Environmental pollutant arising from the degradation of nonionic surfactants in sewage Nonoxynol-9, one of the APEs, is used as a surfactant in cleaning and cosmetic products, and as a spermicide in contraceptives.; Nonylphenol is an organic compound of the wider family of alkylphenols. It is a product of industrial synthesis formed during the alkylation process of phenols, particularly in the synthesis of polyethoxylate detergents. Because of their man-made origins, nonylphenols are classified as xenobiotics. In nonylphenols, a hydrocarbon chain of nine carbon atoms is attached to the phenol ring in either the ortho (2), meta (3), or para (4) position, with the most common ring isomers being ortho or para (e.g. figure 1 para-nonylphenol). Moreover, the alkyl chains can exist as either linear n-alkyl chains, or complex branched chains. Nonylphenol is commonly obtained as a mixture of isomers, and is thus usually found as a pale yellow liquid at room temperature with a freezing point of -10°C and a boiling point of 295-320°C. However, pure isomers of nonylphenol crystallize readily at room temperatures and for example, para-n-nonylphenol, forms white crystals at room temperature.; Nonylphenol, and a related compound tert-octylphenol, were first detected as an air pollutant in New York City and New Jersey, probably due to its evaporation from the Hudson river and other smaller rivers in the region that routinely receive municipal wastewaters. It is possible that the atmosphere is a destructive sink for nonylphenol as it is probably reactive with atmospheric radicals and/or is photoactive.