Animal research has shown that inhaled nanoparticles can reach all areas of your respiratory tract and, since your lungs have difficulty clearing small particles, they may be allowed to pass into your bloodstream. Other studies have proven some nanoparticles are even able to cross your blood-brain barrier.
If allowed to enter your lungs or penetrate your skin, nanoparticles therefore have the potential to cause widespread damage to your cells and organs, immune system, nervous system, heart and brain.15,16 FDA has previously expressed concern that inhaling these products may be risky, especially to children, and in 2014, Consumer Reports advised parents to avoid spray-on sunscreens until the FDA had finished reviewing the sunscreens.17
Some scientists postulate that the toxic effects of nanoparticles relate to their size being in the range of a virus, which may trigger your body’s immune response.18 The International Agency for Research on Cancer has classified titanium dioxide as a “possible carcinogen” when inhaled in high doses.19
Inhaling higher amounts of zinc oxide can lead to “metal fume fever,”20 characterized by chest pain, cough, dyspnea, reduced lung volumes, nausea, chills, malaise and leukocytosis. One 2012 study21found zinc oxide nanoparticles to be cytotoxic. They elevated zinc levels causing mitochondrial dysfunction and apoptosis (cell death).
Similarly, an Indian study concluded that zinc oxide nanoparticles cause toxicity in human lung cells possibly through “stress-induced apoptosis.”22 Human studies are sorely lacking as to the health effects of inhaling of zinc oxide particles, especially at lower levels, such as from brief exposure to sunscreen spray.
However, using these spray-on products are clearly an unnecessary risk since safer options are readily available. Your safest bet is to use topical zinc oxide or titanium dioxide that does not contain nanosized particles.
Reduce Your Risk of Sunburn With ‘Internal Sunscreens’
While sun avoidance recommendations make it sound as though all sun exposure is dangerous, the primary risk factor of skin cancer is sunburn, which is an inflammatory process that damages your skin. Sensible sun exposure is actually a crucially important component of good health, as your body produces vitamin D in response to UVB light striking your skin.
It’s important therefore to maintain a balance — you want to expose large portions of skin (without sunscreen on) to sunlight on a regular basis (ideally daily), yet be very careful to avoid getting burned.
Aside from covering up before you get burned, you can reduce your risk of sunburn by eating plenty of antioxidant-rich fruits and vegetables, and/or taking an astaxanthin supplement. The latter has been shown to work as an effective internal sunscreen, protecting your skin from UV radiation damage.
In addition to copious testimonials and anecdotal evidence, scientific studies have substantiated these skin protective effects.23 In one study, subjects who took 4 milligrams of astaxanthin per day for two weeks showed a significant increase in the amount of time necessary for UV radiation to redden their skin. Animal studies lend further evidence to astaxanthin’s effects as an internal sunscreen:
- In one study, mice were fed various combinations of astaxanthin, beta-carotene and retinol for four months. Astaxanthin was substantially effective in preventing photoaging of the skin after UV radiation, as measured by markers for skin damage24
- A rat study found astaxanthin was found to be 100 times stronger than beta-carotene and 1,000 times stronger than lutein in preventing UVA light-induced oxidative stress25
- The Journal of Dermatological Science published a study in 2002 finding astaxanthin is able to protect against alterations in human DNA induced by UVA light exposure26
How to Choose a Safer Sunscreen
With all the sunscreens on the market, how do you identify a safe one? The key to remember is that there really are only two known safe sunscreen ingredients — zinc oxide and titanium dioxide27 — and they must not be nano-sized.
Your safest choice is a lotion or cream with zinc oxide, as it is stable in sunlight and provides the best protection from UVA rays.28 Your next best option is titanium dioxide. Just make sure the product does not contain nano sized particles and protects against both UVA and UVB rays.
Keep in mind that SPF protects only from UVB rays (although if the FDA’s proposed rules are implemented, any SPF at or above 15 must protect against both UVA and UVB), which are the rays within the ultraviolet spectrum that allow your skin to produce vitamin D.
The most dangerous rays, in terms of causing skin damage and cancer, are the UVA rays. Avoid sunscreens with an SPF above 50. While not intrinsically harmful, the higher SPF tends to provide a false sense of security, encouraging you to stay in the sun longer than you should.
Moreover, higher SPF typically does not provide much greater protection. In fact, research suggests people using high-SPF sunscreens get the same or similar exposure to UV rays as those using lower-SPF products. What’s more, a recent analysis29 by Consumer Reports found many sunscreens are far less effective than claimed on the label; 24 of the 73 products evaluated offered less than half of the protection promised by their stated SPF.
Other Sensible Sunning Tips
I recommend spending time in the sun regularly — ideally daily. Sunshine offers substantial health benefits, provided you take a few simple precautions to protect yourself from overexposure. Here are my top five sensible sunning tips:
1.Give your body a chance to produce vitamin D before you apply sunscreen. Expose large amounts of your skin (at least 40 percent of your body) to sunlight for short periods daily. Optimizing your vitamin D levels may reduce your risk of many internal cancers, and actually reduces your risk of melanoma as well.