Phosphate Esters

Phosphate esters (triaryl phosphates, triaryl/alkyl phosphates, trialkyl phosphates and trihaloalkyl phosphates) have been widely used since the 1940’s in industrial and consumer products as fire retardant plasticizers and as high temperature functional fluids. Use of fire retardants during the 1960’s and ‘70’s increased greatly because of the demand for improved fire safety in commercial products made from synthetic polymers [1, 2]. Triaryl phosphates (TArPs), triaryl/alkyl phosphates (TAr/AlPs), trialkyl phosphates (TArPs) and trihaloalkyl phosphates (THAPs) are incorporated at low part per hundred concentrations in flexible plastics such as polyvinyl chloride and polyurethane foams where they provide flame retardancy as well as acting as plasticizers. The need for fire resistant hydraulic fluids and lubricants has also created a demand for various TArPs [3]. Phosphate esters have been of toxicological interest since the 1930’s when outbreaks of polyneuritis in the United States were attributed to tri-ortho-cresyl phosphate, a component of tricresyl phosphate oil [4]. In the mid-1970’s tris(2,3-dibromopropyl) phosphate, a fire retardant in polyester fabrics, was demonstrated to be mutagenic and was banned for use in clothing in many countries [5]. Phosphate esters have also been suggested as replacements for polychlorinated biphenyls [6] which has stimulated interest in their environmental toxicology and chemistry.