Can bees transfer plant toxins to honey?

Yes. I assume by toxins, we mean toxic to humans. Normally this only happens when the bees are solely using plants that are toxic to humans. Usually this is not case, but in some circumstances the toxins can build up in honey to levels that can become toxic to humans. Tutin, a toxin from the tutu plant is well known as a natural toxin in honey in some areas of New Zealand.