Difference between essential oils and other types of oils?

What is it about the production of essential oils that makes them not suitable for ingestion. I've heard that it's not recommendable that you dissolve even 1 drop into a bottle of water and drink it. I've heard you could get scarred if you use them on your skin. (Some are called "basic types"... show more What is it about the production of essential oils that makes them not suitable for ingestion. I've heard that it's not recommendable that you dissolve even 1 drop into a bottle of water and drink it. I've heard you could get scarred if you use them on your skin. (Some are called "basic types" like almond oil which are fine but others are stronger and shouldn't be abused with.) And at the same time there are cold-pressed oils that we generously pour onto our salads and are used in cosmetics. So, where does the difference come from?
Update: Wheat germ oil comes to mind. I've seen it in a tiny dark bottle that should be used for cosmetic purposes only. And I've seen it it huge bottles meant for cooking.
5 answers 5