Antibacterial Soap Additive Alters Hormone Activity

Triclocarban, a common antibacterial chemical added to bath soaps can alter hormonal activity in rats and in human cells in the lab, a new study from UC Davis shows.

Scientists are aware that endocrine systems can be negatively affected by a wide variety of substances. Endocrine systems release hormones which act as chemical messengers in our bodies. These messengers interact with cells receptors, triggering responses and normalizing biological functions like growth, embryonic development and reproduction.

An increasing number of epidemiological and experimental studies are now showing that some synthetic chemicals in household products can cause health problems by interfering with normal hormone action. Known as endocrine disruptors, or endocrine disrupting substances (EDS), such chemicals have been linked in animal studies to a variety of problems, including infertility, cancer, reproductive failure and developmental anomalies.

Triclocarban, also known as TCC or 3,4,4′-trichlorocarbanilide, is widely used in household and personal care products including bar soaps, body washes, cleansing lotions, wipes and detergents. Triclocarban-containing products have been marketed broadly in the United States and Europe for more than 45 years; an estimated 1 million pounds of triclocarban are imported annually for the U.S. market.

Testosterone and Prostate Effects Seen

 Normal Endocrine System Activity

The UC Davis researchers found two key effects: In human cells in the laboratory, triclocarban increased gene expression that is normally regulated by testosterone. And when male rats were fed triclocarban, testosterone-dependent organs such as the prostate gland grew abnormally large.

Also, the authors said their discovery that triclocarban increased hormone effects was new. All previous studies of endocrine disruptors had found that they generally act by blocking or decreasing hormone effects in one of three ways.

      • They can act like a natural hormone and bind to a receptor. This causes a similar response by the cell, known as an agonist response.


      • They can bind to a receptor and prevent a normal response, known as an antagonistic response.


    • A substance can interfere with the way natural hormones and receptors are synthesized or controlled.

TCC, however, seems to works by amplifying androgen receptor activity, the study finds, and should be classed as a steroid hormone enhancer, rather that a hormone agonist or antagonist type endocrine disrupting substance.

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