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Polyhalogenated compounds (PHCs) are any compounds with multiple substitutions of halogens. They are of particular interest and importance because they bioaccumulate in humans, and comprise a superset of which has many toxic and carcinogenic industrial chemicals as members. PBDEs, PCBs, dioxins (PCDDs) and PFCs are all polyhalogenated compounds. They are generally non-miscible in organic solvents or water, but miscible in some hydrocarbons from which they often derive.
PHCs are used in a vast array of manufactured products, from wood treatments, to cookware coatings, to non-stick, waterproof, and fire-resistant coatings, cosmetics, medicine, electronic fluids, food containers and wrappings, in everything from furniture and furnishings, automobiles, airplanes, plastics, clothing and cloth, surgery, insulation, adhesives, paints, sealants, lubricating oils, polyurethane foams, cancer therapy and medical imaging. They are also heavily used in pest control.
- Polycholorinated, e.g. PCBs, dioxins (PCDDs), hexachlorophene, dibenzofurans (PCDFs), polychloro phenoxy phenols (PCPPs), polychlorinated diphenyl ethers (PCDEs).
- Polybrominated, e.g., PBDEs, polybrominated biphenyls (PBBs).
- Perfluorinated compounds
- Polyiodinated compounds
Breakdown of compounds
Despite bioaccumulating in humans, patents have been filed for removal of halogen by electrolysis during manufacturing, though toxic chlorinated compounds may be created as byproducts of chlorinated compounds. Another method during manufacture is to use anaerobic bacteria 
- US Patent 4585533 - Removal of halogen from polyhalogenated compounds by electrolysis Archived 2011-06-12 at the Wayback Machine
- Wackett, Lawrence P.; Sadowsky, Michael J.; Newman, Lisa M.; Hur, Hor-Gil; Li, Shuying (1994). "Metabolism of polyhalogenated compounds by a genetically engineered bacterium". Nature. 368 (6472): 627–629. Bibcode:1994Natur.368..627W. doi:10.1038/368627a0. PMID 8145847. S2CID 4315658.