Hardibacker toxic when heated?

I am putting in a wood stove and bought some Hardibacker to use as wall protection. I plan to cover it with 1/4 in slate tile. I have never used Hardibacker before, and noticed that it has a distinct smell, the car still smells of it. I believe it has some mold preventative chemicals and whatever they use in cement. I plan to space it out an inch from the wall to create a convection space. My concern is that heat and hot air circulating will promote off-gassing of chemicals from the Hardibacker throughout our 500 sq ft one-room cabin. Am I being unreasonably worried? I haven't put up the wall protection yet and have thought about just returning the Hardibacker and using sheet metal instead. I would want to paint the metal to match the walls though, which brings up the question of off-gassing of chemicals in the paint. Anybody have any ideas on which option would be better? I used concrete board for the hearth pad, and didn't like having carcinogenic dust in our place. This experience has me wondering if there are completely natural ways to accomplish heat protection for a wood stove.

Here's a link to the manufacturer's safety data:
http://www.jameshardie.com/pdf/msds-interior-medium-density.pdf

They give lots of warnings about breathing in silica dust from cutting, but nothing about off-gassing.

While ideally I would like the most low tech/DIY solution, I came across this stuff, which is probably has a lot more of an eco lifecycle:
http://www.greeneboard.com/index.html

Safety data:
http://www.greeneboard.com/pdf/MSDS2010.pdf

You don't have to worry about off-gassing, the rest of the house will be burning first.

It is not the greenest product, but it works and lasts forever and less embodied energy than anything but site sourced cob. Even site sourced rock has more energy in the mortar in most installations.