R,R'=CnH2n+1; n=4-15
Phthalates are a group of chemical compounds that mainly used as plasticizers -- substances added plastics to increase their flexibility. They are chiefly used turn polyvinyl chloride from a hard plastic into a flexible plastic.
Phthalates, also known as phthalate esters, are the dialkyl or alkyl aryl esters of 1,2-benzenedicarboxylic acid. When added to plastics, they allow the long polyvinyl molecules slide against one another. About one billion pounds of them are produced each year. They are colourless, odourless liquids produced by reacting phthalic anhydride with an appropriate alcohol (usually 6 to 13 carbon). The most widely used phthalates are di-2-ethyl hexyl phthalate (DEHP), diisodecyl phthalate (DIDP) and diisononyl phthalate (DINP).
Phthalates are controversial because many phthalates have shown hormonal activity in animal studies. Studies on animals involving large amounts of phthalates have shown damage to the liver, the kidneys, the lungs and the developing testes. Since phthalate molecules are not chemically bound to the polymer, a significant migration is possible. The plastics industry insists that phthalates pose no risk to humans because of the small amounts of phthalates that people are exposed to.
Other uses for phthalates include in nail polish, adhesives, caulk, and paint pigments.