In this context may also be relevant discussions among coffee enthusiasts who talk about this and that chemical process during the brewing process, lending it a bitter or rich taste – the coffee is full of chemicals.
I’m allergic to the word “chemicals” in discussions such as this, because it is too vague to define anything specific. It generally is used as a degradation of a thing that the speaker doesn’t like. But that’s all there is to it. The speaker can just as well say “I’m suspicious of this thing that you hold there”, and this communicates exactly the same thing, maybe with a bit more care about ones words.