Pentachlorophenol (CED0000031)

Pentachlorophenol (C6HCl5O) is a solid organic compound with an average molecular weight of 266.34 g/mol. Pentachlorophenol belongs to the halophenols, a subclass of phenols within the organic compounds. This exogenous compound is classified as a benzenoid and is utilized industrially as a pesticide (PMC11411717), biocide, fungicide (PMC7009407), and degradant/impurity. Environmentally, it is recognized as a persistent organic pollutant (PMC11049475), and biologically it serves as an inhibitor (PMC3985935) and human xenobiotic metabolite. Exposure occurs via oral, inhalation, and touch routes, with recorded sources including drinking water, building and construction materials such as floors and roofs, food processing, household cleaning products, electrical and electronic equipment, and various household items. It is present in polyethylene terephthalate but not detected in polycarbonate. The compound acts on numerous protein targets. It inhibits phenol-sulfotransferases, including SULT1A1 and SULT1A3, and inhibits acetylcholinesterase in erythrocyte membranes. Pentachlorophenol disrupts thyroid homeostasis by competing for thyroxine binding sites on SERPINA7 and competing with thyroxine for uptake into cerebrospinal fluid at the T4 binding site of transthyretin. It further inhibits O-acetyltransferases, such as CRAT and CHAT. As an organochloride, it inhibits Na+/K+ ATPase and Ca2+ and Mg2+ ATPase (including ATP1A1, ATP1A2, ATP1A3, and FXYD2), leading to intracellular free calcium ion accumulation and subsequent central nervous system stimuli propagation. It also inhibits mitochondrial ATP-ase activity via ATP4A and ATP4B, preventing ATP formation. Additionally, it antagonizes GABA-A receptors (including GABRA1, GABRA2, GABRA3, and GABRA4), blocking chloride ion uptake and causing central nervous system hyperexcitability. Health effects associated with pentachlorophenol include lymphoma (PMC5453502, PMC6625894) and an increase in non-Hodgkin lymphoma (PMC10598475).