Mercury in mascara

Is there mercury in your mascara?

16 days ago, the United Nations’ Minamata Convention for Mercury was signed by about 140 countries. Among other measures to reduce the use of mercury, this global treaty specifies that the production and import of some products containing mercury will be banned.

As reported by Scientific American, 

‘Under a new global treaty that limits the use of mercury, some light bulbs will be banned. Some batteries, thermometers and medical devices will be banned too. But mascara is exempt.’

The reason is then explained:

‘But mascara and other eye makeup is exempt because “no effective safe substitute alternatives are available” and “the intention is not to cover cosmetics, soaps or creams with trace contaminants,” the treaty says.’

Not surprisingly, this news has sparked quite an outrage. What? Do you mean we have been applying mercury around our eyes? How can this continue to be allowed?!

So… Why does mascara contain mercury?

Some mascara products (as well as other products such as eyedrops & vaccines) may contain mercury in the form of thiomersal, which is used as a preservative. Thiomersal is an organomercury compound which contains approximately 50% mercury by weight.

Chemical structure of thiomersal

The US FDA allows mercury in eye cosmetics at a limit of 65 parts per million (which is 0.0065%, in case anyone was wondering).

As a preservative, thiomersal inhibits the growth of bacteria and fungi which can spoil the products and also lead to nasty eye infections.

What harm do mercury compounds cause?

The world became aware of the toxicity of methylmercury in the late 1950s, when the dumping of methylmercury into Minamata Bay, Japan by a local petrochemical and plastics company resulted in widespread consumption of mercury-contaminated fish and shellfish. The consequences were devastating. Methylmercury proved to be a neurotoxin (affecting the nerves and brain) and led to illness, foetal abnormalities and death.

Currently, the US Environmental Protection Agency has set a reference of 0.1 µg/kg/day as a guideline for safe exposure levels to methylmercury.

Much less is known about thiomersal, which is a derivative of ethyl mercury. An animal study by Magos et al. in 1985 directly compared the toxicity of ethyl- versus methylmercury in adult male and female rats. Ethylmercury was concluded to be less neurotoxic than methylmercury. Regardless, due to the lack of data, the FDA considers ethyl- and methyl-mercury to be equivalent in its risk evaluation.

Is it possible to avoid mascara and eye products containing mercury?

According to the article by Scientific American,

‘The FDA does not require ingredients that comprise less than 1 percent of a cosmetic product to be divulged on the label, so a lot more products may have thimerosal and consumers would never know, said Kristin Adams, chief executive officer of Afterglow Cosmetics, a natural and organic cosmetic company.’

This afternoon, I did a quick survey of the ingredient labels of a few mascara products at the drugstore. Some products contained phenoxyethanol and parabens (both are preservatives) as ingredients. Some other products did not specify any preservatives on their labels. Does this mean what I think it means? Clearly, all mascaras SHOULD contain preservatives (to prevent eye infections), but the preservatives are not necessarily listed on the label because their concentrations are very low. Kristin Adams was right.

To put things into perspective,

There are many other possible ways that we could be exposed to mercury. For example, eating contaminated fish (which is the most significant source of ingestion-related mercury exposure), taking some Traditional Chinese Medicine preparations, or even accidentally breaking a lab thermometer. With the signing of the Minamata Convention for Mercury treaty, we can hope to look forward to a reduction of mercury contamination in the environment.

Personally, I don’t put on makeup very often (much to the dissatisfaction of hubby), so I am not fearful for my health right now. However, I do believe (and hope) that the increased awareness among consumers will drive the cosmetic industry to use safer alternatives as preservatives for their products. 

References:
1. http://www.scientificamerican.com/article.cfm?id=in-the-public-eye-mascara-exempt-from-mercury-treaty
2. http://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/UCM096228

Stem Cells in Skincare

What are stem cells?

Stem cells are undifferentiated cells which have the potential to differentiate into specialized cell types (such as specific types of skin, muscle, blood cells, etc.). They are capable of multiplying indefinitely, as long as the person is alive. Yet, stem cells in the human body undergo aging, and as we grow old, our body gradually loses its capacity to renew tissues.

Stem cell – based skincare products

For the beauty-conscious, aging means that the renewal of skin cells slows down (due to the aging of our skin’s stem cells). Wrinkles start to appear and wounds or scars take longer to heal. The cosmetic industry has now come up with a new solution: To use stem cell-based products to stimulate our own skin’s stem cells to regenerate and live longer.

Not all stem cell-based products are the same. In fact, their ingredients vary greatly. Here are the different types of active ingredients in products which are marketed as “stem cell-based”:

1.       Plant-derived stem cell extracts

Plant stem cells are mainly found in the tips of the shoot & roots, and in the stems of a plant. Just in case you would like to know. If I didn’t interpret wrongly from this Yahoo article, L’Oreal’s Age Perfect Cell Renew range contains plant stem cell extracts.

2.       Human-derived stem cell extracts

Don’t worry, they don’t use embryonic stem cells. Some products use adult human stem cells. One famous brand, Lifeline, which has been mentioned in several beauty articles on the Internet, uses stem cells developed from unfertilized human eggs. Now, would you like to apply some cream made of unfertilized eggs donated by an anonymous lady from somewhere out there?

3.       Proteins secreted by stem cells

Meaning, the stem cells themselves are not used in the product. Stem cells are grown in a liquid medium, and that liquid medium bathing the cells is collected. To be honest, I don’t know of any particular brand of product that uses this, but I do know that the method has been patented.

What is the science behind stem cells in skin care?

I tried to search for scientific literature studying the use of stem cells in cosmetic products and came up with ZERO results. I repeat: ZERO results, whether it's for plant/animal/human-derived stem cell products. Sure, some companies do mention on their websites that their product has shown great results in a study, but then these results are not made available to the public or even to the scientific community. Sounds rather suspicious, don’t you think?

Let’s think about the plausibility of their claims. Take a look at a statement from Lifeline (taken from the Lifeline website):

“Scientists at Lifeline Skin Care discovered that human non-embryonic stem cell extracts can renew skin -- by replacing old cells with healthy new ones.”

If scientists had truly found a way to reverse aging (i.e. to turn the old cells into healthy new ones), this would be the greatest medical breakthrough of all time. This technology would be applied in every field of medicine possible – to get younger & healthier brains, bones, muscles, etc. We would have discovered the Tree of Life, the fountain of youth. We would live forever, and never grow old. Erm… Does that sound a little less convincing now?

In the end, I believe that “stem cell-based skincare products” sound very science-y, very high-tech, but that’s all just part of marketing strategy. Somehow, stem cells have evolved over the years from being an ethically controversial issue to becoming a mysterious, sort-of trendy promise for the future of medicine (and now, cosmetics). But before we spend a fortune on scientific-sounding products, let’s do our research properly to differentiate a hoax from the real deal. 

Toner, serum, emulsion, etc.

Before I got married, my skincare regimen consisted only of a facial cleanser. Oh, and an antibiotic cream for acne when I was in my teens. But ever since my hubby went to Korea and bought lots of skincare products for me, I've tried using many different products. (Otherwise they will be wasted, right?) J

For someone who’s only known what “cleanser” was, seeing all the different names of the various types of products was a confusing experience for me! These are some of the products that I commonly encounter:

Cleanser:

I guess everyone knows this! J Used for washing your face with.

Toner:

For use after cleansing, usually to remove any excess oil or makeup residue, shrink pores, and restore the pH balance of the skin.

Apparently, there is some controversy about toners nowadays, since many dermatologists and beauty editors believe that toners are not an essential part of a skincare regimen, unless you have extremely oily or acne-prone skin. (I read that here.)

Softener:

The term “softener” is more commonly found in Japanese / Korean products. Softeners are basically toners but as the name suggests, they are meant to hydrate the skin instead of drying it out.

Serum:

Serums are products containing active ingredients such as vitamins / antioxidants in high concentrations and are designed to penetrate into the deeper layers of the skin. Serums are meant to be applied after toner, and before moisturiser. A small amount (a few drops) would be sufficient for the whole face.

Essence:

A lighter version of serum (less concentrated).

Emulsion:

Also known as lotion, this is a moisturiser with a liquid consistency. It’s not as “heavy”/oily as creams.

Cream:

A “heavier” moisturiser with a creamy texture.

These are just the basics! I sometimes encounter other less heard-of terms which are used to describe specific products (or worse, sometimes no English words on the products), so when I don’t know how to use a product, Google is my friend! :P

Alcohols in skincare products

Today’s topic was suggested by my lovely housemate, WL! J

Should we avoid skincare products containing alcohol? There are already many articles out there on the internet discussing and debating this issue. Many articles also talk about “good” alcohols and “bad” alcohols for the skin.

Before we explore this topic further, let’s do a short revision of some ‘A’-level organic chemistry:

Chemical structures of alcohols

In chemistry, the term “alcohol” refers to any of a class of organic compounds characterized by one or more hydroxyl (−OH) groups attached to a carbon atom of an alkyl group (hydrocarbon chain, represented as R in the drawing above). (Definition from Encyclopaedia Britannica.)

The alkyl group, R, can vary in length from short hydrocarbon chains (e.g. ethanol, isopropanol) to long hydrocarbon chains (e.g. stearyl alcohol, cetyl alcohol).

Short chain alcohols

1.       Ethanol (also known as ethyl alcohol. It is also the major ingredient in denatured alcohol or SD alcohol.) This is the alcohol that we drink!

  

2.       Isopropanol (also known as isopropyl alcohol)

Short chain alcohols are the alcohols which are commonly said to be “bad” for the skin as they can disrupt the skin’s protective barrier and dry up the skin. In my opinion, these are not necessarily bad ingredients as they can help to dissolve active ingredients in the product & also help increase the absorption of active ingredients by the skin. (See my previous post on skin penetration enhancers.) But if you have dry skin or eczema, then you may want to avoid products containing these alcohols which can worsen the dryness.

Long chain alcohols

Due to their long hydrocarbon chains, long chain alcohols tend to be greasy/waxy and make good moisturisers. Hence, many articles call them the “good” alcohols.

1.       Cetyl Alcohol 

2.       Stearyl alcohol 

3.       Cetearyl alcohol (which is a mixture of long chain alcohols, mainly cetyl and stearyl alcohols)

4.       Lanolin Alcohol (also known as wool alcohol, produced from lanolin or “wool fat”)

A word of caution though: some people may be allergic to lanolin.

Some other alcohols…

Besides short-chain and long-chain alcohols, some other ingredients also contain “ol” or “alcohol” in their names. Here’s just a few examples:

1.       Glycols (propylene glycol, butylene glycol), glycerol (also known as glycerin)

 

Chemical structures of propylene glycol and glycerol

I suppose most people wouldn’t think of these ingredients as alcohols, but I shall include them here anyway since they are commonly found in skincare products too. LOL. Glycols have 2 –OH groups in their chemical structure, while glycerol has 3. These compounds are humectants, which bind water and help moisturise the skin.

2.       Phenoxyethanol

3.       Dichlorobenzyl alcohol (also used as an antiseptic in Strepsils lozenges!)

 

Chemical structures of phenoxyethanol and dichlorobenzyl alcohol

Both phenoxyethanol and dichlorobenzyl alcohol possess antibacterial activity, so they are sometimes used as preservatives in skincare products.

4.       Vitamins such as retinol (vitamin A), calcitriol (vitamin D), α-tocopherol (vitamin E)

From the different examples mentioned above, we can see that “alcohols” describes huge class of compounds, and different alcohols can have very different effects on our skin. I hope that this blog post has given you a better idea of some of the different types and functions of alcohols used in skincare products. J

Update: My snail cream trial

In my previous post on snail creams, I mentioned that I started my own little trial of products containing snail secretion. Well, it's been 4 weeks, and here are the results of my little "experiment" (albeit a very non-scientific one!):

  

Product: It’s Skin Prestige D’escargot special trial kit

Regimen: 

Morning: Toner & emulsion

Night: Toner & cream

(Disclaimer: This is not an advertisement for the brand! It just happens that this product is what my hubby brought back from Korea for me.)

In my Google search, I didn’t manage to find the percentage of snail secretion filtrate contained in these products. I only came across this description of the cream:

“First class luxurious cream contains mucin (snail mucus), the ingredient with superior cell restoration, moisturization, and skin trouble relieving effects, and EGF (epidermal growth factor), through the combination of which creates a synergy effect to regenerate damaged cells, the fundamental cause for skin aging.”

Oops! So I didn’t realize that the cream contains EGF (epidermal growth factor) as well… That’s another ingredient which is also claimed to repair damaged skin. Hmm. This could present a confounding factor to the results…

Without further ado, here are the results!

Under-eye area:

Under-eye area at baseline, 2 weeks and 4 weeks

Puffiness seems to have decreased. Fine lines under my eye are still present after 4 weeks, but looks slightly improved. (Honestly, I can’t tell by looking in the mirror, but the pictures seem to suggest an improvement.)

Being the skeptic that I am, I was genuinely surprised by the improvement! And happy too, of course.

Hyperpigmentation:

Hyperpigmentation on left cheek at baseline, 2 weeks and 4 weeks

No noticeable difference in the hyperpigmentation spot on my left cheek.

Old chicken pox scars:

Chicken pox scars on right cheek at baseline, 2 weeks and 4 weeks

No noticeable difference in the old chicken pox scars on my right cheek.

Conclusion:

From my own limited experience, I have come to a conclusion that snail cream is definitely not the “miracle cream” it is commonly advertised to be. However (at least for me), it did help to slightly reduce the appearance of fine lines/wrinkles. 

Skin penetration enhancers: Improving skin absorption

The skin is the largest organ of the human body. The outermost layer, called the stratum corneum, consists of dead cells which form a protective barrier to keep the bad stuff (germs & chemicals) out and the good stuff (water) in the body.

The structure of human skin

When we apply skincare products (or medicated gels/creams/ointments), we generally want the active ingredients to be able to penetrate the stratum corneum and enter into the deeper layers of the skin to exert their effect.

How do molecules cross the stratum corneum?

1.  Intercellular route – Molecules pass through the spaces between the dead cells. This is the predominant route.
2. Transcellular route – Molecules directly pass through the dead cells. This is the path of greatest resistance as the molecules need to penetrate the cell membranes and cell contents of the dead skin cells.
3.  Transappendageal route – Through sweat glands or hair follicles. Since sweat glands and hair follicles occupy only 0.1% of the total human skin surface, the contribution of this route is considered to be small (although it is still important).

How molecules may cross the stratum corneum

Why is it difficult for molecules to cross the stratum corneum?

As mentioned earlier, the predominant route of transport of molecules across the stratum corneum is via the intercellular route. But the spaces in between the dead skin cells are not just empty space; these spaces are filled with lipids (cholesterol, ceramide & free fatty acids) which form the lamellar lipid bilayer. These lipids contain hydrophilic (water-loving) head groups and lipophilic (greasy, oil-loving) chains. So, in order to cross the stratum corneum, molecules must be able to cross the lamellar lipid bilayer.

Structure of the lamellar lipid bilayer

What are skin penetration enhancers?

Skin penetration enhancers are compounds that are added into the formulation of a product to enhance the delivery of its active ingredients across the skin barrier.

How do skin penetration enhancers work?

These substances work through various mechanisms:

1.  By interacting with the hydrophilic head groups of the lipids in the lamellar lipid bilayer – this disrupts the packing order of the lipids, making it easier for active ingredient to diffuse through. (e.g. propylene glycol)
2.  By interacting with the greasy chains of the bilayer lipids. This also disrupts the packing order of the lipids. (e.g. oleic acid)
3. By hydrating the skin (e.g. urea)

What are some of the commonly used/studied skin penetration enhancers?

1.       Alcohols

a)      Short chain alcohols (e.g. ethanol, isopropyl alcohol)

b)      Long chain alcohols (e.g. octanol, nonanol, decanol, undecanol, lauryl alcohol, tridecanol, myristyl alcohol, oleyl alcohol, linoleyl alcohol, and linolenyl alcohol

2.       Fatty acid esters

-          Isopropyl myristate, ethyl oleate, glyceryl monolaurate, glyceryl mono-oleate, lauryl lactate, isopropyl palmitate, methyl oleate, oleyl oleate and sorbitan mono-oleate.

3.       Glycols

-          Propylene glycol

4.       Glycol ethers

-          Transcutol®

5.       Fatty acids

-          Oleic acid

6.       Sulphoxides

-          Dimethyl sulphoxide (seldom used due to skin irritating effects)

7.       Urea and derivatives

8.       Surfactants (e.g. Tween)

9.       Terpenes (found in essential oils)

References:

1.       Lane. Int J Pharm. 2013 Apr 15;447(1-2):12-21

2.       Trommer & Neubert. Skin Pharmacol Physiol. 2006;19(2):106-21

Parabens: Cause for concern?

Increasingly, cosmetics and skincare products are being advertised to be “paraben-free”. Today, I took a quick look at the ingredients in my shampoo, conditioner, body wash and some skin care products – no parabens in them, even though I haven’t been actively looking out for paraben-free products. But what are parabens, and why the concern over their use?

A simple Google search yielded many useful articles about parabens, and among them is an article from the FDA containing information to answer enquiries about the safety of parabens used in cosmetics.

To summarize, parabens are esters of p-hydroxybenzoic acid, and they are widely used as preservatives in cosmetics as well as in food and drugs. Methylparaben, propylparaben, and butylparaben are the most commonly used.

Chemical structure of parabens

So, why the health scare over parabens? All the websites I’ve visited quoted the famous 2004 study by Darbre, and here I quote from the FDA article:

“A study published in 2004 (Darbre, in the Journal of Applied Toxicology) detected parabens in breast tumors. The study also discussed this information in the context of the weak estrogen-like properties of parabens and the influence of estrogen on breast cancer. However, the study left several questions unanswered. For example, the study did not show that parabens cause cancer, or that they are harmful in any way, and the study did not look at possible paraben levels in normal tissue.”

But, the FDA also assures consumers that the estrogen-like activity of parabens (which could potentially be linked to cancers) is very, very low. Furthermore, parabens are used in very low levels in cosmetics. Presently, the FDA believes that there is no cause for concern over cosmetics containing parabens.

Well, the article by FDA was written in October, 2007. Almost six years have passed now, so let’s take a look at the current perspective on parabens.

Parabens and breast cancer

After the 2004 study by Darbre, no other significant studies have tried to link parabens to breast cancer. A 2010 literature review concluded that there is no link between parabens and breast cancer.^[2]

Effect of parabens in men

Due to concerns about the estrogen-like activity of parabens, the effect of parabens on the male reproductive system has also been studied. However, animal studies in mice and rats have shown conflicting results on the reproductive effects of parabens. In humans, a study in men with fertility problems showed no correlation between sperm count/motility and paraben levels.^[3]

Paraben allergy

Though uncommon (in 0.5 to 3.5% of the population), parabens can cause allergies in some people. The allergic reaction usually appears as an eczema-like rash. Compared to other preservatives, the rates of paraben allergy are among the lowest.^[3]

The move away from paraben-containing products has led to the emergence of a wide range of alternative cosmetic products that paraben-allergic patients can turn to. However, replacing parabens with other preservatives may well lead to the placing on the market of products whose toxicity and allergenicity are not as well-documented.[4]

Current Government and Regulatory Control of Parabens^[3]

·       In the European Union (EU):  Parabens can be safely used in cosmetic products at concentrations of 0.4% for any individual paraben and 0.8% for total paraben concentrations.

·       In Denmark: In 2011, the use of parabens was banned in personal care products intended for children younger than 3 years of age.

·       In the United States: the Cosmetic Ingredient Review (CIR) has recommended the same maximum paraben concentrations as legislated by the EU. However, the CIR recommendations are only guidelines, not laws.

·       In Canada: Likewise, Health Canada agrees with the FDA and the CIR in regards to the safety of parabens and the adoption of maximum concentration guidelines. However, these are also recommendations, not laws.

Conclusion

From the current data available, it appears that parabens are still considered safe for use within the recommended limits. However, as a marketing strategy, many cosmetic and skincare companies are moving away from parabens and into more "natural" alternatives. With "natural" alternatives, there may be a higher risk of microbial contamination (germs!) and greater care must be taken to adhere to expiration dates. 

References:

1.      http://www.fda.gov/cosmetics/productandingredientsafety/selectedcosmeticingredients/ucm128042.htm

2.   Witorsch & Thomas. Crit Rev Toxicol. 2010 Nov;40 Suppl 3:1-30.

3.       Kirchhof & de Gannes. Skin Therapy Lett. 2013 Feb;18(2):5-7.

4.       Castelain & Castelain. Eur J Dermatol. 2012 Nov-Dec;22(6):723-7

Snail Creams - Do They Work?

Recently, snail creams have become a popular trend in Korean beauty products. They contain snail slime, which we all know as the gooey trail left behind by a snail as it moves along. (Eww!) Manufacturers claim that snail slime-containing products are able to improve acne, spots, blemishes, wrinkles, stretch marks and fine lines.

A garden snail

My dearie got me some samples of snail slime-containing products too! So, being curious as well as skeptical, I tried to search for any clinical or scientific trials which have been carried out to demonstrate the benefit of snail creams.

 

My own sample pack of snail secretion extract products

The first article that I came across was a very old article from 1982, by Iguchi et al..[1] Snail slime extract was collected from African giant snails (captured in Okinawa) and tested for antibacterial activity.  Indeed, the mucins (carbohydrate-conjugated proteins) present in the extract was found to possess antibacterial activity against a few different types of bacteria (both gram-positive and gram-negative).

The second article that I found was a report of a small clinical trial by Fabi et al..[2] In its introduction, the rationale behind the use of snail slime was explained. When snails are exposed to UV light or x-rays, they retract their tentacles and secrete a large amount of mucus as a defense mechanism. This mucus helps to repair the snail’s damaged skin in less than 48 hours. Maybe it can repair human skin too!

This trial was a 2-center, double-blind, randomized, 14-week study, with a sample size of 25 female patients with moderate to severe wrinkles around the eyes and mouth. The treatment used was an 8% emulsion and a 40% liquid serum containing snail secretion filtrate from Cryptomphalus aspersa (also known as Helix aspersa, or the common garden snail). The snail slime-containing emulsion & serum were applied to one side of the face, while a placebo emulsion & serum was applied to the other side. The result? The snail slime-treated side showed a trend towards greater improvement of wrinkling around the eyes compared to the placebo-treated side of the face. However, the difference was not statistically significant (probably owing to small sample size). Was the difference noticeable? At week 8 of using the products, patients reported an improvement in fine lines on the snail slime-treated side but did not report a difference in the overall quality of their skin.[2]

In the same article, a previous pilot trial by Tribó-Boixareu et al. was also mentioned. The pilot trial was a small nonrandomized, open-label study with 15 participants. The study had yielded promising results with improvement in sallowness, fine lines, deep wrinkles, elasticity, dryness and roughness of the skin.

 

Nope. Unfortunately, the effects of snail cream are not THIS pronounced.

But how does snail slime work? Brieva et al. set out to study the scientific basis for the regenerative properties of snail slime. They discovered that snail secretion:[3]

1.       Possesses antioxidant properties.  Snail secretion has multiple modes of action as an antioxidant: It possesses certain enzymatic (superoxide dismutase [SOD] & glutathione S-transferase [GST]) activities, which enables it to inactivate free radicals and reactive oxygen species which are already present. It is also able to scavenge free radicals, halting the chain reaction which produces more free radicals.

2.       Enhances the growth of fibroblasts (a type of cell that synthesizes the extracellular matrix and collagen, important for wound healing).

3.       Stimulates fibronectin secretion and assembly (also important in wound healing).

4.       Reduces the production of matrix metalloproteinase enzymes (Increased metalloproteinase expression has been associated with impaired wound healing and regeneration).

Fibroblasts

Am I convinced?

Based on the trial by Fabi et al., there seems to be some evidence to suggest that snail slime products may help to decrease the presence of wrinkles. Although the effect is not that pronounced, I think that many women (being the vain creatures that we are) would be willing to try these products out for even a modest benefit.

As for the skin healing and regenerative properties of snail slime, I think it’s really great that its benefits has been shown in vitro (i.e. in cells growing in petri dishes). But the big question is: Do these observations translate to real-life clinical benefits? How would the HUGE proteins in snail slime penetrate the skin barrier to exert their effect? Theoretically, it might work if applied on broken or inflamed skin. Some dermatologists may use laser to create tiny holes in the skin before applying snail cream, and this may work too. But on healthy, intact skin? I have my doubts.  

So, I will be conducting my own open-label trial, sample size = 1. I shall try out my snail slime products for a month (or until the product is finished), and if there is any improvement to my skin, I’ll make sure to update on this blog. ^_^
*Update: Click here for the results of my little trial of snail slime products!

References:

1. Iguchi et al., Comp Biochem Physiol A Comp Physiol. 1982;72(3):571-4.
2. Fabi et al., J Drugs Dermatol. 2013 Apr;12(4):453-7.
3. Brieva et al., Skin Pharmacol Physiol. 2008;21(1):15-22

Sunscreen

Many beauty products today contain sunscreen. Most BB creams and foundations come labelled with an SPF factor and PA grade. The ones which Dearie recently bought for me are no exception!

Some of my skincare products which contain sunscreen

And I’d say he bought them for me just in time! Because, is that an age spot developing on my left cheek??! Why?? I’m not even 30 yet! T_T

Age spot? T_T

I remember learning about sunscreens back when I was still an undergraduate student, but I couldn’t recall much of it anymore… Time to hit the books (or rather, internet) again! To my pleasant surprise, this exercise not only refreshed my memory but I discovered new information along the way. So, let me share with you what I’ve learnt. These information apply to sunscreen in general, not just in facial products.

Sunscreen is not a stand-alone protective measure against UV radiation. Remember to also use other sun-protection measures:

·       Avoid the sun at its hottest, i.e. between 10am to 4pm.

·       Wear protective clothing, i.e. long pants, long sleeves, sunglasses, and an umbrella or a wide-brimmed hat.

What is the difference between SPF and PA grade?

Firstly, a short introduction to UV radiation:

There are 2 types of UV rays that reach the earth’s surface: UVA (wavelength 320-400 nm) and UVB (wavelength 290-320 nm). UVB causes skin redness, inflammation and stinging – effects we can easily identify as sunburn. UVA penetrates into the deeper layers of the skin and may have greater destructive effects.

SPF = Sun Protection Factor. SPF mainly measures UVB protection.

Note: I used to think that SPF number corresponds to the length of time you can be exposed to sunlight without burning, e.g. if I would normally get a sunburn after 10 mins, an SPF 30 sunscreen would allow me to stay out 30 times longer (300 mins) before getting a sunburn. But, to my surprise, I found that this is not exactly accurate. Another piece of info: the relationship between SPF and UVB protection is not linear - a sunscreen with SPF 15 can filter 94% of UVB radiation, whereas SPF 30 provides >97% protection.

But let’s not get caught up with the details. The most important factor contributing to the efficacy of sunscreen is not really the SPF number, but whether or not we use it correctly – which I will talk about later below.

PA = Protection grade of UVA. This is the Japanese measurement of sun protection, and is not recognized by the FDA. The rating system ranges from + (lowest protection) to +++ (greatest protection).

Besides PA grade (commonly used in Asian products), product labels in other countries use different ways to indicate UVA protection. In the US, the FDA requires delineating “broad-spectrum” and sun protection factor (SPF) information on the label of sunscreens which protect against both UVA and UVB. In the European Union, the UVA logo is used.

FDA requirement for "broad spectrum" to be displayed on label

EU UVA logo

When you choose a sunblock, make sure to select one that confers both UVA and UVB protection!

What is the active ingredient in sunscreen?

There are 2 main types of active ingredients:

·       Physical sunscreens – these are particles such as zinc oxide and titanium oxide which physically reflect UV radiation. Very similar to wearing clothes to block the sunlight! The downside, though, is that the texture of these products can be pasty and clumpy. They may also leave a white residue on the skin. However, with advances in nanotechnology, these particles can now be processed to be really, really small so that they no longer cause these problems.

·       Chemical sunscreens – these are organic compounds which absorb UV radiation. Different active ingredients absorb UV radiation at different wavelengths, so it is not uncommon to see several active ingredients blended together in the same product in order to achieve broad-spectrum coverage.

What is the correct way to use sunscreen?

·       Apply a generous amount of sunscreen to dry skin 30 minutes before sun exposure.

·       Apply sunscreen to all skin surfaces that will be exposed to sun, e.g. face, ears, hands, arms and lips. If you don't have much hair on your head, apply sunscreen to the top of your head or wear a hat.

·       Reapply sunscreen every 2 hours, and immediately after swimming or heavy sweating.

·       Be aware that sand, water, snow and concrete reflect sunlight, making it all the more important to use sunscreen.

·       UV light can pass through clouds, so use sunscreen even when it's cloudy.

What is the incorrect way to use sunscreen?

The use of sunscreen to enhance tanning and deliberately prolong exposure to the sun is an abuse of the product and may actually increase the risk of skin cancer. A common misperception is that sunscreens decrease the risk of sunburns and therefore, it’s OK to stay out in the sun for a long time. But this could increase the risk of skin cancers and cause photoaging (e.g. wrinkles, sunspots).

What can sunscreen protect me against?

·       Sunburn (Yep, that’s a no-brainer.)

·       Immunosuppression. Yes, that’s right. UV radiation can suppress our immune system, and this can contribute to the development of skin cancers. Quite scary, huh? Thankfully, research shows that broad-spectrum sunscreens do protect against immunosuppression.

·       Skin damage such as solar elastosis (thickened, dry, wrinkled skin) and decreased skin elasticity. Interestingly, sunscreens are still beneficial even at lower levels of UV exposure which do not cause sunburn.

·       Some types of skin cancers. Sunscreens can help prevent the formation of squamous cell carcinoma and actinic keratosis (thick, scaly patches of skin which can potentially progress to squamous cell carcinoma). However, there is no strong evidence that they also prevent other types of skin cancers such as basal cell carcinoma and melanoma.

Are there any harmful side-effects of sunscreen?

·       Although rare, there are people who develop allergies to some chemical sunscreens.

·       Some chemical sunscreens may be absorbed through the skin into the bloodstream. (This is less of a concern with non-soluble sunscreens such as zinc oxide & titanium oxide.) Could it potentially cause harm in the body? Some animal studies suggest that selected sunscreens may alter hormone levels. However, such effects have not been shown in humans.

·       Are nanoparticles of zinc oxide and titanium oxide small enough to be absorbed by the skin? Worry not, many studies have shown that they do not penetrate the skin.

If sunscreens may cause harm, should I still use them?

UV radiation has long been known to cause skin damage and even cancers. These harmful effects can be prevented by taking sun-protective measures including staying out of the sun, wearing protective clothing and using sunscreen. There may be some concerns about product safety of sunscreens, but it is definitely reassuring to know that each active ingredient has to pass a very stringent safety evaluation before their approval in the EU, US and Japan. With the very favourable risk-benefit profile of sunscreens, I would definitely recommend their use.

Of course, if you develop an allergic reaction, stop using the product immediately. See a doctor, especially if the allergic reaction is severe.

If I were pregnant or breastfeeding, I might choose to be kiasi (Singlish for “afraid to die”) and use physical sunscreens instead of chemical ones - just for the peace of mind that the sunscreen will not be absorbed into my body and passed to the baby.

References:

1.       Mayoclinic

2.       Jou PC, Feldman RJ, Tomecki KJ. Cleve Clin J Med. 2012 Jun;79(6):427-36

3.       Krause et al., Int J Androl. 2012 Jun;35(3):424-36

4.       Lodén et al., Br J Dermatol. 2011 Aug;165(2):255-62.