When specific forms of cancer, such as leukemia, are considered, the natural incidence rate is lower. become more significant. Thus, small increases in the incidence Several studies have been made to determine whether there is an increased incidence of certain cancers among various groups of veterans who participated in nuclear tests. The following sections briefly summarize these efforts. 8.2 CENTERS FOR DISEASE CONTROL STUDIES. The Centers for Disease Control (CDC) was the first organization to study military participants in the atmospheric nuclear weapons tests from a health point of view. In the latter part of 1976, CDC learned of a veteran who related his acute myelocytic leukemia to radiation exposure he claimed to have received during participation at Shot SMOKY, a 44-kiloton detonation that took place on 31 August 1957 as part of Operation PLUMBBOB. Extensive publicity regarding this case prompted the CDC to initiate a study to determine if there was an excess incidence of leukemia among the nuclear test participants that might be attributable to radiation exposure. Plans were to focus on the military participants at Shot SMOKY. The identification of a SMOKY cohort proved more difficult than expected. The index case was a member of Task Force BIG BANG, an Army unit selected to study how well military personnel who had never witnessed a nuclear explosion would perform various military tasks after such an experience. Because of an “unexpected shift in wind direction, the exercise planned for Task Force BIG BANG had to be postponed. As a result, the unit observed Shot SMOKY from the press area approximately 30 kilometers away. After observing Shot GALILEO, detonated on 2 September 1957, the unit conducted its exercise in an area contaminated by 2-day-old SMOKY fallout in addition to fallout from at least three previous PLUMBBOB shots. conjunction with Shot SMOKY. Another military maneuver was conducted in Task Force WARRIOR, a reinforced infantry company from the lst Battle Group, 12th Infantry, 4th Infantry Division, performed exercises upwind of the SMOKY ground zero shortly after the shot. The area was essentially free of SMOKY fallout but was contaminated by fallout from previous PLUMBBOB shots. 181