Understanding Sunscreen

How does sunscreen work?

Sunscreens are composed of UV filters, which disperse UV rays so they are not absorbed by the our skin. These UV filters can be made of chemicals or minerals.

Chemical UV filters use chemicals like Oxybenzone and Octinoxate to deflect UV rays from our skin by converting light energy into heat energy, which is then released by our skin. These chemicals can have negative effects on not only corals, but also us humans.

Mineral UV filters instead use Zinc Oxide and Titanium Dioxide to reflect and scatter the UV rays, blocking them from being absorbed by our skin. When formulated responsibly, they are considered less harmful to us and marine life, and break down more naturally in the environment.

Oxybenzone is found in over 3,500 sunscreen products worldwide, making it very common. Oxybenzone is found to be present in many aquatic environments and has been shown to disrupt coral reproduction, cause coral bleaching, and damage coral DNA. Oxybenzone is absorbed through the skin and can be found to bioaccumulate in our bodies and has been found in urine as quickly as 30 minutes after application. Bioaccumulation is the build-up of toxins in an organisms body over time. Oxybenzone has been found present in bird eggs, fish, coral, humans, and other marine animals. Oxybenzone can also be biomagnified, the process of the concentration of toxins increasing up the food chain. When a prey item has toxins bioaccumulated in its body and it is then eaten, those toxins then pass to the predator. This process continues with each predator in the food chain, ultimately leaving the apex predator with the highest accumulation of toxins. Through this process, Oxybenzone may be passed to us through the seafood we eat. The more Oxybenzone washed into the water, the more likely this is to happen, and is an active threat as it has been found in parts per trillion concentrations off the coast of Barrow, Alaska, U.S.A, to parts per billion on coral reefs in the Caribbean, Pacific, and Red Sea.  One of the highest concentrations measured in the marine environment was in Trunk Bay in the U.S. Virgin Islands National Park, St. John Island, U.S. Virgin Islands, where the beach can have up to 5,000 people daily.

Octinoxate is absorbed directly through the skin by applying sunscreens and other personal care products. It has been shown to absorb less into the skin, leaving more to wash into the water. Octinoxate can potentially be stored in the body long-term as fat tissue or in lipid-rich tissue due to it being a fat-soluble chemical. Octinoxate is also at risk of being bioaccumulated in organisms and biomagnified through the food web. A number of aquatic and marine species have been discovered to be contaminated, from carp, catfish, eel, white fish, trout, barb, chub, perch, and mussels to coral, mahi-mahi, dolphins, sea turtle eggs, and migratory bird egg. Octinoxate is also found in large concentrations; in coral reef environments, Octinoxate can reach more than 10 parts per billion. Along the west coast of Maui in 2015, in Hawaii, 11 coral reef sites that were sampled had Octinoxate concentrations from 6.9 parts per trillion to 1,516 parts per trillion.

How do I avoid these chemicals?

You can avoid the bad side effects of chemical sunscreens by opting to use mineral sunscreen. Mineral sunscreens use Zinc Oxide and Titanium Dioxide, both naturally occurring minerals, as the only active ingredients to scatter and reflect UV rays to protect the skin. Unlike chemical sunscreen, Zinc Oxide and Titanium Dioxide can reflect both UVA and UVB rays. Non-nano zinc oxide is best, as the larger particle size prevents absorption in our bodies, and ingestion by marine life.

Key Takeaway: Sunscreens labeled as “Reef Safe” do not always mean mineral. Always check the active ingredients list and look for Zinc Oxide and/or Titanium Dioxide as the only active ingredients. You can also opt for alternative sun protection, such as brimmed hats, sun shirts, sun leggings, UV sunglasses, using an umbrella, and seeking shade from 10 AM to 2 PM (prime sun-light hours).