ROBERT A. HOWD is Chief of the Water Toxicology Section in the Office of Environmental Health Hazard Assessment of the California EPA, supervising the production of California Public Health Goals for chemicals in drinking water. Dr. Howd has authored or coauthored over fifty formal scientific publications and numerous government reports. ANNA M. FAN is Chief of the Pesticide and Environmental Toxicology Branch, Office of Environmental Health Hazard Assessment, California EPA. Dr. Fan has served on the U.S. EPA Science Advisory Board, Drinking Water Committee; the U.S. EPA Endocrine Disruptors Screening and Testing Advisory Committee; and other national advisory committees. She is an editor of the Journal of Environmental Science and Health, Part C: Environmental Carcinogenesis and Ecotoxicology Reviews.

Currently accepted for use as landscaping, it becomes clear that recycled water will be injected into drinking water chain. That use makes the material in the book more important. (Journal of Hazardous Materials, January 31, 2008) "Provides a comprehensive reference on state-of-the-art risk assessment methodologies for drinking water." (International Food Information Service, 2007)

• Contributors ixForeword xiPreface xiii1 Introduction to Drinking Water Risk Assessment 1Robert A. HowdDevelopment of Drinking Water Regulations 2The Risk Assessment Process 8Public Perceptions and the Precautionary Principle 13References 142 Summary of the Development of Federal Drinking Water Regulations and Health-Based Guidelines for Chemical Contaminants 17Joyce Morrissey Donohue and Wynne Maynor MillerSelecting Candidates for Regulatory Consideration 19Key Components for Regulatory Development 20Development of Regulatory Values 28Nonregulatory Options 30References 323 Interpretation of Toxicologic Data for Drinking Water Risk Assessment 35Robert A. Howd and Anna M. FanAnimal Toxicity Studies 38Human Toxicity Studies 47Conclusions 57References 574 Exposure Source and Multiroute Exposure Considerations for Risk Assessment of Drinking Water Contaminants 67Kannan Krishnan and Richard CarrierExposure Source Considerations in Risk Assessment 68Routes of Exposure and Dose Calculations 72References 865 Toxicokinetics for Drinking Water Risk Assessment 91John C. LipscombEvaluation of Toxicity Data 93Toxicokinetics: PBPK Modeling 95Risk Assessment 101Conclusions 117References 1186 Health Risk Assessment of Chemical Mixtures in Drinking Water 123Richard C. Hertzberg, Glenn E. Rice, Linda K. Teuschler, J. Michael Wright and Jane E. SimmonsDrinking Water Mixture Concerns 124Estimating Exposures to Multiple Chemicals in Drinking Water 130Toxicological Concepts for Joint Toxicity 139Chemical Mixtures Risk Assessment Methods 143New Approaches for Assessing Risk from Exposure to Drinking Water Mixtures 155Conclusions 162References 1637 Protection of Infants Children and Other Sensitive Subpopulations 171George V. Alexeeff and Melanie A. MartyFactors Influencing Differences in Susceptibility Between Infants and Children and Adults 173Critical Systems and Periods in Development 185Age at Exposure and Susceptibility to Carcinogens 189Drinking Water Standards Developed to Protect Sensitive Subpopulations 190References 1928 Risk Assessment for Essential Nutrients 201Joyce Morrissey DonohueAssessment Approaches 203Comparison of Guideline Values 206Risk Assessment Recommendations 210References 2119 Risk Assessment for Arsenic in Drinking Water 213Joseph P. BrownOccurrence and Exposure 214Metabolism 216Health Effects 221Risk Assessment 245Conclusions 250References 25210 Risk Assessment for Chloroform Reconsidered 267Richard SedmanCarcinogenic Effects 268Noncancer Toxic Effects 268Mechanisms of Carcinogenicity 271Regulation of Cancer Risk 280Discussion 281References 28311 Risk Assessment of a Thyroid Hormone Disruptor: Perchlorate 287David TingBackground 287Human Health Risk Assessment 292Risk Characterization and Conclusions 296References 29812 Emerging Contaminants in Drinking Water: A California Perspective 303Steven A. Book and David P. SpathEmerging Chemicals of the Recent Past 304Newer Emerging Contaminants 306Future Emerging Chemicals 306Conclusions 311References 31213 U.S. EPA Drinking Water Field Office Perspectives and Needs for Risk Assessment 315Bruce A. MaclerThe Nature of Regulatory Risk Assessments 315Use of Drinking Water Risk Information in EPA Field Offices 318Conclusions 322References 32214 Risk Assessment: Emerging Issues Recent Advances and Future Challenges 325Anna M. Fan and Robert A. HowdEmerging Issues 326Advances in Science Approaches and Methods 332Conclusions 357References 359Index 365