tricresyl

Tricresyl, more commonly referred to as tricresyl phosphate (TCP), is a family of organophosphate esters derived from cresyl alcohols. The term covers a class of triaryl phosphates in which three cresyl groups (from ortho-, meta-, and/or para-cresol) are bound to a central phosphate. The most hazardous member is tri-ortho-cresyl phosphate (TOCP). The generic compound has the formula C21H21O4P and a molecular weight of about 368 g/mol. TCPs are typically colorless to pale yellow, viscous liquids that are poorly soluble in water but highly soluble in organic solvents.

Production and use: TCPs are produced by esterification of cresyl alcohols with phosphorus oxychloride or related phosphorus reagents, followed by hydrolysis and purification. They have historically been used as plasticizers for polyvinyl chloride (PVC) and as components in various lubricants, hydraulic fluids, and flame-retardant formulations. Due to toxicity concerns, many applications have declined or become subject to regulatory controls, and consumer-product uses have diminished in favor of safer alternatives.

Toxicology: TCPs are organophosphates and can inhibit acetylcholinesterase. TOCP, in particular, is a potent neurotoxin and has been linked to organophosphate-induced delayed neuropathy (OPIDN) in both animals and humans. Acute exposure can produce cholinergic symptoms, while delayed neuropathy may develop days to weeks after exposure. Because of these risks, handling of TCPs requires appropriate safety controls, and certain uses are restricted or regulated in many jurisdictions.

Environment and regulation: TCPs are lipophilic and can persist in the environment, with a tendency to accumulate in soils and sediments. Due to toxicity concerns, regulatory agencies typically impose labeling, exposure controls, and restrictions on certain TCP applications and releases.