Polystyrene safe for Tokays?

[D70Challenger]

Hello all,
So I just got my ExoTerra terrarium yesterday. It came with a polystyrene (that foam material made of tiny balls) background. I like the look of the background but I was not sure if 1) it was safe as it sits for their health? and then i have a followup question if it is safe, 2) If it is safe, would I be able to place a Under Tank Heater behind it? Or would that heat it up causeing it to release toxic fumes? Reason I would want to put it behind is that I dont want to have a big ugly UTH stuck on the side of the tank, I would rather hide it.
Thanks for all the input!

 

[Aimless]

the styrofoam will insulate the heat, and if it gets too warm you will definitely have toxic fumes.

have you considered a bulb from above? that's what I do for mine, you just need to make sure the fixture's small so you don't melt the plastic frame on top of the cage.

 

[Riverside Reptiles]

You can heat from above with a CHE on a thermostat and/or put your uth on the bottom of the enclosure (you should have your uth on a thermostat as well).