Can zinc oxide is sunscreen cause cancer? It's a rumor bouncing around the web. I received the question from a reader and here is my scholarly opinion!
Dear Dr. Bailey,
I really like your skin care blog! I've also noticed that many of the sunscreen products that you recommend contain zinc oxide. I have family members who have seen news reports that using sunscreen containing zinc oxide actually causes skin cancer when the skin is directly exposed to the sun. How do I answer their concerns? -Susan H.
Actually all of the sunscreen products that I recommend - that I use for my family and that I personally use - contain zinc oxide. I'm a big zinc oxide fan and I trust the protection that it provides. I also see the benefits of how well it reduces skin cancer risk every day in my dermatology practice; once patients begin using zinc oxide sunscreen, along with following my advice for sun protection, they get fewer skin cancers and precancerous growths.
Your question is great because the safety of sunscreen is a hot topic right now.
There are a bunch of recent media discussions that have started over a new scientific study done on cells in a petri dish. The study suggests that nano-zinc oxide plus UVA is harmful. The study, about to be published in the Journal of Toxicology and Applied Pharmacology, is a study of vulnerable cells in a dish that are completely different than the cells in healthy human skin.
Results of studies done on skin cells in a petri dish are not directly indicative of the same conclusions being valid on your living human skin because your skin is much more complex. The studies are intriguing, but more study is always needed - Dermatologist Dr. Cynthia Bailey
As is sadly common, the media's questions sound like conclusions and, unfortunately, it's scaring people who want to do the right thing for their skin health. The situation is that human lung cell in a petri dish were bathed in a solution with nano-zinc oxide and then exposed to UVA. The researchers found that more cells exposed to the nano-zinc oxide died compared with the cells not exposed.
The scientific paper is not even out yet, so I don't have the details - yet media 'conclusions' are being made! The BIG point is that our skin is not like vulnerable cells in a petri dish; human skin has a complex structural barrier called the stratum corneum covering its living cells.
Excellent scientific studies show that nano-zinc oxide in sunscreen doesn't get into human skin. Plus, it's applied to a complex living system that's nothing short of a miracle. There's simply no comparison between the skin and the petri dish cells, so valid conclusions cannot be drawn. Even the lead author, Dr. Yinfa Ma, is quoted by media sources (Science Daily, Huffington Post) as saying that you can't conclude that sunscreen applied to your skin is bad. He cautions people from drawing conclusions and he recommends the use of sunscreen. He says:
More extensive study is still needed. This is just the first step. I still would advise people to wear sunscreen. Sunscreen is better than no protection at all.So, Susan, add to this all the data we have showing that sunscreen use actually prevents skin cancer IF it's broad spectrum, and I think we know what to do:
- Wear our broad spectrum zinc oxide sunscreen and know that we are taking good care of our skin.
- Cover as much skin as possible with clothing and shade our face with a broad brimmed hat when outdoors because wearing broad spectrum sunscreen does not mean it's safe to run around in the sun exposing our skin to UV rays.
- Seek out shade when possible.
- Eat lots of fresh fruits and veggies to load the skin from the inside out with free radical fighting antioxidants.
- Apply antioxidant rich skin care products to the outside of your skin. I think the best topical antioxidants for fighting skin cancer are the green tea polyphenols in my Green Tea Antioxidant Skin Therapy.
I hope that helps you sort out the confusion surrounding sunscreens and your skin's health.
Cynthia Bailey MD, Dermatologist
J Clin Oncol. 2011 Jan 20;29(3):257-63. Epub 2010 Dec 6. Reduced melanoma after regular sunscreen use: randomized trial follow-up. Green AC, Williams GM, Logan V, Strutton GM.
Skin Pharmacol Physiol. 2009;22(5):266-75. Epub 2009 Aug 18. Stratum corneum is an effective barrier to TiO2 and ZnO nanoparticle percutaneous absorption. Filipe P, Silva JN, Silva R, Cirne de Castro JL, Marques Gomes M, Alves LC, Santus R, Pinheiro T.
J Biomed Opt. 2008 Nov-Dec;13(6):064031. Imaging of zinc oxide nanoparticle penetration in human skin in vitro and in vivo. Zvyagin AV, Zhao X, Gierden A, Sanchez W, Ross JA, Roberts MS.
Disclaimer: Please realize that availing yourself of the opportunity to submit and receive answers to your questions from Dr. Bailey does not confer a doctor/patient relationship with Dr. Bailey. The information provided by Dr. Bailey is general health information inspired by your question. It should not be a substitute for obtaining medical advice from your physician and is not intended to diagnose or treat any specific medical problem (and is not an extension of the care Dr. Bailey has provided in her office for existing patients of her practice). Never ignore your own doctor’s advice because of something you read here; this information is for general informational purpose only.