This is somewhat inaccurate as there is plenty of evidence that 90% of nitrosamines, are carcinogenic:-


http://en.wikipedia.org/wiki/Nitrosamine

http://www.ncbi.nlm.nih.gov/pubmed/19542621


Basically, nitrosamines are formed from nitrites, especially in the presence of heat(ie cooking) and acidic conditions, such as in the human stomach. Nitrosamines are not only found in cooked foods, but also in cigarette-smoke.

The notion that nitrates are harmless to humans appears to be somewhat unlikely, given:-

http://en.wikipedia.org/wiki/Nitrates#Human_health_effects

Interestingly, the authorities were aware of the dangers of nitrosamines in cooked bacon, so they greatly reduced the levels of sodium nitrite in bacon and added ascorbic acid to the mix which apparently counters nitrosamine formation to some extent:-

http://lpi.oregonstate.edu/f-w00/nitrosamine.html

Geoff.

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Most studies are flawed in they don't properly account for variables and co factors. MOST people who eat more processed meat probably eat flour with it and wash it down with soda. A paleo person will eat it with vegetables and more fat and protein. That would GREATLY affect how the liver would process out the toxins.
I am not advocating a diet dominated by processed meats. Fresh meat as the bulk of diet is obviously better. However, I really doubt that a paleo person is going to get any increased cancer rate with the consumption of Bacon.
-David