Sunscreen is the primary photoprotection factor that creates physical barriers reflecting and scattering light and chemical barriers absorbing light. It is topical use to put on the skin to protect our body from certain damages caused by the sun’s ultraviolet radiation.
There are increasing studies showing that some active ingredients of sunscreen are toxic to the body and brings about damages to corals adversely affecting the marine ecosystem.
This article summarizes the factors when choosing an effective and safe sunscreen that is both protective to the body and safe for the sea. To learn about what the sun does to our body and overall suncare, check out this article here.
WHAT DOES SUNSCREEN SPF MEAN?
Both UVA and UVB directly cause DNA damage and skin cancers. UVA causes the formation of reactive oxygen species, which can indirectly cause DNA damage by creating breaks in the tertiary structure. UVB is absorbed by DNA and causes structural damage.
Sunscreen is often labeled with an SPF (sun protection factor), which tells you how much more solar energy it takes to burn you (damages caused by UVB) while you’re wearing it than when you’re not:
SPF = sunburn radiation dose with sunscreen / sunburn radiation dose without sunscreen
For example, provided with certain UV conditions, it’d take 10 minutes for unprotected bare skin to start going red; an SPF30 sun protection product would prevent this for 30 times longer (thus 300 minutes or 5 hours). This doesn’t mean that with a higher SPF, a person can spend longer time in the sun as the blocking effect wears off within 2 hours. So the sun care product needs to be reapplied regularly within 2 hours to prevent sunburn. When in touch with water, a water-resistant sunscreen should be reapplied every 40 minutes or as instructed with the sunscreen
.According to the American Cancer Society, the protection offered by sunscreens of different SPFs is as follows:
- SPF15 protects against 93% of all UVB rays
- SPF30 filters out 97%
- SPF50 blocks 98%
No sunscreen blocks all or 100% of UVB, and a significant increase in SPF will boost the blocking strength by only an insignificant percentage. In addition, products with an SPF 2-14 cannot claim to offer broad-spectrum protection or to reduce the risk of skin cancer and early skin aging in the United States.
Broad-spectrum protection protects against both UVA & UVB rays. Sunscreen indicating broad-spectrum protection, blocks UVA rays in the same proportions that SPF filters UVB. A safe sunscreen should be broad-spectrum protection SPF15 or above.
Apply sunscreen for almost 30 minutes before going into the sun, and re-application is advised after every 2 hours. When putting it on, pay close attention to your face, ears, neck, arms, and other areas not covered by clothing. Sunscreen is available in many forms – lotions, creams, ointments, gels, sprays, wipes, and lip balms, to name a few.
What are Water Resistant Sunscreens?
There is no waterproof sunscreen as sunscreens can be washed off. The efficacy of sunscreen is determined by UVB protection which is measured by the sun protection factor (SPF) and substantivity.
Substantivity is the ability of a sun care product to withstand difficult condition such as water and sweat. FDA has defined the labelling of substantivity as below, both can qualify as sweat-resistant:
- Water-resistant or water-resistant (40 minutes) sunscreen refers to a 40-minute protection with water immersion and moderate activity.
- Very water-resistant or water-resistant (80 minutes) sunscreen refers to the extended protection for 80 minutes.
WHAT ARE PHYSICAL / MINERAL SUNSCREEN AND CHEMICAL / ORGANIC SUNSCREEN?
There is a wide range of sun care products available on the market, often labeled physical and chemical sunscreen.
Physical sunscreens, consisting of zinc oxide and titanium dioxide, are considered safe sunscreens by the FDA. They reflect and scatters UV light similar to the way clothes do. The reflective index, the size of the particles, the film thickness, and the dispersion of the base determine the effectiveness of the sunscreens. Decreasing the particle size to a micronized form (10 to 50 nm) is more for cosmetic reasons than sun protection. A thick coat is better for reflection thus more protective but is less cosmetically appealing. Iron oxide can be added to augment UVA protection, and silica and dimethicone are often added to stabilize zinc oxide and titanium dioxide.
Chemical sunscreens are known as organic sunscreens. Their chemical structure allows high-energy UV rays to be absorbed. They can consist of UVA and UVB blockers.
Broad-spectrum sunscreens protect from both the UVA and UVB portions. They include methylene-bis-benzotriazolyl tetramethylbutylphenol (MBBT) and bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT). MBBT is considered advantageous as it decreases the possibility of systemic absorption or endocrine effects. It absorbs, scatters and reflects UV radiation, particularly UVA versus UVB. BEMT is photostable and doesn’t affect the endocrine system.
As supported by research, it’s considered effective and safe to use physical/mineral sunscreen of zinc oxide and titanium oxide as active ingredients, provided that other elements in the products are also secure. Chemical / organic active ingredients are generally considered unsafe for human beings or hazardous for the sea.
Here’s a quick overview of Physical (Mineral) and Chemical (Organic) sunscreens active ingredients:
|PHYSICAL( MINERAL) SUNSCREEN||CHEMICAL (ORGANIC) SUNSCREEN|
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The danger of Inhaling Titanium Dioxide and Zinc Oxide and Nano-sized
The usage of nanoparticles of titanium dioxide can result in an increased production of free radicals and damage to DNA and proteins as these smaller particles can form complexes with the protein that can behave as haptens, inducing autoimmune conditions.
Nano-sized titanium dioxide should not be inhaled due to the toxicity and inflammation responses, and it should be used in cosmetics with great care. It’s advised to use more researched titanium dioxide in place of nano-sized as sun care active ingredient. In addition, sun care products shouldn’t be used on the face in the form of a spray, powder (makeup powder), or aerosol spray to avoid harm to the respiratory organs.
SUNSCREEN AND THE SEA
Over half of all coral reefs worldwide are currently threatened. Some coral reefs’ poor health or destruction is due to natural and manufactured disruptions (changes in ocean temperature, ultraviolet radiation, bacterial pathogens, pollution, and some sunscreen products, etc.). The damage or death of coral reefs has a multiplicative negative domino impact on other life forms because they directly or indirectly support a large variety of animals, including fish, jellyfish, shrimp, lobsters, crabs, and turtles.
Organic/chemical ultraviolet (UV) filters, including oxybenzone (benzophenone-3), 4-methyl benzylidene camphor, octocrylene, and octinoxate (Ethylhexyl methoxycinnamate), and Ethylhexyl salicylate are not easily removed by standard wastewater treatment, can be found in various species of fish with possible consequences for the food chain as well as coral bleaching. In addition to oxybenzone and octinoxate in coral toxicity, increasing number of sunscreen components are being identified as harmful to the sea. Other components that are
Estimated amount of sunscreen affecting the reef-containing areas:
- an average application dosage of 2 mg/cm (as recommended by the FDA) for a full body surface of 1 square meter, an average application dose comes up to 20 g per application
- 2 applications per person per day for an average of 5 days by 78 million visitors (10% of world tourists) in the coral reef-containing locales,
- 10,000 tons of sunscreen produced annually, with 25% of applied sunscreen washed off while in the water = 4,000 to 6,000 tons in reef-containing areas.
As sunscreens components are lipophilic, they can accumulate in aquatic animals. Given the significant volume, the levels of sunscreens present in the sea are toxic to coral reefs at a significant number of locations.
HOW TO CHOOSE A SAFE SUNSCREEN?
Sunscreen should not be your only line of defense; instead, avoid direct sun exposure, and use UV-blocking clothes, sunglasses and hats for a sunny outing.
To protect yourself while not putting an environmental load on the sea, take into account of the below tips to choose a safe sunscreen not just to be protective of the sun rays but also not damaging to the aquatic environment:
- Choose Mineral Sunscreen. UV radiation protection active ingredients zinc oxide and titanium dioxide are considered safe and effective. If possible, avoid sunscreen using nanoparticles of zinc oxide and titanium dioxide. Avoid spray, powder sunscreen products on the face. When selecting a product, also remember to verify the safety of other ingredients in the product too. Verify the ingredients using EWG‘s web platform (Environmental Working Group, a non-profit organization) that identifies the safety level of major ingredients.
- Avoid Chemical UV Filers. Chemical / organic sunscreen active ingredients include benzophenones and dibenzoyl methane, oxybenzone, octinoxate, avobenzone, octisalate, octocrylene, or homosalate, can cause allergy, endocrine disruption, or harm to the sea.
- Include Secondary Protective Factors. Secondary protective factors include antioxidants (vitamin C, vitamin E, silymarin and green tea polyphenols etc), osmolytes (taurine and ectoine), and DNA repair enzymes that can help to limit skin damage by disturbing the photochemical cascade that occurs with UV sunlight. Topical antioxidants function from within the cell to decrease the shortage of antioxidants and can remain active for several days after application.
Sun is a beautiful natural resource when enjoyed mindfully, but it can also damage the eyes, and cause skin cancers. Use a safe sunscreen for your body that is also safe for the sea, too – because just like the sun, the sea is also an incredible natural asset of our planet!