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Polybrominated Diphenyl Ethers


Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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CATEGORY*: Endocrine disruptor

FOUND IN: Hair products, spermicides, cleaning products and detergents, indoor air and dust

THE GIST: Alkylphenols are industrial chemicals used in the production of detergents and other cleaning products. They're also found in personal care products, especially hair products, and are an active component in many spermicides. Alkylphenols are endocrine disruptors that have been shown to alter mammary gland development in rats.

The State of the Evidence on Alkylphenols

Alkylphenols are industrial chemicals used in the production of detergents and other cleaning products, and as antioxidants 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. As such, people are exposed to these compounds in a variety of ways, including through the skin and from contamination of both air and water.


Choose household cleaning products that fully disclose all ingredients and seek out safety ratings for these products. Avoid products that contain alkylphenol ethoxylates (found in some detergents and stain removers).

More healthy home tips >

In the Silent Spring Institute study of household contaminants, 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 (Rudel, 2003). Substantial concentrations of these chemicals have also been found in wastewater associated with domestic sewers and municipal landfills (Slack, 2005; Swartz, 2006).

NHANES data examining chemical levels in urine of American adults found 4-NP in 51 percent of samples evaluated (Calafat, 2005). Similar results were found in blood serum samples of nursing Swedish women three weeks after they had given birth (Gyellenhammar, 2012), and significant levels of both 4-NP and 4-octylphenol (4-OP, another alkylphenol) were found in breast milk samples from Taiwanese women (Chen, 2010).

The alkylphenols, including 4-NP, have been shown to mimic the actions of the natural estrogen estradiol, with their biological effects being regulated by interactions with the cellular estrogen receptor. They also bind to the cell membrane estrogen receptor and mimic cellular signaling responses usually controlled by estradiol (Thomas, 2006). In a study examining the effects of 4-NP in human breast tumor cells (MCF-7 cells) in vitro, changes in gene expression were observed in several genes involved in cell proliferation, DNA transcription and cell signaling — all systems that are disrupted in tumor formation (Oh, 2009).

Prenatal exposure of rats to 4-NP causes altered development of the mammary gland as well as abnormal levels of both estrogen and progesterone receptors in several reproductive tissues, including mammary tissue (Moon, 2007). 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 (Acevedo, 2005).

*For chemicals that have been shown to be carcinogens, we provide classifications from two authoritative bodies: the International Agency for Research on Cancer (IARC, an international body) and the National Toxicology Program (NTP, a division of the U.S. Department of Health and Human Services). We have categorized endocrine-disrupting compounds where the body of peer-reviewed research indicates a strong foundation for doing so.