Scientists know little about how releasing some of the more than 2 million tons of nanoparticles produced every year will affect organisms in the environment. A new study reports that earthworms (Eisenia fetida) can ingest gold nanoparticles from their surrounding soil and accumulate them in their tissues-a finding with significant implications for food webs (Environ. Sci. Technol., DOI: 10.1021/es101885w).

Manufacturers add nanoparticles to cosmetics, clothing, and medical devices. Normal use of these products-such as washing your clothes-can release nanoparticles into wastewater, where they end up in sewage sludge. In the U.S. and Europe, farmers apply sewage sludge to their fields as fertilizer.

Environmental toxicologist Jason Unrine of the University of Kentucky, Lexington, and colleagues wanted to know if nanoparticles applied to these fields eventually made their way into the food chain. “Because we expected the nanomaterials to aggregate onto soil particles, we were initially very skeptical that organisms could take them up from the soil,” Unrine says.