Nitrates are produced in our own bodies and are in our saliva. Nitric oxide is beneficial to our bodies. Nitrosamines are the bad ones.
80-90% or some such of nitrates come from vegetables in our diet.
In farm country like the Midwest with shallow water table and very porous soils fertilizers deliver a lot of nitrates into the water supplies and along with phosphates cause a lot of bad teeth bones etc/
Nitrates are in just about all of our water. Too much cured meat such as three meals a day definately isn't a good idea.
Vegetables cooked at high heat can produce nitrosomines too.
Cured meats won't kill us in moderation. The salt is more of the problem with havign to drink more water and increaded blood pressure.