Regarding working with ACQ pressure treated wood, (the chemical compound that replaced the one that contained arsenic,) the EPA says :
"After working with wood, wash exposed skin thoroughly.
Wash work clothes separately from other household clothing to avoid cross-contamination. "
From that caution, might you be safe if you put little booties on your chickens' feet before tucking them in for the night? After all, as I said, they're in constant contact with this wood for a third of their lives.
A major component of ACQ is copper which is a fungicide and is very corrosive (hence the need for galvanized or stainless steel fasteners to avoid corroding ordinary fasteners.) The other component is quaternary ammonium which acts as an insecticide.
I haven't seen any research on the effects of exposing a chickens feet to these chemicals for 8 to 10 hours a day but I'm pretty sure the folks that will tell you they use it all the time do not sleep with it strapped to the soles of their feet every night of their lives.
Did I miss the reason why the original poster feels it is necessary to use it as a roost?
Wayne