Melting glaciers in the Swiss Alps are releasing pollutants that have been frozen in the ice for decades. A new study suggests that by accelerating global ice loss, global warming is likely to increase environmental contamination with persistent organic compounds that are no longer widely used, such as PCBs and DDT. Persistent organic pollutants are chemicals that can travel long distances in the atmosphere and once deposited can remain in the environment for many years. They accumulate in the food web, affecting the health of living organisms. Examples include PCBs (polychlorinated biphenyls), now banned but previously used in industry, organochlorine pesticides, such as DDT, and synthetic musk compounds used as fragrances in body care products and household detergents. In the 1950s-1970s, even remote glaciers high in the Swiss Alps were affected by global emissions of persistent organic chemicals. These pollutants have accumulated in the glaciers after being trapped in the surface ice through deposition from the atmosphere. Accelerated glacial melting caused by climate change will release these pollutants and may affect the use of glacial meltwater in irrigation systems, such as drinking water in Alpine huts and in the artificial production of snow. In addition, wildlife and fishermen may be exposed to increased concentrations of these contaminants in the environment.