Are nanoparticles of titanium dioxide and zinc oxide harmful?

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

While nanoparticles of titanium dioxide and zinc oxide have been controversial, the American Academy of Dermatology notes that they "have a long history of safe use in sunscreens." The nanoparticles appear not to penetrate the skin. They block both ultraviolet A and ultraviolet B (UVA and UVB) rays that can cause sunburn and skin cancer. Talk to a dermatologist for more information.


Dr. Ellen Marmur, MD
They could possibly prove harmful because their tiny size may be able to penetrate into the dermis through hair follicles and then into the bloodstream. The good news is that zinc oxide and titanium dioxide used to look like white diaper cream on your skin, and now they've become nearly transparent thanks to this micronization. A lot of mineral makeup and powder sunscreen formulations utilize nanoparticles of titanium dioxide and zinc oxide too. But now this active ingredient, or drug, is not only blocking ultraviolet light by sitting on top of the skin, it's being delivered through the pores into the body. Most sunblocks use nanoparticles (although products don't have to disclose that information on the label). A measurement of a nanometer is one billionth of a meter - approximately one ten-thousandth the diameter of a strand of human hair.
The concern is that these ingredients, if they are absorbed, could then create free radicals that damage DNA. In fairness, the lab studies involving nano-size titanium dioxide didn't concern sunscreens but were done using photoactive titanium dioxide (sun enhancers that break down chemical contamination). Sunscreen products use coated nanoparticles designed to deflect sunlight and are not made to generate free radicals. Most of the scientific studies done on nanoparticles over the past ten years have not detected penetration through human skin. Environmental groups such as Friends of the Earth complain that there have not been enough studies done and that products containing nanoparticles should be required to state that on the label. And that's a good point. The Environmental Working Group (EWG), a consumer advocacy organization, still recommends products with these physical blockers, whether they are nano-size or not. They argue that nanoparticles of titanium dioxide and zinc oxide are just as toxic as chemical sunscreens such as oxybenzone and octinoxate that the EWG claims can be absorbed into the skin and cause abnormal activity in the body.
Simple Skin Beauty: Every Woman's Guide to a Lifetime of Healthy, Gorgeous Skin

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Simple Skin Beauty: Every Woman's Guide to a Lifetime of Healthy, Gorgeous Skin

What if a leading dermatologist just happened to be your best friend and you could ask her anything? DR. ELLEN MARMUR, a world-renowned New York City dermatologist, answers all your questions with...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.