4. If new staff need to gain experience in conducting cluster investigations, training might be ajustification for investigating these cases. More commonly, cancer clusters generate publicconcern, which, in turn, often results in political pressure. Perhaps one of the affected personsis a member of the mayor’s family. A health department needs to be responsive to suchconcerns, and should investigate enough to address the concerns with facts. Finally, legalconcerns may prompt an investigation, especially if a particular site (manufacturing plant,houses built on an old dump site, etc.) is accused of causing the cancers.