Nanoparticles or No-No particles?
Image: Flickr, Argonne National Laboratory
Could Nanoparticles Cause "Dramatic Mutations?"
Nanoparticles, hailed as the solution for everything from the next generation of micro-electronic gadgets to curing cancer, are poorly understood. When scientists first mastered the technology for creating and manipulating microscopic balls and tubes, toxicologists speculated that the tiny particles would have properties similar to the same chemicals on an every-day scale. Occupational hygienists worried about new exposure routes, like inhaling fine nano-dusts. Industry argued that nothing changed: For example, silver ions (the negatively charged silver atom, which is normally part of a silver salt) have been used for antibacterial purposes for years without (too many) major fish kills, so nanosilver should be fine, maybe even an improvement.
But as the use of silver nanoparticles increases, in everything from washing machines to the new Tata water filter intended to bring safer water cheaply to billions of potential customers, a new study confirms disturbing evidence that silver nanoparticles cause "dramatic mutations" in fish. "'I think we jumped the gun' by creating such large volumes of nanoparticles," study author Darin Furgeson, of the Nano Institute at the University of Utah,told Scientific American. Most of the silver nanoparticles used in applications like sunscreens, anti-odor treatments and filters are discharged into the environment as the product incorporating the nanosilver is used. The nanosilver cannot be treated by current wastewater handling systems, nor can it be detected by traditional analytical methods.
From a report on the study in Environmental Health News:
In one new experiment, Furgeson, a professor of pharmaceutical sciences, exposed zebrafish embryos to silver nanoparticles in a laboratory, and found that some died and others were left with dramatic mutations. "Some of the fish became extremely distorted, almost making a number nine or a comma instead of a linear fish," he said.
Is it the Nano or the Silver Causing the Damage?
That silver nanoparticles are bad actors is not a big surprise to toxicologists. Silver has long been known to be one of the most toxic heavy metals in the aquatic environment. But, the mechanism of toxicity of silver ions, which disrupt the normal use of sodium and potassium ions for regulating biological functions, would not be expected from nanosilver, which is metallic and not ionic. Instead, nanoparticles seem to behave in new, unexpected ways: An earlier study conducted at the University of Singapore also found that silver nanoparticles disrupt the embryonic formation of the zebrafish, but that silver ions did not cause similar deformation.
Nanoparticles have a length under 100 nanometers (nm). For comparison, a human red blood cell is 8000 nm, and the HIV virus is about 130 nm. The toxicity of silver nanoparticles is not due to the particle size alone though. The Nano Institute of Utah study found that silver nanoparticles disrupt embryo development but that gold nanoparticles do not.
Conclusion: the problem is that nanosilver is both silver and nano. It is not enough to know how nanoparticles behave and how silver behaves to deduce the effects of nanosilver. Corollary: all new nanoparticles need a whole new set of research in order to understand potential new risks and new safety measures.
So Silver Nanoparticles are Regulated, Right?
Governments around the globe are juggling the questions of how to deal with nanotechnology, in particular, how to regulate potential risks without throwing up obstacles that could hurt their national competitiveness in this rapidly growing field. One major problem: most developed countries require industry to register any new "substances" before they start large scale production or sales. But many nanoparticles are just a different form of "existing substances" -- and therefore are not covered by existing laws.
This leads to the strange irony that new molecules such as carbon nanotubes or carbon fullerenes -- which have a chemical structure distinct from that of carbon in well-known substances such as coal or diamonds -- are regulated as "new substances." Their safety must be proven before they can be produced in industrial volumes. But under these laws, silver nanoparticles are treated like cute, little mini-silver ingots. The more, the better!
Consequently, industries using silver nanoparticles are invited by the US EPA to participate in a voluntary Nanotechnology stewardship program but are not required to prove the safety of silver nanoparticles. The US EPA issued a Nanotechnology Research Strategy in Oct. 2009 to step up investigation of the environmental and health effects of nanoparticles, presumably looking for the "silver bullet" they need to get congress to pass new laws extending their authority on nanotechnology. In the meantime, EPA is also using laws regulating pesticides to control consumer uses of the antibacterial properties of nanosilver.
The challenge now is to gain the tremendous potential benefits of nanotechnology without entering a whole new era of environmental risks.
More on Nanosilver:
Nanosilver in consumer products: No silver lining for fish
Nano Silver in Your Underwear? 600 Products With Nanoparticles Are Barely Regulated
Samsung's SilverCare Washing Machine
Nano, Nano, Everywhere: the Nano Dishwasher
New Biocide Research Pits Stinky Feet Against Fish
Beware The Silver Lining: A Risk Management Review Of Commercial Nanotechnology
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