Cured Meat
Sodium nitrate is a naturally occurring salt traditionally used to preserve meat, according to the University of Minnesota Extension. It is converted into sodium nitrite during the preserving process, and is commonly used in commercially cured meats such as bacon, ham, hot dogs, lunch meat, corned beef and smoked fish.
. Sodium nitrate is still used in traditional preparations such as country ham. Neither sodium nitrate or nitrite have been shown to be carcinogenic; sodium nitrite can form into cancer-causing nitrosamines, but this is prevented by adding ascorbic or erythorbic acid.
http://www.livestrong.com/article/264858-list-of-foods-that-have-sodium-nitrate/