We’ve all heard it—as pleas from caring parents, product taglines, or public service announcements: “Wear sunscreen to prevent skin cancer!”
During summer months, we dutifully comply—rubbing, spritzing, and slathering coconut-scented creams and sprays onto our exposed skin. And why wouldn’t we? It’s a simple equation: The sun produces ultraviolet (UV) rays, which cause sunburns and potentially skin cancer. Using a full-spectrum sunscreen helps prevent said UV rays from penetrating the skin, reducing our skin cancer risk.
But what if the equation isn’t so simple?
According to the Environmental Working Group (EWG), a nonprofit that works to protect human health and the environment, scientists and public health agencies alike “have found little evidence that the use of sunscreens in isolation from other sun protective measures prevents most types of skin cancer.”
This seems to align with the steady increase in skin cancer cases. According to the National Cancer Institute, melanoma rates “have been rising on average 1.5 percent each year over the last 10 years.”
While this evidence shouldn’t have us tossing our sunscreen habits out the window, it certainly suggests we should take a moment to re-examine our relationship with and understanding of sunscreen so we can make better-informed decisions about our health and the health of our families.
Is sunscreen effective against skin cancer?
Without a doubt, UV rays cause skin cancer. But under the umbrella term “UV rays” are UVA rays and UVB rays—both dangerous in their own ways.
UVB rays make up about 3 to 5 percent of the UV rays reaching the Earth’s surface and are the primary cause of precancerous DNA mutations and the dreaded sunburn. Many sunscreens, when applied correctly, block UVB rays and therefore prevent sunburn.
However, prolonged sun exposure, even when not resulting in sunburn, can have dangerous consequences. UVA rays—responsible for tanning—penetrate deeper than UVB rays, generating free radicals that can lead to DNA damage and cause skin cancer. Unfortunately, most sunscreens protect from sunburn and not much else, since UV rays break down the most common chemical UVA filter, avobenzone.
Protection against your sun protection
To better understand the difference between “good” sunscreens and “bad,” it’s important to distinguish between those using mineral filters and those using chemical filters as the active ingredients.
Mineral filters consist of zinc oxide and titanium dioxide, which are stable in sunlight and protect well against both UVA and UVB rays. Mineral-only sunscreens tend to stand up to the EWG’s thorough analysis, as they’re also often free of harmful additives.
Chemical filters, on the other hand, have a less-than-stellar reputation and include avobenzone, homosalate, octinoxate, octisalate, octocrylene, and oxybenzone.
Oxybenzone—a known allergen—is particularly concerning as a hormone disruptor, as demonstrated by a 2016 study from the Agency for Toxic Substances and Disease Registry. Higher levels of the chemical were associated with lower levels of testosterone in adolescent boys.
Sunscreen and the environment
One thing we often don’t consider with respect to sunscreen is its cumulative effect on the environment. But think about it: We slather potentially harmful chemicals all over our bodies only to jump into a pool or ocean where those same chemicals leach into the surrounding water.
Thanks to global warming, coral reefs are already facing unprecedented rates of bleaching, with mass bleaching occurring five times more frequently than in the 1980s. Now we can add sunscreen to its list of threats. A recent report from the International Coral Reef Institute cites several studies suggesting oxybenzone may contribute to “bleaching of coral fragments and coral cells from various species of hard coral.”
It has been suggested that oxybenzone also harms fish embryos, as shown in a 2018 study analyzing sunscreen chemicals found in the waters of Shenzhen, China. The researchers found that although zebrafish exposed to multiple common UV filters showed no signs of problems, their offspring displayed abnormalities.
What to look for this summer
Generally speaking, mineral-only sunscreens are your best bet when it comes to sun protection since they’re safe and protect against both UVB and UVA rays. Although these formulas are often made with zinc oxide and titanium dioxide nanoparticles, there is no evidence to suggest the particles penetrate the skin (phew!). You can find a range of mineral sunscreens at your local natural health retailer.
With more Americans being diagnosed with skin cancer each year than all other cancers combined, it’s fair to say that sun safety is more important than ever. Until recently, many of us chose our sunscreen based on superficial factors such as look, smell, and price. Now we need to take into consideration individual ingredients—not only for our health, but also for the planet’s.
The FDA has proposed new sunscreen regulations that recognize two active sunscreen ingredients as safe and effective: the mineral filters zinc oxide and titanium dioxide. Twelve other active ingredients currently on the market—all of them chemical filters—would require further safety and efficacy testing, including trials that would reveal how much of these ingredients can be absorbed into the body. So far, research on chemical sunscreen ingredient absorption is sobering; see p. 39 to learn more. (P.S. The new FDA regulations would also require improved UVA protection from sunscreens!)
Will this be the sunscreen of the future?
Recognizing the hazards potentially contained within many of our current sunscreen products in the form of chemicals toxic to both human and marine life, scientists are busy researching alternative UV-shielding ingredients to replace these chemicals.
One such ingredient is shinorine, a natural compound produced in many aquatic organisms that are exposed to strong sunlight, including cyanobacteria and macroalgae, to protect them from solar radiation.
Work is underway to develop an economical and sustainable production method to harvest shinorine for use in sunscreens and cosmetic moisturizers.