In searching for tips on not killing poinsettia plants, I found The Poinsettia Pages from the University of Illinois.  They provide this helpful bit of trivia:

A study at Ohio State University showed that a 50 pound child who ate 500 [leaves] might have a slight tummy ache.

I’m glad someone finally researched that!  I’ve been asking for years.  However, how did the study show that, exactly?