Sunblocks are so important for protection of the skin, avoidance of skin aging changes and overall health and beauty.
This article from the NY Times discusses the unknowns and controversy about titanium oxide sunblock. Trust me, I'm still using mine till I hear differently and would suggest that you do the same.
Ask Well: Nanoparticles in Sunscreens
By DEBORAH BLUM
July 17, 2014 1:19 pmJuly 22, 2014 3:15 pm
Credit Chip Litherland for The New York Times
What are the risks from nanoparticles of titanium in sunscreens?
Asked by David • 153 votes
I am curious about the dangers of nanoparticles in sunblocks.
Titanium dioxide nanoparticles have been used increasingly in sunscreens in the last decade to protect the skin because the tiny particles directly absorb the radiation from sunlight, especially in the UVB range. But because the articles are so tiny — generally about 100 nanometers across, compared with about 3,000 to 9,000 nanometers for a speck of dust — some scientists have raised concerns about whether they might do harm by seeping through the skin and into the bloodstream.
Concerns grew when studies in mice showed that when injected under the skin, titanium dioxide caused inflammation . In addition, the International Agency on Cancer Research, part of the World Health Organization, decided in 2006 to classify titanium dioxide as a potential human carcinogen, based mostly on inhalation studies in animals, though the group called the evidence “conflicting at best.”
But research has largely dismissed such concerns about absorption, and most experts say that sunscreens containing nanoparticles can be safely used.
More recently, concerns have focused on the possibility that these nanoparticles could promote skin aging. Nanoparticles tend to heat up a little when they absorb UV radiation, says Paul Westerhoff, a professor at Arizona State University’s School of Sustainable Engineering and the Built Environment, and some research suggests that this process could cause oxidative damage to the skin, particularly with one form, called anatase, when it was delivered in uncoated particles.
Dr. Westerhoff says most manufacturers now coat the nanoparticles with silicon or aluminum as a buffer against such harm and as a way to increase light absorption. But, researchers say, there’s some evidence that those coatings can break down over days or weeks, which may be an issue for sunscreens stored too long.
“I’m not saying that titanium dioxide is bad,” Dr. Westerhoff said. But he noted recently in Environmental Science and Technology that the products have not been thoroughly studied and are minimally regulated. The only Food and Drug Administration rule for sunscreens is that the titanium dioxide concentration be less than 25 percent (most are 2 percent to 15 percent). “I’m just saying we need to figure out if we should worry.”