The U.S. Army recently announced that it is constructing two bridges out of recycled plastic. And apparently, the bridges are strong enough to carry tanks.

The bridges, scheduled to be built as part of a $957,000 contract with Axion International Holdings, will replace old wooden bridges at Fort Eustis in Virginia. Both structures’ railroad cross-ties will be made completely out of consumer and industrial plastic waste, and the 40- and 80-foot bridges will have a high-load rating of 130 tons.

The company claims that a bridge made from recycled plastic is 40% lighter and 25% to 30% cheaper than traditional bridges. Axion’s bridges are also less energy-intensive than wood or steel models, and they don’t need to be painted.

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The British Royal Society of Chemistry reported that, “Compost bins of the future could contain biodegradable electronic circuits,” US researchers suggest. Stanford University scientists Christopher Bettinger and Zhenan Bao “set out to fabricate a biodegradable and biocompatible transistor. For two of the device’s components — the substrate and the dielectric — the researchers selected biodegradable polymers that have been approved for medical use by the US regulatory authorities.”

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Nanotechnology promises great benefits, but its ecological effects are poorly understood.  The rapid proliferation of nanotechnology can potentially present long-lasting and unanticipated effects.  Recently, plasticware and clothing items have been imbedded with nanoparticulate silver to retard bacterial growth. 

The New York Times recently reported that “When it comes to killing bacteria, fungi and the like,” silver ions are very “effective antimicrobial agents.” Now, there are “hundreds of consumer products that contain small amounts” silver, “in the form of nanoparticles that release ions slowly over time,” which, for instance, “include “socks, whose silver nanoparticles help control odor. But socks and other antimicrobial textile products need to be laundered, which raises the possibility that some of the silver may end up in the wastewater.” As a result, there are concerns “that silver may kill beneficial bacteria and other small organisms.”

A recent Swiss study “found large variations in the amount of silver released in the first washing,” and suggested “that mechanical stress in the washing machine was responsible for most of the release.” The researchers say further studies are needed to determine particles’ “precise composition and how they behave once they end up in wastewater.”

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