Pouring It On
Nitrate Contamination of Drinking Water
Pouring It On
Pouring It On
Nitrate Contamination of Drinking Water
Nitrate in drinking water at levels greater than the Federal standard of 10 parts per million (ppm) can cause methemoglobinemia, a potentially fatal condition in infants commonly known as blue-baby syndrome. According to Dr. Burton Kross, of the University of Iowa's Center For International Rural and Environmental Health, nitrate poisoning via drinking water contamination "certainly contributes to national infant death rate statistics" (Johnson and Kross 1990). Agriculture is the primary source of nitrate contamination.
An Environmental Working Group review of nearly 200,000 water sampling records found that over two million people -- including approximately 15,000 infants under the age of four months -- drank water from 2,016 water systems that were reported to EPA for violating the nitrate standard at least once between 1986 and 1995 (Table 1). All of these water systems were termed "significant non-compliers" by EPA and 60% were repeat violators. The ten largest water systems that violated the federal nitrate standard between 1986 and1995 were Columbus, OH; Scottsdale and Chandler, AZ; Decatur, IL; Upland, CA; Bloomington, IL; Peoria, AZ; Manteca, CA; Rialto, CA; and Gilbert AZ.
Water utilities in Decatur, Bloomington, Streator, and Pontiac, Illinois all violated the nitrate standard in eight years out of the ten. Danville, Illinois was close behind with seven violations during the same time period. Columbus, Ohio violated the standard five years in a row from 1985 through 1989, at which time they were granted a special "waiver" from subsequent violations. Under this deal with the state, the utility can serve water that exceeds that standard without being cited for violating the standard as long as the community is warned about it (Evans 1995).
An additional 3.8 million people drink water from private wells that are contaminated above the 10 ppm nitrate standard. In seven states -- California, Pennsylvania, New York, Illinois, Wisconsin, Minnesota, and Iowa -- more than 100,000 people are exposed to nitrate above the federal standard via private drinking water wells (Table 2).
Over twelve million people in the United States drink water from nearly 1,000 water systems where some or all of the drinking water supply is contaminated by nitrate at levels above the EPA's 10 ppm standard (Table 3); 8.7 million of these people are in California (Table 4). While the majority of these systems are still able to provide drinking water that meets the 10 ppm standard, often this comes at significant cost to water utilities and ratepayers.
Unlike virtually all other contaminant standards, the 10 ppm federal drinking water standard for nitrate contains no safety factor. This means that several days' worth of infant formula mixed with water contaminated with nitrate at levels over 10 ppm can easily cause methemoglobinemia in infants under four months of age. Repeated consumption of this water over a period of days or weeks can cause severe blue baby syndrome, and even death.
320 "water systems to watch" serving 2.8 million people in the 21 states have had at least one nitrate sample between nine and ten parts per million. Infants are at significant risk in these communities because prolonged exposure to nitrate at levels extremely close to the 10 ppm standard typically occurs with no efforts to warn the population or reduce nitrate levels in drinking water (Table 5).
Role of Water Utilities
To their credit, water suppliers with nitrate contamination problems frequently solve problems before they are officially considered to be in violation of EPA standards. In some cases individuals in these communities, including vulnerable infants were likely served water with unsafe concentrations of nitrate, even as water suppliers took aggressive measures to ensure that citizens in these communities could drink water that met EPA standards. Based on published estimates of the cost to fix nitrate problems in California and Iowa (Huber 1992, Anton et al. 1988), we estimate that nationwide, ratepayers spend more than $200 million per year to protect infants from nitrate contaminated water. Polluters, of course, pay none of these costs.
Solutions on the Farm
Farmers will, and must, continue to use nitrogen fertilizer. They do not, however, have to overuse it. Each year, there are 8 billion pounds more nitrogen available in farm fields than can be used by the crops growing on this land (NRC 1993). This excess nitrogen has to go somewhere, and much of it ends up in drinking water supplies (NRC 1989, NRC 1993, Hallberg 1989). Other sources such as sewage treatment plants, septic tanks, and atmospheric deposition pale in comparison to the farm contribution.
By following a few simple guidelines -- accounting for all sources of nitrogen in a field (manure and nitrogen fixing crops), timing applications properly, using nitrogen soil tests, and setting realistic yield goals -- farmers can dramatically reduce nitrogen application rates, while maintaining profits and high yields (NRC 1989; NRC 1993; Hallberg and Keeney, 1993; Hallberg, et al. 1991). In Iowa, farmers have successfully implement such a plan and reduced their use of nitrogen-based fertilizers while maintaining high yields (Hallberg et al 1991, Iowa State University 1993).
In the four years from 1991 through 1994, Iowa farmers used eighteen percent less fertilizer per acre of corn than farmers in other Corn Belt states -- and had a corn yield that matched those same Corn Belt farmers. In fact, statewide, Iowa corn growers achieved record yields in 1992 and 1994.
Congress is rewriting laws that regulate nitrate and other contaminants in drinking water. Amendments to the Safe Drinking Water Act passed by the Senate in November 1995, would make nitrate contamination problems even worse. The new legislation would give states and communities no new powers to prevent polluters from fouling tap water supplies, and would prevent them from taking action until it is too late: when contaminants have already exceeded standards. In the House, many members seem poised to support a weaker Safe Drinking Water Act. A Clean Water Act rewrite that passed the House in 1995 would roll back basic water quality protections.
To protect the tens of thousands of infants exposed to unsafe nitrate contamination in drinking water, we recommend that the EPA and the Congress:
- Immediately establish a new drinking water standard for nitrate of 5 ppm. This new standard -- which would be comparable to standards already established in Germany and South Africa -- would provide a modest two fold safety factor for the infant population.
- Adopt tough source water protection provisions when amending the Safe Drinking Water Act and the Clean Water Act, giving water suppliers and public health officials clear authority to stop pollution at its source and avoid the danger and expense caused by nitrate contamination of water supplies.
- Provide technical and financial assistance to farmers to help them improve the efficiency and consistency of their nutrient use to reduce nitrate contamination of source water.
- Require states to report cases of methemoglobinemia to the Centers for Disease Control.
We believe Congress and the EPA should take steps to protect against nitrates in drinking water, including:
- Establishing a more protective standard for nitrate in drinking water,
- Adopting tough source water protections in the Safe Drinking Water Act and Clean Water Act,
- Providing technical and financial assistance to farmers to help them reduce nitrate contamination of source water.