Chemicals

Random thought: "chemical" has a negative association for people because the only time we hear it, growing up, is in the context of "cleaning chemicals". So, people grow up with an "ugh" reflex for the word, because they think: "I don't want bleach/detergent/409/whatever in my FOOD! Gross!", followed by post hoc rationalization.

That, or physics is awesome and chemistry sucks.