Furans are by-products of natural and industrial processes and are considered environmental pollutants. They are chemical substances found in small amounts in the environment, including air, water and soil. They are also present in some foods. Although the amounts are small, they are persistent and remain in the environment for long periods of time, also accumulating in the food chain. The U.S. Environmental Protection Agency's (EPA) Persistent Bioaccumulative and Toxic (PBT) Chemical Program classifies furans as priority PBTs.

Furans belong to a class of organic compounds known as heterocyclic aromatic hydrocarbons. The basic furan structure is a five-membered ring consisting of four atoms of carbon and one oxygen. Various types of furans have additional atoms and rings attached to the basic furan structure. Some furans are used as solvents or as raw materials for synthesizing chemicals.

Polychlorinated dibenzofurans (PCDFs) are of particular concern as environmental pollutants. These...