Is Agave Sap Poisonous?

Q: Is the sap from an agave plant poisonous? My finger was stabbed by the tip
of a leaf a week ago and it still hurts! 

A: I can sympathize! A wound from an agave is almost guaranteed to
engender a loud swear word. Agave sap contains calcium oxalate, which
forms bundles of needlelike crystals called raphides. The sharp tip of an agave
leaf easily penetrates skin and immediately releases irritants that cause
immediate pain and long-lasting soreness. My agave-loving friend David
McMullin (newmoongardens.com) wears special puncture resistant gloves and
is extra careful where he backs up. He says the dead black tip of each leaf can
be removed with toenail clippers but be careful not to cut into the green part of
the leaf. Local gardening teacher Sally Elliott says she has a basketball-size
Queen Victoria agave, Agave victoriae-reginae, that is currently blooming on
a twelve-foot-tall stalk!