Using biosolids—or sewage sludge—as fertilizer on farms could contaminate groundwater with a variety of chemicals, including prescription drugs and purportedly hormone-disrupting compounds from antibacterial soaps and other cosmetic products says a recent study by the U.S. Geological Survey (USGS). According to USGS Research Hydrologist Dana Kolpin, these types of compounds are not just sitting on the top soil layer, but moving down through the soil, where they can potentially enter groundwater.
After testing for several years on an eastern Colorado wheat field that uses treated sludge from a Denver wastewater treatment plant, the researchers noted that 57 “emerging” contaminants appeared with increasing regularity. They found 10 of the contaminants anywhere from seven to 50 inches down in the soil 18 months after the sludge was applied at points where the contaminants did not previously exist. Other studies have found hormones, detergents, fragrances, drugs, disinfectants, and plasticizers in treated sludge, but this is evidently the first study to show how they can persist and move in soil. See Environmental Health News, May 12, 2014.