Risk Assessment for Chemicals in Drinking Water

A comprehensive reference on state-of-the-art risk assessment methodologies for drinking water Risk Assessment for Chemicals in Drinking Water discusses the major steps and goals in risk assessments and suggests ways to improve the methodologies and accuracy, while consolidating up-to-date information on the current principles and practices in one authoritative reference. After an enlightening overview of risk assessment practices and regulatory guidelines, it: Includes descriptions of the use of variability analysis, exposure analysis, physiologically based pharmacokinetics, and modeling for both cancer and non-cancer endpoints Describes the practices of major organizations, including the U.S. EPA, Health Canada, World Health Organization, and California Office of Environmental Health Hazard Assessment Includes complete chapters on risk assessment for essential nutrients, arsenic, chloroform, and perchlorate Explains how to address susceptible sub-populations, including the elderly and infants and children, in risk assessments Covers the potential of using genomic and proteomic screens Addresses recent advances, emerging issues, and future challenges With contributions and perspectives from leading scientists, this is the definitive resource for health and environmental scientists, toxicologists, risk assessors and managers, regulators, consultants, and other professionals responsible for the safety of drinking water.

Contributors ix Foreword xi Preface xiii 1 Introduction to Drinking Water Risk Assessment 1 Robert A. Howd Development of Drinking Water Regulations 2 The Risk Assessment Process 8 Public Perceptions and the Precautionary Principle 13 References 14 2 Summary of the Development of Federal Drinking Water Regulations and Health-Based Guidelines for Chemical Contaminants 17 Joyce Morrissey Donohue and Wynne Maynor Miller Selecting Candidates for Regulatory Consideration 19 Key Components for Regulatory Development 20 Development of Regulatory Values 28 Nonregulatory Options 30 References 32 3 Interpretation of Toxicologic Data for Drinking Water Risk Assessment 35 Robert A. Howd and Anna M. Fan Animal Toxicity Studies 38 Human Toxicity Studies 47 Conclusions 57 References 57 4 Exposure Source and Multiroute Exposure Considerations for Risk Assessment of Drinking Water Contaminants 67 Kannan Krishnan and Richard Carrier Exposure Source Considerations in Risk Assessment 68 Routes of Exposure and Dose Calculations 72 References 86 5 Toxicokinetics for Drinking Water Risk Assessment 91 John C. Lipscomb Evaluation of Toxicity Data 93 Toxicokinetics: PBPK Modeling 95 Risk Assessment 101 Conclusions 117 References 118 6 Health Risk Assessment of Chemical Mixtures in Drinking Water 123 Richard C. Hertzberg, Glenn E. Rice, Linda K. Teuschler, J. Michael Wright and Jane E. Simmons Drinking Water Mixture Concerns 124 Estimating Exposures to Multiple Chemicals in Drinking Water 130 Toxicological Concepts for Joint Toxicity 139 Chemical Mixtures Risk Assessment Methods 143 New Approaches for Assessing Risk from Exposure to Drinking Water Mixtures 155 Conclusions 162 References 163 7 Protection of Infants Children and Other Sensitive Subpopulations 171 George V. Alexeeff and Melanie A. Marty Factors Influencing Differences in Susceptibility Between Infants and Children and Adults 173 Critical Systems and Periods in Development 185 Age at Exposure and Susceptibility to Carcinogens 189 Drinking Water Standards Developed to Protect Sensitive Subpopulations 190 References 192 8 Risk Assessment for Essential Nutrients 201 Joyce Morrissey Donohue Assessment Approaches 203 Comparison of Guideline Values 206 Risk Assessment Recommendations 210 References 211 9 Risk Assessment for Arsenic in Drinking Water 213 Joseph P. Brown Occurrence and Exposure 214 Metabolism 216 Health Effects 221 Risk Assessment 245 Conclusions 250 References 252 10 Risk Assessment for Chloroform Reconsidered 267 Richard Sedman Carcinogenic Effects 268 Noncancer Toxic Effects 268 Mechanisms of Carcinogenicity 271 Regulation of Cancer Risk 280 Discussion 281 References 283 11 Risk Assessment of a Thyroid Hormone Disruptor: Perchlorate 287 David Ting Background 287 Human Health Risk Assessment 292 Risk Characterization and Conclusions 296 References 298 12 Emerging Contaminants in Drinking Water: A California Perspective 303 Steven A. Book and David P. Spath Emerging Chemicals of the Recent Past 304 Newer Emerging Contaminants 306 Future Emerging Chemicals 306 Conclusions 311 References 312 13 U.S. EPA Drinking Water Field Office Perspectives and Needs for Risk Assessment 315 Bruce A. Macler The Nature of Regulatory Risk Assessments 315 Use of Drinking Water Risk Information in EPA Field Offices 318 Conclusions 322 References 322 14 Risk Assessment: Emerging Issues Recent Advances and Future Challenges 325 Anna M. Fan and Robert A. Howd Emerging Issues 326 Advances in Science Approaches and Methods 332 Conclusions 357 References 359 Index 365