Nanosilver: Naughty or nice?

Silver is beautiful – and a killer. But some scientists are beginning to worry that overusing the technology might cause problems. The shiny white metal is a natural antibiotic. That means it kills bacteria. People have recognized this benefit since ancient times. In fact, historians think that silver helped keep spoiled food from making them sick.

Beginning around 2005, companies started adding a special form of silver to a wide range of everyday products

This silver was fashioned into amazingly tiny particles, called nanosilver

• These particles measure between 1 and 100 nanometers, or billionths of a meter, across, and are nearly impossible to see under a microscope.

Little particle, big surface

Nanosilver is so tiny that it can find its way into tiny spaces. These spaces include our cells and the cells of other living things.

• Because nanosilver particles are so small, they have very high surface areas. That means that relative to their volume, their surface is fairly big.
• Particles undergo chemical reactions on their surface. The more surface area, the more chemical reactions.

Power Words

Antibiotic

• A germ-killing substance prescribed as a medicine for the treatment of disease
• Bacterium
• A single-celled organism that dwells everywhere on Earth, from the bottom of the sea to inside animals
• Cancer
• Any of more than 100 different diseases characterized by the rapid uncontrolled growth of abnormal cells
• Carbon
• Carbon exists freely as graphite and diamond and is the physical basis of all life on Earth
• Cell
• The smallest structural and functional unit of an organism
• Colloid
• A very finely divided substance scattered throughout another substance
• DNA
• A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions
• electron
• A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids
• ion
• An atom or molecule with an electric charge due to the loss or gain of one or more electrons
• embryo
• The early stages of a developing vertebrate, or animal with a backbone, consisting only one or a or a few cells

A lot of the little

There are no studies to suggest how much nanosilver might be too much, says Ramune Reliene.

• Studies have shown that it can damage human cells, but those studies exposed cells to anywhere from 100 to 10,000 times more silver than what we currently encounter in the environment, and the cells were in a Petri dish.
• It is important to go beyond cell studies and try to test in animals.

Citations

“Scientists say colloid.” Eureka! Lab. February 9, 2015.

• “Nano air pollutants strike a blow to the brain.” Science News for Students. December 17, 2014. “Germs help each other fend off antibiotics.” (both in Science News and in the Journal of Nanotoxicology.)
• Nanoparticles’ indirect threat to DNA. Science News. November 5, 2009
• Project on Emerging Nanotechnologies: Silver nanotechnology in commercial products database.

No silver lining to this pollution

Andrew Maynard is an environmental health scientist at the University of Michigan in Ann Arbor.

• If nanosilver is going to cause problems, it will probably show up in the environment
• Nanosilver can flow long distances in water and get picked up by fish and enter root systems
• They also can settle onto sediment at the bottom of a river or lake, harming microbes that live there

This silver bullet might not last

A steady stream of nanosilver into the environment could foster harmful microbes to become resistant to the germ killer.

• If that happened, doctors could no longer rely on silver-coated medical devices or silver-treated bandages to keep such germs from sickening their patients.

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