In a Phoenix suburb, eleven children contract leukemia. On a Connecticut street with nine homes, five children develop brain tumors. In this program from the Medical Detectives series, medical investigators search for answers as to why these neighborhoods are "cancer clusters." In Phoenix, epidemiologists examine benzene gas emissions from a local petroleum processing plant, the proximity of electric power lines, and farm insecticide runoff as possible causes for the outbreak. In Connecticut, a cellular biologist and an environmental epidemiologist examine the possibility that electromagnetic radiation from a local substation may be causing the cancers there. All of the studies prove inconclusive. This program accurately portrays the difficulties and frustrations involved in determining the environmental causes of cancer clusters. (24 minutes)