Brave new world of nanotechnology
Manmade nanoparticles are being added to more and more foods, drugs, and other products and are ultimately finding their way into the environment. The name of these minuscule particles comes from the word “nanometer,” which is one-billionth of a meter. How small is that? A sheet of newspaper is 100,000 nanometers thick; a pinhead, about a million nanometers across. The synthesis and use of these particles is called nanotechnology, which is playing a role in everything from engineering and physics to biology and chemistry.
Where are nanoparticles found?
Almost everywhere. More than 1,700 consumer products containing nanoparticles have been introduced into the marketplace since 2005. A paper in Environmental Science & Technology revealed that titanium dioxide nanoparticles, for instance, are now widely used in food (notably chewing gum, sweets, and candies), dietary supplements, and personal care products (notably sunscreens and toothpastes), sometimes accounting for as much as 10 percent of their total weight. Nanotechnology is also used to make auto parts, and nanoparticles are added to clothing, cosmetics, food packaging, bandages, and medical productsas well as in some dental implants and eyeglass lenses.
Why do manufacturers use them?
The nano particle size provides many desirable properties—allowing products to be lighter in weight yet stronger, for instance, and to have greater chemical reactivity than their larger-particle counterparts. The chemical composition of the nanoparticles is an important factor, since chemistry as well as size determine both beneficial and potentially toxic effects.
In sunscreens, nanoparticles of zinc oxide and titanium dioxide allow efficient blocking of ultraviolet rays without a white pasty look. Drugs made with nanoparticles can have improved solubility and bioavailability, allowing for faster therapeutic action. A bone paste used in bone surgery allows for faster fracture repair. Eyeglass lenses made with nanotechnology are harder to scratch and easier to clean. The auto industry uses nanotechnology to make lightweight materials. Some clothing (such as underwear and socks) contains nanosilver, which is marketed to reduce odor. In foods, nanoparticles can add dramatic flavors and brighter colors and increase shelf life).
Many food-related uses for nanoparticles are in development—for instance, to improve the bioavailability of fat-soluble nutrients such as lycopene and beta carotene; to enhance satiety of diet foods; and to improve probiotic supplements so that their potentially beneficial bacteria survive longer in the large intestine.
Do nanoparticles pose health or environmental risks?
Humans have always been exposed to nanoparticles. Many air pollutants from volcanic eruptions, forest fires, and motor vehicles are nanoparticles, which unfortunately allows them to penetrate deep into our lungs when we inhale them. But it’s the new uses of nanotechnology that are raising concerns among scientists as well as environmental and consumer groups.
For instance, one laboratory study showed that titanium dioxide nanoparticles in solution can damage potentially beneficial bacteria, raising the concern that high concentrations in sewage may have adverse ecological effects. This may occur, for instance, when people swim and nanoparticles in their sunscreens wash off into oceans and lakes, or when they bathe and the particles go down the drain and pass through sewage treatment plants into marine ecosystems. When products containing nanoparticles are disposed of, they end up in landfills, and the particles eventually get into soil and waterways, with unknown effects on animals and crops.
The EPA recently began studying nanoparticles in commercial products to determine if they pose environmental and health risks. But little is known. Some animal studies have found that nanoparticles can cross the blood-brain barrier, which protects the brain from potentially toxic substances in the blood. And lab experiments have found that exposure to titanium dioxide nanoparticles can affect human cells in ways that may damage DNA and increase cancer risk.
What is known is that occupational exposure to nanoparticles can be hazardous. According to a 2015 report from the NIH, nanoparticles stay airborne longer, are more likely to be deposited in the respiratory tract, can remain in tissues longer, and are more biologically active than larger particles. The CDC, on its occupational health website, states that nanoparticles are more toxic than larger particles and are able to migrate from the respiratory system (when they are inhaled) to other organs. The few studies involving occupational exposure have suggested that certain types of nanoparticles may lead to lung damage.
Are nanoparticles being regulated?
Very little. So far the FDA has put the responsibility for nanoparticle safety primarily in industry’s lap and does not require the labeling of nanoparticles, even in food. Two leading consumer organizations, the Environmental Working Group and Consumers Union, have called for increased safety assessments and regulation by the government. In contrast, the European Union now requires the labeling of nanoparticles in foods.