Long gone is the time when we covered ourselves in mud or olive oil to protect our skin from UV-rays. Today, sunscreens are made in the lab and available everywhere at any price and texture. The down side is? Whether you pick the cheap 5L tub or a fancy mist recommended by your pharmacist, you are probably exposing your skin to loads of nasties... ​In my twenties, I had absolutely no idea [and no care] what my sunscreen contained, as long as I didn’t get a burn... What’s more, I considered sunscreen an unpleasant thing and I wouldn’t put much thought into choosing one for me. As summer came around, I would go to the store and get it over with: pick the highest SPF at the lowest price. What I didn't know was that my life as a marine biologist would have me involved with sunscreens more than I could ever have imagined! But that will be the topic of another blog. This one is about helping you understand sunscreens and giving you what it takes to make an informed decision on your next purchase. To act as required, sunblocks must contain some type of UV-filter that absorb, reflect or scatter UV light. Listed as ‘active ingredients’ on your tube, these filters are either of chemical or mineral origin (sometimes, both are used together in one formula). Formulators then achieve desired texture by adding varying qualities of anti-microbial preservatives, moisturizers and anti-oxidants, which are labeled ‘inactive ingredients’ and account for up to 70% of the product.​Oxybenzone (aka benzophenone-3 or BP-3), benzophenone-4 (BP-4), para-aminobenzoic acid (PABA) and PABA esters, cinnamates, salicylates, camphor derivatives, dibenzoylmethanes and anthranilates [2]... The list of chemical UV-filters is awfully long and unfamiliar. What’s more, they are generally used in combination because no single one, at currently permitted concentration, provides sufficient protection against UV radiation...Hello chemical cocktail!!That was enough to raise my suspicions on a product I apply on my skin everyday.  I started browsing the scientific literature and soon discovered that not all UV-filters are created equal. Chemical filters have been under the radar of the Environmental Working Group after scientific studies revealed – among other things - hormone disruption effects, photo-oxidative stress and  - in some cases - skin cancer! [1, 3-5]. In 2008, the Scientific Committee on Consumer Products (SCCP) declared not advisable to apply chemical sunscreens [oxybenzone, avobenzone] before the age of 2. A few years later, several chemical UV-filters were detected in 85% of Swiss breast milk samples [2]. From then, it was not recommended to wear chemical sunscreen while breastfeeding either. And guess what? That same study, detected oxybenzone in 96% of urine samples in the US, meaning ingredients contained in sunscreen enter the bloodstream via the skin. If that wasn’t enough, recent research also revealed that oxybenzone and its relatives [octinoxate, octocrylen, avobenzone] continue their destructive path on marine life and corals down the drain (read more in my next blog). It is not recommended to use chemical-based sunscreen when breast-feeding. © Ignacio Campo on Unsplash With oxybenzone and other chemical filters present in over 97% of sunscreens and cosmetics on the market, does that mean we should give up on sun protection and increase risks of sunburns, photo-aging or even skin cancer?​Fortunately, we have a good alternative in the minerals UV-filters zinc oxide and titanium dioxide. Also called physical, these filters are photo-stable and, unlike chemical filters, they have the advantage of blocking both UVA and UVB rays, providing broad-spectrum protection (although titanium dioxide doesn’t protect against the whole range of UVA rays). It is important to note that mineral filters are sometimes used in the form of nanoparticles (ultrafine particles ranging from 1 nm to 100 nm). Research shows that nanoparticles are potentially hazardous under UV illumination, creating a wide range of toxic effects in various environments [6, 7]. So, carefully read the tag and prefer non-nano when it comes to mineral filters. If you are looking for a clean sunblock, non-nano zinc oxide and titanium dioxide are the way to go, with zinc oxide being most efficient at reflecting the full range of UVs. But keep in mind that it is not all about sunscreen! Wear a hat, protective clothing, and try to avoid prolonged sun exposure between 11am and 3pm. If you haven’t been in the sun recently, try to gradually build your tan. And remember, the Sun created life on Earth and has many health and mental benefits like the secretion of Vitamin D and serotonin (the good mood hormone) in the body. References: ​ 1. Chisvert, A., M. Pascual-Marti, and A. Salvador, Determination of the UV filters worldwide authorised in sunscreens by high performance liquid chromatography. . Journal of Chromatography 2001. A 921(2):207-15. .2. Krause, M., et al., Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV‐filters. International journal of andrology, 2012. 35(3): p. 424-436.3. Hanson, K.M., E. Gratton, and C.J. Bardeen, Sunscreen enhancement of UV-induced reactive oxygen species in the skin. Free Radical Biology and Medicine, 2006. 41(8): p. 1205-1212.4. Autier, P., Sunscreen abuse for intentional sun exposure. British Journal of Dermatology, 2009. 161(s3): p. 40-45.5. Sharma, P., et al., Reactive Oxygen Species, oxidative damage, and antioxidative defense mechanism in plants under stressful conditions. Journal of Botany, 2012. vol. 2012 (Article ID 217037): p. 26 pages.6. Yung, M., C. Mouneyrac, and K. Leunga, Ecotoxicity of Zinc Oxide Nanoparticles in the Marine Environment. . Encyclopedia of Nanotechnology 2014.7. Lewicka, Z., et al., Photochemical behavior of nanoscale TiO2 and ZnO sunscreen ingredients. . Journal of Photochemistry and Photobiology A: Chemistry, 2013. 263, pp.24–33. .