Blog – KindofStephen https://kindofstephen.com A cosmetic chemist's blog on the latest skin care and cosmetic research, ingredients, and beauty news Tue, 13 Nov 2018 13:54:16 +0000 en-CA hourly 1 https://wordpress.org/?v=4.9.8 https://i1.wp.com/kindofstephen.com/wp-content/uploads/2017/06/cropped-profile-2.jpg?fit=32%2C32&ssl=1 Blog – KindofStephen https://kindofstephen.com 32 32 114122149 #BeautyRecap: November 13th, 2018 https://kindofstephen.com/beautyrecap-november-13th-2018/ Tue, 13 Nov 2018 13:54:16 +0000 https://kindofstephen.com/?p=3134 Products and Reviews Lush Cosmetics teams up with RuPaul’s Drag Race queens for its Merry DRAGmas campaign HelloGiggles.com A review of the Kopari Coconut deodorant during a marathon Elle.com Kylie Cosmetics to launch in Ulta, in time for the holidays Allure.com Artis is launching customized makeup brushes in their Bespoke range Elle.com MAC and Patrick […]

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Products and Reviews

Lush Cosmetics teams up with RuPaul’s Drag Race queens for its Merry DRAGmas campaign
HelloGiggles.com

A review of the Kopari Coconut deodorant during a marathon
Elle.com

Kylie Cosmetics to launch in Ulta, in time for the holidays
Allure.com

Artis is launching customized makeup brushes in their Bespoke range
Elle.com

MAC and Patrick Starr to launch a holiday makeup collaboration
Allure.com

Dr Almas Ahmed hopes to develop Acarrier, a cosmetic additive to help prevent acid attacks
INews.co.uk

A review of the Bumble and Bumble BB Glitter finishing spray
TeenVogue.com

A look at the Too Faced Gingerbread Spice eyeshadow palette on different skintones
TeenVogue.com

A review of VDL Cosmetics’ Metal Cushion Primer
Refinery29.com

A look at the MAKE Marine Salves blushes
NewBeauty.com

Kylie Cosmetics created a custom lip kit for Travis Scott’s Astroworld tour
TeenVogue.com

Dollar Shave Club dabbles in fine fragrance with men’s fragrance Blueprint and vending machines
AdAge.com

Sheer lipsticks and lip balms recommended by Teen Vogue
TeenVogue.com

Makeup artists recommend their favourite setting sprays
Elle.com

10 acne products recommended by Teen Vogue
TeenVogue.com

Vogue Australia’s beauty tips for the summer
Vogue.com.au

16 products recommended by SHEN Beauty’s Jessica Richards
NewBeauty.com

Retailers, Brands, and Trends

US FDA requests comments on new consumer survey about allergens in cosmetics
FDA.gov

“For skincare brands, urban pollution is good for business”
QZ.com

Cannabis being used in makeup products is on the rise
Independent.co.uk

Coty announces new CEO, Pierre Laubies, and shifts corporate focus to financials
Coty.com

Garnier goes organic in L’Oreal’s bid to lift mass market sales
Reuters.com

Canada’s Cake Beauty to launch in the US at Rite Aid
PRNewswire.com

Revlon jumps as investors embrace beauty giant’s slim-down plans
BloombergQuint.com

Glossier launches two-story New York flagship retail space
Forbes.com

South Korean brand Cremorlab launches in Poland
YonhapNews.co.kr

Shiseido to form a Philippine unit with Singapore’s Luxasia
ABS-CBN.com

Drew Barrymore’s Flower Beauty is coming to Australia in January 2019
Vogue.com.au

“Why US FDA approval of cosmetics may not be necessary”
DermatologyTimes.com

Health Canada links cosmetics colourant solvent Violet 13 exposure to possible cancer risk
ChemicalWatch.com, Canada.ca, EC.GC.ca, Gazette.GC.ca, ECHA.Europa.eu

EU publishes revised guidance on cosmetic ingredients testing
ChemicalWatch.com, EC.Europa.eu

Skincare and Beauty

“Why vanity and selfie stigma is stupid”
Allure.com

“How I learned to embrace aging through mirror meditation”
Allure.com

Why inclusivity in the drugstore makeup aisle is important
Allure.com

A look at semi-permanent BB cream and whether its safe or recommended
Allure.com

Charlotte Tilbury shares the makeup she used during this year’s Victoria’s Secret Show
TeenVogue.com, Elle.com

11 Victoria’s Secret models share where they get the best facials
Elle.com

A look at newer skincare treatments geared specifically to people of colour
MarieClaire.com

Nam Vo gives tips on applying setting powder with a small brush
Allure.com

Three celebrity makeup artists give tips on building a makeup kit
Elle.com

Blush application tips from makeup artists
Allure.com

A look at witch hazel’s use in skincare
Elle.com

Endo announces positive results from trials of its cellulite-reducing injection
NewBeauty.com

New psoriasis drug, Bryhali, approved by the US FDA
Allure.com

A look at tranexamic acid, an ingredient for treating hyperpigmentation
Vogue.com

Dermatologists recommend treatments for post-summer hyperpigmentation
NewBeauty.com

Celebrities and Interviews

Victoria’s Secret executive Ed Razek talks about why their shows are not more inclusive
Vogue.com

An interview with Tiffany Young about beauty and K-Pop
Allure.com

Real Housewives of New Jersey star Teresa Giudice’s beauty Routine costs $22,077
Glamour.com

Research and Technology

Effect of platelet-rich plasma injection for rejuvenation of photoaged facial skin
JAMA Dermatology

Platelet-rich plasma with microneedling and trichloroacetic acid peel for treatment of striae distensae
JAAD

Photodynamic inactivation of bacteria to decolonize meticillin‐resistant Staphylococcus aureus from human skin
BJD

Short contact with nickel causes allergic contact dermatitis
BJD

Quantitative sensory testing in patients with sensitive skin
BJD

An evaluation of the effects of makeup on perceived age based on skin color in Korean women
Journal of Cosmetic Dermatology

Raman characterization of human skin aging
Skin Research and Technology

Effect of spraying of fine water particles on facial skin moisture and viscoelasticity in adult women
Skin Research and Technology

Cosmetic benefit of a biomimetic lamellar cream formulation on barrier function or the appearance of fine lines and wrinkles in randomised proof‐of‐concept clinical studies
International Journal of Cosmetic Science

Reduction in human hair graying by sterubin, an active flavonoid of Eriodictyon angustifolium
Journal of Dermatological Science

Lentigines formation in Caucasian women – interaction between particulate matter and solar ultraviolet radiation
Journal of Investigative Dermatology

The calcium-sensing receptor regulates epidermal intracellular Ca2+ signaling and re-epithelialization after wounding
Journal of Investigative Dermatology

Use of lasers in wound healing: How to best utilize laser technology to prevent scar formation
Current Dermatology Reports

The increase of interfollicular epidermal stem cells and regulation of aryl hydrocarbon receptor and its repressors in the skin through hydroporation with anti-aging cocktail
Journal of Cosmetic Dermatology

Efficacy of platelet‐rich plasma in androgenetic alopecia patients
Journal of Cosmetic Dermatology

ZnO:SBA-15 nanocomposites for potential use in sunscreen: Preparation, properties, human skin penetration and toxicity
Skin Pharmacology and Physiology

In vivo human skin penetration of the UV filter ethylhexyl triazone: Effect of lipid microparticle encapsulation
Skin Pharmacology and Physiology

Allergic contact dermatitis to hydroperoxides of limonene and dose‐response relationship – a repeated open application test (ROAT) study
Contact Dermatitis

Pulsed‐dye laser as a novel therapeutic approach for post‐filler bruises
Dermatologic Therapy

Mitochondrial dysfunction in affected skin and increased mitochondrial DNA in serum from patients with psoriasis
Experimental Dermatology

Detection of fluid secretion of three‐dimensional reconstructed eccrine sweat glands by magnetic resonance imaging
Experimental Dermatology

Tabernaemontana catharinensis leaves effectively reduce the irritant contact dermatitis by glucocorticoid receptor-dependent pathway in mice
Biomedicine and Pharmacotherapy

P66: a small molecule therapeutic against atopic dermatitis and UV‐induced skin cancer
Internal Medicine Journal

Evaluation of the phytochemical composition, antimicrobial and anti-radical activities of Mitracarpus scaber (Rubiaceae)
Journal of Medicinal Plants Research

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Paperview: Sunscreen application to the face persists beyond 2 hours in indoor workers https://kindofstephen.com/sunscreen-office-indoors/ Wed, 24 Oct 2018 12:50:54 +0000 https://kindofstephen.com/?p=3109 What happens to your sunscreen throughout a work day? I often get this question, especially from people who work inside for most of the day. A group of researchers at Mahidol University in Thailand did an experiment that may provide us with some guidance. The researchers took 20 people (15 women) with mostly skin phototype […]

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What happens to your sunscreen throughout a work day? I often get this question, especially from people who work inside for most of the day. A group of researchers at Mahidol University in Thailand did an experiment that may provide us with some guidance.

The researchers took 20 people (15 women) with mostly skin phototype III and up. Skin phototype III means that they tan, but sometimes get mild burns.

The participants were asked to apply 1 gram of sunscreen to their face. The sunscreen was mixed with a blue fluorescent dye that would glow under UV light. This glow allowed the researchers to see the sunscreen on the skin and note changes in its brightness throughout the day.

The people only wore the sunscreen and were asked not to reapply. They weren’t allowed to use makeup or other skincare. They were also allowed up to 1 hour outside. The temperature outside was between 23 and 35 degrees Celsius throughout the day and described as humid. The indoor condition was inside the air conditioned Siriraj Hospital.

Every 2 hours, the researchers took a photo of the people and measured the glow of the sunscreen under a UV light. They looked at the cheeks, forehead, nose, moustache area, and the chin. They used a Visia device to help make sure the photos were consistent.

Sunscreen brightness reduction every 2 hours by percent. The bars indicate the range in measurement values.

The researchers found that the fluorescent glow on the people’s faces decreased the most in the first 2 hours after applying the sunscreen. On average the areas of the face were 16.3% less bright.

Between 2 hours and 4 hours after application, the brightness decreased by a further 7.4 percentage points on average. Between 4 hours and 8 hours, there was an average 4.5 percentage point decrease in brightness.

At the end of the day, there was about a 30% decrease in brightness on average compared to just after applying the sunscreen.

A 30% decrease in brightness in this experiment doesn’t necessarily mean a 30% decrease in sunscreen on the skin. There are ways to model this more accurately, but they did not have the tools in this experiment.

So what does this mean for you? At the end of the day, you’ll still have to use your best judgement.

If you pigment easily, are very concerned about photoaging, or have a family history of skin cancer – I think the best recommendation is to be on the safe side and reapply at least once around 2 hours.

If don’t care that much, consider the opposite, about 70% of the glow from the sunscreen still remained after 8 hours.

In either case, that first application is important. I’d recommend choosing a sunscreen with a high SPF and UVA protection and aiming for a 2 mg/cm² layer. An easy way to make it more likely you’ve applied that amount is to apply your sunscreen in two layers.

Source: Rungananchai, C., Silpa-archa, N., Wongpraparut, C., Suiwongsa, B., Sangveraphunsiri, V., & Manuskiatti, W. (2018). Sunscreen Application to the Face Persists Beyond 2 Hours in Indoor Workers: An Open Label Trial. Journal of Dermatological Treatment, 1–14. doi: 10.1080/09546634.2018.1530440

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A quick look at collagen https://kindofstephen.com/a-quick-look-at-collagen/ Thu, 20 Sep 2018 12:55:40 +0000 https://kindofstephen.com/?p=3050 Collagen, you’ve seen it in your skincare products and have probably eaten it at some point (Yay for artificially-coloured and jiggly gelatin). But what is it? Collagen is composed of a triple helix, three strands of proteins made up of joined amino acids wrapped around each other. The main amino acid constituents of these proteins […]

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Collagen, you’ve seen it in your skincare products and have probably eaten it at some point (Yay for artificially-coloured and jiggly gelatin). But what is it?

Collagen is composed of a triple helix, three strands of proteins made up of joined amino acids wrapped around each other. The main amino acid constituents of these proteins are glycine, proline, hydroxyproline, lysine, and hydroxylysine. The unique chemical structure of the amino acids helps form the shape and structure that their compounds make.

There are many types of collagen, which differ in their amino acid composition. Type I collagen is the most abundant in the human body, and Type I, III, IV, and others are found in our skin. In our body, multiple strands of collagen are found bundled together in fibrils.

You may have heard that ascorbic acid or Vitamin C is crucial in the formation of collagen, but how? Ascorbic acid is used in the conversion of proline to hydroxyproline along with oxygen, and alpha-ketoglutarate. The reaction is catalyzed or sped up by the enzyme prolyl hydroxylase and an iron. Similarly, it is needed in the hydroxylation of lysine to hydroxylysine by the enzyme lysyl hydroxylase.

Collagens are naturally glycosylated, meaning they have sugar molecules bound to them – they are found attached to the lysine and hydroxylysine molecules by the enzymes galactosyltransferase and glucosyltransferase. While this glycosylation is not fully understood, they seem important in forming and retaining the structure of the collagen. You may have heard of glycation or advanced glycation endproducts (AGEs), this happens when excessive sugar molecules are bound to the collagen non-enzymatically and can affect its structure, function, and flexibility.

The additional -OH (hydroxy) group on the hydroxyproline helps water molecules bind tightly to collagen. The coiled structure of collagen’s triple helix gives it impressive tensile strength and allows it to stretch when forces are applied. When too much force is applied the triple helix structure can become disorganized and damaged, no longer able to return to its triple helix form.

Experiments, where collagen was exposed to UV radiation in vitro, have shown that free radicals generated from the UV energy can cleave or break apart some of the bonds holding the amino acids together. When enough bonds are broken the triple helix structure can no longer be maintained and the collagen fibre loses its shape and function. Adding ascorbic acid to the solution of collagen, when it was exposed to UV, reduced some of the free radicals produced – leading to fewer bonds breaking and structure disruption. This may highlight one of the ways naturally present antioxidants in the skin help us defend against the environment.

N. Metreveli, L. Namicheishvili, K. Jariashvili, G. Mrevlishvili, A. Sionkowska. Mechanisms of the influence of UV irradiation on collagen and collagen-ascorbic acid solutions. International Journal of Photoenergy (2006), DOI: 10.1155/IJP/2006/76830

Duer Research Group. Collagen glycation and diabetes. Website, URL: https://www.ch.cam.ac.uk/group/duer/research/collagen-glycation-and-diabetes

A. Masic, L. Bertinetti, R. Schuetz, S.W. Chang, T.H. Metzger, M.J. Buehler, P. Fratzl. Osmotic pressure induced tensile forces in tendon collagen. Nature Communications (2015), DOI: 10.1038/ncomms6942

J.M. Waller, H.I. Maibach. ge and skin structure and function, a quantitativeapproach (II): protein, glycosaminoglycan, water, andlipid content and structure. Skin Research and Technology (2006), DOI: 10.1111/j.0909-752X.2006.00146.x

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The enzyme lysozyme and xanthan gum https://kindofstephen.com/the-enzyme-lysozyme-and-xanthan-gum/ Sun, 16 Sep 2018 19:45:54 +0000 https://kindofstephen.com/?p=3060 These are crystals of lysozyme, an enzyme which can break apart cell wall peptidoglycan of certain bacteria. It is part of our and other animals’ immune systems. Lysozyme is more effective against gram-positive bacteria, as gram-negative bacteria have additional cell membranes that make it harder for the lysozyme to reach the peptidoglycan. Lysozyme is often […]

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These are crystals of lysozyme, an enzyme which can break apart cell wall peptidoglycan of certain bacteria. It is part of our and other animals’ immune systems. Lysozyme is more effective against gram-positive bacteria, as gram-negative bacteria have additional cell membranes that make it harder for the lysozyme to reach the peptidoglycan.

Lysozyme is often used in the processing of xanthan gum. Xanthomonas campestris, a gram-negative bacteria, produce an exopolysaccharide which is a gooey, thick, and sticky slime. This slime may help the bacteria create a comfortable environment for itself and also act as camouflage from other organism’s immune systems.

The slime (aka xanthan gum) is used in cosmetics because it imparts viscosity, lubricity, and acts as a humectant water-binding film former. It also increases the yield stress of water, meaning things suspended in it don’t settle as fast. “Raw” xanthan gum can resemble snot and be cloudy.

In a series of processing steps, the Xanthomonas campestris’ cells are stripped of their membranes and broken apart – this can be done by heating in alkaline water then by treatment with lysozyme and protease. The xanthan gum becomes less gloopy and crystal clear.

Lysozyme can be sourced from a variety of things, but most commonly hen egg whites. It’s not often clear what the source of lysozyme is, so depending on the transparency of the supplier, it’s possible that products labelled ‘Vegan’ may have used animal lysozyme treated xanthan gum.

Plant-based lysozymes do exist, but their structures and functions often differ from animal lysozymes. Genetically modified organisms have been created to produce lysozymes more closely resembling animal lysozymes, but GMOs can be an issue for those who choose vegan products.

I first encountered this conundrum during a meeting with a supplier when they were promoting their vegan xanthan gum, which was slightly less clear than their regular grades. I’d always assumed xanthan gum was vegan, since it was made from bacteria. Sadly, the product line has been discontinued, but one of the largest chemical companies in the world recently launched a clear vegan xanthan gum that’s also GMO-free.

To see more images of lysozyme crystals, check out Dr. Kalju Kahn’s gallery created by students at UCSB.

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Paperview: Evaluation of the protection of a broad-spectrum SPF50+ sunscreen against DNA damage https://kindofstephen.com/paperview-evaluation-of-the-protection-of-a-broad-spectrum-spf50-sunscreen-against-dna-damage/ Wed, 22 Aug 2018 17:00:36 +0000 https://kindofstephen.com/?p=3000 Cyclobutane pyrimidine dimers (CPDs) are a form of DNA damage that is caused by UV exposure. CPDs interfere with base pairing during DNA replication – which can lead to mutations and cancer. UVB radiation is directly absorbed by DNA. The energy causes changes in the bonding of pyrimidine structures found in DNA leading to CPDs […]

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Cyclobutane pyrimidine dimers (CPDs) are a form of DNA damage that is caused by UV exposure. CPDs interfere with base pairing during DNA replication – which can lead to mutations and cancer.

UVB radiation is directly absorbed by DNA. The energy causes changes in the bonding of pyrimidine structures found in DNA leading to CPDs and pyrimidine-pyrimidone (6-4) photoproducts.

UVA on the other hand is poorly absorbed by DNA, but was also found to cause CPD formation in human skin. CPDs were found to remain longer in the skin when there was UVA exposure, leading to speculation that UVA may also suppress a repair mechanism.

Our cells do have DNA repair capabilities, where damaged DNA is excised and replaced – but these processes can be overwhelmed by an accumulation of damage.

Experiments have measured the amount of CPD formation in human skin when exposed to UVB. One study found that CPDs were formed even when there was no visible sunburn (0.5 sunburn dose). They also found CPDs in both the epidermis and dermis and these levels were elevated for about 10 days as the skin sloughed off.

These two images from the paper show (A) skin that was not exposed to UVB and (B) skin that was exposed to UVB. The brown staining of the cells indicates presence of CPDs.

The amount of CPDs found in both the epidermis and dermis increased as UVB exposure increased.

A recent experiment performed by Pierre Fabre (manufacturers of Avène) looked at the effect sunscreen had on the  formation of CPDs in human skin after UV exposure.

14 volunteers applied a sunscreen to their forearm and were exposed to UVB and UVA on skin protected by the sunscreen and also on unprotected skin. The area covered in sunscreen received 15 times the dose of UV to cause sunburn, whereas the unprotected skin received 2 times the dose.

After this exposure, their skin was blistered by vacuum and the contents of the blister were examined for CPDs using two different methods: immunostaining and spectrometry (HPLC-MS).

They found that the unprotected skin after exposure to UV had an elevated ratio of CPDs to normal DNA bases (90 CPD to 106 DNA bases). In comparison, the skin protected with the sunscreen had an amount of CPDs similar to unexposed skin and statistically significantly less than the unprotected skin (P < 0.001) – even though the area received more UV exposure. The CPD to normal DNA base ratio was not reported for the sunscreen protected and unexposed skin.

The sunscreen was not named, but it is SPF 50+, broad spectrum, and contained; Tinosorb M and S, Iscotrizinol, Avobenzone, and the antioxidant bis-ethylhexyl-hydroxydimethoxy benzylmalonate.

Preventing the formation of CPDs from reducing UV exposure is the most well-researched option, but there are other newer methods that are emerging – some of which are already available on the market.

Photolyase is a DNA repair enzyme that can be activated by the absorption of a photon and transfer an electron to the CPD, this can separate the CPD back into two normal pyrimidine bases – with the right timing. In humans, the photolyase enzyme no longer works, but there is some evidence that topical application of photolyase may reduce the formation of CPDs. An experiment where photolyase encapsulated in liposomes combined with light exposure was applied to human skin reduced the formation of CPDs by 40%-45% after exposure to UVB.

You can watch a lecture given by Aziz Sanzar about photolyase and DNA repair below. He won the Nobel Prize in Chemistry in 2015 for his work along with his colleagues Tomas Lindahl and Paul Modrich.

S.K. Katiyar, M.S. Matsui, H. Mukhtar, Kinetics of UV light–induced cyclobutane pyrimidine dimers in human skin in vivo: An immunohistochemical analysis of both epidermis and dermis, Photochemistry and Photobiology (2002), DOI: 10.1562/0031-8655(2000)0720788KOULIC2.0.CO2
J. Gwendal, T. Douki, J. Le Digabel, et al, Evaluation of the protection of a broad-spectrum SPF50+ sunscreen against DNA damage, Journal of the American Academy of Dermatology (2018), DOI: 10.1016/j.jaad.2018.05.570

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Urban particulate matter in air pollution penetrates into the barrier-disrupted skin and produces ROS-dependent cutaneous inflammatory response in vivo https://kindofstephen.com/urban-particulate-matter-in-air-pollution-penetrates-into-the-barrier-disrupted-skin-and-produces-ros-dependent-cutaneous-inflammatory-response-in-vivo/ Fri, 13 Jul 2018 05:00:03 +0000 https://kindofstephen.com/?p=2955 Anti-pollution or anti-particulate matter has become a huge buzzword in cosmetics. Pollution and particulate matter have been linked to many negative health effects (mainly cardiovascular) and while the link to skin health and acceleration of ageing are logical…does the data support it? There have a been a few correlational studies that have shown that people […]

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Anti-pollution or anti-particulate matter has become a huge buzzword in cosmetics. Pollution and particulate matter have been linked to many negative health effects (mainly cardiovascular) and while the link to skin health and acceleration of ageing are logical…does the data support it?

There have a been a few correlational studies that have shown that people living in areas with higher levels of pollution exhibit more signs of oxidative stress in skin lipids and some have even correlated it with increased wrinkling. But what’s the mechanism and can particulate matter even penetrate the skin?

A group of researchers from Seoul used an in vivo mouse and in vitro keratinocyte model to study this.

First was the collection of particulate matter from the air. To do this they set up a vinyl tarp on a rooftop near a busy intersection to collect dust. The particulate matter was then purified and separated to be used in the experiment. The majority of the particles ranged from 200 to 300 nm. Particulates found included: Naphthalene, biphenyl, acenaphthylene, acenaphthene, fluorene, dibenzothiophene, and 28 others identified.

For the in vitro portion of the experiment, cell cultures of human primary keratinocytes were performed with varying concentrations of the particulate matter. The cells absorbed the particulate matter, and the researchers found a concentration-dependent increase of inflammatory cytokine IL-8 and collagenase MMP-1. They also found that the addition of an antioxidant, n-acetyl cysteine, was able to suppress this effect.

In the in vivo portion of the experiment, the researchers used mice that did not produce melanin and divided them into two skin conditions: One with their skin intact, and another with barrier-damaged skin. To damage the skin barrier they stripped the skin 10 times with tape to remove layers of the stratum corneum. The particulate matter was applied 10 times over 2 weeks and included a skin penetration enhancer (DMSO).

While the in vitro results may be “scary”, the in vivo results were milder. Particulate matter was shown to penetrate into the intercellular space of the barrier-disrupted mice, but not the intact mice. Particulate matter was found in hair follicles of both, but there was no epidermal penetration of the particulate matter in the intact mice.

The researchers did find an increase in inflammation in the particulate matter treated skin compared to skin not exposed- whether or not the sin was intact or tape-stripped. However, the inflammation was much more severe in the tape-stripped group. The researchers also showed that intradermal n-acetyl cysteine was able to ameliorate the increase in inflammation caused by particulate matter, but they did not perform this portion of the experiment on the intact mice. It’s likely this same treatment will have a similar effect in the intact mice, but it is unknown.

The researchers also point out some issues with their own experiment: The concentration of particulate matter may not reflect the amount that a person would be exposed to and that their sampling of particulate matter had a high concentration of sulfur which may be unique to their location. It’s also important to remember that mice are not humans, and we may react differently.

While it’s likely that the addition of anti-inflammatories and antioxidants may help attenuate some of the potential inflammation caused by pollution and particulate matter, it’s unknown which chemicals and what combinations are most effective for humans. There’s also no standard measurement to gauge a protective effect so it is impossible to compare one product to another. Again, we see another case of the marketing being ahead of the science.

Source: Jin Seon-Pil, Li Zhenyu, Choi Eun Kyung, Lee Serah,
Kim Yoen Kyung, Seo Eun Young, Chung Jin Ho, Cho Soyun.Urban particulate
matter in air pollution penetrates into the barrier-disrupted skin and produces ROSdependent
cutaneous inflammatory response in vivo.Journal of Dermatological Science
https://doi.org/10.1016/j.jdermsci.2018.04.015

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Skin penetration of Vitamin C (Ascorbic acid): Part II https://kindofstephen.com/skin-penetration-of-ascorbic-acid-part-ii/ Wed, 13 Jun 2018 12:00:48 +0000 https://kindofstephen.com/?p=2627 “Applying 15% Vitamin C for three consecutive days creates a reservoir effect in the skin.” Firstly, I want to remind you that this study was done on pig skin – not humans. The way that ascorbic acid is stored and metabolized in pig skin may vary from human skin. Most animals, like pigs, are able […]

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“Applying 15% Vitamin C for three consecutive days creates a reservoir effect in the skin.”

Firstly, I want to remind you that this study was done on pig skin – not humans. The way that ascorbic acid is stored and metabolized in pig skin may vary from human skin.

Most animals, like pigs, are able to synthesize their own ascorbic acid from glucose, but humans cannot. It’s possible that this data from pigs will be similar to human data, but it’s also very possible that it won’t be. Neither has been proven yet. Presenting an assumption as truth is misleading – but often done in marketing.

I also want to remind you that the way that the ascorbic acid was applied to the skin was not the same way that we apply our skincare. In these experiments, the ascorbic acid solution was applied with a Hill Top Chamber, which occludes the skin, reducing evaporation and theoretically enhancing skin penetration.

For this part of the experiment, Pinnell and his group applied a 15% ascorbic acid solution at pH 3.2 to pig skin for 5 days with a Hill Top Chamber. After the 5th day, application of the ascorbic acid was stopped and ascorbic acid levels in the skin were monitored for an additional 5 days.

After the 3rd day of application of the ascorbic acid serum, the ascorbic acid levels in the skin do appear to reach a peak around 1100 pmol/mg. The deviation around the mean does appear to be reducing with each further day between the 3 subject pigs.

We do need to consider if this theoretical peak amount of ascorbic acid is reached in real-life situations. The living conditions of the pigs in the study were not described, so it’s possible that they were not exposed to natural daylight. It’s understood that UV exposure reduces the amount of ascorbic acid in the skin. UV increases the production of free radicals in the skin, and ascorbic acid is part of the natural antioxidants in the skin which help neutralize these free radicals.

In an experiment using human skin models, it was found that exposure to 16.9 joules/cm² (About 12 minimal erythemal dose equivalent) of UV reduced ascorbic acid levels in the skin model by almost ⅓. This was a higher amount of UV exposure the experimenters expected, they were also unable to detect dehydroascorbic acid in the skin. The study does have some issues which “may be explained by the high levels of ascorbate present in the [tissue] medium…added by the manufacturer to increase collagen synthesis”.

“Vitamin C remains in the skin for 3-4 days and doesn’t wash out”

This marketing claim may be due to some confusion of the term “washout”. In drug experiments a “washout period” refers to the period of time when treatment is stopped, it does not necessarily mean that the skin is washed out.

After applying the 15% ascorbic acid solution to the pig skin, they discontinued application and monitored ascorbic acid levels in the skin. Unfortunately, the methodology in this portion of the experiment isn’t explicitly described. It is unclear, for example, if the pig’s skin was washed each day. The washing procedure is described as “…at the end of the experiment, the formulation was washed vigorously from the skin with water.”

Because most of us use surfactant based cleansers to wash our skin, this data may not be as applicable as the pig’s skin was washed with only water. However, the pig’s skin was removed of stratum corneum before ascorbic acid measurement and the lower layers of skin are likely less affected by the washing and surfactant based-cleanser.

Based on this data, the half-life (the amount of time it takes for the detected ascorbic acid levels to drop by half) was estimated at around 4 days. But as mentioned above, it’s unclear what the living conditions of the pigs were and whether or not they were exposed to sunlight which reduces antioxidant levels in the skin.

Can Vitamin C derivatives increase levels of Vitamin C in skin?

The last portion of the Pinnell experiment looked at whether or not the topical application of Vitamin C derivatives could increase levels of Vitamin C as ascorbic acid in pig skin.

For 24 hours, solutions of dehydroascorbic acid, 10% ascorbyl-6-palmitate, 12% magnesium ascorbyl phosphate, and 15% ascorbic acid were applied to pig skin. Compared to control, only the 15% ascorbic acid solution created a statistically significant increase in ascorbic acid levels in the skin.

For the derivatives, there was no statistically significant difference between the application of the derivative and control (no application of derivatives or Vitamin C) – which implicates that, at least for pig skin, these specific derivatives do not convert to Vitamin C.

For the solutions of dehydroascorbic acid, pig skin levels of ascorbic acid were 7.51 ± 3.34 pmol/mg for 20 mM dehydroascorbic acid and 8.70 ± 2.13 pmol/mg for 1 M dehydroascorbic acid. Where no dehydroascorbic acid was applied levels of ascorbic acid were 9.24 ± 3.55 pmol/mg.

In conclusion…

It surprises me how influential this one study on ascorbic acid applied to pig skin has become in terms of marketing language for brands.

Even later studies with Dr. Pinnell as an author leave out that the data are collected from pig skin, “Following topical application, once the skin is saturated with L-ascorbic acid, it remains with a half-life of about 4 d (Pinnell et al, 2001).”

While this experiment is some of the best data we have in terms of ascorbic acid penetration based on formulation, the key point to remember is that human skin cannot be assumed to behave the same as pig skin.

So if you see a claim similar to “15% Vitamin C at pH 3.5 is the most effective concentration”, please imagine me beside you whispering “…for pigs”.

Edit: An error was made in the original version published, pigs can synthesize Vitamin C from glucose, but humans can not. Guinea pigs also cannot synthesize their own Vitamin C.

Edit: An error was made in the original version published, pmmol was corrected to pmol.

Source: Pinnell, S. R., Yang, H. , Omar, M. , Riviere, N. M., DeBuys, H. V., Walker, L. C., Wang, Y. and Levine, M. (2001), Topical L‐Ascorbic Acid: Percutaneous Absorption Studies. Dermatologic Surgery, 27: 137-142. DOI: 10.1046/j.1524-4725.2001.00264.x

Podda, M., Traber, M.G., Weber, C., Yan, L., Packer, L. (1998), UV-Irradiation Depletes Antioxidants and Causes Oxidative Damage in a Model of Human Skin, Free Radical Biology and Medicine, 24: 55-65. DOI: 10.1016/S0891-5849(97)00142-1

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Skin penetration of Vitamin C (Ascorbic acid): Part I https://kindofstephen.com/skin-penetration-of-ascorbic-acid/ Thu, 24 May 2018 12:45:44 +0000 https://kindofstephen.com/?p=2584 Today I wanted to look at a research paper primarily led by Dr. Sheldon R. Pinnell. He is one of the founders of Skinceuticals and contributed much of the early research on the use of Vitamin C as ascorbic acid on skin. He and his group also discovered the synergistic effect of Vitamin C, Vitamin […]

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Today I wanted to look at a research paper primarily led by Dr. Sheldon R. Pinnell. He is one of the founders of Skinceuticals and contributed much of the early research on the use of Vitamin C as ascorbic acid on skin. He and his group also discovered the synergistic effect of Vitamin C, Vitamin E, and Ferulic acid – which is commonly used in many products on the market today.

The data from this paper is often quoted in marketing material for Vitamin C serums, but one extremely important piece of information is often left out – the data was collected from pigs, white Yorkshire pigs to be exact.

Many people also have ethical concerns when it comes to the use of animals in cosmetic research. Synthetic and lab grown human skin equivalents are being researched and tested which will one day replace the use of animal as well as human testing in cosmetics.

It should be clear that human skin and pig skin are not the same, but they do have similar properties which is why it is often used in experiments. However, one should never assume that data from a pig can be assumed to be the same for a human. The movement and deposition of chemicals often differs between human and pig skin.

From my searches, I haven’t been able to find similar research performed on humans. This paper in particular has led to some of the often quoted “rules” about ascorbic acid.

“Ascorbic acid must have a pH below 3.5 for effective penetration.”

Pinnell and his group tested a 15% ascorbic acid solution adjusted to different pHs ranging from 2 to 5. The 15% ascorbic acid solutions also contained 2% zinc sulfate, 0.5% bioflavonoids, 1% hyaluronic acid, and 0.1% citrate.

While the control situation wasn’t described it’s likely either the vehicle (product without the ascorbic acid) or a water solution was applied to the skin. The control measurement shows that there is some inherent levels of ascorbic acid already present in the skin from the diet.

The test solutions were applied to the pig skin using a Hill Top Chamber. A Hill Top Chamber is a small and round disk which is placed on the surface of the skin, the product is placed in the chamber or a piece of fabric is soaked in the testing material, and the entire chamber is then sealed. This reduces loss of product from evaporation and is a common method of performing occlusive test patches.

The ascorbic acid solutions at pH 2.5, 3.0, 3.5, 4.0, and 5.0 were performed on three pigs, however the control, pH 2, and 4.5 were only performed on two pigs.

The Hill Top Chamber was soaked with 0.2 mL of the ascorbic acid solution then sealed for 24 hours. After this period of occlusion, the skin washed then stripped of the stratum corneum and then small pieces of the skin was removed and tested for ascorbic acid content.

As you can see from the data, the amount of ascorbic acid found in the skin was much higher in ascorbic acid solutions at pH 3.5, 3.0, 2.5, and 2.0. The researchers theorize that it is due to the pKa of ascorbic acid which is 4.2. When the pH of a solution containing ascorbic acid is lower than its pKa more of the ascorbic acid will be protonated. Protonated ascorbic acid is neutrally charged which may allow it to enter the skin more easily.

It’s important to notice the error bars on the amount of ascorbic acid absorbed at pH 2.0. There is considerable deviation from the mean in the results even though it was only tested on 2 subjects. More test subjects would provide a clearer idea of how much ascorbic acid would penetrate at pH 2 on an average population of pigs.

Statistical differences also weren’t calculated between the data points, for example it’s difficult to tell from the way that the data is presented if there is a change in ascorbic acid content between the control, pH 4.0, 4.5, and 5.0 – even if they look different on the graph. Likewise, it’s difficult to tell if there is an increase in ascorbic acid penetration between pH 3.0 and pH 2.5 – despite the trend with pH 2.0 pushing you towards that inference. It’s likely that there is a statistically significant difference between absorption between pH 3.5 and 3.0, but a larger study would provide us  with more confident answers.

So based on this data, many further studies and brands have assumed that a pH below 3.5 results in considerable more skin penetration of ascorbic acid on humans – despite these results being performed on pigs, and relative low strength of the study. If the reason why ascorbic acid is more easily absorbed into the skin is due to the pKa then this would likely hold true for humans as well.

This assumption is often presented as fact, which is misleading. It also doesn’t take into account other factors present in a cosmetic product, such as penetration enhancers. Encapsulation, surfactants, and solvents could increase (or decrease) the amount of ascorbic acid absorbed into the skin regardless of the product’s pH.

In this experiment, the stratum corneum was removed before measurements of ascorbic acid to test for deep penetration of ascorbic acid. It’s possible that some of the benefits conferred by topical application of ascorbic acid aren’t facilitated by deep penetration, the antioxidant and photoprotective effect of ascorbic acid may still occur when it is present in or on the stratum corneum. Other benefits like reduction of hyperpigmentation and an increase in collagen production are likely dependent on penetration past the stratum corneum.

Unfortunately I haven’t been able to find further studies on humans or otherwise to provide answers to these questions.

“Ascorbic acid serums must be at least 10% to be effective”

After the first experiment of testing 15% ascorbic acid with different pHs, Pinnell and his group tested how concentration of ascorbic acid affects skin penetration. This time they tested 7 ascorbic acid solutions with varying concentrations all at pH 3.2. The concentrations of the rest of the formulation are assumed to be the same as the previous experiment.

The ascorbic acid solutions were applied in the same manner, with a Hill Top Chamber for 24 hours, followed by washing, stripping, and then assessment.

The maximum amount of ascorbic acid penetration was seen when 20% ascorbic acid at pH 3.2 was used.

All concentrations were tested on 3 pigs, and there is quite a bit of deviation from mean between absorption among the 3 pigs tested. This makes it difficult to assess the true difference in absorption between a 10% and 15% ascorbic acid, and a 15% and 20% ascorbic acid.

Absorption also seemed to peak at 20%, the 25% ascorbic acid solution penetrated less than the 20%, and the 30% even less so. The researchers did not explore or hypothesize on why this occured, and I’ve been unable to find an answer in any later research as well.

While 20% ascorbic acid certainly led to the greatest increase in levels of ascorbic acid, the 5% solution still increased ascorbic acid levels in the pig skin by about 6 fold.

It’s very important to remember that the way that this experiment was performed does not mimic the way that ascorbic acid solutions are often applied to the skin. With the Hill Top Chamber, the solvent’s (in this case water) evaporation is reduced – whereas when we apply it to the skin the solvent evaporates. What this means is that the kinetics of ascorbic acid penetration into the skin may not be the same.

For example, if half of the solvent of a 10% ascorbic acid solution evaporates, it is equivalent to a 20% ascorbic acid solution – the total amount of ascorbic acid by mass is the same, but the concentration has changed. This may mean that we could see a different maximum absorption by concentration in an experiment where the solvent was allowed to evaporate the way that it is often applied.

Human clinical trials with “low” ascorbic acid concentrations, 3% ascorbic acid cream and a 5% ascorbic acid cream, were able to show statistically significant improvements on measurements of photodamage and photoageing in their study groups.

Another thing many people hold on to is the concept that their products must be working at “maximum efficiency”, unfortunately this is unrealistic and there’s going to be variations in the amount of ascorbic acid that penetrates your skin with each application – even the amount that you apply to your skin will vary each time. This is why good cosmetic studies are performed over a longer period of time.

For example, if we look at the 20% concentration, the pig skin concentration of ascorbic acid increased to about 1100 pmol of ascorbic acid per mg of pig skin, which is about 0.19 μg ascorbic acid per mg of pig skin. 1.0 mg of a 20% ascorbic acid (w/w) contains about 1135589.37 pmol of ascorbic acid, if that helps give you a sense of the “efficiency”. In these experiments, 200 μL or 0.2 mL solution was used in total for each application, which contains about 227117874.1767 pmol of ascorbic acid if we assume density of the solution (w/w) is 1.

Higher concentrations of ascorbic acid may lead to more irritation (measured by skin redness or erythema), but I haven’t found any studies that looked at this specifically.

Continued in Skin penetration of Ascorbic Acid: Part II

Source: Pinnell, S. R., Yang, H. , Omar, M. , Riviere, N. M., DeBuys, H. V., Walker, L. C., Wang, Y. and Levine, M. (2001), Topical L‐Ascorbic Acid: Percutaneous Absorption Studies. Dermatologic Surgery, 27: 137-142. DOI: 10.1046/j.1524-4725.2001.00264.x

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Should you avoid sunscreens with Avobenzone? https://kindofstephen.com/should-you-avoid-sunscreens-with-avobenzone/ Thu, 10 May 2018 12:45:16 +0000 https://kindofstephen.com/?p=2642 I’ve received quite a few questions about the organic sunscreen chemical Avobenzone over the years and I wanted to shed some light on one of the most common concerns – its photodegradation in UV. These concerns are usually raised by websites that say things like, “Avobenzone degrades in the sun, resulting in the release of free […]

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I’ve received quite a few questions about the organic sunscreen chemical Avobenzone over the years and I wanted to shed some light on one of the most common concerns – its photodegradation in UV. These concerns are usually raised by websites that say things like, “Avobenzone degrades in the sun, resulting in the release of free radicals that may actually increase the risk for cancer.”

What these quotes often leave out is the context, which is important in understanding why Avobenzone is so commonly used in sunscreens and why it is effective.

Avobenzone or butyl methoxydibenzoyl methane is an organic sunscreen that absorbs in the UVA region and has global approval. Among the sunscreen chemicals available in the US it is the strongest and most effective UVA absorber. Avobenzone exists in two chemical forms when in solution, the enol form and the diketo (or keto) form.

When exposed to UV light some Avobenzone in the enol form can be changed into the keto form – however this is slowly reversed once Avobenzone is removed from UV light.

In its keto form Avobenzone is susceptible to photodegradation from UV light. The energy from UV light causes structural changes in the Avobenzone that can lead to breakdown products. In many cases, those breakdown products no longer effectively absorb UVA and UVB (some of them will absorb UVC). Some of these breakdown products are also thought to be irritants. The other concern is that some singlet oxygen can also be formed – a reactive oxygen species which can damage DNA and cells.

The above only relates to Avobenzone on its own though, the material that Avobenzone is dissolved into and other chemicals in the formula can change how easily Avobenzone photodegrades. Other modifications like encapsulating Avobenzone have also been tested, though the benefit is often reduced contact between Avobenzone and the skin – not photostability.

Photostabilizers generally work by absorbing energy from the Avobenzone before it becomes unstable and breaks and down. Effective photostabilizers will then be able to take this energy and dissipate it in safer forms, most often heat.

A company that produces Avobenzone, DSM Nutritional Products, performed a study testing different photostabilizers and their effect on Avobenzone’s phostability. The most commonly used and known photostabilizer of Avobenzone is the organic sunscreen chemical Octocrylene, but there are other photostabilizers that don’t act as sunscreens such as Polyester-8 and Polysilicone-15.

To perform the test, 4% Avobenzone and different photostabilizers were dissolved into a mixture of 70% ethanol, 15% caprylic/capric triglyceride, and 15% C12-15 alkyl benzoate. The solutions were placed on glass slides at a density of 2 mg/cm2 then exposed to 25 MED (Minimal Erythemal Dose, 1 MED defined by the US FDA as 200 Joules/Meter2) units of UV light. After exposure, the amount of Avobenzone remaining was determined.

What the researchers found was that the combination of 4% Avobenzone and 3-5% Octocrylene maintained 90% of the Avobenzone after 25 MEDs of UV light. Based on this, they tested different combinations of Octocrylene and other photostabilizers to see how well they stabilized Avobenzone.

They found that 3.6% Octocrylene with 4% Bis Ethylhexyloxyphenyl Methoxyphenol Triazine or 4% 4-Methylbenzylidene Camphor were able to completely stabilize the Avobenzone after 25 MED of UV.

There’s currently no global standard on photostability, different regions have their own standards. In the US as part of the Broad Spectrum test, sunscreens are pre-irradiated with 4 MED before testing.

Just like how some chemicals can increase the photostability of Avobenzone, others like Octinoxate (Octyl Methoxycinnamate) are known to speed up the photodegradation of Avobenzone. This paper is often misquoted to include Oxybenzone (2-Hydroxy-4-Methoxybenzophenone), often mischaracterized as not photostable, as a chemical that increases the photodegradation of Avobenzone, but it was included as an internal standard to allow comparison between samples – as it did not photodegrade in the experiment.

What matters when it comes to the protection offered by a sunscreen are the values and ratings determined from standardized tests like SPF, PPD, Broad Spectrum, etc and not the appearance of an ingredient on the INCI.

Basing assumptions on INCI is dangerous, as the only way to truly know is to test the products. An experiment on 6 different commercial sunscreens on their photostability highlights this. 4/6 of the organic sunscreens tested exhibited a decrease in photoprotection after UV exposure. Of the two photostable organic sunscreens one contained a combination of Avobenzone and 4-Methylbenzylidene Camphor and the other Octocrylene, Avobenzone, Mexoryl SX, and Titanium Dioxide. The one inorganic sunscreen tested was shown to be photostable after UV exposure.

Keep in mind, this study tested commercial sunscreens available in 2006, where photostability was a relatively newer concern for sunscreens and standards had not yet been defined. It was around this time that Neutrogena began marketing its Helioplex patent, a photostable combination of Avobenzone, Diethylhexyl 2,6-Naphthalate, and Oxybenzone. The Helioplex US patent was granted in 2002 and other patents for increasing photostability of Avobenzone are present as early as 1999, when the US FDA finalized the use of Avobenzone in sunscreens.

While we still do not have a global standard for photostability, the options for and knowledge to stabilize sunscreens has grown considerably. It also still very important to reapply your sunscreen throughout UV exposure, this compensates for any protection lost through photodegradation as well as physical changes in the film of sunscreen on the skin.

Source: C. Mendrok-Edinger, K. Smith, A Janssen, J. Vollhardt. The Quest for Avobenzone Stabilizers and Sunscreen Photostability, Cosmetics and Toiletries, http://www.cosmeticsandtoiletries.com/formulating/category/suncare/premium-the-quest-for-avobenzone-stabilizers-and-sunscreen-photostability-214405251.html

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Everybody’s free to wear sunscreen https://kindofstephen.com/everybodys-free-to-wear-sunscreen/ Wed, 28 Mar 2018 14:35:15 +0000 https://kindofstephen.com/?p=2522  You’ve probably seen this photo of a man who received chronic UV exposure on the left side of his face over the course of 28 years working as a truck driver. While this shows the effect that UV has on the skin, what’s important to keep in mind is that windows only block UVB […]

"Everybody’s free to wear sunscreen" on KindofStephen.

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You’ve probably seen this photo of a man who received chronic UV exposure on the left side of his face over the course of 28 years working as a truck driver. While this shows the effect that UV has on the skin, what’s important to keep in mind is that windows only block UVB light whereas UVA is often passed through.

Chronic UVA exposure can result in thickening of the epidermis and stratum corneum, as well as destruction of elastic fibers.

Unfortunately, for those of us living in Canada, the US, and Australia the amount of UVA protection offered by sunscreens is only given in relative terms. The UVA circle logo, for example, let’s you know that the UVA protection is at least 1/3rd of the SPF protection of the sunscreen, but it’s not as informative as a UVA protection factor (UVAPF) or persistent pigmentation darkening (PPD) number. While the PA system used in some Asian countries is based on a PPD number, the data is compressed into categories.

My personal thought is that the UVA protection should be as close to the SPF protection as possible. These are the sunscreens that I personally recommend; based on UVA protection, how they feel and wear on the skin, and affordability. While there are many great sunscreens out there, many of them are too expensive for me and I end up “rationing” them – which is a no-no when it comes to sunscreen application.


Bioderma Photoderm MAX Spray SPF 50+ with UVAPF 33 is a large sized and affordable sunscreen with a moderately high UVAPF. It is a lipid based formula (Dicaprylyl Carbonate) which spreads easily and is not greasy on the skin. I recommend the larger 400 mL size which comes with a snap lock which makes it easy to travel with. I use this on face and body.

It prices out to about 10 US cents per mL.

Sunscreen filters in bold:

Aqua/water/eau, Dicaprylyl Carbonate, Octocrylene, Methylene Bis-benzotriazolyl Tetramethylbutylphenol [Nano], Butyl Methoxydibenzoylmethane, Bis-ethylhexyloxyphenol Methoxyphenyl Triazine, Cyclopentasiloxane, Methylpropanediol, Ectoin, Mannitol, Xylitol, Rhamnose, Fructooligosaccharides, Laminaria Ochroleuca Extract, Decyl Glucoside, C20-22 Alkyl Phosphate, C20-22 Alcohols, Xanthan Gum, Propylene Glycol, Citric Acid, Caprylic/capric Triglyceride, Sodium Hydroxide, Microcrystalline Cellulose, Pentylene Glycol, 1,2-Hexanediol, Caprylyl Glycol, Cellulose Gum, Disodium EDTA.


Ombrelle Ultra Light Advanced Weightless Body Lotion SPF 50 is another affordable sunscreen I recommend. Canada’s Ombrelle was acquired by L’Oreal which is why this product contains Mexoryl sunscreens, which are patented and used exclusively by L’Oreal companies. Because of regulations, the UVAPF or PPD is not able to be listed, but this does have the UVA circle logo. It contains 2% Mexoryl SX which is the stronger UVA absorber compared to Mexoryl XL. It is lightweight, dries quickly, affordable, and easily accessible for Canadians. While it is marketed as a body sunscreen, I use it on my face. It’s much lighter in texture compared to Ombrelle’s other sunscreens marketed for the face.

It prices out to about 12 US cents per mL.

Sunscreen filters in bold

Homosalate: 10%, Oxybenzone: 6%, Octisalate: 5%, Octocrylene: 5%, Avobenzone: 3%, Ecamsul (Mexoryl® SX): 2%. Others/Autres: Aqua, Cyclopentasiloxane, Alcohol Denat., Cyclohexasiloxane, Styrene/Acrylatescopolymer, Silica, Dicaprylyl Ether, PEG-30 Dipolyhydroxystearate, Dimethicone, Triethanolamine, Glycerin, Nylon-12 Polymethylsilsesquioxane, Dicaprylyl Carbonate, Tocopherol, Dodecene, Phenoxyethanol, PEG-8 Laurate, Poly C10-30 Alkyl Acrylate, Poloxamer 407, Caprylyl Glycol, Disteardimonium Hectorite,Disodium EDTA, Lauryl PEG


Sheer Zinc Face Dry-Touch Sunscreen Broad Spectrum SPF 50 is a newer sunscreen and contains only Zinc Oxide as its sunscreen filter. Be warned, this has a very strong whitecast and a thick silicone texture which can pill. I find it best to apply this to small areas of the skin while blending thoroughly.

The reason why I recommend this sunscreen, despite its drawbacks, is based on a presentation that Johnson & Johnson gave at the 2017 American Academy of Dermatology’s Annual meeting showing that their 21.6% Zinc Oxide sunscreen had a UVAPF of 30. Other inorganic sunscreens I’ve seen have only been able to reach a UVAPF of about 18-25.

While the Neutrogena Sheer Zinc was not explicitly named, the launch time and Zinc Oxide content of 21.6% suggests to me that this is the product described.

They compared its absorption spectrum, in vitro, with other common inorganic sunscreens and were able to show that it absorbed more UVA in comparison

I must say again how strong the white cast is, hopefully in the future they release tinted versions!

Based on the above chart it’s likely that the tinted Elta MD SPF 41 with 9.0% Zinc Oxide and 7.0% Titanium Dioxide has a UVAPF of around 28, I’ve not personally tried the product, but I do know it is popular. It prices out to about 35 US cents per mL.

The Neutrogena Sheer Zinc prices out to about 15 US Cents per mL.

Sunscreen filters are in bold

Zinc Oxide 21.6%. Others: Water, C12-15 Alkyl Benzoate, Styrene/acrylates Copolymer, Octyldodecyl Citrate Crosspolymer, Phenyl Trimethicone, Cetyl PEG/PPG-10/1 Dimethicone, Dimethicone, Polyhydroxystearic Acid, Glycerin, Ethyl Methicone, Cetyl Dimethicone, Silica, Chrysanthemum Parthenium (Feverfew) Flower/leaf/stem Juice, Glyceryl Behenate, Phenethyl Alcohol, Caprylyl Glycol, Cetyl Dimethicone/bis-vinyldimethicone Crosspolymer, Acrylates/dimethicone Copolymer, Sodium Chloride, Phenoxyethanol, Chlorphenesin.


J.R.S. Gordon, J.C. Brieva, Unilateral Dermatoheliosis, The New England Journal of Medicine (2012), DOI: 10.1056/NEJMicm1104059

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