How does nitrate poisoning happen?
The greatest danger is for babies less than one year old. Small babies have a bacteria in their digestive tract that converts nitrate into nitrite, which is toxic. Nitrite reacts with a substance in the blood called hemoglobin. Hemoglobin is part of the red blood cell that transports oxygen to all parts of the body. When nitrites are present, hemoglobin will preferentially combine with nitrite instead of oxygen. The new substance formed is called methemoglobin and does not carry oxygen. As the amount of methemoglobin increases, the amount of oxygen in the blood decreases, eventually causing internal suffocation. The most common symptom of nitrate poisoning is a bluish color to the skin, particularly around the eyes and mouth. The blood will also turn a chocolate-brown color, which reflects the lack of oxygen. After six months to one year, the digestive system no longer contains the nitrate-converting bacteria. In older children and adults, nitrate is not changed to the toxic nitrite. I
