Biocides end up in farm fertilizer

Already concerned that he could detect the biocide triclocarban (TCC), used in antibacterial soaps and other personal care products, in water sources in Baltimore, Rolf U. Halden of Johns Hopkins University Center for Water & Health decided to track TCC (shown) after it goes down household drains (Environ. Sci. Technol., published online April 26, dx.doi.org/10.1021/es052245n). Halden and coworkers found that some three-quarters of the compound going into a wastewater treatment plant survives the facility's physical, chemical, and biological treatments. Most of the surviving TCC ends up in the sludge, much of which gets recycled as fertilizer. Each of the largest of the U.S.'s roughly 18,000 wastewater treatment facilities could accumulate more than 1 ton of TCC per year, Halden calculates. Whether TCC and other biocides in the environment pose actual hazards, such as contributing to the development of antibiotic-resistant bacteria, remains unknown. Some observers, including Hans Sanderson of the Soap & Detergent Association, argue that the benefits of the biocides outweigh their risks. He and Halden agree that neither the health risks nor the benefits of TCC in soaps have been well-documented, let alone quantified.