Nitrate compounds

Nitrates are nitrogen-oxygen compounds released into the environment from the widespread use of nitrogen-based fertilizers, human sewage and animal manure. High nitrate levels in well water can cause the sometimes-fatal “blue baby” syndrome in infants, impairing the blood’s capacity to carry oxygen. Over years, adults consuming excess nitrates can suffer kidney and spleen damage. According to the Agency for Toxic Substances and Disease Registry, nitrates can react with the body’s amino acids to form nitrosamines, linked to cancer in test animal studies. The U.S. Environmental Protection Agency sets a limit of 10 parts per million for nitrates in drinking water.

In estuaries, nitrates cause algae blooms that quickly deplete the water of oxygen and create “dead zones,” killing bottom-dwelling organisms such as shellfish and crabs and fish that cannot escape the area. In January 2008, the U.S. Geological Survey (USGS) reported that two-thirds of the nitrogen causing the 8,000-square-mile Dead Zone in the Gulf of Mexico came from fertilizer runoff from farms along the Mississippi River. Application of nitrogen-based fertilizers also leads to emissions of nitrous oxide, a greenhouse gas that has 300 times the global warming potential of carbon dioxide.

The Environmental Working Group has been in the forefront of the effort to reform agriculture policies, advance conservation and curb the pollution that is killing the Gulf. In a 2006 report, Dead in the Water, EWG concluded that farms encompassing just 15% of the land in the Mississippi River Basin are responsible for 80% of the spring surge of nitrates feeding the Dead Zone; in the areas where nitrate runoff is worst, the study found, the U.S is spending just $1 on water quality for every $500 in crop subsidies. In a 2007 report, Trouble Downstream, EWG recommended that farmers who benefit from taxpayer support be required to show tangible progress in reducing soil erosion and nitrate runoff.

In a 2008 analysis, The Unintended Environmental Impacts of the Renewable Fuel Standard, EWG concluded that increased corn cultivation to make biofuel would accelerate soil erosion, intensify use of chemical fertilizers and pesticides and aggravate nitrate runoff into the fragile Gulf. Also, EWG said, expanding corn farming would heighten demand for water for irrigation, stressing underground water sources, and degrade shrinking wildlife habitat.