Are current U.S. drinking water standards sufficient?

Viewpoint: Yes, while not perfect, current U.S. drinking water standards are sufficient, and new government regulations continue to improve these standards.

Viewpoint: No, current U.S. drinking water standards are not sufficient and must be improved to ensure public health.

Every day the average U.S. citizen uses 100 gal (380 l) of water; every year, the average household uses 100,000 gal (380,000 l) of water; and every day Americans drink more than one billion glasses of water. All of this water comes from many sources and, because different treatment methods are used, the quality of drinking water varies throughout the country.

At the beginning of the twenty-first century, water experts consider U.S. drinking water to be generally safe. But during the nineteenth century, diseases like cholera and typhoid could be traced to the U.S. water supply, so in 1914 the U.S. Public Health Service set standards for drinking water and has continued improving on antibacteriological water technologies ever since.

Most people agree that U.S. public drinking water supplies are probably among the world's most reliable, but not everyone thinks current U.S. drinking water standards are sufficient. Those who think drinking water standards are sufficient cite statistics offered by the National Environmental Education and Training Foundation: 91% of U.S. public water systems reported no violations of health-based drinking water standards in 1998-1999, and almost all of the reported violations in that period involved reporting and monitoring requirements rather than water-standards health violations. They also cite the National Centers for Disease Control and Prevention, which said the proportion of reported diseases linked to problems at public water treatment systems declined from 73% in 1989-1990 to 30% in 1995-1996. This decline was a direct result of improved water treatment and water treatment technology.

The Environmental Protection Agency (EPA) Office of Ground Water and Drinking Water administers the 1974 Safe Drinking Water Act (SDWA), which made drastic advances in enforcing voluntary Public Health Service standards by requiring the EPA to set national uniform water standards for drinking water contaminants.

The EPA drinking water standards are called maximum contaminant levels (MCLs) and apply to private and public systems that serve 25 people or 15 homes or businesses for at least 60 days per year. MCLs are established to protect the public health based on known or anticipated health problems, the ability of various technologies to remove the contaminant, their effectiveness, and cost of treatment. In 1986 Congress strengthened the SDWA by enacting amendments that increased regulations on 83 contaminants in three years and for 25 more contaminants every three years thereafter. Since the mid-1970s a network of governmental agencies has been developed to act on the SDWA. In 2002, the nation's 55,000 U.S. community water systems tested for more than 80 contaminants.

Those who don't believe current U.S. drinking water standards are sufficient cite a case involving the source of carcinogens in the 1970s leukemia cluster in Woburn, Massachusetts, which was the basis for Jonathan Harr's book A Civil Action. In the Woburn case, illegally dumped trichloroethylene and other possible carcinogens seeped into two city wells. Although water standards were not the issue, the story has lessons for authorities who make cost/benefit decisions when setting standards.

The EPA has been considering more stringent regulation of arsenic in water, but says that a significant reduction in the MCL allowed by law could increase compliance costs for water utilities. The MCL for arsenic in drinking water is 50 parts per billion (ppb) or 50 micrograms per liter (μg/l); in 1998 the EPA estimated that arsenic occurrence in groundwater exceeded that limit in 93 U.S. public drinking water systems. The EPA issued a 10 ppb (μg/l) regulation to begin in January 2001, but Christine Todd Whitman, the EPA administrator, suspended implementation of the new standard in March 2001 to allow for further review. After considerable public outcry and the publication of a National Research Council (NRC) report that spelled out a significant cancer risk, the government pledged to issue a new standard by February 2002. In the meantime, how many people were adversely affected?

The NRC issued another report in September 2001 noting that even very low concentrations of arsenic in drinking water were associated with a higher incidence of cancer. The report found that people who consume water with 3 ppb (μg/l) of arsenic daily have a 1 in 1,000 risk of developing bladder or lung cancer during their lifetime. At 10 ppb (μg/l) the risk is more than 3 in 1,000; at 20 ppb (μg/l) it is 7 in 1,000, based on consumption of 1 qt (1 l) of water per day.

Arsenic is not the only contested standard. Methyl tert-butyl ether (MTBE) is a common gasoline additive used throughout the United States to reduce carbon monoxide and ozone levels caused by auto emissions. Now MTBE is contaminating ground and surface water supplies from leaking underground storage tanks and pipelines, spills, emissions from marine engines into lakes and reservoirs, and to some extent from air contaminated by engine exhaust. MTBE falls under the EPA's Unregulated Contaminant Monitoring Rule, and its long-term health risk is still being studied.

Lead is another contaminant that is hazardous to infants, children, and adults. The MCL for lead is 15 ppb (μg/l), and the goal is zero exposure. Much of the exposure to lead in drinking water comes from household plumbing, not from an EPA-regulated external water source. With a long demonstrated risk of delayed physical and mental development in children exposed to lead in drinking water, there should be compelling regulations to end this preventable exposure.

Safeguards built into the U.S. legislative process to protect citizens from hasty and oppressive laws make it difficult to provide new drinking water standards and to enforce them in a reasonable timeframe, even when scientific evidence calls for change. According to a timeline published by the EPA, it takes eight years from the date a contaminant candidate is put on the first list to the date when regulatory determinations are announced.

—CHERYL PELLERIN

Viewpoint: Yes, while not perfect, current U.S. drinking water standards are sufficient, and new government regulations continue to improve these standards.

One Billion Glasses of Water

Water flows naturally throughout the world. It is an essential component to all life on Earth. Over many years mankind has learned to divert the flow of water to serve desired purposes such as drinking. In the United States safe drinking (or tap) water is critical for maintaining the public health. Americans use millions of gallons of water each day in homes, industries, farms, and countless community activities. According to the Environmental Protection Agency (EPA), the average U.S. citizen uses about 100 gal (380 l) of water each day, and the average household uses around 100,000 gal (380,000 l) of water each year. Americans drink more than one billion glasses of water every day. Because water is accessed from many different sources and various methods are used to treat water, the quality of drinking water varies throughout the country. But, even with all of these inconsistencies, according to the EPA's Office of Water, more than 90% of U.S. water systems meet federal standards for tap water quality.

Water experts consider the drinking water of the United States to be generally safe. In fact, according to Mary Tiemann of the Environment and Natural Resources Policy Division within the Congressional Research Service, "When compared to other nations, the United States is believed to have some of the safest drinking water in the world." The following discussion spotlights some of the more important reasons why the U.S. water supply is safe and current drinking water standards are sufficient.

Early Water Movements

During the nineteenth century, diseases such as cholera and typhoid could be traced to the U.S. water supply. In response to such problems, major public health movements were instituted from that time to the early twentieth century. Because of those early efforts, the debilitating diseases cited above have been virtually erased through effective water disinfections and improved sanitary engineering practices. Federal regulations of drinking water quality began in earnest in 1914 when the U.S. Public Health Service set standards for drinking water. Since that time, the United States has continued to improve on antibacteriological water technologies that provide safe water throughout the country. Erik D. Olson, senior attorney at the Natural Resources Defense Council, a national nonprofit public-interest organization, is confident that these public health movements yielded, and continue to yield, enormous public health benefits.

Current Water Quality

According to the EPA's Department of Water (DOW), the United States enjoys one of the best supplies of drinking water in the world. The National Environmental Education and Training Foundation (NEETF) concurs with the DOW and has stated, "Most drinking water in the United States is quite safe to drink." NEETF also has asserted that community water suppliers deliver high-quality drinking water to millions of Americans every day. In fact, of the more than 55,000 community water systems in the United States, the DOW indicated in 1996 that only 4,769 systems (about 8.7%) reported a violation of one or more drinking water health standards. According to the NEETF, 91% of America's public water systems reported no violations in 1998-1999 of any health-based drinking water standard, such as failures of water treatment and actual contaminants in the drinking water. More importantly, all of the reported violations during this time period involved reporting and monitoring requirements. In addition, owners of drinking water systems have spent hundreds of billions of dollars to build state-of-the-art drinking water treatment and distribution systems and, as a group, they continue to spend an additional $22 billion per year to operate and maintain these systems.

The quality of drinking water has been improving over the past 10 decades in large part due to governmental regulations. According to the National Centers for Disease Control and Prevention (CDC), the proportion of reported diseases that have been linked to problems at public water treatment systems has consistently declined from 1989 to 1996. This improvement, according to the CDC, directly relates to improvements in water treatment and water treatment technology, all of which are overseen by federal legislation.

The Laws

Contamination of water supplies gained the attention (and the concern) of the U.S. public in the early 1970s and, soon after, the political action of the U.S. Congress. This increased awareness promptly led to the passage of several federal health laws, one of the most important being the Safe Drinking Water Act (SDWA) of 1974. The EPA's Office of Ground Water and Drinking Water administers this law, along with its subsequent amendments. The act made drastic advancements to effectively enforce numerous voluntary U.S. Public Health Service standards by requiring the EPA to set national uniform water standards for drinking water contaminants. The SDWA provided for (1) regulations that specified maximum contaminant levels or treatment techniques, (2) regulations for injection-control methods to protect underground water sources, and (3) grants for state programs involving groundwater and aquifer protection projects.

Maximum contaminant levels (MCLs), the official name for EPA drinking water standards (or regulations), are applied to both private and public systems that serve at least 25 people or 15 service connections (such as homes and businesses) for at least 60 days during the year. By the year 2001, the EPA estimated that across the country about 170,000 public water systems serving 250 million people were regulated under the act. These MCLs are part of the multiple-barrier method for protecting drinking water. The major aspects of MCLs include (1) assessing and protecting drinking water sources, (2) protecting wells and other collection systems, (3) making sure water is treated by qualified and regulated operators, (4) ensuring the integrity of distribution systems, and (5) making information available to the public concerning the quality of their drinking water. For example, an MCL was established in 1975 for arsenic exposure in water at a level no greater than 50 parts per billion (ppb) or 50 micrograms per liter (μg/l). Exposure to naturally occurring and industrially produced arsenic in water is a contamination problem for the majority of U.S. citizens. In January 2001, the EPA announced a new standard for arsenic in drinking water that requires public water supplies to reduce arsenic to 10 ppb (μg/l) by 2006. With the involvement of the EPA, state governments, water utilities, communities, and citizen groups, these methods ensure that tap water in the United States is safe to drink.

In 1986 Congress strengthened the SDWA by enacting several major amendments that strengthened standard procedures for 83 contaminants. Congress also strengthened and further expanded the act's requirements on compliance, monitoring, and enforcement, especially emphasizing the need for more research on contaminants that are most dangerous to children and other susceptible people. The new law also focused on the public's right-to-know (and need-to-know) about tap water, the necessity of federal financial assistance to water treatment facilities, and the desire to give individual states greater flexibility in dealing with water-quality issues.

Since the mid-1970s a network of governmental agencies has been developed to act on the SDWA. The EPA and state governments set and enforce standards, while local governments and private water suppliers possess direct responsibility for the quality of drinking water. Engineers of community water systems test and treat water, maintain the distribution systems that deliver water to consumers, and report on their water quality to the state. States and the EPA provide technical assistance to water suppliers and take legal action against systems that fail to provide water that meets state and federal standards. Some of the agencies, such as state departments of environmental protection, choose to enforce standards that are stricter than EPA standards; all state laws must be at least as stringent as the federal standards.

Setting Drinking Water Standards

A method called risk assessment is used to set drinking water quality standards. The major division of cancer versus noncancer risks is evaluated with respect to the degree of exposure to an undesirable chemical in drinking water. The first step is to measure how much of the chemical could be in the water. Next, scientists estimate how much of the chemical the average person is likely to drink, and call this specific amount the exposure. In developing drinking water standards, the EPA assumes that the average adult drinks.5 gal (2 l) of water each day throughout a 70-year average life span. Risks are estimated differently for cancer and noncancer effects. For cancer influences, a risk assessment estimates a measure of the chances that an individual may acquire cancer due to being exposed to a drinking water contaminant. The EPA normally sets MCLs at levels that limit an individual's health risk of cancer from that contaminant to between 1 in 10,000 and 1 in 1 million over a lifetime. For noncancer influences, the risk assessment process estimates an exposure level below which no negative effects are expected to occur. Risk assessment is a uniform and effective way that the EPA can monitor water quality throughout the nation.

MCLs are established to protect the public health based on known or anticipated health problems, the ability of various technologies to remove the contaminant, their effectiveness, and the cost of treatment. The limit for many substances is based on lifetime exposure and, for the most part, short-term limits are not considered a health risk (unless the short-term risk poses an immediate threat). In 2002, the nation's approximately 55,000 community water systems needed to test for more than 80 contaminants. In 1996, 4,151 systems (about 7.5%) reported one or more MCL violations, and 681 systems (less than 1.3%) reported violations of treatment technique standards. All in all, the system for setting water standards has prompted a consistent level of quality water.

Water Treatment Processes

Water suppliers use a variety of treatment processes to remove contaminants from drinking water. In order to most effectively remove undesirable contaminants from the water, these individual processes are grouped into what is commonly called a treatment train. Filtration and chlorination are longtime effective treatment techniques for protecting U.S. water supplies from harmful contamination. Today, other commonly used processes include filtration, flocculation, sedimentation, and disinfection. Additional decontamination processes have been implemented over the years. In the 1970s and 1980s, improvements were made in membrane development for reverse osmosis filtration and other treatment techniques such as ozonation, ion exchange, and adsorption. A typical water treatment plant will possess only the combination of processes that it needs in order to treat the particular contaminants in its source water. Recently, the implementation of a new approach called multiple barriers has been implemented to counter tap water contamination from source waters. The multiple barriers technique is one that allows for different treatments of water along the decontamination process in order to decrease the possibility of degradations. It also provides, in some cases, for physical connections between water supplies, so that if one supply is degraded water can be diverted around the problem. In addition, modern water treatment technologies (such as membranes, granular activated carbon, and more advanced disinfectants) and improvements in distribution systems also have been installed.

Recently the CDC and the National Academy of Engineering named water treatment as one of the most significant public health advancements of the twentieth century. Moreover, the number of treatment techniques that have been developed (along with the various combinations of those techniques) is expected to increase in the future as more complex contaminants are discovered and regulated.

After Twenty-five Years

On December 16, 1999, the Safe Drinking Water Act was honored for twenty-five years of service to the citizens of the United States. Under the current law, every public water system must test for more than 80 individual contaminants. Water utility professionals under state drinking water program offices then study and investigate the testing results. Utility and state personnel finally compare the results with the established federal drinking water standards.

Since the enactment of the 1974 SDWA, the government, the public health community, and water utilities throughout the country have worked together to protect the nation's drinking water supplies and to ensure the law safeguards public health. In addition, water utilities have helped to strengthen the law by keeping customers informed about their drinking water. According to the American Water Works Association, annual consumer confidence reports (CCRs) on water quality help consumers to understand a number of different things about their drinking water. Since 1999, nearly all water utilities have been required to distribute a water quality report to their consumers. CCRs, sometimes called water quality reports, must be prepared each year by water systems to explain what substances were found in drinking water and whether the water is safe to drink. The report provides information on local drinking water quality, including the water's source, the contaminants found in the water, and how local consumers can get involved in protecting drinking water.

Conclusion: Consistently High Quality

Few things are as important to our personal well-being as drinking water. At the beginning of the twenty-first century, U.S. consumers possess more information than ever before about the quality of their drinking water. The NEETF states the "United States is one of the few nations in the world that consistently enjoys high-quality drinking water from the tap. But no system is perfect and local differences in tap water quality can be significant."

It is acknowledged that the condition of water safety in the United States is not perfect, and that the water standards currently enacted also are not perfect. It is widely known that water safety within the nation has its problems, and that water standards do not encompass all of the problem areas within water safety. However, water safety and the standards that protect water safety are continually improving, and they provide sufficient safety of the water supply and to the citizens who drink that water.

Unfortunately, there are a growing numbers of threats (especially those made by individuals or groups) that could possibly contaminate drinking water. Nonetheless, actual occurrences of serious drinking water contamination occur infrequently, and typically are not at levels that endanger near-term health. But with the likelihood of such menacing events increasing, drinking water safety cannot be taken lightly. The EPA and its partners, water suppliers, and the public must constantly be vigilant in order to ensure that such events do not occur frequently in the water supply. Even though more types of water contamination are possible, and more threats of degradation to water supplies are likely, the good news is that the water treatment technology of the United States is very capable of removing the vast majority of contamination from the public's drinking water.

—WILLIAM ARTHUR ATKINS

Viewpoint: No, current U.S. drinking water standards are not sufficient and must be improved to ensure public health.

"It must be in the water." Although this common expression is usually said in jest, unfortunately, and sometimes tragically, "it" is in the water, as with the source of carcinogens in the 1970s leukemia cluster in Woburn, Massachusetts. "It" was the basis for the best-selling book A Civil Action (1995) by Jonathan Harr. In the Woburn case, illegally dumped trichloroethylene and other possible carcinogens seeped into two of the city wells. Criminal acts and failure of the city to properly test the water, not standards, were the issue. Although this incident occurred several decades ago, the story of the Woburn case should be required reading for all public water-supply providers to make personal the consequence of tainted water at any time from any source, including consequences from inadequate testing. Standards, testing, and enforcement have to be one issue.

The story also should be required reading for the authorities who make many of the cost/benefit decisions on setting standards. The U.S. Environmental Protection Agency (EPA), the federal regulatory body responsible for drinking water standards, has been considering a more stringent regulation of arsenic in water, but notes a significant reduction in the maximum contaminant level (MCL) allowed by law could increase compliance costs for water utilities. The question arises: How much is a child's life worth?

Arsenic Standard Controversy

A longstanding standard for arsenic in drinking water (since 1975) was 50 parts per billion (ppb) or 50 micrograms per liter (μg/l). In 1998 the EPA estimated that arsenic occurrence in groundwater exceeded that limit in 93 U.S. public drinking water systems. The EPA issued a regulation in January 2001 mandating that the standard fall to 10 ppb by 2006, but Christine Todd Whitman, the EPA administrator, suspended implementation of the new standard in March 2001 to allow for further review. After considerable public outcry and the publication of a National Research Council (NRC) report spelling out a significant cancer risk, the government issued a new standard by 2002.

An extensive study of research on the health effects of various levels of arsenic in drinking water was conducted by the NRC, an independent, nongovernmental organization affiliated with the National Academy of Sciences whose work includes convening experts to study scientific and public health issues of interest to the federal government and other parties. The NRC began its study of arsenic in drinking water in 1997 and issued its first comprehensive report in 1999. The 2001 proposed change in the drinking water standards for arsenic was in response to that report.

The NRC issued another report in September 2001 which reinforced their risk assessment that even very low concentrations of arsenic in drinking water appear to be associated with higher incidence of cancer. The committee found that people who consume water with 3 ppb (μg/l) arsenic daily have about 1 in 1,000 risk of developing bladder or lung cancer during their lifetime. At 10 ppb (μg/l) the risk is more than 3 in 1,000; at 20 ppb (μg/l) it is approximately 7 in 1,000, based on the consumption of about 1 qt (1 l) of water per day—a conservative amount of water to drink in one day.

MTBE in Water

The U.S. drinking water standards clearly are inadequate for arsenic. Although it may be one of the best-publicized debates, arsenic is not the only contested standard. Another potential hazard that has been in the news is MTBE (methyl tert-butyl ether). MTBE has been a common additive used in gasoline throughout the United States to reduce carbon monoxide and ozone levels caused by auto emissions. It replaced lead as an octane enhancer, because lead was (justifiably) regulated as a very serious health risk.

Now MTBE is contaminating ground and surface water supplies where it imparts a foul odor and taste to the water. MTBE gets into water supplies from leaking underground storage tanks and pipelines, spills, emissions from marine engines into lakes and reservoirs, and to some extent from air contaminated from engine exhaust. The long-term health risk is still being studied, although a Consumer Acceptability Advisory Table published by the EPA (summer 2000) includes under margin of exposure a reference for cancer effects for two concentration levels. MTBE falls under the EPA's Unregulated Contaminant Monitoring Rule.

MTBE is being phased out of gasoline, but the same contamination sources will continue to exist. What will the risk be from the additive(s) that replace it? With the amount of gasoline stored and used in the United States on a daily basis, it is naive to believe the drinking water supplies will be safe from exposure if the replacement turns out to be a contaminant.

The safeguards built into the legislative process in the United States to protect citizens from hasty and oppressive laws make it difficult to provide new drinking water standards, and effective enforcement of them, in any reasonable time, even when scientific evidence cries out for change. According to a timeline published by the EPA, it takes eight years from the date a contaminant candidate is placed on the first list to the date when regulatory determinations are announced.

EPA Story

The EPA is an independent agency in the executive branch of the federal government that was formed in 1970 to consolidate the government's environmental regulatory activities under the jurisdiction of a single agency. Among the 10 comprehensive environmental protection laws administered by the EPA are the Clean Water Act and the Safe Drinking Water Act (SDWA). Within the agency, the Office of Water is in charge of water quality, drinking water, groundwater, wetlands protection, marine estuary protection, and other related programs. The SDWA was first enacted in 1974 and was amended in 1977, 1986, and 1996.

One of the significant edicts of the EPA is the National Primary Drinking Water Regulation, a legally enforceable standard that applies to public water systems. Another EPA document is the National Secondary Drinking Water Regulation, a nonenforceable guideline regarding contaminants that may cause cosmetic effects or aesthetic effects in drinking water. The arduous process for setting standards includes input from a 15-member committee created by the SDWA, the National Drinking Water Advisory Council. There is no fast-track process for enacting changes to standards. Where scientific research and information technology have reached the twenty-first century, the EPA has not.

The National Primary Drinking Water Standards are listed as maximum contaminant level goal (MCLG), the level of contaminant in drinking water below which there is no known or expected risk to health, and as maximum contaminant level (MCL), the highest level of contaminant that is allowed in drinking water. The EPA says MCLs are set as close to MCLGs as feasible, using the best available treatment technology and taking cost into consideration. Only MCLs are enforceable standards.

Contaminants are listed under the following headings: microorganisms, disinfectants and disinfection by-products, inorganic chemicals, organic chemicals, and radionuclides. Under microorganisms is a heading for turbidity, which serves as a general catchall to indicate water quality and filtration effectiveness. This is justified because one reason for turbidity is the presence of microorganisms. The listing of disinfection by-products was necessary because contaminants such as total trihalomethanes, many of which are carcinogenic, are produced by the disinfection process, making a bad situation worse.

Age Factor

While the standards for the vast majority of contaminants are considered adequate, research continues. It has become clear that some groups are more vulnerable to contaminants, and that for some contaminants the health effects can vary significantly with the age of the exposed individual.

Nitrates are an example of an age-dependent heath risk. Infants below the age of six months can die from blue-baby syndrome if exposed to nitrates above the MCL. The nitrates' MCL and MCLG are both10 parts per million (ppm) or 10 mg/l. Nitrates occur naturally in soil and water in low concentrations. When fertilizers are applied in excess, nitrate levels in groundwater used as drinking water sources can be raised to dangerous levels quickly from rain or irrigation. In some areas, high-risk individuals, particularly pregnant women, may have to use bottled water.

Lead is another contaminant that is more hazardous to infants and children, although it is also hazardous to adults. The MCL for lead is 15 ppb (μg/l), where the goal is zero exposure. Much of the exposure to lead in drinking water comes from household plumbing, not from an EPA-regulated external water source. With a long-demonstrated risk of delayed physical and mental development in children exposed to lead in drinking water, there should be compelling regulations to end this easily preventable exposure. The challenge may fall under another agency than the EPA; perhaps a housing authority should be brought into the mix.

Trichloroethylene, suspected to be the primary offender in the Woburn leukemia cases, has an MCL of 5 ppb (μg/l) with a goal of zero. There is no mention of it being a more serious carcinogen in children, but most of the victims in Woburn were young. In fact sheets published by the EPA, increased risk is more serious with exposure over a year or longer.

Bottled Water

The water tasted strange to the Woburn victims and they did complain to authorities. Bottled water was not readily available in 1970, but it is today. Bottled water is considered a food product by the government and thus is covered by the U.S. Food and Drug Administration (FDA) regulations. As with public drinking water, it is regulated at the state and local level as well as by the federal government. The FDA ensures the water, like food, is processed, packaged, shipped, and stored in a safe and sanitary manner. Since 1993 the FDA has implemented standard definitions for terms used on the labels of bottled water, such as "mineral," "spring," "artesian," "well," "distilled," and "purified." There is no guarantee the source is in total compliance with all EPA regulations and recommendations because the source of the water may be unregulated, or it may be from a public drinking water source that is not completely in compliance. The EPA regulates drinking water supplies down to as small as 25 users, but not below that. According to the EPA's published information, in 1996 more than 6% of community water systems violated MCL or treatment levels in 36 states. In 13 of these states, more than 11% of the systems were out of compliance.

Current Research

More up-to-date studies are being done to ensure safe drinking water. Issues related to safe drinking water are frequently reported in news of current research. A study was conducted at the University of Illinois at Urbana-Champaign (UI) in 2001 on a sequential disinfection process that would better handle Cryptosporidium parvum, a parasitic protozoan that can infiltrate a public water supply. In Milwaukee, Wisconsin, in March 1993, more than 400,000 people were infected with symptoms similar to food poisoning during an outbreak of cryptosporidiosis. Most treatment plants disinfect drinking water using chlorine, which has little effect on C. parvum outside of its host. The Illinois study used a sequence of ozone followed by chlorine to more effectively kill the parasite than either treatment alone. Benito Marinas, a UI professor of civil and environmental engineering, directed the research.

At Brigham Young University (BYU) researchers have created molecules that glow in the presence of metal pollutants such as zinc, mercury, and cadmium, which could provide an early warning system to alert regulators to the contamination of drinking water and waste streams. A BYU press release in July 2001 stated that, according to the EPA's toxic chemical release inventory, from 1987 to 1993 cadmium releases were primarily from zinc, lead, and copper smelting and refining industries, with the largest releases occurring in Arizona and Utah. The research was led by Jerald S. Bradshaw, professor emeritus of chemistry, and Paul B. Savage, associate professor of chemistry.

A better water-quality sampling scheme has been developed at the University of Arkansas. The researchers Thomas Soerens, assistant professor of civil engineering, and Marc Nelson, director of the Arkansas Water Resources Center Quality Lab, pointed out in a May 2001 news release that timing is everything in taking test samples, especially during storms.

The public drinking water supplies in the United States are among the world's most reliable, but that does not mean they are all they could or should be. There is no room for complacency when it comes to drinking water standards, especially as new information becomes available. The procedures for developing new standards must keep pace with the information on contaminants and their effects on health. Testing procedures and enforcement of safe drinking water standards are equally important; without them, the standards have no meaning. A Woburn, Massachusetts, scenario must never happen again.

—M. C. NAGEL

KEY TERMS

ADSORPTION:

The process in which organic contaminants and color-, taste-, and odor-causing compounds are adhered to the surface of granular or powdered activated carbon or other high-surface-area material in order to be removed from drinking water.

AQUIFER:

Bodies of rock that are capable of containing and transmitting ground-water.

CARCINOGEN:

A cancer-causing agent such as trichloroethylene.

CHLORINATION:

The process to treat or combine with chlorine or a chlorine compound.

CHOLERA:

An often fatal, infectious disease caused by the microorganism Vibrio comma.

DISINFECTION:

The process in which water is decontaminated before entering the distribution system in order to ensure that dangerous microbes are killed. Chlorine, chloramines, or chlorine dioxide are often used because they are very effective disinfectants.

FILTRATION:

The process used by many water treatment facilities to remove remaining particles from the water supply. Those remaining particles include clays and silts, natural organic matter, precipitants (from other treatment processes in the facility), iron and manganese, and microorganisms. Filtration clarifies water and enhances the effectiveness of disinfection.

FLOCCULATION:

The water treatment process that combines small particles into larger particles, which then settle out of the water as sediment. Alum and iron salts or synthetic organic polymers (alone, or in combination with metal salts) are generally used to promote particle combination.

INORGANIC CHEMICAL:

An element, ion, or compound that does not contain bonded carbon.

ION EXCHANGE:

The process used to remove inorganic constituents when such contaminants cannot be removed adequately by filtration or sedimentation. Ion exchange can be used to treat water that is rich in calcium and magnesium salts (commonly called hard water). It also can be used to remove arsenic, chromium, excess fluoride, nitrates, radium, and uranium.

ORGANIC CHEMICAL:

Any compound that contains bonded carbon. The compound can be man-made or naturally occurring.

OZONATION:

The process that is used to treat or impregnate water (or other substances) with ozone, a colorless, gaseous variation of oxygen (that is, ozone possesses three atoms rather than the usual two atoms in oxygen).

PUBLIC WATER SYSTEMS:

As defined by the Environmental Protection Agency, a system that delivers water for human consumption if such a system has at least 15 service connections or regularly serves at least 25 individuals 60 or more days out of the year. Such systems include municipal water companies, homeowner associations, schools, businesses, campgrounds, and shopping malls.

RADIONUCLIDE:

A radioactive element such as radium or an elementary particle such as an alpha or beta particle.

REVERSE OSMOSIS FILTRATION:

The process by which pressure is used to force fresh water through a thin membrane in order to remove undesired minerals from the water, based on their inability to pass through the membrane.

SEDIMENTATION:

A gravity-based process that removes heavier, solid particles from water.

TYPHOID:

A highly infectious disease, commonly called typhoid fever, which is caused by the typhoid bacillus ( Salmonella typhosa ). It is normally transmitted by contaminated food or water.

FLUORIDE IN DRINKING WATER: GOOD OR BAD?

Fluoride is the only compound whose concentration is limited by law on the EPA's National Primary Drinking Water Standards list of contaminants that is also an additive in the public drinking water—for more than 144 million people in the United States. "Concentration" is the key word for fluorides. The Environmental Protection Agency (EPA) has set an enforceable drinking water standard for fluoride of 4 parts per million (ppm) or 4 milligrams per liter (mg/l), and a secondary cosmetic standard of 2 ppm (mg/l).

The lower standard is suggested because young children exposed to too much fluoride get what was dubbed "Colorado brown stain" in the early 1900s by Frederick McKay, a young dentist in Colorado Springs who noticed that children with the stains also had fewer cavities. He got the cooperation of H. V. Churchill, an ALCOA chemist in Pittsburgh, Pennsylvania, who identified fluoride as the substance in the water that was causing both the staining and the stronger teeth.

Many studies were conducted on fluoride following this discovery. A 1946 study by Joseph Mueller, a young dentist in Indiana, found that when a fluoride compound of tin (stannous fluoride) was applied directly to tooth enamel it gave the same protection. Soon after, the well-known toothpaste print advertisement "look, Mom—no cavities" appeared, often with an illustration by Norman Rockwell of a smiling boy or girl.

Fluoride prevents tooth decay through both direct contact with the teeth and when people drink it in the water supply. The most inexpensive way to deliver its benefits is by adding fluoride to the drinking water. The National Center for Chronic Disease Prevention and Health Promotion advocates providing optimal levels of fluoride. A one-size-fitsall approach does not apply to determining optimal levels of fluoride, so some organizations oppose putting fluoride in drinking water.

The Water, Environment, and Sanitation division of the United Nations Children's Fund recognizes fluoride as an effective agent for preventing tooth decay. However, because a diet poor in calcium increases the body's retention of fluoride, people's nutritional status must be considered in determining the optimal level for daily fluoride intake. This potential for the retention of too much fluoride put fluoride on the EPA's enforceable standard list. Too much fluoride can cause skeletal fluorosis, a bone disease. For this reason, fluoride is removed from water supplies where the natural fluoride level is too high.

—M. C. Nagel

Are current U.S. drinking water standards sufficient

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