WHAT IS THE DIFFERENCE BETWEEN A SUNSCREEN and a SUNBLOCK and HOW DO THEY WORK?
An eco-makeup artist aka chemistry nerd’s quest for no-alternative facts!
The sun just left me a message saying ‘it’s not you, it’s me’, apologizing for my uncomfortable, lobster-red burn. Spending days at the pool or beach as a kid, I never burned, just tanned. Nowadays, no such luck. I’ve since DIY’d my own sunblock, which is not as simple as you might think, though I now know why and how, and to all those asking me what they should buy and why, since sunscreen is a strictly regulated, skincare category, i cannot share or sell it without proper certification.
So here’s what I can offer you: knowledge.
Arm yourself with it this summer and choose yourself a clean sunblock you love, to save your skin from damaging UVA and UVB rays and save our oceans from nasty chemicals that kill coral. By the end of this, you should know how to choose a good one, all by yourself! You’re welcome! <3
WHAT IS LIGHT? BABY DON’T HURT ME.
There are a large number of chemicals used to absorb and/ block ultraviolet light. Before discovering what these are and how they work, let’s find out what ultra-violet light is first, and why we should care.
Ultraviolet light describes different kinds of electromagnetic radiation (or light rays) emitted by the sun. Often these light rays are divided into two types*:
UV-A which has a longer wavelength (320-360/400nm) and is not absorbed by the ozone layer. it damages collagen (connective tissue) and blood vessels, causing free radicals and aging effects such as wrinkled skin.
UV-B, which has a shorter wavelength (280-320nm), is partially absorbed by the ozone layer. It causes the skin to burn. B for Burn. There, that’s easy!
Shorter wavelengths mean higher energies. So the shorter rays of UV-B light or radiation, are more damaging than UV-A.
UV-C is the shortest wavelength but is effectively screened out by the ozone layer. *1
Now that we know what Ultraviolet light is, knowing how to block it is next.
There are two ways in which chemicals (that includes minerals like zinc oxide and titanium dioxide), can effectively protect your skin from ultraviolet light. One way is by absorbing the light- this is what SUNSCREENS do. The other is by reflecting the light- this is what SUNBLOCKS do.
“There are a large number of chemicals used to block ultraviolet light rays and these include opaque white mineral powders like zinc oxide and titanium dioxide. These two reflect or scatter light of many frequencies, from infrared to ultra-violet. That is why they appear opaque white.
Other chemicals, such as benzophenone, are designed to be invisible- they don’t block visible light. So if you don’t wish to paint yourself white, you can paint yourself with a colour that absorbs ultraviolet light, but is transparent to visible light. “ *1 Say what? How do i use invisible colour to absorb invisible light?!
A CHEMISTRY LESSON
“Molecules absorb light when the light’s wavelength is just the right length to cause electrons in the molecule to vibrate in time with the light. The electrons resonate in the molecule. In some molecules, the electrons are not bound to a single atomic nucleus but instead roam free across several nuclei in what are called resonance bonds. You may notice that sometimes, a six sided ring is shown with alternating double and single bonds, while at other times it is shown with a circle inside. Both forms are showing the same thing. The circle just draws attention to the fact that the bonds don’t really alternate between single and double- they are more like one and a half bonds. On average, the electron spends half the time in one place and half in the other.
In Para-amino-benzoic acid (PABA), there is another resonance structure right next to the six-sided ring. It is a carboxyl group, shown with a single bond between carbons and a double bond between the carbon and the oxygen. This is also a place where the electron can bounce around between the three nuclei.
EVERYTHING IS VIBRATION:
It is even possible for an electron to move back and forth across all of the resonance bonds- from one end of the molecule to another. This lets the electron slosh back and forth like water in a bathtub. In the case of para-amino benzoic acid (PABA), the rhythm of the sloshing matches the frequency of the UV-B light. The electron can move in time with the light wave and absorb its energy. The energy is later released as photons of longer wavelength light, such as heat.
Knowing this, chemists can design other molecules that have resonance structures that will catch UV-B rays. One such molecule is benzophenone, and a derivative called benzophenone-3, also known as OXYBENZONE…The resonance bonds can be modified a little bit to get a broader absorption range, expanding into the longer wave UV-A region. Such a designer molecule is OCTOCRYLENE…Another class of UV-B absorbers is the CINNAMATES. These molecules are not water soluble, are able to stick to the skin well, and are highly effective in water-resistant sunscreens….There are many more in use that all have the same resonance bonds in common.” *1
Manipulating benzone molecules to create chemicals that absorb light at a longer range, is all well and good until someone realizes these chemicals along with many others like pthalates and parabens, common to many sunscreens, can disrupt our endocrine system (hormones), irritate our skin, cause allergies*****5, and even destroy coral reefs**2. Oh yeah and they might be neurotoxic to humans too!**2 Doh!!
SORTA SAFE: ZINC OXIDE AND TITANIUM DIOXIDE NANOPARTICLES
As if worrying about harmful chemicals like oxybenzone (aka Benzophenone-3), octinoxate, homosalate (aka: homomethyl salycilate or 2-ethylhexyl salicylate) , avobenzone, octisalate, octocrylene, retin-A, PABA, the cinnamates (like octyl methoxycinammate) and many more in sunscreens which we slather all over our bodies wasn’t scary enough, there are other chemicals in safe, non-nano particle zinc oxide and titanium dioxide based sunblocks, that we need to be weary of too, for our health and that of our planet.
Whoah, hold up. What’s a nano-particle and why use them?
Before we get to talking about dimethicone, aluminum hydroxide and fragrance, we need to talk about nano-particles.
"Because powders of inorganic zinc oxide (ZnO) and titanium dioxide (TiO2) are very effective at blocking UV-light, these are largely used in sunblocks. However, the fact that their common forms (i.e. particles in the micrometre range) have a white colour, this makes them less appealing to customers for application on skin. However, when they are in the form of nanoparticles (NPs), they become transparent, keep their UV absorption properties when exposed to UV for long periods of time, which enhances the stability of sunscreens and their ability to protect the skin from ultraviolet light, therefore making sunscreens one of the applications where the emerging nanotechnologies have been developed….******6
ARE NANO PARTICLES SAFE?
“The present Literature review (*7) showed that there is evidence that:
o This toxicity and genotoxicity of ZnO and TiO2 nanoparticles have been demonstrated in a wide range of cell types;
o A diversity of other potential negative health effects observed in laboratory animals upon administration of ZnO and TiO2 nanoparticles.
NANO IS SAFE:
However, the majority of experimental studies have shown that both ZnO and TiO2 nanoparticles either do not penetrate or minimally penetrate through the outer layers of skin and suggest that the absorption of nanoparticles into the body, and the accompanying toxicity, is highly unlikely.
In addition, neither TiO2 nor ZnO NPs when used in sunscreens on humans in the absence of UV or non-UV light were found to possess notable skin irritation (reversible skin damage), corrosion (irreversible necrotic damage extending into the dermis), or sensitisation properties.
NANO-MITIGATION: COATING & DISPERSION
How can the potential toxic effects of titanium dioxide and zinc oxide nanoparticles be reduced in sunscreen products? In order to reduce their potential to generate reactive oxygen species (ROS), even after UV exposure, which largely mediate their toxicity for cells and genotoxicity, the surface of nanoparticles can be modified by coating them with aluminium hydroxide, polymers or inert oxides of silica.
Anti-oxidant compounds (such as vitamins A, E or C) can also be added to the sunscreen formulation. Dispersing ZnO particles in some kinds of triglycerides was shown also experimentally to reduce ROS formation.
However, it has been shown that the integrity of the coating layer can be disrupted and the NP coating be stripped under certain circumstances, principally by calcium and hypochlorite ions, which, for example are present in swimming pool water."
Based on the current evidence, the report concluded that neither titanium dioxide nor zinc oxide nanoparticles in the way they are used as coated ingredients in sunscreens, are likely to cause harm.
On the contrary, the report underlined that the current state of knowledge strongly indicated that the minor risks potentially associated with nanoparticles in sunscreens are vastly outweighed by the benefits that nanoparticles containing sunscreens afford against skin damage and, importantly, skin cancer.
The report also mentioned that, in 2012, the Scientific Committee on Consumer Safety (SCCS) of the European Commission concluded that in sunscreens, zinc oxide nanoparticles can be considered to not pose any risk of adverse effects in humans after application on healthy, intact or sunburnt skin. A similar position was upheld in their review of TiO2 nanoparticles2.” *7
In summary, it is best to avoid chemical sunscreens and opt for mineral based sunblocks. Wether or not you choose to use a nano-particle or non-nano particle zinc oxide or titanium dioxide (mineral) based sunblock, is up to you.
NOT BAD, /NOT GREAT: A few other common sunscreen ingredients to consider
Dimethicone is a silicon-based polymer. Simply put, it’s a lab-made silicon oil, not the same as the mineral silica (re: silicon dioxide SiO2), which is an inorganic compound that occurs naturally and abundantly in various forms in nature. Man made silicon based polymers like dimethicone and other silicon based cross polymers like dimethicone copolyol, cyclo-methicone and cyclo-dimethicone are used in personal care products for their anti-foaming and skin and hair -smoothing properties.. They are hydrophobic- meaning they repel water and are mostly insluble in it (except for dimethicone copolyol) and do not wash off skin or out of hair easily.
Like petroleum products, silicone oils can be occlusive and can actually make dry skin worse over time. Instead of sinking into your skin and nourishing it from the inside out, like healthy ingredients do, silicones form a sort of plastic-like film or barrier on the outside of skin, their inert, molecular structure being too large to absorb into the epidermis. That barrier can lock in moisture but it can also trap dirt, sweat, bacteria, sebum, dead skin cells and other debris along with it. Acne prone? Tend to swerve on the dry skin side, especially before or after sun exposure? You want to avoid this ingredient.
If breaking out and making dry skin worse isn’t your cup of tea, another reason to avoid silicones and dimethicones - also super common in hair oils, shampoos and conditioners that temporarily smooth the frizzies all summer- is that they are not biodegradable. Anyone want dimethicone laced fish tacos? Not me!
Avoiding sunblocks with silicone compounds is advisable for these reasons and it is usually listed first or high in the ingredient list, so easy to spot. To avoid this ingredient, stay away from all dimethicone and similar ingredients like cyclomethicone, dimethiconol, and phenyl trimethicone. Many sunscreens contain at least two to three of these different kinds of silicones in them, even ‘safe’ and ‘clean’ ones by brands like COOLA, CLINIQUE, and the ever-popular Shiseido *11 at major department stores and drugstores. It’s up to you to read the ingredients and choose what to use. My recos are at the end and contain no silicone/dimethicone derivatives.
Another super common ingredient in ‘clean’ and ‘safe’ sunblock formulations is aluminum hydroxide. It is used to coat Titanium Dioxide and prevent it from clumping and allows for an even application. Rather than penetrating the skin, it forms a refractive layer that helps reflect UV rays away from the skin. In fact, an aluminum coating is recommended in the Guidelines for Natural Cosmetics of the BDIH. *9
Aluminum hydroxide is not to be confused with the controversial Aluminum Chlorohydrate, which is believed by many to cause cancer and Alzheimer's disease. Yet it should be noted that both ingredients comprise of Aluminum-a proven neurotoxin.” *9
“Skin is permeable to aluminum salts when, for example, they are topically applied. According to researchers at Keele University “It will accumulate in the skin and be transported to sites throughout the body. It is highly likely that the everyday use of sunscreens/sunblocks is an hitherto unrecognised contributor of aluminium to the human body burden of this non-essential (to human bodies!) metal. Perhaps of immediate significance is the potential for aluminium in the skin to act as a pro-oxidant. “ *9
Again, buyer beware. It can be tricky to get past the green washing when it comes to aluminum hydroxides, dimethicone, silicones. Canadian super-clean brand I love and trust Consonant, lists aluminum hydroxide in it’s sunscreen ingredient list *10 and everyone’s favourite brand of oat- based skincare, Aveeno’s “Sensitive Skin” Mineral Sunblock with an SPF 50 which is 100% zinc oxide based, lists dimethicone as it’s first ingredient! Dang! I bought this one for my nieces and tried it while I was away this summer and it worked, but I regret buying it now..
This is such a big category of TOXIC that I will have to cover it in another blog post. Suffice it to say, that since this category of ingredient is covered under proprietary trade secret laws, it is anbody’s guess as to what they are putting on their skin and the effects it is having on our bodies, when this ingredient is listed.
As someone with serious fragrance allergies and sensitivities, I truly think that smelling like vanilla, coconut and ‘sunscreen’ to the detriment of ones’ health or the well being of your neighbor at the beach, is unnecessary! Stay tuned for my next in depth exploration into fragrance and it’s nasty effects on our bodies, (coming soon) and seek clean options with no fragrance or ‘natural fragrances’ listed. Since citrus essential oils can be photo-sensitizing, negatively reacting with light waves on the skin, look for ‘bergaptene-free’ bergamot or non-orange, grapefruit and lemon scented sunscreens.
So what to buy?! Ultimately, it’s up to you to find a texture and formula you like and consider safe and effective enough for you. Hopefully this information will be useful to you to make a wise and safe choice. Here are some I recommend that are non-nano, zinc or titanium dioxide based, non-chalky or thick and sticky, silicone and aluminum free and synthetic-fragrance-free too!
KABANA SKINCARE GREEN SCREEN $6.99 USD
Drunk Elephant Umbra Tint SPF 30 $47 CAN
THE FOLLOWING ARE available at the GOOP store ONLINE and at the Hazelton Hotel in Toronto, where I will be from 12-5pm tomorrow June 28th, 2019, and again on July 5th and July 19, 2019! Come say hi and get some clean, green sunblock.
Naturopathica Daily UV Defense Cream $58 USD (available at the Hazelton Goop Pop Up Shop)
Beauty Counter Counter Sun Mineral Sunscreen Stick SPF 30 $20USD (n/a at this time in Canada)
Beauty Counter Dewy Skin Moisturizing Coverage $56 (available at the Hazelton Goop Pop Up Shop in a nice choice of 10, sheer shades. Come see me and get colour-matched!)
I have not listed any spray sunscreens for a few reasons. The first is it’s flammable and having it in my bag in 30 degree weather is maybe not the best idea? Oh yeah, being on fire is a close second. i think I’d rather get a sunburn?! Second, inhaling that stuff or making others, including kids around me inhale it, is also not my idea of a fun time at the beach or rooftop pool. Speaking of kids, if yours are super squirmy, teach them how to apply their own sunblock with a stick version if you can. Make it fun and let them do all the hard work with touch-ups by you on ears, back of neck, and their cute little noses. Third, the propellants and other toxic chemicals in those bottles are enough for me not to buy or use these.
What’s usually NOT inside ie: zinc oxide or titanium dioxide is also reason enough for me not to buy these. I don’t want to spray a cloud of toxins over myself. Again, would rather get a bit burned, or stay out of the sun altogether during the hottest hours. PROTECTIVE clothing like sunhats, umbrellas and long sleeves are always safe options to consider and increasingly available in an array of SPF-savvy, eco-friendly materials.
Whatever you use, make sure to apply a nice even coating of it, and if you are a fan of spray, apply it over top of a lotion, to be sure you are getting full coverage. Happy Canada Day/ 4th of July Weekend! Saty safe!
*1 Field, Simon Quellen; Why There’s Antifreeze in Your Toothpaste: The Chemistry of Household Ingredients, Chicago Review Press, 2008 pgs. 7-12
** 2 Joanna A. Ruszkiewicz,a,⁎ Adi Pinkas,a Beatriz Ferrer,a Tanara V. Peres,a Aristides Tsatsakis,b andMichael Aschner; Neuro toxic effect of active ingredients in sunscreen products, a contemporary review. 2017 Pub Med ONLINE AT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615097/?fbclid=IwAR0_yiMIAjPabl7-BfDxesvIa9EUqSBecl-zr3cRXic0TIaKMpD9PpdRd9o
***3 Moulite, Maritza; Hawaii Bans Sunscreens That harm Coral Reefs , July 3, 2018. ONLINE AT: CNN.com at: https://www.cnn.com/2018/07/03/health/hawaii-sunscreen-ban/index.html * Will only take effect in 2021.
***4 Shoot, Brittany: Key West Wants to the Put the Cap on Sunscreens to Save Coral Reefs ONLINE AT: http://fortune.com/2019/01/16/key-west-sunscreen-ban-hawaii-coral-reefs/
*****5: Pub Med: Sunscreen Allergy: A Review of Epidemiology, Clinical Characteristics and Responsible Allergens ONLINE AT: https://www.researchgate.net/publication/6984803_Sunscreen_Allergy_A_Review_of_Epidemiology_Clinical_Characteristics_and_Responsible_Allergens
*6 Excerpts quoted in full from Safety of Zinc Oxide and Titanium Dioxide Nanoparticles in Sunscreens, 2016 ONLINE ATt: https://www.greenfacts.org/en/sunscreens-nanoparticles-zinc-titanium/index.htm
*7 Australian Government Department of Health: Literature Review on the safety of titanium dioxide and zinc oxide nanoparticles in sunscreens, 2016 ONLINE AT: https://www.tga.gov.au/sites/default/files/nanoparticles-sunscreens-review-_2016_1.pdf
*8 Aragon, Britta, The Truth Behind the Common Cosmetic Ingredient: Dimethicone, August 26, 2013. ONLINE at: https://www.bewell.com/blog/the-truth-behind-the-common-cosmetics-ingredient-dimethicone/
*9 Truth In Aging: ALUMINUM HYDROXIDE ONLINE AT: https://www.truthinaging.com/ingredients/aluminum-hydroxide
*10 Consonant Sunblock ingredient list https://consonantskincare.com/collections/sun-care/products/the-perfect-sunscreen
*11 SEPHORA: COOLA: https://www.sephora.com/ca/en/product/spf-30-mineral-face-matte-cucumber-P421629?icid2=products%20grid:p421629:product CLINIQUE: https://www.sephora.com/ca/en/product/pep-start-daily-uv-protector-broad-spectrum-spf-50-P415773?icid2=products%20grid:p415773:product Shiseido: https://www.sephora.com/ca/en/product/wetforce-ultimate-sun-protection-lotion-broad-spectrum-spf-50-for-face-body-P429243