I’m not so sure. Now, my degree is psychology, so no MD here, but most of the oils are pretty benign, and most are rated for topical treatment (and some, like Lemon or Tangerine are rated for ingestion).
If I check my bottle of Lemon Oil, the ingredients are Lemon. The Young Living Essential Oils don’t have any carrier oils, so that’s all you get.
The same for all their other EO. YL, and probably doTERRA don’t have any carrier oil at all, so there isn’t all of ingredients that can impact you. My wife usually uses coconut oils when she makes a mix to put on.
My wife has found that when she switch from scented candles to EO, she has felts a lot better. Scented candles used to give her a runny nose and a headache, so it’s been a nice change, since EO seems to not do that (especially peppermint, which I find, has been good when my stomach is upset). We also found that switching to the Young Living soap and laundry detergent had eliminated my eldest daughters eczema (I guess my daughter had sensitive skin). It likely that switch to any less harsh cleaning supplies would have done the same, but she was a fan of Young Living Brand and it worked.
Finally, I have to say, I like the Young Living Cleaning supplies, since it’s basically soap and EO. It’s a bit safer around the kids, especially compared to Windex or Bleach. I’m not as concerned about the girls trying to chug that stuff (which my parents have told me my older brothers did at that age because it was bright orange).
That being said, some of the essential oils are very bad for cats and other animals and there are a lot of cheaper oils that are mostly carrier oils.