Alkylphenols 

Alkylphenols are industrial chemicals used in the production of detergents and other cleaning products, and as anti-oxidants in products made from plastics and rubber. They are also found in personal care products, especially hair products, and as an active component in many spermicides.  In the Silent Spring Institute study of contaminants in samples from homes, alkylphenols — especially 4-nonylphenol (4-NP) and its breakdown products — were found in all samples of house air and 80 percent of house dust samples. Substantial concentrations of these chemicals have also been found in wastewater associated with domestic sewers and municipal landfills. 

The alkylphenols, including 4-NP, have been shown to mimic the actions of estradiol, mediating their effects through the cellular estrogen receptor (ER). They also bind to the newly described cell membrane ER and mimic cellular signaling responses usually controlled by estradiol.

Prenatal exposure of rats to 4-NP causes altered development of the mammary gland, as well as changes in steroid receptor populations in several reproductive tissues. A recent study showed that treatment of mice with 4-NP led to an increased synthesis of estriol, a weak natural estrogen, by the livers of the treated animals. When compared with mice treated with equivalent amounts of estradiol, the mice exposed to 4-NP had an increased risk of mammary cancer.

See below for a table of air pollutants, including alkylphenols, linked to increased breast cancer risk. A PDF of this table is also available.

Learn more about policy and research recommendations to reduce exposure to air contaminants »

For references, see State of the Evidence 2008.