Slather On That Nano Sunscreen, Dermatology Group Says
by Gwyneth K. Shaw | Apr 25, 2011 6:30 am
(NHI Nanoblog) Amid confusion and concern over super-small sun-blockers, a group of dermatologists has made a strong statement: the benefits of shielding your skin from harmful rays outweigh any risk from the sunscreen itself.
The Nanodermatology Society, a group founded last year, recently released a “position statement” aimed at quelling some of the anxiety over sunscreens that use nano-sized titanium dioxide and zinc oxide as a key ingredient.
These substances are prized for their ability to block ultraviolet rays, and shrinking them to the nanoscale (a nanometer is a billionth of a meter) makes them transparent, eliminating the blaze of white that used to grace the noses of lifeguards. These types of sunscreens often appeal to people who want to avoid the so-called “chemical” sunscreens, which can be irritating to sensitive skin.
But as with other nanomaterials, changing the size alters their properties, and scientists are struggling to figure out whether, how and why that shift can make these substances dangerous in the process.
As nanoparticles have become more common in sunscreens—as well as lots of other products—some advocacy groups have called for better labeling and more stringent rules. Friends of the Earth, for example, has released a number of reports on nanoparticles and sunscreens, and has urged consumers to seek more information from manufacturers.
The dermatology society’s analysis acknowledges the serious concerns that have been raised about titanium dioxide and zinc oxide. The group concludes, however, that there’s little evidence that the nanoparticles penetrate the skin deeply enough to get into the bloodstream. Given the strong UV-blocking abilities of titanium dioxide and zinc oxide, sunscreens that contain them are smart to use, according to the statement.
Adam Friedman, the society’s vice president and the director of dermatologic research at the Albert Einstein College of Medicine, said the risk associated with titanium dioxide, for example, seems to come from inhaling the material, not in applying it to the skin. While spray-on sunscreens are increasingly popular, he said he’s unaware of an aerosol product that’s sold in the U.S. that contains it.
The big risk with sprays, Friedman said, is that you don’t put enough on to protect yourself.
For creams and lotions, he said, the titanium dioxide particles are coated as part of the formulation, so they don’t absorb the UV rays and create damaging free radicals. They’re also generally designed to clump together, or agglomerate.
“In truth, at the end of the day, they’re not truly nanoparticles” because of the clumping, Friedman said.
The group’s statement does note that these substances may pose a risk to the workers who manufacture sunscreens, and that there is the potential for environmental damage.
It’s true that nobody has studied much about what happens when these substances are applied to broken skin, Friedman said. Is stands to reason that if you were apply a nano-titanium dioxide to an open wound, bad things might happen, he added.
“You could say the same thing if you put arsenic in an open wound,” he said.
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