I think Bookertoo is absolutely right.
Free availability is, as Victoria says, no guarantee of safety. Yes there certainly are products which were said to be harmless and then have proved otherwise.
A modicum of sense and careful usage tho should do away with most people's worries. There is no 100% guarantee to life and limb and nor should we expect it.The number of posters worried about growing plants with a reputation for toxicity are increasing - we all seem to be frightened to do or use anything these days and rely on "Government" to tell us what is good, or not so good, for us.
Yes, there are dangers lurking - a walk in the countryside, crossing a busy road,
If you applied the "if you don't know what it is, don't use it " I can see most processed/fast food going down the toilet - before consumption I should add.......... not a bad thing overall