Earth & Environment

Plastics ingredient causes genetic response
A new study shows for the first time that bisphenol A — a building block of some plastics and food-packaging materials — can trigger hormone-responsive gene changes in people. An international research team collected blood and urine from 96 male recruits. As urinary markers of BPA exposure rose, the likelihood that estrogen-responsive genes were activated in the blood also increased, an international team of scientists report online August 10 in Environmental Health Perspectives. Concentrations eliciting the changes were representative of those found in the general population. The authors conclude that BPA is active in humans “and that associations with hormone signaling and related disorders are biologically plausible.” —Janet Raloff

Solution for drugged waters
A new technology shows promise for cleansing surface waters of drugs and personal-care products (like antibacterial cleaners) that go down the drain. Water-treatment plants were never designed to remove pharmaceutical wastes, which is why these pollutants tend to pass through such facilities unscathed. So researchers from the University of Texas at Arlington engineered an oxidative process that uses cobalt and a sulfate-based compound called peroxymonosulfate to break apart a range of druglike pollutants. In the August Environmental Engineering Science, they show that the treatment destroyed several target compounds: the antimicrobial triclosan, the antibiotic sulfamethoxazole and the pain reliever acetaminophen. —Janet Raloff

When cleaning up also dirties up
Disinfecting water with chlorine or monochloramine can turn a family of fairly benign medical wastes toxic, an international team of scientists reports in the Aug. 15 Environmental Science & Technology. Disinfection chemicals can transform otherwise harmless iodine-based contrast agents — used to bring out soft tissue in X-rays — into pollutants that can damage cells and even DNA. Naturally occurring iodine-based chemicals in water can do the same thing. However, the scientists report, in many municipal waters they studied, X-ray contrast agents proved the major source of iodinated materials and the likely starting material for toxic iodine-based disinfection byproducts. —Janet Raloff

Chicken: Organic farms cut antibiotic resistance
A new study confirms what many had expected: Ceasing continuous, prophylactic use of antibiotics in chickens leads to fewer antibiotic-resistant germs. University and U.S. Food and Drug Administration scientists studied five conventional farms that used antibiotics as growth promoters and five farms that were launching a transition to certified organic practices (which prohibit antibiotics). Within a few months, the frequency of multi-drug resistant germs in feed, litter and water from organic farms was less than 25 percent that on conventional farms, the scientists report online August 10 in Environmental Health Perspectives. —Janet Raloff

Unseen current
Oceanographers have spotted a new and major player in the great North Atlantic “oceanic conveyor belt” that ferries warm water to high latitudes and cool water back toward the equator. Shipboard surveys off northern Iceland reveal details of a current, dubbed the North Icelandic Jet, that carries dense water south. Rising ocean temperatures may change the flow of the oceanic conveyor belt, so scientists want to understand all the factors that play into it. Norwegian, American and Icelandic researchers describe the jet online August 21 in Nature Geoscience. —Alexandra Witze