Palythoa toxin has been found to be one of the most deadly toxins in the animal kingdom, but the extremely potent zoanthids are not usually available to hobbyists. That being said, protopalys of all types (zoanthids that slime) can present a problem if the slime is taken into an open wound. Especially if the person exibits an alergy to the toxin.
Just take precautions when handleing zoanthids of all types. Use rubber gloves esp. when fragging.
And that being said, you should also take precautions when placing your hand in a tank with lionfish, touching anemones and bubble corals (some pple are suseptable to inflamation and other symtoms with various corals), don't handle rattlesnakes, pet stray dogs, drive while intoxicated, eat chicken that has not been handled/cooked properly, breath the air in large cities, eat potato chips, smoke cigs, talk on the phone or be on the PC during lightening storms just to name a few of the dangers that man faces in his daily adventures while living on this planet.