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Nanotechnology-what are the implications for public health? March 1, 2010

Posted by Gretchen Giannelli in Environmental Health, Global Health, Healthcare, Occupational Health.
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There are lots of products showing up on the market touting “nanotechnology” on the label.  The Project on Emerging Technologies has an online nanomaterials database for consumers which reveals there are thousands of “nano” products used in the electronics, automotive, cosmetic, and food and beverage industries. But what does nanotechnology mean and what are its advantages in all these applications? Are there any risks to health and the environment?

Dr. Jennifer Sass of the Natural Resource Defense Council defines nanotechnology as:

the convergence of chemistry, physics and engineering at the nanoscale, to take advantage of unique physical properties associated with small size. The products of these efforts are called nanomaterials….

Nanomaterials are objects at the atomic scale, which are 100 nanometers or less. This means they are no larger than one billionth of a meter. To put this into further perspective, our DNA is 2 nanometers wide, viruses are about 100 nanometers wide and the average human hair is 80,000 nanometers wide.

According to Dr. Paul Howard at FDA’s Center for Toxicological Research, there is a multibillion dollar market for nanotechnology because of the enormous benefits to using nanomaterials in both industrial and consumer products.  Nanoscale titanium dioxide is used in sunscreen and cosmetics to make it more easily absorbable, more transparent, and to provide more even coverage and better protection from UVB rays. It is used in shampoo to make hair feel silky and smooth, in oral vitamin D spray to make it more bioavailable (see my previous blog on importance of vitamin D) and in chocolate shakes to make cocoa blend better.

Other uses include nanomaterials impregnated into clothing to repel stains, nanosilver in cutting boards to disinfect, and nanomolecules used as adhesives in fast food packaging, which is far more advantageous than traditional adhesives. In 2005, bicycles with some parts engineered from carbon nanotubes were used in the Tour de France.  Carbon nanotubes are stronger than steel, but weigh considerably less, a clear advantage in racing.

The National Institutes of Health website has a slideshow on nanodevices used in cancer, which indicates that one of the most promising uses of nanotechnology is in the field of molecular medicine. A type of nanoparticle called a quantum dot is used to detect cancer by revealing the “cancer signature.”

…[S]cientists can design quantum dots that bind to sequences of DNA that are associated with the disease. When the quantum dots are stimulated with light, they emit their unique bar codes, or labels, making the critical, cancer-associated DNA sequences visible.

In addition to detecting cancer, quantum dots can eliminate the need for biopsies as well as deliver therapeutic agents to targeted cancer cells without harming adjacent cells. They can also ensure  a steady delivery of the agent for maximum efficacy.    The Nanotechnology Characterization Laboratory (NCL) of the NCI performs pre-clinical characterization of nanomaterials intended for cancer therapeutics and diagnostics.

So why would anyone be less than ecstatic about this new technology after hearing about the amazing things it can do? For one thing, scientists agree we really don’t have a good characterization of these chemicals because they have not been tested.  Cosmetics are only one application of nanotechnology, but most people are surprised to find out that the FDA does not have the authority to require cosmetic companies to submit safety data or do pre-market testing.  Furthermore, there is no authority to obtain post market safety data. The end result is that we have limited toxicology profiles for these chemicals.

Also, there is no labeling requirement. If manufacturers  feel consumers are positive about nanomaterials  they may decide to use labeling; otherwise, they may keep the information off the label. This means we won’t know our exposure levels.

Why might these tiny particles be dangerous? Because their small size may make them behave differently than larger particles. When size changes it may alter the physical properties and the risks to health. The unique ability of nanomaterials to penetrate our skin and access our blood, tissues and organs may mean they can cause inflammation, damage brain cells and cause pre-cancerous lesions.  Dr. Sass says:  “Ultrafine air pollution, much of which is nano-sized, is associated with reduced lung function and increased likelihood of asthma, respiratory disease, and deaths from lung and heart disease.”  Animal studies done in 2009 showed DNA damage and genetic instability from titanium dioxide nanomaterials (like those used in sunscreen) administered in drinking water.

Dr. Howard says shape may play a role in toxicity too. Carbon nanotubes are shaped like asbestos fibers, which are long and rigid. Studies showed that these nanotubes behaved like asbestos fibers and could not be phagocytized, (removed from the tissues and broken down.)

This preliminary research indicates nanomaterials could be harmful to consumers, and to workers exposed on the job, who may not be wearing personal protective equipment.  Children are another concern because they are still developing and thus more vulnerable to the toxic effects of chemicals.  Also, little is known about now these materials will behave in the environment and what the risks are for exposure.

Better risk assessment is needed to understand how nanomaterials behave in humans and the environment. Manufacturers want clearer guidance, too, so they can plan ahead. The Environmental Protection Agency has agreed that we need to do a better job of regulating chemicals including nanomaterials and has committed to reform of the Toxic Substances Control Act (TSCA). The Kid Safe Chemical Act addresses children’s unique exposure risks.  Last year, the Europeans strengthened requirements on nanomaterial use and have called for safety testing, and Canada, too, mandated reporting of toxicity data on nanomaterials.

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