Putting it in food allows perfect tracing when the stuff is uncovered. You could see when and where it was made, who was responsible and so on, and eventually you could charge someone with gross negligence at least. This way whatever it is they are spraying can be blamed on anything. They could always say: "It wasn't me".
Almost no one knows what's in those chemtrails, which is why they are doing it to themselves and their children. They think it's largely harmless as there are no immediate visible and perceptible effects. Those who know, they are nowhere near chemtrails.
Bottom line: make sure you have a damn good hepa air filter running and don't spend time outside when you see chemtrails.