Junk Food - would you knowningly eat a poison?

The following are some commonly purchased foods and their ingredients. All 3 companies list their ingredients panels as chemical names (not numbers) so normally you would see a string of numbers. Do these ingredients have health effects? Of course. Down the bottom I have put a link to the safety data listed for one of the ingredients : sodium acid pyrophosphate. It actually lists it as poisonous if ingested! All have been cut and paste sections direct from their websites.
KFC
Gravy
Food Starch-Modified, Maltodextrin, Enriched Wheat Flour (Niacin, Reduced Iron, Thiamine Mononitrate, Riboflavin, Folic Acid), Chicken Fat, Wheat Flour, Salt, Partially Hydrogenated Soybean Oil, Monosodium Glutamate, Dextrose, Palm And Canola Oils, Mono and Diglycerides, Hydrolyzed Soy Protein, Natural and Artificial Flavor (With Hydrolyzed Corn Protein, Milk), Caramel Color (Treated With Sulfiting Agents), Onion Powder, Disodium Inosinate, Disodium Guanylate, Spice, Spice Extractives, With Not More Than 2% Silicon Dioxide Added As An Anti-caking.
Contains Milk, Wheat and Soy.
OR
Wheat Flour, Modified Corn Starch, Monosodium Glutamate, Salt, Dextrose, Soybean Oil, Onion Powder, Spice, Caramel Color, Torula Yeast, Hydrolyzed Soy Protein, Turmeric, Autolyzed Yeast, Oleoresin Paprika and Natural Flavoring.
Contains Wheat and Soy.
*Will contain one of the Ingredient statements above, depending upon regional suppliers
KFC® Grilled Chicken
Fresh Chicken Marinated With: Salt, Sodium Phosphate, and Monosodium Glutamate. Seasoned With: Maltodextrin, Salt, Bleached Wheat Flour, Partially Hydrogenated Soybean and Cottonseed Oil, Monosodium Glutamate, Secret Kentucky Grilled Chicken Spices, Palm Oil, Natural Flavor, Garlic Powder, Soy Sauce (Soybean, Wheat, Salt), Chicken Fat, Chicken Broth, Autolyzed Yeast, Beef Powder, Rendered Beef Fat, Extractives of Turmeric, Dehydrated Carrot, Onion Powder, and Not More Than 2% Each of Calcium Silicate and Silicon Dioxide Added As Anticaking Agents.
Contains Wheat and Soy.

Subway
9-GRAIN WHEAT Enriched wheat flour (wheat flour, barley malt, niacin, iron, thiamin mononitrate, riboflavin, folic acid), water, yeast, high fructose corn syrup, whole wheat flour, wheat gluten, contains 2% or less of the following: oat fiber, soybean oil, salt, wheat bran, rolled wheat, rye nuggets, dough conditioners (DATEM, sodium stearoyl lactylate), yeast nutrients (calcium sulfate, ammonium sulfate), degermed yellow corn meal, rolled oats, rye flakes, caramel color, triticale flakes, parboiled brown rice, refinery syrup, honey, barley flakes, flaxseed, millet, sorghum flour, azodiacarbonamide, natural flavor (maltodextrin, natural flavor, silicon dioxide, lactic acid). Contains wheat.
MacDonalds
French Fries:
Potatoes, vegetable oil (canola oil, hydrogenated soybean oil, natural beef flavor [wheat and milk derivatives]*, citric acid [preservative]), dextrose, sodium acid pyrophosphate (maintain color), salt. Prepared in vegetable oil (Canola oil, corn oil, soybean oil, hydrogenated soybean oil with TBHQ and citric acid added to preserve freshness). Dimethylpolysiloxane added as an antifoaming agent.
CONTAINS: WHEAT AND MILK *(Natural beef flavor contains hydrolyzed wheat and hydrolyzed milk as starting ingredients).
Look at this link for Sodium Acid pyrophosphate.
http://www.sciencelab.com/xMSDS-Sodium_acid_pyrophosphate-9924954