Treated sludge harbors antibiotic-resistance genes

Abstract

To kill microorganisms that can potentially cause disease, the world’s most advanced sewage treatment plants essentially pressure-cook wastewater. But new research indicates that this process may not get rid of genes that impart antibiotic resistance to microbes. Because treated sludge is regularly spread on lands used to grow crops for human consumption, this finding could have public health implications, said Sarah Fischer, an environmental chemist at the University of Maryland, College Park, during a Division of Environmental Chemistry session at the ACS national meeting in Washington, D.C. The U.S. Environmental Protection Agency estimates that more than 7 million metric tons of biosolids—the residue from wastewater treatment, also called sludge—is applied to U.S. lands each year as fertilizer. Increasingly, organic farmers are debating the possible use of biosolids, pointed out Mustafa Selim of East Carolina University’s Brody School of Medicine, who co-organized the symposium. The U.S. Department of...