You're correct, DonkeyHody, wood is naturally anti-bacterial. It is the best cutting board surface for this reason! For links to some relevant scientific proof of this, go to my blog post: "Cutting Boards: What Kind Do You Want?"
OPG3, I've checked the toxicity of each of the species of wood that I use, including purpleheart. It's certainly true that purpleheart is a "sensitizer," meaning that it and many exotic hardwoods can lead to an allergic reaction through persistent contact with the wood, and, especially, the sawdust of the wood. HOWEVER, there is no evidence that this species can cause an allergic reaction through either food contact or contact with the finished wood. It's used for furniture world wide, for example. I've actually received this caution before ... and can't find any scientific proof of toxicity beyond the common admonition to be careful while working with the wood.
Billy Boy, we're going to respectfully disagree on the proper surface treatment for a cutting board. I use mineral oil specifically as it is both shelf stable and will not go rancid. Hemp oil is neither of those, and has a relatively short shelf life according to Mrs M (my wife!), who uses hemp oil in some of her small batch lotions & balms. Mineral oil is FDA approved for human consumption, and that's the gold standard for me.
My current plan is to treat the underside of this board with Good Stuff
, which is a treatment for wooden counters that is FDA approved for food contact. This is a urethane that is water proof, and should provide better protection for the wood in the hot/wet environment it's going to be in. I'm also going to admonish the homeowner to sterilize the counter opening that appears to have a mold infestation and not put a wet board back into that opening. Finally, I'm going to give them my board care kit, which includes mineral oil and Mrs M's own board butter (locally harvested beeswax + mineral oil) so that they can keep the board well oiled & protected from water damage.
Make sense? Anyone?