I've avoided plants with livertoxic PAs for years.
Livertoxic pyrrolizidine alkaloids (PAs) are insidious. Devious. They will give you a silent disease.
You won't even know you're ill until your liver is over the hill.
So the trouble with livertoxic PAs is, you don't get adverse effects reports. You can tell you have the problem if you do a liver biopsy, but how often do you see those done? Or you can see the trouble if you do an autopsy, but you're not all that likely to order a liver autopsy, either: it's "well, aunty was poorly, may she rest in peace".
The biopsy or autopsy would have shown veno-occlusive liver disease, if you've ingested enough livertoxic PAs. This is a disease which you cannot get in any other way. The usual herbalist's defense of "well, it was the meds, not the herbs", is invalid with veno-occlusive liver disease. It's the herbs, every time.
Livertoxic pyrrolizidine alkaloids are catalysts, and therefore dangerous in very small doses. One molecule will destroy many liver cells.
And that's not all. Healthy liver cells will try harder with livertoxic PAs, and therefore a healthy liver will be damaged more by livertoxic PAs.
There's nontoxic PAs, too. For instance, Echinacea contains nontoxic PAs.
I've avoided plants with livertoxic PAs for years, and will continue to do so. That's almost all if not all plants in the Boraginaceae including borage (Borago officinalis), comfrey (Symphytum spp.), lungwort (Pulmonaria spp.), and some plants in the Asteraceae, including coltsfoot (Tussilago farfara, Petasites spp.), and various senecios, to mention a few. A list of European plants which contain livertoxic PAs can be found here.