The effects of radiation on our health
The mission of EPA’s Radiation Protection Program is to protect human health and the environment from unnecessary exposure to radiation. This page provides basic information about the health effects of radiation. EPA uses current scientific understanding of the health effects of radiation exposure to create protective standards and guidance.
Ionizing radiation has sufficient energy to cause chemical changes in cells and damage them. Some cells may die or become abnormal, either temporarily or permanently. By damaging the genetic material (DNA) contained in the body’s cells, radiation can cause cancer. Fortunately, our bodies are extremely efficient at repairing cell damage. The extent of the damage to the cells depends upon the amount and duration of the exposure, as well as the organs exposed.
A very large amount of radiation exposure (acute exposure), can cause sickness or even death within hours or days.
In general, the amount and duration of radiation exposure affects the severity or type of health effect. There are two broad categories of health effects: chronic (long-term) and acute (short-term).
Chronic exposure is continuous or intermittent exposure to radiation over a long period of time. With chronic exposure, there is a delay between the exposure and the observed health effect. These effects can include cancer and other health outcomes such as benign tumors, cataracts, and potentially harmful genetic changes.
Low Levels of Radiation Exposure
Current science suggests there is some cancer riskriskThe probability of injury, disease or death from exposure to a hazard. Radiation risk may refer to all excess cancers caused by radiation exposure (incidence risk ) or only excess fatal cancers (mortality risk). Risk may be expressed as a percent, a fraction, or a decimal value. For example, a 1% excess risk of cancer incidence is the same as a 1 in a hundred (1/100) risk or a risk of 0.01. from any exposure to radiation. However, it is very hard to tell whether a particular cancer was caused by very low doses of radiation or by something else. While experts disagree over the exact definition and effects of “low dose,” U.S. radiation protection standards are based on the premise that any radiation dose carries some risk, and that risk increases directly with dose.
This method of estimating risk is called the “linear no-threshold model (LNT LNT) The assumption that the risk of cancer increases linearly as radiation dose increases. This means, for example, that doubling the dose doubles the risk and that even a small dose could result in a correspondingly small risk. Using current science, it is impossible to know what the actual risks are at very small doses.).” The risk of cancer from radiation also depends on age, sex, and factors such as tobacco use.
Effects of Radiation on the Human Body