The universe may be ever-expanding but the world as we know it is definitely shrinking — down to the microscopic nano level. Which is very, very small. Think one-billionth-of-a-meter small. Here on earth, the widespread use of nanotechnology is rapidly expanding, too, revolutionizing everything from your electronics to your moisturizer.
Nanoparticles aren’t new in the personal care industry. They’ve been common for over a decade with beauty giant L’Oreal ringing in as #6 on the US list of nanotech patent holders back in 2006. At the time, the effects of nanoparticles on both our skin and the environment were understudied and poorly understood. Progress has been made on the research side, but the results are often confusing, contradictory and still leaving consumers in the dark.
We waded through the pro-nano propaganda and risk-assessment alarm bells to better understand the big impact these tiny particles are having on our skincare (and planet). At the end of the day more research (and new research techniques) are needed to understand the specifics of different nanoparticle sizes and shapes, but the potential is promising and they aren’t going anywhere.
Nanotechnology is defined as the science of manipulating atoms and molecules at a nanoscale. To put nanoscale into perspective, one strand of human hair is about 80,000 nanometers thick. Nanoparticles are simply particles measured on that nanoscale. Cosmetic manufacturers (and regular folks who just want their products to work better) are obviously wooed by the benefits of ingredients in their nanoscale version — better UV protection, deeper skin absorption, longer-lasting effects, better color payoff and finish quality...the list goes on. To some, nanotechnology is the way of the future providing opportunities in dermatology to develop new biocompatible and biodegradable therapies and delivery systems. And the future is now. (1, 2, 3)
Big brands are proudly marketing their nano-prowess, which often shows up on labels as micronized, fullerenes, quantum dots, liposomes or nano-anything. But like a lot of new-to-the-scene ingredients, these tiny particles come with tiny amounts of research on their long-term effects.
Watchdogs like the Environmental Working Group, International Coral Reef Initiative and European Union have raised concerns that there’s not enough data to measure the long-term health and environmental effects, especially as more and more nanoparticles are being inhaled, topically applied and distributed through water-treatment facilities, groundwater and into oceans. Several studies on mice and fish have verified that nanoparticles are indeed small enough to absorb through the skin and into the bloodstream, finding their way into organs and lymphatic systems. Yet, several other studies haven’t found conclusive evidence that they cross the skin barrier in significant amounts or, depending on the size and shape of the nanoparticle, cross at all. (4, 5, 6)
Several studies have confirmed that nanoparticles can penetrate the skin barrier, especially if the skin is broken from acne, psoriasis or scrapes. But even intact skin seems to be surprisingly permeable to nano-scale particles. What’s less known is to what degree nanoparticles cause harm once they’re in the bloodstream and how many nanoparticles it takes for that damage to warrant concern. At least a couple of studies have linked fullerenes, a common nanoparticle found in moisturizers and face creams, to brain damage in fish and bactericidal properties. Another highlighted the genotoxicity (a fancy word for destructive to DNA) of fullerenes in human lymphocytes in a controlled environment — even at lower dosages. (7, 8, 9)
Because nanoparticles are so microscopically small they have easier access to your bloodstream (and therefore internal organs through a process called uptake) either via inhalation into the respiratory tract or absorption through the skin barrier. Both, you can imagine, are concerning, especially considering that more than one study has linked increased nanoparticle exposure to brain damage (in fish).
Nanoparticles small size has another side-effect: the production of reactive oxygen species (ROS), including free radicals. Which, if you’ve read anything on the internet about skincare ever, you know that free radicals are enemy number one and often blamed for causing oxidative stress, inflammation and damage to vital proteins that literally keep us together, including our skin. Nanoparticles tiny size means they have a higher surface-area-to-mass ration, which in turn increases their reactivity and, potentially, photoactivity.
But the giant caveat to nanotoxicity is dose and size. Different shapes/sizes of nanoparticles impact skin and DNA differently, but the differences aren’t fully understood. (10)
Nanoparticles are a favorite among sunscreen makers because most of us won’t wear sunscreen that leaves a white, chalky film on our skin...kinda ruins the suave beach vibe, ya know. The smaller the filter, whether zinc oxide or titanium dioxide, the more transparent the sunscreen is on the skin. (Ironically, larger particles offer better UVA protection).
The research on the toxicity of nanoparticles in sunscreen seems inconclusive at best. Seeing a trend here? In one study, zinc oxide nanoparticles damaged stem cells in mice. In other, titanium dioxide nanofilaments were vaguely connected with cytotoxicity — but the level of toxicity fluctuated with the size and shape of the particles. In yet another, nanomaterials in sunscreen penetrated layers of pigskin within 24 hours, but in more recent ones, they didn’t. Part of the problem with understanding nanotoxicity is that there isn’t an agreed-upon size or shape that defines when a particle goes from regular to nano size. Nor is there agreement on what constitutes a significant amount of skin penetration that could realistically lead to cell damage in people. (11, 12, 13)
Before you decide you’re cool with a mild nano-invasion via your sunscreen or face moisturizer, consider the environment. As much as we don’t really know the longterm effects of nanoparticles on human health, we also poorly understand the implications of releasing nanoparticles into our oceans and air via sunscreen and other beauty products. Various studes (with more in the works), have verified the effects of nanotoxicity to sea urchin, coral larvae, mussels and marine algae across the globe — even those labeled as “eco-friendly.” (14)
The general consensus, it appears, with nanoparticles running rampant in the environment is the same as nanoparticles getting under our skin: there is no consensus and more research is needed. Perhaps more necessary than more research is a standard that defines size, shape and dose requirements of nanomaterials in cosmetic products to ensure that consumers, folks like you and me, are getting the best of the nano-world without risking our brain cells or the next coral reef extinction. In the 40 years since nanoparticles hit the beauty scene, surprisingly little has been done by way of clinical testing or regulatory oversight to make sure that this micro-sized revolution weighs big benefits and big risks with thoughtful care. (15)
