They may have been treated with creosote, chromated copper arsenate (CCA), or pentachlorophenol (penta). If you can detect the creosote, they probably weren't also treated with the other. I burned a pile of railroad ties that had been pulled out of landscaping, and the creosote was quite dense in some parts, not weathered away. Any wood smoke is somewhat toxic and I wouldn't recommend standing in it, but I certainly didn't get ill. Creosote burns very hot; it's what causes chimney fires and forms from a combination of wood smoke and moisture, and can burn at 2000 degrees. The wood preservative is distilled from coal tar. The good thing about it is that the fire and smoke don't linger as though you were trying to burn out tree stumps; it's fast and hot and is over quickly.

The EPA says not to burn creosote-treated wood, and that it should be put in a municipal dump, so presumably they think burying it in a landfill is better. They say the same thing about CCA. Penta, on the other hand, make contain dioxin and I don't how one would safely dispose of it.

Creosote:
http://www.epa.gov/pesticides/factsheets/chemicals/creosote_prelim_risk_assess.htm
CCA:
http://www.epa.gov/oppad001/reregistration/cca/cca_consumer_safety.htm

Here is a link that might be useful: Pentachlorophenol

DPallas...thanks for your reply...that is what we needed to know. I knew that someone here would know about it.

Jan

Jan- Creosote is like burning rubber tires. take them to a landfill.
And treated posts should go without saying. The tag on them at the stores states 'do not burn this wood'. Fire spreads the chemicals pretty far and the ashes are poisoned.
If you are trying to get rid of it, I'd try calling the local landfill or similar and ask. There is a way.

The regulations for organic farms suggests leaving treated posts in the ground, because removal causes more harm.

Thanks everyone for your info. These poles were short pieces that someone left at our campground for "us to burn"...we have removed them so none of the campers can get to them.

Jan

I burnd a small log size cut of one in my fire place.
Only part of it burned. Do I have something to worry about.
I did breathe in some of the direct smoke.

Bump. ^me too

Is the stub blackened before burning or greenish, lighter wood color? The dark one is probably creosoted, elderly pole. The lighter one was probably copper treated, like pressure treated wood. A quick call to the lumber yard might get information about what to do for breathing the treated wood smoke. This is because customers do burn it instead of sending it to a dump site. On the Creosote poles, you might look up information about treating victims of burning on the computer. Lots of old uses for creosote in the past, railroad ties, poles, fence posts, so I would think there is information available for treatment. Probably a bit won't kill you, but could cause problems. Just getting creosote on your skin will often burn it. We had special medication in our First Aid Kits for use after handling the poles into position, getting creosote on ourselves. As smoke in your lungs, it could do damage, but the Dr would be your best bet for that, to check you physically. There were elderly, usually thin poles, made of cedar, no preservatives on them. We still have some around here, over 40 years in use. Newer poles were bigger to handle wind and heavy wire, so they quit using the cedar.