A mixture of synthetic solids, containing three or more bromine atoms, that is virtually insoluble in water but is soluble in fat and various organic solvents. There are 209 different molecular combinations, or congeners, that are possible for polybrominated biphenyls. These mixtures are no longer used or produced in commercial quantities in the United States. Residues remaining in and around plants that formerly manufactured, processed or produced products using polybrominated biphenyls are the current sources for human exposure. The primary routes of potential human exposure to polybrominated biphenyls are ingestion, inhalation, and dermal contact. A commercial mixture of these compounds is reasonably anticipated to be a human carcinogen. (NCI05)

Biphenyl compounds which are extensively brominated. Many of these compounds are toxic environmental pollutants.