The new rules apply to those veterans who participated in "radiation-risk activities" while on active duty, during active duty for training or inactive duty training as a member of a reserve component.

The definition of radiation-risk activities has also been expanded to include service at Amchitka Island, Alaska, prior to January 1, 1974, if a veteran was exposed while performing duties related to certain underground nuclear tests. The new definition also includes service at gaseous diffusion plants located in Paducah, Ky., Portsmouth, Ohio and an area known as K25 at Oak Ridge, Tenn. The previous definition was limited to service members who took part in the occupation of Hiroshima or Nagasaki or onsite at atmospheric nuclear weapons tests, or American POWs interred in Japan during World War II. People in these groups are frequently called "atomic veterans."

In 1988, Congress established a presumption of service connection for 13 cancers in veterans exposed to "ionizing radiation," with later changes bringing the number to 16.

Under current statutes, the following diseases are presumed to be service connected if the veteran participated in a radiation-risk activity: leukemia (other than chronic lymphocytic leukemia), cancer of the thyroid, breast, pharynx, esophagus, stomach, small intestine, pancreas, gall bladder, bile ducts, salivary gland, or urinary tract, multiple myeloma, lymphomas (except Hodgkin's disease), primary cancer of the liver (except if cirrhosis or hepatitis B is indicated) or bronchiolo-alveolar carcinoma.

VA's changes ensure equity between veterans and federal civilians who may be entitled to compensation for these cancers caused by radiation under comparable federal laws such as the Radiation Exposure Compensation Act (RECA) of 1990, as amended in 2000.