The second (and more important) reason processed meats are so strongly correlated with cancer is, I believe, the continued use of a cancer-promoting additive called sodium nitrite.
This ingredient, which sounds harmless, is actually highly carcinogenic once it enters the human digestive system. There, it forms a variety of nitrosamine compounds that enter the bloodstream and wreak havoc with a number of internal organs: the liver and pancreas in particular. Sodium nitrite is widely regarded as a toxic ingredient, and the USDA actually tried to ban this additive in the 1970's but was vetoed by food manufacturers who complained they had no alternative for preserving packaged meat products.
You can find sodium nitrite in nearly every packaged meat product imaginable. It's listed right on the label of products like bacon, breakfast sausage, beef jerky, pepperoni, sandwich meat, ham, hot dogs, and even the meats found in canned soups. If you and I walked into any grocery store in America, I could show you hundreds of products that contain this ingredient right now. And I believe this sodium nitrite is the primary cause of pancreatic cancer in humans who consume even moderate quantities of processed meats.
If sodium nitrite is so dangerous, why does the food industry use it? Simple: this chemical just happens to turn meats bright red. It's actually a color fixer, and it makes old, dead meats appear fresh and vibrant. Thus, food manufacturers insist on using sodium nitrite for the simple reason that it sells more meat products. Consumers are strongly influenced by the color of grocery products (which is why Florida oranges are often dipped in red dye, by the way), and when meat products look fresh, people will buy them, even if the true color of the months-old meat is putrid gray.
