Book excerpt: Introduction to Chemical Exposure and Risk Assessment focuses on the principles involved in assessing the risks from chemical exposure. These principles include the perception of risk, an understanding of how numbers are handled, and how chemicals affect health. The book briefly describes the major sinks, such as water and air, where chemicals are introduced. This is followed by a discussion on how concentrations are estimated and risk assessments are made. A discussion of risk benefit analysis and a presentation of several case studies using the principles for assessing risks are also included.