I’ve seen people say many times that Neem fried their plants when they sprayed them with it. I used it when I received spider mite infested clones, and it worked well, and the plants seemed to love it. Since then I’ve used it weekly on everything, including clones and small seedlings, with no ill effect whatsoever. When I saw a few fungus gnats over the summer, I watered them with it as well which cleared the gnats up quick.
I love the stuff!
I did google harmful effects on humans as I had heard the same thing. Found a few articles about people drinking large quantities of it. Think they said she had injested 125 ml of it!!
I can’t imagine The 1tsp per litre of water sprayed on foliage I will never eat, or use in any way, can be too harmful