Water Contamination and Health

Integration of Exposure Assessment, Toxicology, and Risk Assessment

Rhoda G.M. Wang

• Publisher: CRC Press
• Year: 2020
• Print ISBN: 9780824789220
• eBook ISBN: 9781000148152
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

This volume examines every potential means of exposure to water contaminants, provides in-depth discussions on toxicology, and explains up-to-date techniques for evaluating human health risk. It develops a methodology for assessing the cumulative absorbed dose of contaminants through all routes of exposure, including ingestion, inhalation and dermal. Federal and state efforts to monitor and treat water are examined.

WATER CONTAMINANTS: MONITORING, TREATMENT, AND HEALTH IMPACT

1
A Retrospective on Drinking Water

Charles O. Abernathy

U.S. Environmental Protection Agency, Washington, D.C.

I. Introduction

Water is essential for all organisms; it comprises 60–95% of the weight of living cells (1), and losses through various metabolic and excretory processes must be balanced by an adequate intake. However, water may contain substances, whether natural or anthropogenic, that can affect the quality and existence of life.

It is important to distinguish between pure water and safe water. Pure water may be defined as water that is free of extraneous substances (2), whether harmless or not, and, from a practical standpoint, impossible to produce. On the other hand, safe water is water that is not likely to cause undesirable or adverse effects (2), although it may contain various contaminants. The crux is embodied in the definition of “safe.” In the regulatory sense, safe means that, although the “purified” water may contain some contaminants, the risks imposed by those contaminants are of an acceptable nature. For example, chlorination is used extensively to disinfect water in the United States. This process introduces trihalomethanes (THM) into the finished product, however, and THM pose potential health risks (3). As expected, differences of opinion exist about the “safety” or “acceptable nature” of contaminants in drinking and surface water, and there is considerable public awareness of this problem, as evidenced by recent articles in the New York Times (4), Washington Post (5), and U.S. News and World Report (6).

It is also informative to consider the business aspects of water purification. The production of potable water in the United States is a very large industry. Moeller (7) estimates that it costs $5 billion/year to operate the 60,000 water treatment facilities and that these plants have required a capital investment of approximately $250 billion. These facilities produce 40–50 billion gallons/day (approximately 180 gallons per capita). Over one-half is used in the home, and nearly one-third is consumed by industry. The rest is used by public services or lost in the distribution process (Figure 1). In 1985, approximately 60% of the 36,500 million gallons of water withdrawn per day in the United States came from surface water; the remainder was from groundwater sources (8).

Figure 1 Percentage use by various sectors of municipally treated water in the United States in 1985. (From Reference 8.)

The objectives of this chapter are to provide a brief history of water use and purification, to give a few examples of the types of adverse effects associated with water contaminants, to mention some risk assessment methods, and briefly to consider drinking water regulations. Details of risk assessment methodology for specific end points or for various exposure routes are covered in subsequent chapters.

II. History

Since many writings have been lost, our knowledge of the early history of drinking water treatment is stochastic in nature (Table 1). The following is a brief overview; those wishing a more detailed history are referred to Baker (9).

Table 1 Important Dates in the History of Drinking Water Treatment

Date	Comment
2000 BCE, India	Exposure to sunlight, boiling, and filtration through charcoal or sand
1500 to 1300 BCE, Egypt	Use of wick siphons
600 BCE, Persia	Cyrus the Great took boiled water for his troops
400 to 200 BCE, Greece	Boiled and filtered water through cloth and porous vessels
97 CE, Rome	Frontius was first water engineer
Eighth century	Geber used distillation to purify water
Eleventh century	Avicenna recommended boiling to purify water while traveling
Fifteenth century	Venice had filter-cisterns
1675	Walcott given the first water purification patent (distillation)
1804	Gibb used filtration to provide purified water to Paisley, Scotland
1806	Happey...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Preface
• Table of Contents
• Contributors
• Water Contaminants: Monitoring, Treatment, and Health Impact
• Exposure Assessment of Water Contaminants: Specific Dosimetry on Radon and Chloroform
• Methodology Development in Exposure Assessment and Dose Estimates
• Human Health Risk Assessment and Water Contaminants
• Epidemiological Evaluation of Water Contaminants and Toxicological End Points
• Index