Early in the Bush administration, a political row erupted over proposed changes in the maximum contaminant level (MCL) for arsenic in drinking water. In its final weeks, the Clinton administration initiated a 10-fold reduction in the MCL for arsenic, from 50 parts per million (ppm) to 5 ppm. The Bush administration suspended the change pending a reexamination of the science by the National Research Council.
The new MCL would be particularly burdensome on poor, rural communities, Bush administration officials explained. While the health risks of maintaining the MCL at 50 ppm appeared to be small, the compliance costs for reducing it were very high.
A similar small risk/high cost drinking water regulation has received almost no attention: the limit on nitrate in drinking water, currently set at 10 ppm. That regulation is costing U.S. communities and homeowners hundreds of millions of dollars per year, and the cost is increasing.
The Environmental Protection Agency is increasing its pressure on state agencies to enforce the standard, even though there is no evidence of a problem. Moreover, as communities grow, more are reaching the threshold at which the regulation is enforced. (The regulation applies to community water systems serving more than 15 homes or 25 people.)
Basis for Current Standard
Nitrate levels in drinking water are regulated for one reason only: to prevent blue baby syndrome, medically known as infantile methemoglobinemia. Blue baby syndrome affects infants less than one year old, most often those younger than 6 months. The syndrome occurs when nitrites bind to hemoglobin (the oxygen carrier in red blood cells), knocking off oxygen, and thereby preventing oxygen transport. The condition literally turns babies blue, the color of deoxygenated blood.
The federal MCL for nitrates was established in 1963 and is based on data from a mere five blue baby cases identified in a survey conducted in 1949 by the American Public Health Association (APHA). During the 1940s, a number of blue baby cases connected to water contaminated with high nitrate levels was reported in medical journals. It was known that nitrites were toxic and caused methemoglobinemia in humans of all ages. On the theory that gut bacteria can convert nitrate (NO3) into toxic nitrite (NO2), the APHA concluded the evidence warranted limiting infant exposure to nitrates. (At the time, many infants were fed powdered infant formula reconstituted with well or tap water, exposing them to nitrates in drinking water.)
In an effort to determine a safe level of nitrates, the APHA surveyed state health departments asking for information on blue baby cases “definitely associated with nitrate-contaminated water.” All but one state responded to the survey. Seventeen states submitted data on a total of 214 blue baby cases. Most cases occurred at nitrate levels greater than 40 ppm, while five were reported at nitrate levels between 11 and 20 ppm. Since no blue baby cases were reported at levels below 10 ppm, this became the federal MCL.
No one knows if the information gathered by the APHA in 1949 is accurate. Many of the survey’s blue baby cases were never formally diagnosed. Moreover, the survey is badly flawed because nitrate concentration data were often collected months after the blue baby event; nitrate levels in drinking water can vary dramatically over relatively short periods of time.
Finally, APHA never considered the fact that blue baby syndrome can be caused by internal (endogenous) factors, without any exposure to external nitrates or nitrites. APHA simply assumed that in blue baby cases where nitrates were present, the nitrates were the cause.
The most common cause of endogenous blue baby syndrome appears to be gastrointestinal maladies, such as gastroenteritis and diarrhea. Symptoms of gastrointestinal disorders, such as diarrhea and vomiting, are present in a majority of blue baby cases linked to nitrate-contaminated water.
Moreover, doctors in the 1940s were unable to cause blue baby syndrome in hospitalized infants by exposing them to formula with 100 ppm nitrate alone. Blue baby syndrome occurred only when the infants were exposed to 100 ppm nitrate nitrogen and pathogenic bacteria. Even then, the effects weren’t dramatic. Thus, the relatively low nitrate levels in the five blue baby cases from the APHA survey were likely unrelated to the blue baby occurrences.
Reexamining the MCL and Prevention Approach
Today, blue baby syndrome is an extremely rare event in developed countries. Most rural doctors in the United States have never seen even a single case, let alone a death. It is unclear whether this is due to increased awareness in areas where nitrates are present, a reduction in the use of powdered/concentrated infant formula that requires reconstitution with water, or a reduction in the endogenous factors that cause blue baby syndrome (i.e. gastrointestinal infections, diarrhea, etc.).
EPA estimated in 1990 that 66,000 infants are exposed annually to drinking water whose nitrate levels exceed the MCL, so we obviously haven’t removed infant exposures to water with moderate nitrate levels.
While the supposed health threat from nitrates is limited to young infants, the MCL is imposed on all water from public water systems. This is a colossal waste of money, as 99.99 percent of the water is used for purposes other than diluting concentrated infant formula. It would be far cheaper simply to ban the sale of concentrated infant formulas, or even to provide 6 months of fully constituted infant formula to all mothers in affected areas.
Raising the MCL to 20 ppm nitrate-nitrogen would not be without precedent. Oklahoma, for example, maintained an MCL of 20 ppm until 1994, when EPA pressured the state to adopt the federal standard. Despite the higher MCL, Oklahoma had only one blue baby case reported in public health records over the past 40 years.
With the adoption of the lower federal MCL, some 20 rural Oklahoma communities suddenly face huge costs to solve a health problem none has ever experienced. For example, the small town of Hennessey, Oklahoma (population 2,058) is facing nearly $2 million in water treatment equipment costs, sizeable annual maintenance expenditures, and at least a doubling of the town’s annual water use. All of the additional water used will be waste water from continually flushing the membrane filtration system in an area already short of water. The purpose of all this expense and waste? Reducing the nitrate levels in the town’s water from 12 ppm to 9.9 ppm nitrate-nitrogen. This is just one tiny town in one state.
Nor does this regulation affect only municipal water suppliers. Any water system that serves more than 15 homes or 25 persons must comply. Individual homeowners are affected as well, because many homebuyers won’t purchase a home with well water that does not meet a federal health standard. Homeowners whose groundwater exceeds the federal MCL find themselves either digging new wells, paying $1,000+ per tap to install point-of-use water treatment systems, or investing several thousand dollars in a whole-house filtration system.
When all of these costs are added up, the burden on U.S. communities likely exceeds $150 million per year and perhaps far more. Unfortunately, not even EPA has a credible estimate. In virtually all currently affected areas, the nitrate levels are less than 20 ppm, meaning a revision of the MCL would virtually eliminate these costs.
EPA’s current MCL for nitrates in water has a shaky scientific basis and a dubious public health benefit, while costing huge sums for those communities affected. Congress has a duty to demand a thorough scientific review of the nitrate MCL by the National Research Council.
Alex Avery is director of research at the Hudson Institute’s Center for Global Food Issues. Additional information can be found at http://www.cgfi.org.
