Your anecdote sounds more likely a result of improper preservation than anything else, since it's unlikely everyone present would have had an intolerance. The a

Your anecdote sounds more likely a result of improper preservation than anything else, since it's unlikely everyone present would have had an intolerance. The author of the page you linked also seems to imply that their reaction was somehow specifically due to the annonacin, however I think a food allergy/intolerance is more likely (many people are allergic to citrus, or other tree fruit, for example). Annonacin toxicity is certainly a concern and effects of long-term exposure are not well understood, however the population from the most frequently cited study (namely, the well-known Guadeloupe study) also regularly consumed tea made from the leaves and bark of the tree which contain significantly more annonacin than the fruit -- in addition to eating several serving of the fruit nearly every day. I think for most, having a pawpaw every now and then will not do any harm. That being said, it is good to use a little caution when trying a new family of fruit (or plant in general) since you could be unlucky enough to have a reaction.