this shows you are an idiot.of cyanide poisoning. Sryince easily pierces plastic food wrappings. HOw many food items are in metal cans, hmm? HOw long before the rest of it ROTS, hmm? How you going to stop people from shopping? From poisoning food on the trucks, trains, in the warehouses? The ONLY way that they caught Thompson was he tried to extort money from Tylenol. He was only convicted of extortion, only served 80 months in Fed prison.
After they figure out where the poison came from - i.e. the food, they simply institute a "pen stock" situation. where you present your grocery list, and they pick the food for you and you pay. You don't get to handle anything other than what you bought. if you return something, they simply chuck it in the garbage.
You inconvenience them for about a week or two. It will, of course make things more expensive, but that would be about the extent of it.