Performance fabrics that offer anti-bacterial and anti-odor qualities, as well as sun protection, may contain nanoparticles that are largely untested for human health effects.
If you’ve been shopping for workout clothes lately, you may have seen labels making some extraordinary claims—namely, that you can work up a sweat and your clothes won’t smell when your exercise session is over. Sound too good to be true?
You may want to think twice about buying clothes making such claims, because the anti-bacterial properties are brought to you by nanotechnology. While certain nanoparticles in clothing can kill off bacteria, as a whole they are largely untested, barely regulated, and may pose serious risks to your health and the Earth.
Nanotechnology involves the use of very small particles, called nanoparticles, to bring certain characteristics to a product. Nanoparticles are defined as being between the range of 1-100 nanometers in size. A billion of them can fit on the head of a pin. Nanomaterials are currently used in body care products, as well as consumer products like cutting boards, towels, food, and, yes, clothes.
The most common nanomaterials in clothing are nanosilver and nano-titanium dioxide. Nanosilver is woven into fabric to give it anti-bacterial properties, fending off the bacteria that make those clothes smell after you sweat. Nano-titanium dioxide adds sun protection to clothing just as it does in sunscreen.
The use of nanoparticles to achieve fresh-smelling clothes and UV protection may not be safe.
“Concerns from the human health perspective are that these different-shaped/-sized particles may behave differently within the biological systems of our bodies,” says Dave Andrews, senior scientist at the Environmental Working Group (EWG), an environmental research nonprofit. “Different sizes may be more likely to be transported … through skin and through organs, or cause toxicity effects in body.”
Take carbon. In its normal form, it’s a building block of life and nontoxic to humans and the environment. But since 2003, several studies, including one from 2008 conducted by the University of Edinburgh, found that carbon nanotubes—one-billionth of an atom wide—reacted in the lungs of mice in a similar manner to asbestos, which causes the deadly lung cancer mesothelioma.
But because of the ways in which products and ingredients are regulated in the US, manufacturers have not been required to demonstrate the safety of nanomaterials prior to using them in consumer products.
“Our [regulatory] system does not consider nano-versions to be different materials, so [consumers] are left trying to catch up to understand the risks and hazards,” says Andrews.
Nanosilver and the Environment
Nanosilver may harm the environment when it moves through the wastewater system. Silver, which has anti-bacterial properties, is used in its nano form in clothes through a variety of methods, from actually spinning textile fibers together with silver nanoparticles to sticking the nanoparticles to the fabric through an electrostatic process.
The nanosilver in the fabric then works to kill off bacteria lingering in sweaty gym clothes, keeping them smelling fresh.
Studies have found that some of the nanosilver washes off of your clothes and goes into your wash water, where it is then captured in sewage sludge and ends up in biosolids, or sludge that has been treated and processed for use. About 60 percent of such biosolids are applied on farmland, forest, or wetlands as fertilizer. The rest is incinerated or landfilled.
The nanosilver in that sludge may disrupt ecosystems by lowering soil quality. A 2010 study presented at the Ecological Society of America found that soil with a concentration of nanosilver found in biosolids had reduced growth of one of the tested plant species by 22 percent and reduced the microbial biomass—the good microbes needed to aid plant growth—by 20 percent.
In addition, silver is toxic to aquatic species: Fish exposed to nanosilver particles washed into waterways have lower rates of growth and reproduction, according to a study published in May 2015 by the Journal of Biodiversity and Environmental Sciences.
Nanosilver and Health
When it comes to human health, some scientists are concerned that too much silver in the environment could make this metal’s anti-bacterial benefits less effective when society truly needs them.
“I would rather avoid [clothes treated with nanosilver] … to prevent the release of too much silver into the environment and onto my skin, which may result in the loss of silver’s antibacterial activity,” says Natalie von Goetz, a researcher ETH Zurich University who has been studying clothing treated with nanomaterials. “Silver is a potent antibiotic that can be used when bacteria strains are resistant against organic antibiotics, and it would be a shame to lose that in times when many ‘old’ antibiotics have already lost their potency.”
Also, what about the environment of your body when you sweat during a workout? Studies replicating workout conditions have found that nano-silver particles in clothing can be released from the fabric into sweat. Dr. von Goetz’s study, published in Environmental Science and Technology in 2013, demonstrated that nanosilver is released from the fabric through sweat, and that those particles can be absorbed through the skin.
Though silver as a metal is considered low-toxicity, scientists know little about how even small exposures to nanosilver will affect human health. One 2014 study from the University of Southern Denmark, published in the journal ACS Nano, found that if nanosilver enters a human cell, it can cause the development of cell-damaging free radicals. Over-production of free radicals, in turn, can lead to cancer, Alzheimer’s, and Parkinson’s, note the researchers in a press statement.
“We don’t know how much is needed, so we cannot conclude that nanosilver can make you sick. But we can say that we must be very cautious and worried when we see an overproduction of free radicals in human cells,” note study researchers Frank Kjeldsen and Thiago Verano-Braga.
Sunscreen in Your Shirt
It is common to find nanoparticles of titanium dioxide in sunscreens, and you can now find them in the fabric of certain types of clothing, giving them a higher ultraviolet protection factor. Studies out of Europe, including one by von Goetz, that replicated the wear and tear a garment containing nano-titanium dioxide would go through during a workout found that the nanoparticles “barely released from fibers into sweat,”says von Goetz.
That said, if your skin absorbs even a little nano-titanium oxide, it may lead to health issues. The American Cancer Society’s Dr. Kenneth Portier published a fact-sheet online that warns, “Recent research has shown that [nano-titanium dioxide particles], when injected in low dose under the skin of mice, produce a significant, but reversible, inflammatory response. This could be a concern given what we are learning about the negative health effects of chronic inflammation.”
The EWG says that the potential effects of nano-titanium dioxide on the environment “have not been sufficiently assessed.”
As a precaution, avoid clothing with nano-titanium dioxide.
What to Watch For
No US laws require manufacturers to label clothing that uses either nano-silver or nano-titanium dioxide.
Watch for labels making claims like “anti-bacterial,” “odor-eliminating,” or “hygienic,” which may indicate the presence of nanosilver. Clothing labeled as offering sun protection may contain nano-titanium dioxide. Contact manufacturers and ask questions before purchasing. And let them know you want them to avoid nanoparticles in their products.
“Consumers are the ones driving the market and having power,” says Andrews. “Asking questions of manufacturers—that’s where change will come in the market.”
—Sarah Tarver-Wahlquist, Tracy Fernandez Rysavy, and André Floyd