Your definition "1" describes just about anything. Water, for example, produces a chemical effect. So do amino acids. Your entire metabolism is a chemical proce

Your definition "1" describes just about anything. Water, for example, produces a chemical effect. So do amino acids. Your entire metabolism is a chemical process, as is the growth of plants. What I think that people mean when they talk about "chemicals" in their food is artificially synthesized chemicals and that's easy enough to say.