The Truth About Sunscreen


Summer has officially hit Shanghai and I am loving the beautiful hot sunny days (as opposed to the humid and wet ones that we get hit with here as well). I have been making a solid effort to apply sunscreen not only on my face (so important) but also on my body as well on days I venture out to explore. Sunscreen is so important in terms of protecting our face and body from free radical damage, premature ageing and getting sunburnt. I cannot stress the importance of sunscreen, and even more so if you are anything like me and enjoy being out in the sun and developing a bit of a tan (I am a terrible Asian in this respect). 

In recent years through, there have many articles and claims that suggest perhaps the sunscreen that we are using is in fact dangerous, toxic or debilitating to our health. There have even been suggestions from other websites, bloggers and other influential media personalities that we should avoid using sunscreen altogether (and cover up/avoid the sun at its most potent). EWG releases a ‘safe’ sunscreen guide every year educating consumers on what sunscreens to ‘avoid’ and what to purchase. Our cancer research institutions such as the Australian Cancer Council and the American Cancer Society all claim that sunscreens sold in both markets are safe and are regulated. As a consumer, again its so hard what and who to believe as you have two trustworthy entities with two very different point of views. In today’s blog post I try my very hardest to try an give you a better understanding on sunscreens, the ‘controversy’, the ingredients and the research behind it all. Please be wary, it is a long blog post and is quite a bit of a read. 

What Does Sunscreen Do?
Incase you have been living under a rock for most of your life, sunscreens are a product which that combines different ingredients to aid in blocking the sun’s ultraviolet (UV) rays from our skin. Sunscreens are available in all different forms these days thanks to research and development departments. They are traditionally found in a cream or lotion form but now you can often find sunscreen as a mist or even in powder form. Each of these different forms of sunscreen ultimately are there to do the same thing, aid in the protection of our skin. 

What is Ultraviolet Radiation?
UV Radiation comes from the sun’s powerful rays and is part of the electromagnetic light spectrum that reaches the earth from the sun. It is not able to seen by the naked eye. There are two types of UV Radiation that effect our skin – UVA and UVB. Both types of radiation increase the chances of you developing skin cancer, but also speed the process of skin ageing and general damage to the skin. 

How different UV rays can penetrate the skin.  Image Source: www.coolasuncare.comHow different UV rays can penetrate the skin.  Image Source:

How different UV rays can penetrate the skin. 
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UVB rays are what is most commonly associated with many of us looking like rock lobsters after too much time in the sun. It generally effect the out layers of our skin and therefore it is the most common cause for sunburn (painful!). UVB rays also play a huge role in the development of skin cancers. 

UVA rays penetrate the skin’s deeper layers and has a bigger effect in the skin’s ageing process (ie wrinkling and hyperpigmentation). UVA rays also have an effect in the development and initiation of skin cancers.

What is SPF?
Sun Protection Factor, otherwise known as SPF is a measure of a sunscreen’s ability to block out UVB rays from damaging the skin. The way that SPF works is relatively simple – it measures how long it will take for UVB rays to redden (thus causing some damage) to the skin when using a sunscreen vs how long it will take the skin to redden without it. For example, if a sunscreen is rated SPF 15, it should take 15 times longer for the skin to burn. If you go outside into the sun and start to burn in 20 minutes, then with SPF 15 on the skin it will technically prevent your skin burning for 5 hours (15 times longer than 20 minutes). 

Image Source: www.coolasuncare.comImage Source:

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SPF can also be looked at in percentages, an SPF of 15 will block out 93% of the sun’s UVB rays, SPF30 will block out 97% and SPF50 will block about 98-99% of UVB rays. Anything that is above the value of SPF50 is generally unwarranted as no sunscreen will block out 100% of UV rays. 

Chemical vs Physical Sunscreen
So now that we have a general knowledge of how sunscreen works, did you know that sunscreen can be divided into two different types? These types are determined on the ingredients used to protect out skin from UV rays and are known as either chemical blockers or physical blockers. 

A diagram that shows how both chemical (classic) and mineral sunscreen work to protect the skin.  Image Source: www.coolasuncare.comA diagram that shows how both chemical (classic) and mineral sunscreen work to protect the skin.  Image Source:

A diagram that shows how both chemical (classic) and mineral sunscreen work to protect the skin. 
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Chemical sunscreens will use different chemicals to filter, absorb and dissipate UV radiation through our skin. Chemical sunscreens are what you will generally find when you go shopping for sunscreens at your local supermarket or drugstore as they are the most widely available. 

Physical sunscreens use mineral compounds to reflect UVB rays from the skin and does not absorb into the skin in any way. Complete physical sunscreens are generally a little bit harder to find but now due to the sunscreen debate are slightly more accessible than there were about 10 years ago.  

Below is a table which shows and summarises the main differences between the two different types of sunscreens:

Adapted from: from:

Adapted from:

As you can see there are a lot of aspects of physical and chemical sunscreens that are quite different. It is important to note the type of protection that each do offer. Zinc Oxide is the only physical sunscreen that offers protection from both UVB and UVA rays, whereas all chemical sunscreens will offer protection from both and more coverage as well (depending on how stable it is). Protection is also instant with physical sunscreen whereas with a chemical sunscreen, it is important to wait at least 20 minutes before exposing your skin to the sun. Physical sunscreens are also not as resistant to sweat and strenuous exercise like their chemical counterparts which have often been engineered to stay on better. Most notably from the above diagram is the ingredients used as both a physical sunscreen and chemical sunscreen. There are only two physical ingredients listed however, there are quite a number of chemical ingredients listed. Many sunscreens on the market will actually incorporate both types of ingredients as well. 

The Fuss About Oxybenzone
Out of all the ingredients listed in the above table, none has been more controversial than popular sunscreen ingredient, Oxybenzone. Oxybenzone is a type of chemical sunscreen agent that is widely used in sunscreen formulations due to its stability and in conjunction with other active sunscreen ingredients. In 2001, a study done by Swiss scientists found that female lab rats which were fed oxybenzone every day for 6 consecutive days, had a 23% increase in their uterine weight. Thus leading scientists in this study to conclude that oxybenzone is a hormone disrupter as it mimics oestrogen and activates oestrogen cells to cause such an increase in uterine weight. This is considered to be quite serious as the ingredient was found to disrupt the normal functioning of reproductive hormones. Due to this study and studies similar that show similar results, EWG Skindeep Database has given oxybenzone a rating of 8 (10 being the most hazardous) and has spurred them to release a comprehensive guide of recommended sunscreens every year. This study also sparked a lot of interest in the safety of our sunscreens within the media (some news articles are quite misleading) which I guess has lead me to this blog post today. 

Image Source: www.totalbeauty.comImage Source:

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It is important to note whilst, yes this study did show a significant and large increase in the uterine weight of the female lab rats what many media outlets and EWG failed to mention was that these female lab rats were fed an extremely large dose of oxybenzone. It also important to also highlight, that these rats consumed the ingredient. As humans, when we use sunscreen, we do not ingest sunscreen – it is applied topically on to the skin and also at a much smaller amount that the lab rats had ingested. To absorb equal amounts of the rats in this study, a human female will need to apply sunscreen on her face, neck, arms and hands everyday for the 277 years according a review published in 2011. Whilst we do some studies on rats, it is important to also note that rats are quite different to humans in many ways. A serious topic such as sunscreen ingredients needs to be looked at in humans and studies have been conducted but have shown to be inconclusive. 

Table from Wang et al,  Safety of Oxybenzone: Putting Numbers Into Perspective, 2011 Image Source: from Wang et al,  Safety of Oxybenzone: Putting Numbers Into Perspective, 2011 Image Source:

Table from Wang et al, Safety of Oxybenzone: Putting Numbers Into Perspective, 2011
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Another study that is often cited, is one that was conducted in 1997, the study concluded that the use of oxybenzone in sunscreen was dangerous to humans as the ingredient was found to have penetrated into human skin. It is important to note that this study was based on one brand of sunscreen and also encouraged participants to use more than 6 times the recommended amount needed to protect the skin from sunburn. Further correspondence to the journal from peers, also state the following in response to the findings:

Despite these high amounts Hayden et al found that there was actually little skin penetration of oxybenzone. Over the extended period of application (12 h), they reported that only 1–2% of the oxybenzone in the applied product penetrated the skin. Such low levels of cutaneous absorption and penetration have been previously recorded and, in fact, are generally taken as evidence supporting the safety of oxybenzone in sunscreen products.

A more recent study conducted in 2004, had scientists look at the effect of oxybenzone in humans in a more natural setting. In the study, 32 participants made up of both male and females were exposed to sunscreen topically applied all over their bodies for 4 days. Scientists measured the participants blood and urine outputs on a regular basis. The study showed that whilst oxybenzone was found in both the blood and urine samples of the participants, it could not conclude that the ingredient was indeed an hormone disruptor. 

Further to these studies, the European Council ordered a comprehensive review of oxybenzone as an ingredient used in sunscreen. This review compromised of many different reviews of journal articles and further studies. They concluded in 2001, that there is inconclusive evidence of the danger of oxybenzone as a hormone disrupter or as an ingredient which accelerates skin cancer and was deemed safe to use in concentrations up to 10%. The only thing oxybenzone is found guilty of is that it can cause allergic reactions within some patients. 

And the Nanoparticles?
The OTHER concern about sunscreen that has popped up in recent years is also the use of nanoparticles in the more attractive option, physical sunscreen. Nanoparticles are microscopic particles that are less than 100nm (nano metres) in size. To put this in perspective of how small this particles are: one nanometre is one millionth of a millimetre or human hair is about 80 000 nano metres in diameter…tiny! There have been many technological advancements in recent years in the science industry, especially in the relatively new field of nanotechnology. The use of nanoparticles have been adopted by some cosmetic companies to deal with some of the drawbacks that titanium dioxide and zinc oxide have in terms of its texture and application on the skin. Traditional physical sunscreens have a particle size of 200nm which is large enough to reflect light which gives them the traditional ‘white cast’. Since the advancements of nanotechnology, some companies have made these particles smaller to scatter the light, thus making the appearance and finish on skin a lot more aesthetically pleasing. There has been concern about the absorption of these physical sunscreens into the skin and also poses the risk of inhalation. 

The effect of different sized particles of Titanium Dioxide on the skin, you can see how lighter the smaller size looks on the skin! Image Source: effect of different sized particles of Titanium Dioxide on the skin, you can see how lighter the smaller size looks on the skin! Image Source:

The effect of different sized particles of Titanium Dioxide on the skin, you can see how lighter the smaller size looks on the skin!
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Whilst there have been quite a few studies on the toxicity of nanoparticles in both penetration of the skin and in the area of inhalation of the skin, there is no conclusive evidence that nanoparticles in sunscreen are dangerous, toxic or are bad for you. A review in the area of nanoparticles written recently in 2013, looked at several studies that examined dermal penetrations of nano sized particles of titanium dioxide. It concluded that only particles with the right molecular weight and right formulation would be able to penetrate through the skin’s thick barrier. The only cause for concern is if that barrier is damaged or broken due to a cut or sunburn would there may be a risk in penetration. Further studies were discussed that tried to mimic these situations done in pigs and also on human lab tissue (which is not the same as actual living human skin, it has different properties) but the results in all these studies still did not prove that these nanoparticles could penetrate the skin and cause disruption to human cells. The Australian Department of Health has issued a similar statement. 

Inhalation of nanoparticles is a cause for concern as there are a lot of studies that show the effects of inhalation of particulate matter (PM) in countries with heavy pollution and the same sort of theory can also be applied to the nanoparticles used in powdered physical sunscreens. According to the Australian Department of Health, inhalation of a large amount of Titanium Dioxide can prove to be harmful to health – but please note this is in large quantities. With regards to the use in the cosmetics industry, breathing in small amounts of nanoparticles from powders will not cause any harmful effects on humans. This is due to 1) the low amount being inhaled 2) most nanoparticle powders will ‘clump’ and therefore will only reach the upper airways and will be dispelled from the body as per normal. This inhalation related mainly to the ‘powdered’ sunscreens we see available on the market and not the liquid forms. The EWG have concluded also that zinc and titanium-based sunscreens are among the safest and most effective sunscreens on the market and this give both these physical sunscreen ingredients a rating of 1-3 on the database.  

What Should We Do?
So to wear sunscreen or not to wear sunscreen is the big question. Are sunscreens safe enough to wear? For me, that is a really easy answer…YES! WEAR SUNSCREEN! Whether it be full of nanoparticles and oxybenzone or not, I cannot stress how important sunscreen is for you. Whilst there have been some studies that show certain sunscreen ingredients are potentially harmful to us, the jury is still out and for me personally the scientific data is a little far fetched or completely out of context. I adopt the better to be safe than sorry approach with the sunscreen debate, as I would rather slather on the cream and be protected from the sun than worry about the plethora of inconclusive studies. If the data from oxybenzone studies do not sit well with you, then opt for a different sunscreen by carefully reading the ingredients label, using the EWG Safe Sunscreen guide is a great option and a wonderful place to start. 

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With regards to physical vs. chemical sunscreen, that is completely a personal preference for everyone. Some people maybe highly allergic to chemical sunscreen ingredients, so physical sunscreens are the only way to go for them. Others may be wary of scientific reports about certain ingredients in chemical sunscreens and would rather a more ‘natural’ physical sunscreen such as zinc oxide. Some other people might not like the idea that chemical sunscreens ‘absorb’ into the skin and again opt for something that will reflect. Popular beauty personality Zoe Foster Blake swears by physical sunscreen as it helps her with her pigmentation issues. My good friend hates the feeling and look of physical sunscreens on her skin so opts for a more lightweight chemical one instead – as you can see the reasons for physical vs chemical is endless. It depends entirely up to you, your stance on the sunscreen debate and what works best for you. 

Bottom Line
Remember that sunscreen is not your only defence against UVA and UVB rays, whilst it is a means of protection when you are out and about, the best way to avoid the sun and its UV rays is to stay in the shade or indoors. The sun is at its peak during the hours of 10am to 2pm, and it is recommended to seek shade or stay indoors during these hours. If you are out and about however, adopt the old Australia saying that I grew up on “Slip, Slop, Slap” – for me to decipher what that means – slip on a shirt, slop on some sunscreen and slap on a hat. It’s that simple. 



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