Acute vs. Chronic Exposure

There are two broad categories of health effects: chronic (long-term) and acute (short-term).

Acute exposure is exposure to a large, single dose of radiation or a series of moderate doses received during a short period of time. Large acute doses can result from accidental or emergency exposures or from specific medical procedures (radiation therapy). For approved medical exposures, the benefit of the procedure may outweigh the risk from the exposure. In most cases, a significant acute exposure to radiation causes both immediate and delayed effects. Delayed biological effects can include cataracts, sterility, cancer, and harmful genetic defects.

Chronic exposure is continuous or intermittent exposure to low doses of radiation over a long period of time. With chronic exposure, there is a delay between the exposure and the observed health effects. These effects can include cancer and other health outcomes such as benign tumors, cataracts, and potentially harmful genetic changes.

Current science suggests there is some cancer risk from any radiation exposure. However, it is nearly impossible to tell whether a particular cancer was caused by low doses of radiation or 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 the risk increases directly with the dose. This method of estimating risk is called the "linear no-threshold" (LNT) model. Age, sex, and factors like tobacco use also affect the risk of cancer from radiation.

To learn more about HAZWOPER visit our HAZWOPER 40 Hour Online Training web page.