US farms 1 trillion ears of corn a year, using a chemical called Atrazine that in the concentration of 1 part per billion causes male frogs to grow ovaries! Strangely, a higher dosage reduces the risk. Atrazine is the most widely used weed killer in the United States. It has also been linked to cancer in people.
Corn tortillas are made using nixtamalization, an ancient Mesoamerican method of soaking corn in an alkaline solution that makes it more nutritious and easier to grind.