Environmental Science

Nanosilver Lining

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Science  13 Dec 2013:
Vol. 342, Issue 6164, pp. 1293
DOI: 10.1126/science.342.6164.1293-a
CREDIT: © LIANEM/ALAMY

From socks to children's toys, nanoparticles of metallic silver (i.e., “nanosilver”) are being incorporated into more and more consumer products for their antimicrobial properties. But as these products are used or reach the end of their life cycle and enter the waste stream, they can have negative impacts on natural or engineered microbial communities, such as those in wastewater treatment plants or compost reactors. Gitipour et al. analyzed the impact that realistic low levels of silver nanoparticles had on the microbial communities responsible for biodegrading disposed organic matter during composting. In compost treated with nanosilver or free silver ions, the species present in the bacterial communities differed from a control reactor without any added silver; however, the physical properties of the aged compost and leachate were nearly identical between treatments. Statistical analysis of DNA sequencing data suggests that functional redundancy within the bacterial communities played an important role in maintaining efficient biodegradation. Furthermore, strong associations with organic matter may explain why spectroscopic analyses could not detect surface reactions of silver nanoparticles with abundant anions such as chloride, potentially limiting the bioavailability and toxicity of silver in the compost.

Environ. Sci. Technol. 10.1021/es402510a (2013).

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