There is no denying that sunscreen can help reduce a person’s risk of developing skin cancer, a fact backed by trusted organizations such as the Skin Cancer Foundation, the American Academy of Dermatology (AAD), and the Centers for Disease Control and Prevention (CDC). These associations, along with many others, recommend the general public apply sunscreen to exposed skin every day—even in cloudy conditions—and reapply every two hours if remaining out in the sun for an extended period of time. For short-term outdoor sun exposure, an SPF (Sun Protection Factor) of at least 15 is typically recommended, while a minimum of SPF 30 is advised for long-term outdoor sun exposure.
Of course, when applying anything to our skin, we also need to consider how it is absorbed by our bodies—and whether or not it is safe to do regularly, periodically, or even at all. We know sunscreen helps prevent skin cancer, but what do we know about our body’s absorption of various active ingredients that compose sunscreen when current usage recommendations are closely followed? Do some active ingredients that are absorbed by our bodies reach unsafe levels with regular sunscreen use?
A study published in the Journal of the American Medical Association (JAMA) sought to answer just that by examining the systemic absorption of six active ingredients found in sunscreens of the lotion, aerosol spray, nonaerosol spray, and pump spray varieties. The active ingredients evaluated included avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate—all of which have an FDA-determined concentration limit within the body that, if surpassed, necessitates additional safety testing.
The study was completed over the course of 21 days, and participants were each randomly assigned one of the four sunscreen product formulations to use (lotion, aerosol spray, nonaerosol spray, or pump spray). On the first day, participants conducted a single application of sunscreen (2 mg/cm2) to approximately 75% of their bodies. From days two to four, they then applied the same amount of sunscreen to the same surface area of skin four times per day at two hour intervals. Throughout the 21 days, a total of 34 blood samples were collected from each participant for testing.
Results of the study concluded that all six active ingredients measured higher than the FDA’s maximum concentration limit as early as the first day of the trial—meaning a single application of sunscreen was all it took for systemic absorption to exceed the threshold.
Does This Mean We Should Stop Wearing Sunscreen?
Absolutely not; the use of sunscreen to protect against harmful UV rays is still recommended. The conclusion of the study merely means that further research now needs to be conducted to determine the clinical significance of the findings, ultimately leading to a better understanding of sunscreen safety with chronic use. It is also worth noting that the study had a few limitations—such as being conducted in an indoor setting—which will need to be taken into account and may impact future findings.
Are There Sunscreens Available That Don’t Include These Ingredients?
Again, the fact the study showed that levels of avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate in the body exceeded the FDA’s threshold after a single application does not mean sunscreen is unsafe. Rather, additional testing is necessary.
That being said, individuals who wish to limit—or potentially even avoid—these ingredients do have an option: biodegradable sunscreen. As opposed to UV-blocking chemicals, biodegradable sunscreens typically utilize natural minerals like zinc oxide and titanium dioxide to guard against harmful UV rays, effectively providing sun protection with mostly (if not completely) organic ingredients.
In addition to those who are particularly health-minded, some believe biodegradable sunscreens can be the best choice for people who have sensitive skin, certain allergies, and/or who are environmentally conscious. In fact, as highlighted in our blog regarding the environmental impacts of sunscreen, some research suggests that ingredients like oxybenzone and octinoxate have a negative impact on coral reefs. While additional testing is still needed, this claim has led Florida, Hawaii, Palau, Australia, and others to proactively ban non-biodegradable sunscreens that may be harmful to sea life.
Ultimately, the type of sunscreen you wear is up to you, but regardless of whether you choose chemical-based or biodegradable, the advice remains the same: wear an SPF of at least 15 for short-term outdoor protection on exposed skin, and a minimum of SPF 30 for long-term outdoor exposure—reapplying every two hours when remaining outside.
Previous Post Next Post