From the [url=http://www.fs.fed.us/t-d/pubs/htmlpubs/htm04232327/index.htm]Don't burn trash[/url] link:
[quote]Laboratory research has documented the emissions of some toxic air pollutants from burning wood. Many of these compounds are known to be carcinogenic to humans.[/quote]
They also found cadmium and mercury in campfire ash. After adding trash to their fires, they also found higher levels of these and beryllium and lead. The article writes:[quote]Many elemental metals occur naturally in the Earth's crust and in rocks. Small amounts of many of these metals are necessary to support life. But in larger amounts, they may be toxic.[/quote]
What are we supposed to do?
