Photo by mabe123/

In recent years, headlines have linked sunscreen use to everything from an increased risk of skin cancers, to hormonal disruption, and even damage to aquatic life. The culprits, according to the Environmental Working Group’s 2017 Guide to Sunscreens, are a handful of chemical UV-filters that bioaccumulate in water and fatty tissues, with potentially toxic effects. “All of these chemicals that we’re talking about in the U.S. were approved back in 1978,” says Joseph DiNardo, MD, a retired toxicologist and sunscreen formulation specialist turned conservationist. “And the science that I was doing in 1978 for safety in comparison to what I would do today is significantly different.”

DiNardo has spent the last five years working alongside other researchers to undo the unforeseen ecological damage inflicted by the sunscreen and cosmetics industry. Thanks in large part to the team’s research, this past May, Hawaii passed a first-of-its-kind bill banning the sale of coral-destroying sunscreens containing oxybenzone and octinoxate—two common chemical filters—by 2021. But the environmental toll is just the tip of the iceberg.

Chemical vs. Mineral Filters

Most sunscreens and SPF cosmetics on the market contain a combination of chemical filters (mainly oxybenzone, avobenzone, octisalate, octocrylene, homosalate, and octinoxate). These filters, explains DiNardo, work by absorbing UV rays, which stimulates molecules in the skin and causes them to move faster so that the energy dissipates as heat, Chemical filters have come under fire in recent years for their endocrine-disrupting and allergenic properties, but the jury’s still out on avobenzone—an effective UVA filter—since “it’s not a true benzophenone,” says DiNardo.

Sunscreens touted as “reef-safe” contain the mineral compounds zinc oxide, titanium dioxide, or a combination of the two. These work by reflecting UV rays, though there’s still a low level of absorption. “Zinc is actually the best way to go,” says DiNardo, since it provides great protection across the entire UV spectrum.


Even more concerning, the 2003–2004 National Health and Nutrition Examination Survey found concentrations of oxybenzone and its metabolites in 97 percent of the U.S. population based on over 2,500 urine samples—and sunscreens aren’t the only offender. Oxybenzone and other benzophenones are added to everything from anti-aging serums, perfumes, cosmetics, plastics, cardboard, inks, and even dyed foods to keep pigments from degrading in the light. This makes it extremely ubiquitous in our environment, explains DiNardo. It also makes our true level of exposure difficult to predict—and since the half-life of oxybenzone is 2.4 years, it can hang around for nearly five years.

“Oxybenzone is very fat soluble—it’s sitting inside your fat cells,” says DiNardo, adding that it’s also “in just about every water source that exists.” Oceans contaminated with oxybenzone create a ripple effect up the food chain. “It accumulates in all living tissue, making it very difficult to get rid of.”

False Advertising

Another issue with sunscreens is the misleading marketing. If you think you can stay out twice as long with an SPF 100 than with an SPF 50, that’s simply not the case. “You’re making people believe that they’re protected from the sun and they could stay out in it longer,” says DiNardo, but “in reality, what you’re actually doing is increasing sun exposure, which increases your risk of skin cancer.”

In fact, he points out that, “After 40 years of sunscreen use, we’re not seeing any decrease in skin cancer. Instead, we’re seeing a significant increase in skin cancers all over the world.”

Photo by SNeG17/

Sunscreens Decoded 

Use this cheat sheet to help you navigate sunscreen labels.

UVB: These shorter ultraviolet waves are the culprit behind sunburns. UVB rays penetrate the superficial layer of the skin, where they also play a key role in the development of skin cancers by producing harmful free radicals.

UVA: Accounting for 95 percent of the radiation reaching the Earth’s surface, these longer waves penetrate deep into the skin, and are responsible for melanoma, the deadliest form of skin cancer, as well as signs of premature aging, like wrinkling, leathering, and sagging.

SPF: Short for “Sun Protection Factor,” this rating measures a sunscreen’s ability to protect your skin from UVB rays and prevent sunburn. According to the Skin Cancer Foundation, an SPF 15 sunscreen filters 93 percent of UVB rays, while SPF 30 and SPF 50 formulas filter 97 and 98 percent, respectively. But keep in mind that no SPF formula, no matter how high, can block all UV rays completely.

Broad-Spectrum: Broad-spectrum formulas filter out both UVA and UVB rays to varying degrees, depending on their combination of active ingredients.

Last Resort

Experts agree that sunscreen should be your last line of defense when it comes to staying safe in the sun. “The first step is sun avoidance,” says DiNardo. That means avoiding the sun during peak hours, seeking shade, and wearing protective clothing, along with sunglasses and a wide-brimmed hat.

Of course, you’ll still want to protect yourself with an effective sunscreen formula, so keep reading for our expert-recommended tips to help you choose the right one for you.

Your SPF Strategy

We tapped the experts for their tips on choosing the most effective sunscreen formulas on the market, and how to make them work for you.

  1. Go mineral. Not only does zinc oxide provide the best broad-spectrum protection of all the filters currently approved in the U.S., it’s also the eco-friendly choice. Plus, mineral sunscreens are ideal for those with sensitive skin or allergies to chemical filters, and for babies older than six months, says Jacqueline Dosal, MD, a board-certified dermatologist at Skin Associates of South Florida in Miami.

  2. Pass on nanoparticles. While nanoparticle formulas aim to improve on the absorption and accompanying blue-ish tinge of mineral sunscreens, retired toxicologist Joseph DiNardo, MD, advises to steer clear. “The science on nanoparticles is still questionable. We see some toxicity environmentally and some toxicity in humans, so it’s best until all the data is in to avoid nanoparticles.”

  3. Reach for a higher SPF. Don’t go lower than SPF 30, says Dosal. “In general, we apply less than half the intended amount”—so while an SPF 15 may be better than nothing, it doesn’t really provide enough protection.
  4. Choose lotions over aerosols. Lotions are great for more controlled application, but if you prefer a spray, apply it indoors, out of the wind. Spray it into your palm, then rub into your skin for a more effective application.

  5. Reapply every two hours—even if your formula is SPF 100 and water-resistant! Research published in Free Radical Biology and Medicine found that after just one hour of applying a chemical filter, the skin was back to producing more free radicals than in the control group that did not apply sunscreen.

  6. Darker complexions are not immune. “For the best possible skin, every skin tone needs sunscreen—every day!” says Dosal. Black and Latin Americans can still develop skin cancer, and “sun spots, discoloration, and ruddy complexion come with daily UV exposure in any skin type.”
Marta Ustyanich
Toronto-based freelance writer Marta has been writing about health and fitness for over five years, penning features for Oxygen, Inside Fitness and Inside Fitness Women magazines.