I can buy some of that. Burn pits in active war zones are a known source of cancer, half being in a constant vicinity of something burning and the other half being the properties of the aerosols produced by the thing being burned. That's to say, if the wood is treated it'll be more dangerous than seasoned wood.

When a family member was diagnosed with cancer I was warned heavily about the difference between cooked meat and charred meat. Charring is linked to cancer where cooked meat is a bit more up in the air.