I'm beating a dead horse here, but Sodium Nitrates occur naturally in Sea Salt. The Romans used to bury pieces of meat in sea salt to preserve it AKA the "Corning Process" or Corned Beef.
There are studies out there that show nitrates causing cancer in mice after they consumed the equivilant of 100 lbs of sausage per day over an extended period so don't believe everything you hear. Lots of Fear Mongering in the food world these days, usually to get consumers to buy their "safer" product. One pound of Curing Salt usually contains about .004% Nitrates and one tablespoon will cure around 100 lbs of meat in a dry cure so a little goes a long way.