So my question is, are these natural toxins, in some cases, just as bad (or worse) than synthetic pesticides?[/quote]
Yes. Some plant toxins have been rejected for use as pesticides because they are too dangerous for humans. Here are two examples:
My friend’s father nearly died and suffered permanent brain and liver damage from toxins in artemesia (wormwood) he was taking as a supplement because he believed it was ridding him of parasites and destroying cancer cells. The toxin in wormwood is thujone. Thujone is a volatile organic compound (VOC) also present in herbs such as sage and oregano. In fact, a certain amount of air-polluting VOCs are emitted from California sage bush here in southern CA.
Thujone does kill parasites and cancer cells, as well as insects, but the problem is it will also kill basically any living cell. (A healthy person’s liver will detoxify a small amount in a few minutes, though.)
Another highly toxic chemical, though I forget the name off the top of my head, is produced by walnut trees, and is contained in walnut shells. Apparently walnut trees will tend to have bare ground all around them, from their natural toxin killing off nearby plant competitors. Walnut shells used in horse bedding cause horrible skin ulcers in the horses. Nasty stuff.
So the truth is that plants can contain and emit toxic substances. The whole idea that something is automatically good and wonderful if it occurs in nature, but automatically horrible and dangerous if it’s “synthetic” is completely false. EVERYTHING is a chemical made up of molecules; every molecule, when taken into the body, has a certain effect on the body. The body neither knows nor cares whether the molecule was synthesized by a plant or by a laboratory.