Is Your Sunscreen REALLY Safe For the Ocean?
Published on 12/25/24
Written by Jessica Colla
In this blog, we’ll dive into how the sunscreen you use can impact coral reef health, explore Maui’s groundbreaking ban on chemical sunscreens, and uncover simple, practical ways you can help protect our oceans—starting with your next trip to the beach!
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Did you know that the sunscreen you choose can have a lasting impact on the health of coral reefs? Maui County (Hawai’i) recently made waves by passing an ordinance—Ordinance 5306—banning the sale, distribution and use of chemical sunscreens to protect our oceans. This groundbreaking decision ensures that only mineral-based, reef-safe sunscreens are permitted across the islands of Maui, Lanai, and Molokai. We’re so proud to see Maui leading the charge on this issue, and we’re hopeful that when the rest of the state sees the positive impact, this regulation will expand into a state-wide law.
But why does this matter? What makes mineral sunscreen different, and how can switching sunscreens help preserve marine ecosystems? In this post, we’ll explore the science behind sunscreen, its effects on coral reefs, and how we can all play a part in protecting our oceans—whether you’re enjoying a day at the beach, going for a dive, or just going for a jog by the water.
What’s the Difference Between Chemical and Mineral Sunscreens?
The main distinction between chemical and mineral sunscreens lies in how they protect your skin from the sun’s harmful UV rays.
CHEMICAL SUNSCREENS:
These sunscreens work by absorbing the sun’s UV rays like a sponge. Once absorbed, the sunscreen undergoes a chemical reaction that converts UV radiation into heat, which is then released from your skin. While this method is effective, it introduces synthetic chemicals into your skin and, when washed off in water, these chemicals can harm marine life—especially coral reefs.
MINERAL (PHYSICAL) SUNSCREENS:
Mineral sunscreens, on the other hand, create a physical barrier on your skin. Think of them as tiny mirrors that sit on the surface of your skin, reflecting and scattering the sun’s rays away before they can penetrate and cause damage. Mineral sunscreens use naturally occurring ingredients like zinc oxide and titanium dioxide, which are not only safe for your skin but also more gentle on the environment.
In essence, chemical sunscreens absorb and transform UV energy, while mineral sunscreens block and redirect it. This difference is more than just skin deep—it’s a choice that can significantly impact the health of marine ecosystems.
If you’re wondering why this matters, let me give you a little history:
Back in 2018, Hawaii passed legislation prohibiting the sale and distribution of sunscreens containing the two most harmful chemicals for coral reefs. While this was a good first step, it wasn’t nearly enough. There are over 12 ingredients that negatively affect coral health, yet ONLY the top two ingredients (oxybenzone & octinoxate) were banned from sale and distribution in the Hawaiian Islands. Additionally, this law doesn’t address visitors bringing their own chemical sunscreens from off-island. Maui County’s new ordinance takes things further by banning ALL harmful chemical sunscreens entirely, regardless of where they were purchased.
Why Should We Care?
Great question! As a marine biologist, ocean conservation from anthropogenic (human-caused) threats is my passion. Coral reefs are the foundation of our ocean ecosystems; recognized as home to over 25% of all marine life found in the ocean. Coral reefs support countless marine species, protect our coastlines and even provide us with technological and medical advancement. Check out this blog post on the importance of coral reefs here!
However, corals are extremely sensitive to changes in their environment, including sea temperature rise, changes in pH and salinity, and pollution from … you guessed it … sunscreens! If overwhelmed by any of these stressors, corals undergo a stress response called bleaching. Check out this blog post on the causes and effects of coral bleaching here!
Psssstttt! DID YOU KNOW that chemical sunscreens are also bad for US?! Check out this article by the National Institute of Health, published by the National Library of Medicine on the negative impacts of chemical sunscreens on human health! It’s no wonder these chemicals are also bad for corals!
Direct vs. Indirect Impacts
There are both direct and indirect impacts of harmful sunscreen chemicals in our oceans.
How Sunscreen Ends Up in the Ocean and Affects Corals
When you wear chemical sunscreen, it doesn’t always stay on your skin (this is why it’s crucial to follow the recommended absorption time before entering the water, as this helps minimize the risk of the sunscreen washing off.). If you’re swimming, snorkeling, or even relaxing near the water, the sunscreen begins to wash off (or sweat off) your body. This happens directly in the ocean or through runoff from nearby coastlines. Even if you’re far from the water, sunscreen chemicals can wash off in the shower, enter drains, and eventually make their way into the ocean through wastewater systems.
As the beloved movie Finding Nemo says, “All drains lead to the ocean.”
Once these chemicals reach the ocean, they don’t just dilute and disperse harmlessly—they can bind to coral tissues and disrupting their biological processes. Corals have a unique relationship with microscopic algae called zooxanthellae, which live inside their tissues. These algae provide corals with energy through photosynthesis and are responsible for their vibrant colors. Learn more about this incredible symbiotic relationship here! In many coral species, zooxanthellae supply over 80% of their nutritional needs, with the rest coming from protein (ex. zooplankton) captured using their sticky tentacles.
When chemical sunscreens adhere to corals, the toxins interfere with their ability to maintain this symbiotic relationship and for the zooxanthellae to photosynthesize properly. This can stress the relationship, leading to coral bleaching—a condition where the coral expels its zooxanthellae. Without the colorful symbionts, the coral's translucent tissue reveals the white calcium carbonate skeleton beneath. The coral is left vulnerable, unable to produce energy or fight off disease. If the stressor—in this case, the toxic sunscreen—persists, the coral may die.
Cause and Effect:
Sunscreen washes off and enters the ocean
Chemicals in the sunscreen adhere to coral tissues
These chemicals act as stressors, disrupting the symbiotic relationship between corals and their algae
The coral expels the algae, leading to bleaching
Without its algae, the coral cannot survive for long and may eventually die
This cascading chain of events demonstrates how a seemingly harmless choice, like sunscreen selection, can have profound consequences for marine ecosystems. Opting for reef-safe sunscreens or protective clothing is an easy way to help prevent this damage and protect our oceans.
How Chemical Sunscreens Disrupt Coral Growth and Reproduction
Chemical sunscreens contain ingredients that can act as endocrine disruptors when they enter marine environments. The endocrine system is essential for regulating hormones in all living organisms, including corals. Hormones play a critical role in coral growth, reproduction, and overall health.
When chemicals from sunscreen mimic or interfere with natural hormones, they disrupt these processes. Think of the endocrine system as a network of signals that tells an organism when and how to grow, reproduce, or respond to its environment. Endocrine receptors and hormones fit together like puzzle pieces, but endocrine disruptors mimic the shape of the real hormones, taking their place in the receptor and disrupting normal hormonal functions—almost like forcing puzzle pieces to fit together, preventing the REAL pair from connecting. When endocrine disruptors block or alter these signals, much like forcing the wrong key into a lock—it doesn’t work, and the system gets stuck.
In corals, this disruption can:
INHIBITS GROWTH:
Without proper hormonal signals, corals struggle to grow and repair themselves, leaving them vulnerable to physical damage and disease.
PREVENTS REPRODUCTION:
Endocrine disruptors interfere with the corals’ ability to spawn (reproduce) and create new colonies, halting the natural cycles that replenish reef ecosystems.
The result is a weakened reef system with reduced resilience against other stressors like climate change and pollution. Over time, this disruption can lead to the decline of entire reef habitats, impacting not just corals but the countless marine species that rely on them for shelter and food.
By choosing mineral-based sunscreens or wearing protective clothing, we can reduce our contribution to these harmful disruptions and help safeguard the vital ecosystems that corals support.
How to Choose a Reef-Safe Sunscreen
It can be confusing to tell the difference between chemical and mineral sunscreens, but here’s a simple trick when shopping for a new sunscreen:
Flip the bottle over and check the ingredients list.
If you see long, complicated chemical names (like Avobenzone, Homosalate, and Oxybenzone) it’s likely a chemical sunscreen. PUT IT BACK ON THE SHELF!
Look for these two key ingredients: zinc oxide and titanium dioxide.
These are the only active ingredients you want in a mineral sunscreen. PERFECT, BUY THIS ONE!
The Top 10 REEF-SAFE MINERAL sunscreens:
As a marine biologist dedicated to ocean conservation, I’ve seen firsthand how harmful chemical sunscreens can be to coral reefs. In beautiful destinations like Hawai‘i, we must take care not to “love the reef to death.” If we want to conserve these beautiful underwater ecosystems for future generations, its essential to use reef-safe, mineral (physical) sunscreens while enjoying these spaces.
Now here’s the real kicker … Not all mineral sunscreens are TRULY eco-friendly, despite what some labels claim! (It sucks, I know). Did you know there is NO regulation preventing sunscreen companies from marketing their products as “reef-safe” or “eco-friendly,” even if they contain one or more harmful chemical ingredients known to affect corals? Don’t be misled by clever branding or labels on the front of the bottle—always check the ingredients list on the back to ensure the sunscreen you’re choosing is genuinely safe for coral reefs.
Shopping for sunscreen can be tricky and overwhelming, so I’ve put together a carefully curated list of genuinely reef-safe, eco-friendly options here that offer excellent sun protection while also protecting marine ecosystems for generations to come.
Check out my top mineral sunscreen recommendations below:
Helpful hint: Since mineral sunscreens create a physical barrier against the sun's harmful UV rays, they can sometimes leave a white cast on your skin. But don’t let this be a deterrent! To avoid looking like “Casper the Friendly Ghost”, try these helpful tips:
A little goes a looooooong way. Only use a small dab on smaller surfaces like your face, neck, hands and feet. You can always add more as needed, but its hard to remove excess sunscreen once its been applied.
Rub in the sunscreen thoroughly to avoid globs of white around your hair line and near your ears.
If you have a darker skin tone like me and the white tint is glaringly obvious, you can add some makeup foundation (liquid or powder) to your sunscreen prior to application, reducing the “ghostly glow” of pure-white zinc.
The Best and Most Sustainable Solution: Sun-Protective Gear
While mineral sunscreens are a significant improvement over their chemical counterparts for protecting marine ecosystems, it’s important to recognize that ALL topical sunscreens, even the most reef-safe options, will eventually wash off your skin and into the water. No matter how minor the impact compared to chemical sunscreens, they still contribute to changes in the environment and may affect marine life.
That’s why the BEST and MOST sustainable sun protection method is to cover up with sun-protective clothing and accessories!
Hats, sunglasses, neck buffs, rash guards, long-sleeve sun shirts, swim tights, and swim socks provide full-spectrum UV protection without any risk of washing harmful ingredients into the ocean. These options also save you money in the long run by reducing the amount of sunscreen you need to apply. Plus, they’re reusable, making them a much more eco-friendly choice for sun protection.
As a marine biologist who spends a lot of time in the ocean, I’ve made sun-protective gear an essential part of my routine. When I’m on or near the water, I wear a wide-brimmed hat, polarized sunglasses, a neck buff, and a long-sleeve rash guard to shield most of my body from the sun. For my legs and feet, I rely on swim tights and water socks. These not only provide excellent UV protection but also keep me comfortable, while reducing the need for sunscreen. For the areas that remain exposed, like my face, neck, ears, and the tops of my hands and feet, I apply a high-quality mineral sunscreen. This strategy is common amongst marine biologists, fishmongers, mariners and water sport enthusiasts alike, so don’t just take my word for it!
If you’re looking to go the extra mile for the environment—or just want a cost-effective way to reduce your reliance on sunscreen—investing in sun-protective gear is the way to go. I've included a list of my favorite sun-protective clothing and accessories below, which are not only effective but also stylish (for the water anyway, haha) and easy to pack for any beach or underwater adventure. Check out the links for my top recommendations to help you stay sun-safe while keeping our oceans healthy:
final thoughts
Protecting coral reefs might seem like a daunting task, but mindful choices—like switching to mineral sunscreen—can make a world of difference! These incredible ecosystems are the foundation of marine biodiversity, and their health directly affects the ocean’s ability to sustain life.
By choosing reef-safe sunscreen or opting for sun-protective clothing, you’re not only safeguarding your skin but also supporting the longevity of coral reefs for future generations. Together, we can ensure these underwater treasures remain vibrant and thriving.
The next time you pack for a beach day, remember to check your sunscreen’s ingredients and choose one that’s ocean-friendly. If you’re ever unsure, look for zinc oxide or titanium dioxide, or better yet, cover up with UV-protective gear. Small steps lead to big changes, and every choice matters.
Let’s protect our oceans—one reef at a time! 🌊
What’s your favorite reef-safe sun protection?? Let us know in the comments below!
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