Tris(2-chloroethyl) phosphate (TCEP) is an organophosphate flame retardant that has been widely used in a variety of materials to reduce flammability and slow the spread of fire. It is a colorless to pale-yellow liquid with low volatility and good compatibility with many polymers. Because of its chlorine and phosphorus content, TCEP can interfere with the combustion process, making it effective in meeting certain fire safety standards.

TCEP has been used primarily as an additive flame retardant in flexible and rigid polyurethane foams, polyester resins, polyvinyl chloride (PVC), epoxy resins, and other plastics and rubbers. It can also function as a plasticizer, improving flexibility and processability while providing flame resistance. Common applications have included furniture and automotive upholstery foams, insulation materials, coatings, sealants, and some textiles. In the past, it was also used in electronics, construction products, and various consumer goods where enhanced fire performance was required.

Despite its effectiveness, TCEP has raised increasing concern because of its toxicological and environmental properties. It is relatively persistent, can leach from treated materials, and has been detected in indoor air, house dust, and various environmental media. Studies have shown that TCEP exhibits neurotoxic and reproductive toxicity in experimental animals, and there is evidence of potential carcinogenicity. It can cross biological membranes and has been found in human tissues and fluids, indicating exposure through inhalation, ingestion of dust, or contact with treated products.

Due to these concerns, regulatory authorities in several regions have taken action to restrict or discourage the use of TCEP, especially in products that may result in high exposure for vulnerable populations such as infants and children. It has been listed as a substance of very high concern in some jurisdictions, and its use in toys, children’s articles, and certain consumer products has been prohibited or strongly limited. These measures have encouraged the substitution of TCEP with alternative flame retardants considered to have more favorable health and environmental profiles.

At the same time, the phase-out of TCEP highlights the ongoing challenge of finding flame retardant systems that provide sufficient fire protection without creating new risks. Research has expanded into halogen-free and reactive flame retardants, as well as into material design strategies that inherently improve fire performance, such as intumescent systems and polymer modifications. Nevertheless, legacy use of TCEP in existing products and buildings means that exposure and environmental release will continue for some time, making monitoring, risk assessment, and proper end-of-life management important aspects of chemical safety policy.