Nitrate accumulation in plant and soil, Factors affecting the process and their impact on human and animal health

The growth of crops depends heavily on the availability of nitrogen, which is taken up by plants predominantly in the form of nitrate which reduced for most species in the leaves to ammonium to form amino acids and proteins. Humans and animals rely on the protein built by plants. Thus, the use of mineral N fertilizers is essential to feed the world population, but it is also associated with risks such as increased nitrate concentration in the edible plant parts. The toxicity of nitrate is low, but it is reduced by microorganisms to nitrite, which is known to cause methemoglobinemia in infants and with amines to form nitrosamines, which are known to induce cancer. Up to 70% of the nitrate taken up by humans is derived from vegetables. Vegetables that are capable of accumulating large amounts of NO3 - include lettuce, spinach, cabbage, celery and Chinese broccoli. NO3 - is present in most food at low concentration. But green leafy vegetables contain higher concentration of NO3 - than other foods.