Furans

A class of organic heterocyclic compounds regulated by the U.S. Environmental Protection Agency because of their toxic characteristics. Among other sources, furans can be produced as a byproduct in some pine tar distillation processes. Some derivatives of furans, such as furfuryl alcohol, tetrahydrofurfuryl alcohol, and tetrahydrofuran, are commercially important. Furans can be generated by the same combustion problems described for dioxins.