"In the United States and its territories, thousands of abandoned industrial and commercial facilities and hazardous waste disposal sites exist. Some of these sites may have the potential to adversely affect public health. The mission of the Agency for Toxic Substances and Disease Registry (ATSDR) is to serve the public by using the best science, taking responsive public health actions and providing trusted health information to prevent harmful exposures and disease related to toxic substances. The ATSDR public health assessment process serves as a mechanism to help ATSDR sort through the many hazardous waste sites in its jurisdiction and determine when, where, and for whom, public health actions should be taken. Through this process, ATSDR finds out whether people living near or at a hazardous waste site are being exposed to toxic substances, whether that exposure is harmful, and what must be done to stop or reduce any exposure. This manual is a revision of ATSDR's 1992 Public Health Assessment Guidance Manual. The revised manual builds upon the process described in the 1992 manual and draws from the lessons learned through conducting public health assessments for nearly two decades. More detailed guidance on many of the procedures used to identify hazards and needed public health actions is presented in the manual. New information and techniques that reflect advances in science and technology, including tools and resources available to health assessors, are also presented. Advancements in geographical information systems, computational modeling techniques, exposure investigation approaches, and toxicologic knowledge, for example, enable a more sophisticated analysis of environmental data and exposures than was previously possible." - foreword