A very interesting article in the University Of Minnesota's Alumni Magazine.

Dirty Soap
Liquid hand soap cleans hands, but it might be fouling rivers. Researchers from the University of Minnesota’s College of Science and Engineering have found that toxins from the antibacterial agent triclosan, used in dishwashing liquid, liquid hand soap, and other consumer products, account for an increasing proportion of total dioxins in Mississippi River sediments. Dioxins are a group of toxic chemical compounds typically resulting from industrial processes. They can cause reproductive and developmental problems, damage the immune system, interfere with hormones, and also cause cancer. Triclosan, when exposed to sunlight, generates four dioxins. Researchers found that the levels of these four dioxins in the Mississippi have risen by 200 percent to 300 percent over the past 30 years, while levels of all the other dioxins have dropped by 73 percent to 90 percent.

About 76 percent of commercial liquid hand soaps contain triclosan. It makes its way into rivers through disposal in residential drains, leading to large loads of the chemical entering wastewater treatment plants.

The study appears online in the May 17 issue of Environmental Science and Technology.
Link to the article