You may have noticed that many everyday products are much smaller than they were a few decades ago, with cell phones being a perfect example. Every now and then you may catch a glimpse of those archaic brick phones in a rerun of Saved by the Bell and get a good laugh when comparing to your current phone. The industry of making consumer products smaller is known as microtechnology, and while this industry has been very successful, the even smaller field of nanotechnology takes this concept to a whole new level.
|Scene from “Saved by the Bell” (source: http://gizmodo.com/zack-morris/)|
Nanotechnology is the field of science that deals with the industrial application of particles that are less than 100 nanometers (nm) in size in at least one dimension.
To give you some perspective on just how small these materials are, a nanometer is one-billionth of a meter, or the size of a marble compared to the earth. A DNA double-helix has a diameter around 2nm and the width of a human hair is typically around 50,000 to 100,000nm. These nanoparticles exhibit remarkably different, size-dependent properties that make them very useful. In fact, it is these special size-specific properties that separate microtechnology (which is just miniaturizing everyday products) from nanotechnology.
|A conceptual image of DNA attaching to a carbon nanotube as a biosensor to detect drug effectiveness (source: http://www.futurity.org/science-technology/fuse-dna-nanotubes-for-better-biosensors/)|
Nanotechnology has the potential to solve many of today’s problems in medicine, energy production, and environmental sustainability. Some current benefits of this technology include better and more durable medical devices, electronic components, scratch-free paint, cosmetics, food color additives, and surface coatings. Such benefits have resulted in the widespread use of nanoparticles in consumer products.
For fisheries, nanoparticles could offer lighter and stronger materials for aquaculture, new filter materials for clean water technologies, veterinary diagnostics, and nanoparticles with antibiotic properties could treat fish disease and prevent biofouling. However, some of these materials have been reported to be environmental health hazards.
Microsensor with nanomaterials used in aquaculture under the skin of fish to wirelessly monitor and diagnose the health of fish (source: http://nanopatentsandinnovations.blogspot.com/2010/07/fischfit-monitoring-microchips-under.html)
The morphological alterations in the gill filament of
adult medaka due to nano-sized iron exposure (A
control, B 0.5 µg/ml, C 5µm/ml; source:
Hongcheng et al. 2009).
Safety evaluation has been a complicated issue for many emerging materials. Historically, a lot of substances were initially believed to be safe and later found to be harmful to humans and the environment (e.g. DDT). For nanoparticles, we may be following the same path since development and use of these materials is occurring faster than toxicology studies can keep up.
Research has shown that silver nanoparticles used in socks to reduce foot odor are being released in the wash, flushed into waste water and may destroy bacteria critical to natural ecosystems, farms, and waste treatment processes. Studies on fish have demonstrated that manufactured nanoparticles can accumulate in the gills and brain causing respiratory distress and other forms of cell damage. However, a review by Handy et al. (2011) found acute lethal and some chronic affects on fish occurred at concentrations well above what is currently estimated (using models) to be in the environment.
Most nanomaterials will end up in the environment, and because they are not biodegradable, they will likely remain there for a long time, potentially accumulating to toxic levels. Additionally, there are very few studies on the long-term consequences of these materials on the aquatic environment. We do not know if they cause negative effects on growth, reproduction, development, or whether they can be eliminated from the body to prevent particle build-up. Complicating matters more, methods to test for these materials in the environment are in their infancy. We are, therefore, unable to measure the concentrations of manufactured nanoparticles to determine whether they exceed the levels that cause negative effects demonstrated in the lab.
|Single-walled (A) and multiwalled (B) carbon nanotubes (source: http://jnm.snmjournals.org/content/48/7/1039/F1.expansion.html)|
For people, some carbon nanotubes have been cited as acting like asbestos, potentially causing mesothelioma. Other nanoparticles have been linked with cancer, heart disease, neurological disease, and aging. On the other hand, some nanomaterials have been associated with health benefits such as protection from cell damage.
Dangerous similarity. Long, multiwalled nanotubes (bottom) and asbestos (top) cause similar chronic inflammation in mice. Credit: C. A. Poland et al., University of Edinburgh (Source: http://news.sciencemag.org/sciencenow/2008/05/20-01.html)
While this technology is a very exciting development and the potential benefits very promising, we need to learn from past mistakes. Allowing toxicity studies to “catch-up” will help in the safe development and design of these materials. Regulations also need to be developed with the current technology to prevent widespread contamination before we fully understand the implications of having these materials ubiquitously spread through our ecosystems.
References and other material:
Blasco C, Pico Y. 2011. Determining nanomaterials in food. Trends in Analytical Chemistry. 30: 84-99.
Handy RD and Shaw BJ. 2007. Ecotoxicology of nanomaterials to fish: challenges for ecotoxicity testing. Integrated Environmental Assessment and Management. 3: 458-467.
Handy RD, Al-Bairuty G, Al-Jubory A, Ramsden CS, Boyle D, Shaw BJ, Henry TB. 2011. Effects of manufactured nanomaterials on fishes: a target organ and body systems physiology approach. Journal of Fish Biology. 79: 821-853.
Hongcheng L, Qunfang Z, Wu Y, Fu J, Wang T, Jiang G. 2009. Effects of waterborne nano-iron on medaka (Oryzias latipes): antioxidant enzymatic activity, lipid peroxidation and histopathology.
Johnston BD, Scown TM, Moger J, Cumberland SA, Baalousha M, Linge K, Van Aerle R, Jarvis K, Lead JR, Tyler CR. 2010. Bioavailability of nanoscale metal oxides TiO2, CeO2, and ZnO to fish. Environ. Sci. Technol. 44: 1144-1151.
Li Y. 2010. Safety of nanomaterials. MS Thesis. Northern Illinois University, Department of Mathematical Sciences. UMI Number: 1480721
Shaarifi S, Behzadi S, Laurent S, Forrest ML, Stroeve P, Mahmoudi M. 2012. Toxicity of nanomaterials. Chem. Soc. Rev. 41: 2323-2343.