General chemical structure of the<unk>  functional group<unk> s (also known as phosphate esters, or<unk> Es) are a class of organophosphorus compounds with the general structure O=P(OR)3, a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid. Like most functional groups<unk> s occur in a diverse range of forms, with important examples including key biomolecules such as DNA, RNA and ATP, as well as many insecticides, herbicides, nerve agents and flame retardants.<unk> Es have been widely used in various products as flame retardants, plasticizers, and performance additives to engine oil. The popularity of<unk> Es as flame retardants came as a substitution for the highly regulated brominated flame retardants. The low cost of production and compatibility to different polymers made<unk> Es to be widely used in different industries including textile, furniture, electronics as plasticizers and flame retardants. These compounds are added to the final product physically rather than by chemical bond. Due to this,<unk> Es leak into the environment more readily through volatilization, leaching, and abrasion.<unk> Es have been detected in different environmental compartments such as air, dust, water, sediment, soil and biota samples at higher frequency and concentration.
Organophosphate
Loline alkaloid
Antacid
Querulant
Detergent
Polychlorinated naphthalene
Alcohol 
Alkylphenol