Even though PCBs are no longer commercially produced in the United States, high levels of the chemicals remain in various parts of the country, in poultry, and in fish. This fact sheet will discuss what PCBs are, why they were so prominent, and why threats may still remain.
Radicals are a group of atoms that enter into and go out of chemical combinations without change.
A radical forms one of the fundamental constituents of a molecule. A biphenyl molecule is comprised of two benzene rings of hydrogen and carbon atoms. Benzene rings serve as the building blocks of petroleum, gasoline, and other fuels. These molecules are extremely flammable. By substituting chlorine for hydrogen atoms, the molecule becomes flame-resistant.