The Safe Drinking Water Act of 1974 (PL93-523) required the Administrator of the Environmental Protection Agency to arrange for a study that would serve as a scientific basis for revising the primary drinking-water regulations that were promulgated under the Act. The Study was conducted by the Safe Drinking Water Committee of the National Research Council. A thorough study of the scientific literature was undertaken in order to assess the implications for human health of the constituents of drinking water in the United States. Assessment of the health benefits and the economic or technological feasibility of achieving a given level of contaminant control was outside the scope of the study, although the beneficial effects of some constituents of drinking water were considered. The risk to man of contaminants ingested in drinking water was evaluated on the basis of both epidemiological studies and studies of toxicity in laboratory animals. The theoretical and experimental bases for extrapolating estimations of risk to low levels of dose were reviewed, and some principles to guide the conduct of this and future studies were defined. Five classes of contaminants were examined: Microorganisms, Particulate Matter, Inorganic Solutes, Organic Solutes, and Radionuclides.

Contents

• Preface
• Historical Note
• I. Approach to the Study
  • Introduction
  • Water Consumption
  • Risk and Safety
  • Microbiological Contaminants
  • Particulate Contaminants
  • Inorganic Solutes
  • Organic Solutes
  • Radioactive Contaminants
  • Susceptible Subgroups And Other Considerations
  • References
• II. Chemical Contaminants: Safety And Risk Assessment
  • Effects on Health
  • Irreversible Toxicity
  • Thresholds
  • High-Dose To Low-Dose Extrapolation
  • Interactions
  • Summary—Chemical Contaminants: Safety and Risk Assessment
  • Research Recommendations
  • References
• III. Microbiology of Drinking Water
  • Epidemiology
  • Bacteria
  • Viruses
  • Pathogenic Protozoa and Helminths
  • Summary—Microbiology of Drinking Water
  • References
• IV. Solid Particles in Suspension
  • Introduction
  • Clay Particles and Their Interactions
  • Asbestos: Nomenclature, Occurrence and Redistribution in Water
  • Asbestos Fiber Sampling and Anaylsis
  • Biological Effects of Asbestos Minerals
  • Organic Particulate in Water
  • Microorganisms and Suspended Particles in Water
  • Particulate Removal and Turbidity
  • Summary—Solid Particles in Suspension
  • References
• V. Inorganic Solutes
  • Trace Metals
  • Other Inorganic Constituents
  • Water Hardness And Health
  • References For Trace Metals
  • References for Arsenic and Selenium
  • References for Fluoride, Sodium, Nitrate, and Sulfate
  • References For Water Hardness and Health
• VI. Organic Solutes
  • Introduction
  • Pesticides: Herbicides
  • Pesticides: Insecticides
  • Pesticides: Fungicides
  • Pesticides: Fumigant
  • Other Organic Constituents
  • Summary—Organic Solutes
  • Conclusions
  • Research Recommendations
  • Definitions
  • References—Other Organic Constituents
• VII. Radioactivity In Drinking Water
  • Background Radiation
  • Abundance Of Radionuclides In Water
  • Radiation Dose Calculations
  • Isotopes of Alkaline Earth Elements
  • Doses From Water of Specified Composition
  • Estimation Of Risk
  • Risks from Radioactive Drinking Water
  • Summary—Radioactivity In Drinking Water
  • Conclusions
  • Future Needs
  • References
• Appendix A Legislation and Terms of Reference of the Study The Safe Drinking Water Act of 1974 and the NAS Study (Public Law 93-523)
• Appendix B List of Participants
• Appendix C Executive Summary

At the request of and funded by the U.S. Enviornmental Protection Agency Contract no. 68-01-3139

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the Councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the Committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, The National Academy of Engineering and the Institute of Medicine.