Then recommended reading would be "Germs" (Biological Weapons and America's Secret War) by Judith Miller, Stephen Engelberg and William Broad. One bio attack on food that is documented in this book, happened in September 1984 in Wasco County, Oregon. Followers of a Rajhneeshees cult leader purposely poisoned townspeople in ten restaurants and a supermarket with Salmonella typhimurium. They also boasted about similar attacks in Salem, Portland and other Oregon cities.
We went to a Mexican restaurant a couple of weeks ago. I watched a middle aged man stand at the salsa bar for about ten minutes with his back to us. The same thoughts raced through my mind. Once it happens to you or near where you live, you don't forget.