Nitrosamines (a known carcinogen) found and consumed in regular and high quantities of processed meats (as sodium nitrate and sodium nitrite) can increase risk of stomach and pancreatic cancers by 67%. Specific carcinogenic qualities of nitrosamines are increases when exposed to carbonization by application to heat sources (direct and indirect such as frying, toasting or baking).

http://chemicallypure.com/nitrosamines

http://www.ncbi.nlm.nih.gov/pubmed/16550597 http://www.ncbi.nlm.nih.gov/pubmed/16865769