Summer salutations! Now that warmer and sunnier days are right around the corner, it is more important than ever to make sure you are practicing safe fun in the sun.

The sun plays a large role in bodily vitamin D levels, and too little sun can contribute to vitamin D deficiency. The body forms vitamin D precursors in the skin when exposed to sunlight, which then get converted by the kidneys to the active form of the vitamin. Vitamin D is important for strengthening bones, producing hormones, and supporting a healthy immune system [1]. In order to meet vitamin D requirements, studies have found that it is necessary to expose bare arms and legs to the sun midday (from 10am to 3pm) for 5-30 minutes at least two days per week [2].

However, while vitamin D is very important, too much sun exposure can makes us susceptible to an unhealthy amount of UV radiation, creating a higher chance of developing skin cancer [1]. That being said, sunscreen is a must-have in your skin-care routine. When choosing a sunscreen product it is important to know about the safety of the ingredients, because what we put on our skin can ultimately find a way inside our bodies, as well as our water systems. It is imperative to avoid sunscreens that contain toxic ingredients [3].

Choosing the Right Sunscreen

Sunscreen can be divided into two major categories: those that use chemical UV filters and those that use physical barrier (or mineral) UV filters [3,4]. Chemical UV filters contain tiny particles that are able to pass through our skin and can potentially produce unfavorable reactions in our bodies [3]. Given that chemical UV filters are fat soluble, they can easily accumulate in adipose tissue, the liver, and the brain- this can result in the disruption of hormone synthesis and neuron signalling, and altered gene expression [5].

Physical UV filters contain larger particles that form a strong, protective shield on the surface of our skin and prevent the sun’s rays from entering our bodies [3]. Additionally, the particles in physical UV filters provide broad-spectrum protection against UVA and UVB rays, both of which in excess can be harmful and even cause cancer [1,3]. Most chemical UV filters only protect against UVA or UVB rays [6]. As a rule of thumb, choose sunscreens that contain only physical UV filters like zinc oxide and/or titanium dioxide. Avoid sunscreens that contain chemical UV filters such as avobenzone, and oxybenzone, as they mimic hormones and can cause skin allergies. [1,4].

In addition to selecting a sunscreen that contains only physical UV filters, select one that contains an SPF of at least 15 [1]. Make sure to apply it to your skin every morning [1]. You only need a nickel-sized amount for your face, and about two tablespoons to cover other areas of your body that will not be protected by clothing [1]. Remember to reapply sunscreen every two hours, especially if you are physically active [1].

Protecting the Environment 

Not only is it important to choose safe sunscreens for ourselves, but also to protect marine organisms [1,3,4]. Approximately 4,000 to 6,000 metric tons of sunscreen wash off of our bodies per year when we are in the water, and if they contain toxic chemicals, they can kill and destroy various ecosystems in the ocean [7]. Look out for marine-toxic ingredients, including oxybenzone, octinoxate, butylparaben, retinyl palmitate, and 4-methylbenzylidene camphor [2]. These chemicals are harmful because they are resistant to biodegradation, which means that they have the potential to combine with various waterborne viruses and result in bleaching of coral reefs. Coral reef bleaching can be irreversible and sometimes even deadly to both the coral and the symbiotic zooxanthellae that live within it [7]. With scientists estimating that about 50% of coral reefs have already been permanently bleached, preventing further damage to the ocean’s ecosystem is crucial [1].

Other Safe Sun Practices

While using sunscreen daily is great for protecting skin from the sun, it is not the only way to protect yourself from UV radiation. If you choose not to wear sunscreen, here is a list of additional ways to practice safe sun every day [1,2,3,8]:

• Consume a diet rich in antioxidants, such as beta-carotene, vitamin C, and vitamin E- studies demonstrate that these micronutrients are capable of preventing UV radiation damage from the sun in humans
• Avoid continuous outdoor activities when the sun’s rays are most powerful (10am to 3pm)
• Choose clothing, such as hats, shirts, and pants that shield your skin from the sun- some recommended brands that are Ultraviolet Protection Factor (UPF) rated include Coolibar, Solumbra, and REI.
• Sport a pair of sunglasses not only to make a trendy statement, but to protect your eyes from UV radiation as well, even when it is cloudy out
• Use a water-resistant sunscreen when going to the pool or beach

Written by Hillary N., Bastyr student intern

Resources:

1. Environmental Working Group (2017). 8 Little-Known Facts About Sunscreens. Retrieved from: https://www.ewg.org/sunscreen/report/8-little-known-facts-about-sunscreens/#.Wvu2eNMvzUp
2. Holick, M. (2007). Vitamin D deficiency. N Engl J Med, 357(3), 266-281. Retrieved from: https://www.nejm.org/doi/full/10.1056/NEJMra070553
3. Emerson Ecologics. How to Practice Safe Sun. Provided by MyChelle Dermaceuticals. Retrieved from: https://edu.emersonecologics.com/2018/04/30/how-to-practice-safe-sun/#prettyPhoto/0/
4. Environmental Working Group (2017). The Trouble with Ingredients in Sunscreens. Retrieved from: https://www.ewg.org/sunscreen/report/the-trouble-with-sunscreen-chemicals/#.Wvu1_9MvzUo
5. Ruszkiewicz, J. et al. (2017). Neurotoxic effect of active ingredients in sunscreen products, a contemporary review. Toxicology Reports, 4, 245-259. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615097/
6. Epstein, J. and Wang, S. (2017). UVA & UVB. Skin Cancer Foundation. Retrieved from: https://www.skincancer.org/prevention/uva-and-uvb
7. Danovaro, R. et al. (2008). Sunscreens cause coral bleaching by promoting viral infections. Environ Health Perspect, 116(4), 441-447. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291018/
8. Fernandez-Garcia, E. (2014). Skin protection against UV light by dietary antioxidants. Food & Function, 5(9), 1994-2003. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/24964816