Yup. Just get rid of it. The new stuff is supposed to be more
environmentally friendly by not leeching the treating chemicals into
the soil; I guess by default this would make it more landfill-friendly.

On the other hand if you burn it, you will release these treating
compounds into the air floating on the ashes. There are some talented
chemists here that probably have worked out the new compounds formed
when burning/oxidation takes place, and could tell you what they were
as well as the level of toxicity.

But something intended as poisonous doesn't need to be inhaled by me no
matter what molecular changes have occurred in my fireplace. I say
toss it.

Robert