Eight minutes and 20 seconds. The amount of time a photon of sunlight races through the vast expanse of space before it bombards our atmosphere. The Greek philosopher Anaxagoras first theorized the sun as a flaming ball of molten “something or other” much larger than the small disc we see in the sky (he was of course imprisoned by more enlightened authorities for his teachings). He wasn’t far off though, sunlight is actually the result of hydrogen atoms smashing together to produce helium inside a 4.5-billion-year-old spherical ball of plasma over 91 to 95 million miles away at the center of our solar system. (Earth orbits the Sun in an elliptical pattern so the distance varies. The average distance between the Earth and the Sun is 92.96 million miles.)
From space, sunlight appears white in color. As it collides with our atmosphere the direct solar sunbeams are scattered. This is an important step for life — otherwise, we would all boil. This scattering of sunlight gives us the blue sky we perceive, as the atmosphere scatters short-wavelength visible light more intensely than longer wavelengths. Its intensity (solar radiation) is also reduced by about one third and the majority of the solar IR and UV radiation is filtered out. So on the surface living organisms absorb the small band of visible light and some degree of UV and IR light. The sun actually emits a broad range of wavelengths, from high-energy X-rays and ultraviolet radiation, through visible light, on down the spectrum to the lower energy infrared and radio waves. In fact, tiny neutrinos from the sun are passing through the gaps between the atoms in your body as you read this, but that is getting too far down the nerd rabbit hole.
What matters is that without this complicated procession of photons and electromagnetic waves bouncing off one another, life could not exist. Most life on Earth begins with the transformation of the Sun’s energetic rays into chemical energy through photosynthesis. That breath you just quickly inhaled — from hearing these astounding facts— began as sunlight. A nameless plankton in a far off ocean or some forgotten forest tree a thousand miles away inundates your lungs over and over with your most precious resource — the breath of life.
But the sun’s warmth comes with a cold hubris. Challenging the gods and the larger forces at work in the universe can be deadly humbling. As when Icarus flew too close to the sun, its intensity has the power to give and take life. Once exposed to the heavenly glare, our skin will produce Vitamin D from UVB rays. Exposing skin for about half the time it takes to turn pink is enough to make this essential vitamin (about 10 minutes for light skinned, 15-20 minutes formid- ranged tones or tanned skin, and up to an hour for darker skin). But keep your skin exposed past these times and the sunlight can take life instead of give it.
The intense radiation in the UV spectrum begins to damage skin cells at the cellular level, causing mutations in the DNA. As the body repairs damaged DNA, it occasionally inserts the wrong bases. This improperly repaired DNA can disrupt cellular processes and eventually cause mutations and cancer. To avoid this we apply a greasy barrier between our skin and the sun — sunscreen. Many peer-reviewed studies have shown that applying sunscreen (generally SPF 30 or above) reduces your chance of developing skin cancer. The American Academy of Dermatology concurs. However, you can find a wealth of anecdotal evidence pointing to the dangerous effects to human health from chemicals in sunscreen, although few scientific studies exist to back these claims.
But in recent years, an indirect yet urgent threat to humankind has paradoxically emerged from sunscreen usage. Remember those far off creatures that fill your lungs with air? Well, the marine habitats where many of them are found —like coral reefs— are feeling the burn of sunscreen. Corals are the base of marine ecosystems in the tropics. Most of the marine life we see in the waters around Hawaii would cease to exist without the watery nooks and biological bonanza that coral reefs provide. Corals are one of the longest-lived organisms on Earth, some are known to be up to 4,000 years old (individuals, not the species). The largest living organism on Earth is thought to be the Great Barrier Reef.
Coral reefs provide ecosystem services to the economy and livelihoods of our societies valued at US $30 billion a year. They protect shorelines from the devastating effects of erosion and storm damage. And millions of people rely directly upon them for food, jobs, tourism, recreation, and even emerging pharmaceuticals for cancer, arthritis, asthma, ulcers, human bacterial infections, heart disease, and viruses.
Yet corals are incredibly sensitive creatures. Corals are often mistaken for hard rocky surfaces since most of their structure is just that, hard limestone. However, the outer layer of the reef, that colorful rock your foot is often standing upon, is a living coral organism composed of thousands of tiny coral polyps. This thin outside layer of interconnected little animals (tiny stationary jellyfish called coral polyps) are composed of tissues that are home to colorful photosynthetic zooxanthellae (microscopic plants that turn sunlight into food) and grow on top of a calcium carbonate exoskeleton (the hard underneath of the reef).
Each step can kill these unassuming little overachievers. However, the sunscreen that washes off your body can be even more damaging. Most popular sunscreens contain a chemical called oxybenzone that is toxic to corals. Imagine a beautiful coral reef nestled in a watery lagoon equivalent in volume to roughly six Olympic-size swimming pools. One small drop of oxybenzone from sunscreen is enough to damage and potentially kill the corals in this lagoon. One drop!
It is common knowledge in the science community that corals are very sensitive to environmental conditions. When the waters become too hot, too cold, murky from sediments, too polluted, or too acidic from the tons of carbon absorbed into the oceans (acidification), corals eject their symbiotic zooxanthellae and eventually die. The tiny zooxanthellae plants provide the coral polyps with food, so once they leave, it’s game over. All that remains is the hard white structure of the reef where the little polyps once lived, hence the name “coral bleaching.” In the most recent bleaching event in Hawai’i, the Division of Aquatic Resources (DAR) reported that as much as 50 percent of West Hawaii’s corals bleached and died. This is attributed to elevated ocean temperatures, but adding oxybenzone from sunscreen to the already fragile environment is making the situation much worse.
Since the 1980s, oxybenzone has been widely used and is found in 3,500 sunscreen products worldwide on the market today — the vast majority. Seawater testing in Hawai’i and the Caribbean has shown concentrations of this coral-killing chemical 12 times higher than in “normal” seawater. And it is estimated that 6,000 to 14,000 tons of sunscreen enters coral reef ecosystems annually. Largely because intrepid ocean lovers lather up and head straight for these fun factories of fish, turtles, and undiscovered adventures. When corals come in contact with oxybenzone it can damage their DNA, act as an endocrine disruptor, deform juvenile corals, and induce coral bleaching, often at temperatures several degrees cooler than what corals could normally endure. Keep in mind that corals are already fending off a gauntlet of deadly stressors from those ocean and reef lovers’ lifestyle choices.
Since the onslaught of anthropogenic (human-originated) climate change, ocean acidification, and urban/agricultural pollution and sedimentation, coral reefs have declined across the globe at staggering rates. The situation is so dire that if current trends continue, we could be looking at the extinction of world corals by just after mid-century (2050), These are species that have existed for 240 million years, many of which today are 5,000 to 10,000-year-old continuously growing structures, with some individuals still alive at the ripe old age of 4,000 years. And although they occupy less than one percent of the marine environment, they are home to 25-35% of all marine species. And in barely a century, we may have wiped them from the known universe.
So what can we do right now? Efforts are underway to ban the sale of oxybenzone containing sunscreens throughout the state of Hawai’i during the state’s next legislative session. Senator Will Espero, representing Hawaii’s 19th District on O’ahu, is leading the legislative charge based on current scientific recommendations. Recently, the DAR publicly recommended a transition to sunscreens that don’t contain oxybenzone at the IUCN World Conservation Congress, held on O‘ahu, But travelers come from all over the world and no law will exist for owning sunscreen with oxybenzone, much less policing the use of it. Therefore, it’s up to everyone to spread the word and encourage the use of non-oxybenzone creams throughout our Hawaiian ‘ohana (family) and around the world.
Considering the riches that coral reefs endow people, it’s worth understanding the risks we pose to them, particularly when small changes in our behaviors, which may benefit our direct health anyway, could significantly reduce the incredible amount of stress they already endure. It’s hard to imagine an empty, colorless ocean where once underwater cities of life flourished. It’s even worse to imagine an ocean and planet devastated by the loss of creatures and habitats which provide us food, money, and the very breath we need to live. Although changing sunscreens will not solve every problem, the idea is to develop a mindset of behaviors that eventually will benefit and protect us all.
Fortunately, there are plenty of choices we can make to coexist on this starlit marble that will benefit our health and the world we live upon. We just need to adjust the angle we apply when reflecting upon our sunlight. So much fuss from just a few rays! A single photon can take up to 170,000 years to travel from its birth inside the sun to the surface. It’s taken millions of millennia for life to harness those rays and create the evolutionary theme park we live upon. Let’s reflect this light in a manner worthy of the life it provides. Especially when all we need are some small-time changes like switching to safer sunscreens. It’s been millions of years, but time is no longer on our side, so do hurry. The corals and creatures will thank you with some ‘ono (delicious) fish, a spiritual session with the mighty honu (turtle), a lifesaving medical treatment, and even a clean breath of fresh air.
Sunscreen Best Practices
- Check the label (even if it says safe-for-reefs) for oxybenzone, butylparaben, octinoxate, and 4-methylbenzylidene camphor, which all damage reefs.
- Apply sunscreen at least 10-15 minutes before entering the water, so that it absorbs into the skin.
- Don’t use more than you need. Wearing a rash guard and other sun protective do thing can reduce your sunscreen need by up to 90%.
- Avoid spray on sunscreens as the health effects of inhaling them are not well known and they enter the air, land, and in the water. On a personal note, they will upset your Dive master standing downwind.
- Be coral-friendly and choose the best sunscreen possible for you and the environment.