Sodium nitrite is a preservative that processers use to stabilize the red color in cured meat (without nitrite, hot dogs and bacon would look gray) and impart a characteristic flavor. Adding nitrite to food can lead to the formation of small amounts of potent cancer-causing chemicals called nitrosamines. Nitrite that also occurs in saliva and forms from nitrate in several vegetables can undergo the same chemical reaction in the stomach.
The labels on some “natural” hot dogs and other cured meats brag about “no added nitrite.” Be skeptical. While those products may not contain added sodium nitrite, they often are made with celery powder or celery juice, which are naturally high in nitrate. A bacterial culture is used to convert that to nitrite. Indeed in 2011, the New York Times revealed that “natural” cured meats could have 10 times as much nitrite as conventional products!