Chlorine and Triclosan: Overstated Risk

April 27, 2005

A recent study¹ by Virginia Tech researchers found chloroform can be formed by the chemical reaction of chlorinated drinking water with the widely used antimicrobial agent triclosan. Additionally, the researchers suggested that chlorine and triclosan could react to form dioxins in the presence of sunlight.

Unfortunately, some promotional materials and press stories related to this study raise misleading and unwarranted fears about potential health implications of the research findings. The Chlorine Chemistry Division of the American Chemistry Council offers the following points in response to these concerns:

• Chlorine is added to drinking water to destroy disease-causing organisms, an essential step in ensuring safety. In the United States, chlorine has helped to virtually eliminate waterborne diseases such as cholera, typhoid and dysentery.
• Exposure to low levels of chloroform does not cause cancer. While high doses of chloroform have been shown to cause cancer in laboratory animals, the U.S. Environmental Protection Agency (EPA) has concluded that chloroform is not likely to be carcinogenic to humans unless exposure levels are high enough to first cause other toxic effects. EPA's drinking water regulations for chloroform are set well below levels that may case such effects, even in sensitive populations.
• The experiments conducted by Virginia Tech researchers likely overstate the potential for chloroform formation from typical household uses of products containing triclosan. The reported levels of chloroform formation were reached only after two hours of triclosan and chlorinated water interaction. Furthermore, chlorine levels in household tap water are generally much lower than the levels used in the experiments.
• The dioxin compound that formed when triclosan degraded in sunlight in the study was not a dioxin of public health concern. Dioxin is not one compound, but a family of compounds of widely ranging toxicity. Of the 210 dioxin and furan family compounds, only 17 are considered to be of public health concern.
• There is no evidence that dioxins form when swimmers enter chlorinated pool water with triclosan on their skin. If trace amounts of dioxins do form in these situations, there is no evidence that they would be toxic. Furthermore, the quantities formed would likely be very low, leading to very little skin absorption, especially since the compound(s) would be diluted and washed away in the pool environment.