe damage. However, the exact effects of chronic doses has a random element, so it's not possible to pinpoint how dangerous these doses are beyond probability functions. In general, the more radiation, the higher the probability of cancer.

Radiation Effects

• The immediate effects of radiation exposure are called somatic effects. Prompt somatic effects are things like hair loss and skin damage that usually occur after acute doses. Delayed somatic effects refer to the effects of chronic doses, such as cancer and cataracts.

Genetic Defects

• Radiation can produce genetic defects, meaning damage in reproductive cells that affect the next generation. Plants and animals tend to be more sensitive to genetic effects than humans. Genetic defects can include stunted growth, mental retardation and early cancer.