http://pubs.acs.org/doi/full/10.1021/tx2003118 - OK, that one is regarding Nitrite reactions to form Nitrosamines, not Nitrates
http://www.wjgnet.com/1007-9327/full/v12/i27/4296.htm - that one is the same
http://www.nature.com/bjc/journal/v106/n3/full/bjc2011585a.html - quote from this study "A prospective study found that men in the highest quintile of summed nitrate/nitrite intake from processed meat had a nonsignificantly elevated risk of pancreatic cancer (hazard ratio=1.18, 95% CI=0.95–1.47; Aschebrook-Kilfoy et al, 2011)."
http://www.nature.com/news/red-meat-wrong-bacteria-bad-news-for-hearts-1.12746 - no mention of nitrate in this one
http://www.nature.com/news/2005/050110/full/news050110-7.html - conjecture, not proof - "Researchers are not yet clear which ingredient of meat might trigger cancer. Possible culprits include iron, toxins formed during cooking or the nitrates and nitrites used to preserve processed meats."
http://onlinelibrary.wiley.com/doi/10.1002/ijc.22170/abstract - again, no mention of nitrates
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020456 - again, conjecture, not proof "Nitrites or nitrates added to meat for preservation could increase exogenous exposure to nitrosamines, N-nitroso compounds, and their precursors; meats cured with nitrite have the same effect as fresh red meat on endogenous nitrosation"
The original post suggested eco options for food preservation. I have myself looked at certain options, such as flavinoids as antioxidants, but because of the ph sensitivity and compatibility issues, they only work on things such as citrus-derived products, which is their provenance in any case. I'd be delighted to hear about any 'eco' preservatives that are, as the original poster averred,
"...very rare and very hard to find in the stores". To be fair to the original poster, they seemed to be a little confused between the difference between nitrates and nitrites, E250 being nitrite, not nitrate as originally posted. My response was on the basis of nitrate, not nitrite. If the poster
meant nitrite, then I agree to some degree - being an oxygen scavenger to form nitrate and hence an antioxidant, it serves a role in keeping meat pinky, and a secondary role against certain organisms. In various formulations over the years I have not been able to use nitrites in formulations with amine and amine derivatives precisely because of the possibility of nitrosamine formation. If you
do eat meat, then it's probably sensible to avoid preserved or cured meats and avoid the risk.
P.