I recommend anyone interested to read a few articles pro and con on Nitrates and Nitrites, and form your own opinions, as we all know, credible statistics and research often conflict with each other.
Having said that, here is my biased bacon-lover take on it, from my readings:
Nitrates and Nitrites are used as preservatives to prevent botulism (rotten food bacteria)
They are a variety of salt, read the wiki for the chemistry stuff.
they are used in preserving wines, in getting the bubbles out of liquid glass, in industrial chem, and in cured hams and pastrami.
10% of human intake comes from preserved meats (it varies per person, per culture, per region, etc)
you get 90% of nitrates/nitrites from just about any natural vegetable and fruit has sodium, as well as most canned food in salt.
for it to be toxic, "a 154-lb. adult would have to consume 18.57 pounds of cured meats"
Basically eating this salami is not going to kill you or give you cancer. However, if you have a family history of stomach cancer, you should go easy on heavy salty foods, to improve your odds by an insignificant percentage.
naturally occurring nitrates and nitrites are used to fertilize natural organic plants and veg. So they are present in large numbers in the expensive organic health foods.
Please note that you should do your own readings and make up your own conclusion.
My conclusion is around moderation. everything dies eventually. so enjoy that salami and bacon if it makes you happy, but don't go all Elvis on it as a lifestyle.
If I was that worried about cancer in Southern California, where the smog air pollution is 10x the maximum limit for lung cancer, I'd move out to Montana.
However, given a choice, and no need for long term food preservation, without sacrificing flavor, opt for fresh food.
some people get headaches and migraines after eating a hotdog. its the salts and nitrates. but can also be dehydration.