In my other lfe before "inspectin" 25 years ago I used to buy and sell - after a "real" retrofit of the home as opposed to the newer contractor splash and dash types out there now. I had an old gentleman that would replaster the entire residence using the old Keanes Cement instead of the new Imperial Coat. Hand mixed on the front porch in a wheelbarrow! He had been plastering over both lath and sheetrock for 60 years (was he ever good!) He told me that they used horse hair in plaster and sheetrock to give it rigidity - grey board had the least, green board a little more, and brown board the most. As far as arsnic went, he never mentioned it as an added component. My feeling is that if arsnic was present it was there as a by product. Besides, when you are a young contractor who cares about a little arsnic in the plaster, asbestos in the flooring, lead in the paint? If I were a young dumb buyer and considering an older home this article would probably keep me from entering into the contract as I would probably be dead or bankrupt shortly after moving in! As for the article - he makes it sound like all older homes should be donated to the fire department.