Pesticides are not the only chemical input that may increase with intensifying agriculture. Nitrogen fertilizer is one of the most effective tools for increasing yields, and its use on a global basis grew more than fivefold from 1960 to 1990. It is still climbing today, although at a slower pace (83). Fertilizer consumption in developing countries is projected to double by 2020, with especially rapid growth in Africa and South Asia. (See Fertilizer Use is Climbing.)
Public health officials consider nitrate contamination a significant health risk based on both its wide distribution and its effects on infants. In young infants, exposure to high levels of nitrates can result in a disorder whereby the red blood cells cannot function properly, leading to insufficient oxygen or “blue-baby syndrome,” which can be fatal (85). In adults, high levels of nitrate exposure may increase the risk of contracting some cancers, although the extent of the risk is unclear (86).
Worldwide, the scale of nitrate contamination is undoubtedly quite large. Although no global assessment exists of how many areas exceed the WHO standard, individual country reports indicate that nitrate is one of the most common chemical contaminants found in drinking water. This finding is not surprising given the huge volume of nitrogen fertilizer used worldwide (87)(88)(89)(90). In the United States, for example, nitrate contamination is the nation’s most widespread groundwater pollution problem; in a national survey, 22 percent of wells in U.S. agricultural areas contained nitrate levels in excess of the federal limit (91). Nitrate is also a prime contaminant in Europe (92).