They are amphipathic, meaning they have both hydrophilic and hydrophobic properties, which allows them to surround non-polar substances like oil and grease, isolating them from water.

[17] Another surfactant called nonoxynol, which was once used as intravaginal spermicide and condom lubricant, was found to metabolize into free nonylphenol when administered to lab animals.

[11] Nonylphenol is used in manufacturing antioxidants, lubricating oil additives, laundry and dish detergents, emulsifiers, and solubilizers.

[6] Nonylphenol is partially removed during municipal wastewater treatment due to sorption to suspended solids and biotransformation.

[19][20] Many products that contain nonylphenol have "down-the-drain" applications, such as laundry and dish soap, so the contaminants are frequently introduced into the water supply.

[6] Nonylphenol is considered to be an endocrine disruptor due to its ability to mimic estrogen and in turn disrupt the natural balance of hormones in affected organisms.

Concentrations of NP that inhibit reproductive development and function in fish also damages kidneys, decreases body weight, and induces stressed behavior.

[2] Nonylphenol was discovered to have hormone-like effects by accident because it contaminated other experiments in laboratories that were studying natural estrogens that were using polystyrene tubes.

[11] Subcutaneous injections of nonylphenol in late pregnancy causes the expression of certain placental and uterine proteins, namely CaBP-9k, which suggest it can be transferred through the placenta to the fetus.

[30] Growing embryos and newborns are particularly vulnerable when exposed to nonylphenol because low-doses can disrupt sensitive processes that occur during these important developmental periods.

[31] Prenatal and perinatal exposure to nonylphenol has been linked with developmental abnormalities in adipose tissue and therefore in metabolic hormone synthesis and release (Merrill 2011).

Specifically, by acting as an estrogen mimic, nonylphenol has generally been shown to interfere with hypothalamic appetite control.

[30] Nonylphenol has been shown mimic the action of leptin on neuropeptide Y and anorectic POMC neurons, which has an anti-obesity effect by decreasing eating behavior.

[32] On the other hand, nonylphenol has been shown to increase food intake and have obesity enhancing properties by lowering the expression of these anorexigenic neurons in the brain.

[33] Additionally, nonylphenol affects the expression of ghrelin: an enzyme produced by the stomach that stimulates appetite.

Thus, acting as an estrogen mimic, prenatal and perinatal exposure to nonylphenol has been shown to increase appetite and encourage the body to store fat later in life.

[35] Finally, long-term exposure to nonylphenol has been shown to affect insulin signaling in the liver of adult male rats.

Some argue that nonylphenol's suggested estrogenic effect coupled with its widespread human exposure could potentially influence hormone-dependent breast cancer disease.

For example, food samples were found with concentrations ranging from 0.1 to 19.4 μg/kg in a diet survey in Germany and a daily intake for an adult were calculated to be 7.5 μg/day.

[38] Another study calculated a daily intake for the more exposed group of infants in the range of 0.23-0.65 μg per kg bodyweight per day.

[40] This is a large problem because breast milk is the main source of nourishment for newborns, who are in early stages of development where hormones are very influential.

Elevated levels of endocrine disruptors in breast milk have been associated with negative effects on neurological development, growth, and memory function.

[6] There are standard GC-MS and HPLC protocols for the detection of nonylphenols within environmental sample matrices such as foodstuffs, drinking water and biological tissue.

[47] Because stereochemical factors are thought to contribute to the biological activity of nonylphenols, analytical techniques sensitive to chirality, such as enantioselective HPLC and certain NMR protocols, are desirable in order to further study these relationships.

In other Asian and South American countries nonylphenol is still widely available in commercial detergents, and there is little regulation.