A UNESCO World Heritage site, Australia’s Great Barrier Reef contains the world’s largest collection of coral reefs, with 400 types of corals, 1,500 species of fish and 4,000 types of mollusks.

Ah, summer. Time to enjoy the long days of sunlight with outdoor picnics, paddling, and swims in lakes and pools. In this second season of the year, we take in lots of fresh air—and apply lots of sunscreen.

Unfortunately, while we’ve put decades of research into developing the most effective sunscreens for ourselves, it’s only in the last few years that we’ve been able to learn how these products are affecting the environment: particularly, coral reefs.

As one of the most valuable ecosystems on Earth, coral reefs provide billions of dollars in economic and environmental services, such as coastal protection, food and tourism. But around the world, coral ecosystems are now facing a number of serious threats, including climate change, coastal development, disease, invasive species, land-based pollution and unsustainable fishing. And recently, scientists have discovered that the chemicals commonly found in sunscreen are contributing—in large measure—to the problem.

The sunscreen you apply may not stay on your skin. When you swim or shower, it can wash off and enter waterways. ©National Oceanic and Atmospheric Administration (NOAA)

Bad BP-3 and baby corals

Australia’s Great Barrier Reef is one of the planet’s most spectacular underwater treasures. Visitors from all over the world are drawn by the reef’s colorful corals that serve as a submerged garden for an extraordinary variety of marine life. Snorkelers and scuba divers can swim alongside some of the thousands of species of fish that make the reef their home and might even catch glimpses of several of the six species of marine turtles found here.

In a 2016, however, in a study published in the journal Archives of Environmental Contamination and Toxicology, a team of international scientists reported that a common chemical found in many cosmetics and in sunscreen lotions is highly toxic to juvenile corals and other marine life. Oxybenzone, or BP-3, has four major toxic effects in early, developing coral: increased susceptibility to bleaching, DNA damage, abnormal skeleton growth (via endocrine disruption) and gross deformities.

A single drop of BP-3 in more than 4 million gallons of water is enough to endanger organisms. And, worldwide, BP-3 is used in more than 3,500 skin care products for protection against the sun’s rays. The compound enters the oceans both directly from swimmers wearing sunscreens and through wastewater effluent. So even if you don’t swim after applying sunscreen, it can go down drains when you shower. And aerosol versions of sunscreen often miss their mark, spraying large amounts of the product onto the sand, where it can easily wash into our oceans.


A 2015 study reported that an average of 412 pounds of sunscreen is deposited daily on the Hanauma Bay reef, an Oahu spot that draws an average of 2,600 swimmers per day.

By the numbers, the problem is daunting: 14,000 tons of sunscreen are thought to wash into the oceans each year, and 82,000 chemicals from personal-care products may be tainting our seas.

Good sun and UV below 3

Some nations are already taking steps to help the reefs. For example, on May 1, 2018, lawmakers in Hawaii passed a bill banning the sale of sunscreens containing oxybenzone and octinoxate, another harmful chemical. Hawaii is the first state to pass such a measure, and the law could go into effect by January 1, 2021. On November 1, 2018, the small island nation of Palau announced it, too, would ban selling or using sunscreens that contain any of 10 chemicals harmful to coral reefs, effective in 2020. Other governments are expected to follow.

But ultraviolet (UV) radiation from the sun not only has harmful effects on human health but beneficial ones, too. While excessive sun exposure increases the risk of skin cancer, you need sunlight to maintain adequate vitamin D levels. Beyond that, other possible positive results of sun exposure include suppression of autoimmune disease, reduction in blood pressure and improvements in mood.


Many of the world’s most popular destinations have the most at-risk corals. Some bays in Hawaii off black-sand beaches are among them.

Because of such advantages, Australia’s Cancer Council advises that in order to support vitamin D production, when the UV index is below 3 (which is true for most of the continental U.S. in the winter) “spend some time outdoors in the middle of the day with some skin uncovered.” When the UV Index falls below 3, “you do not require sun protection, unless you are at high altitudes or near highly reflective surfaces like snow, work outdoors or are outside for extended periods.”

Similarly, the British Association of Dermatologists said in a statement: “Enjoying the sun safely, while taking care not to burn, can help to provide the benefits of vitamin D without unduly raising the risk of skin cancer.”

Protecting your skin—and our seas

Here’s what you can do to safely enjoy the sun and care for the world’s coral reefs:

1) Think of sunscreen as your last resort. Clothing, especially that with SPF (sun protection factor) built in, can shield your skin from damaging UV rays. Wearing hats, shirts and other apparel incorporating UV protection can reduce the amount of sunscreen you need by up to 90 percent, and these items will likely last longer than a bottle of sunscreen. An umbrella can also provide cover.

When you do choose to use sunscreen, pick mineral-based sunblocks that use zinc oxide or titanium dioxide with particles above 100 nanometers. ©Fort George G. Meade Public Affairs Office, flickr

2) Plan your day around the sun. Go outdoors in the early morning or late afternoon hours when the sun is lower in the sky.

3) If you must go out mid-day, take cover. Pick shady spots for your activities. On the beach, bring along a beach tent to create your own shade.

4) When you do choose to use sunscreen, choose wisely and check the lists. Choose mineral-based sunblocks that use zinc oxide or titanium dioxide with non-nano-size particles (above 100 nanometers) that can’t be ingested by corals. If you’re not sure whether your sunscreen has nanoparticles, consult the Haereticus Environmental Laboratory, which each year publishes a list of what sunscreens are safe for the environment.


Don’t stay inside; summer adventures can be some of your best. Just do all that you can to make sure that they’re environmentally safe.

Other resources include the Environmental Working Group, which rates products with SPF values—including some 650 sunscreens and 250 moisturizers—on their environmental impact. And the Safe Sunscreen Council works to raise awareness about safer alternatives to environmentally harmful sunscreen ingredients within the skin-care industry and among consumers.

In summer, a world of healthy outdoor adventures beckon. Don’t be afraid to step into the light. Just make sure that you do so with your health—and the world’s—in mind.

Here’s to finding your true places and natural habitats,