Here in the northern hemisphere the days are getting longer and we’re spending more time outdoors. Before you slather sunscreen all over your body you may want to do a little research.
Concerns about Nanoparticles
Remember the lifeguards from days past with white noses and lips? They were using zinc oxide — the same stuff used for diaper rash. Many of the more “natural” sunscreens use zinc oxide and/or titanium dixoide as a physical, rather than a chemical, barrier against damaging UVA and burning UVB rays. Unfortunately, these sunscreens tend to give us a ghostly cast. In an effort to make these sunblocks less visible, some manufacturers chop zinc oxide and titanium dioxide into little pieces, or nanoparticles.
There has been an on-going debate about the health risks of nanoparticles in skin lotions and sunscreens, with some research indicating that nano-sized zinc oxide and titanium dioxide can be harmful when they react with sunlight to release free radicals.
Last fall a study from UCLA, published in the journal Cancer Research, showed that titanium dioxide (TiO2) nanoparticles could increase the risk of cancer in mice:
The TiO2 nanoparticles induced single- and double-strand DNA breaks and also caused chromosomal damage as well as inflammation, all of which increase the risk for cancer. The UCLA study is the first to show that the nanoparticles had such an effect, said Robert Schiestl, a professor of pathology, radiation oncology and environmental health sciences, a Jonsson Cancer Center scientist and the study’s senior author.¹
Now we need to worry about eating sunscreen!
(Well, I have to say that I’ve always thought eating any kind of sunscreen was a bad idea. )
“Unintended exposure to nano-sized zinc oxide from children accidentally eating sunscreen products is a typical public concern, motivating the study of the effects of nanomaterials in the colon,” the scientists note.
Their experiments with cell cultures of colon cells compared the effects of zinc oxide nanoparticles to zinc oxide sold as a conventional powder. They found that the nanoparticles were twice as toxic to the cells as the larger particles.
Although the nominal particle size was 1,000 times larger, the conventional zinc oxide contained a wide range of particle sizes and included material small enough to be considered as nanoparticles. The concentration of nanoparticles that was toxic to the colon cells was equivalent to eating 2 grams of sunscreen — about 0.1 ounce. ²
Safety and Effectiveness
The Environmental Working Group (EWG) publishes a handy sunscreen guide. They rate the health hazard level from zero to ten for different products, citing which ingredients are suspect. They also include an effectiveness rating. You’d be surprised how many sunscreens don’t live up to their SPF claims.
Four percent of high SPF sunscreens (SPF of at least 30) protect only from sunburn (UVB radiation), and provide poor protection from UVA, the sun rays linked to skin damage and aging, immune system problems, and potentially skin cancer. FDA does not require that sunscreens guard against UVA radiation.³
If you’re concerned about nanoparticles, look for sunscreens with the “EU compliant” seal on them: Cosmetics containing nanoparticles must now list them as an ingredient in the European Union. Friends of the Earth also maintains a list of nanoparticle-free sunscreens.
A note about mixed messages: Sun exposure and sunscreen use are topics fraught with strong emotions. Some think that exposing our skin to the sun in small doses, without getting burned is the most healthful because we’ll get some much-needed vitamin D. Others think that we should always cover up to reduce our risk of skin cancer. We’re also told that the chemicals in commercial sunscreens may even increase our risk of skin cancer!
Do your own research. Everyone is different. I love vitamin D, but I also had a basal cell skin cancer on my face in my thirties — very young. I wear a hat most of the year and use a sunscreen that makes me look like death warmed-over when I think I might get burned.
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1) Titanium Dioxide (TiO2) Nanoparticles In Household Products Linked To Cancer In Mice , Scientific Blogging, November 17, 2009.
2) Evidence That Nanoparticles in Sunscreens Could Be Toxic If Accidentally Eaten: ScienceDaily, April 7, 2010.
3) Best Beach & Sport Sunscreens, Environmental Working Group.