Sunscreen Part 2

Natural sunlight to illustrate a blog about ingredients in sunscreen & cosmetics.

Disclaimer: This blog was written & first published in May 2020, before Brexit. Much of the content remains relevant, although laws on sunscreen for the EU may now be different to those for Great Britain or the UK. 

Have you ever wondered about nano particles in cosmetics? Or parabens? Or how about the latest buzzword, 'Blue Beauty'? Have you thought about the impact of your sunscreen on marine life or freshwater? Do you know about the latest 'new generation' sunscreen ingredients? And understand the difference between physical & chemical filters?

Here's what you'll learn about in Part 2 of our Investigating Sunscreen Blog:

- Introduction

- What Makes a Sunscreen?

  • Physical / Chemical UV Filters
  • Nano
  • SPF Boosting Ingredients
  • New Generation Hybrids & Combinations
  • A note on “Natural”
  • MYTH: All Sunscreens are Made Equal

- Human Health & the Environment

  • Dermal Permeation
  • Parabens
  • Endocrine Disruption
  • Coral
  • Nano

- Summary & Conclusions

Part 2 - Ingredients, Health & The Environment


In Part 1, we examined sunscreen generically – what it is, why we need it & how to understand the label. We also debunked some myths. This is Part 2, taking a closer look at the ingredients & addressing some of the concerns that consumers may have about some of the ingredients used in sunscreen. It is a confusing arena & there are no definitive answers, but we can do the research & make informed choices based on science. I have done some of the groundwork for you.

The main message from Part 2? Yes, ask questions about ingredients. Learn to read ingredients lists. Read scientific reports. Consider the data. If necessary, avoid certain ingredients. But whatever you do, DO use a reputable, broad-spectrum sunscreen to protect yourself from skin cancer & accelerated signs of aging.

Note: Please also read the disclaimer. As with Part 1, “I’ve set out to try & demystify sunscreens & to help make it easier for you to choose. I’m neither a doctor nor a dermatologist – so I have researched online through reputable sites such as the British Association of Dermatologists (BAD), the NHS, Cancer charities & the sunscreen brands themselves. I’ve referred to EU Cosmetic Legislation, tapped into industry resources & studied scientific papers.” Lucy Stevens.

For Part 2, I’ve also made direct communication with brands & marine charities, to get their take on environmental & health concerns. All references/sources are in the footnotes.

What Makes a Sunscreen?

Physical / Chemical UV Filters

There are two main types of ultraviolet (UV) filter which work in different ways.


These synthetic chemicals protect the skin by causing a chemical reaction. They work like this:

“Organic filters absorb harmful UV radiation and convert and give this energy back out as infrared. These are sometimes known as ‘absorbers’, or ‘chemical’ sunscreens.” (British Association of Dermatologists)[1]

In chemistry, ‘organic’ means something very different compared to the environmental sense in other industries such as food, so this term in this context can be confusing for the consumer. In chemistry, organic compounds contain carbon, whereas inorganic compounds do not.

There has been some controversy over some chemical filters, due to concerns over the environment & human health, in particular oxybenzone & octinoxate, which we will examine in more depth later.

Regarding terminology, it should be noted that ‘chemical’ is not necessarily in opposition to ‘natural’, because natural ingredients are made up of chemicals, as are we, as is the whole Earth. In this context, Chemical refers to the process by which the filter works & also to the synthetic nature of the ingredients.


Zinc Oxide (ZnO) & Titanium Dioxide (TiO2)

Physical sunscreen filters protect us by adding a layer onto the skin, which reflects or scatters UV light, therefore protecting the skin from harmful rays. Zinc oxide protects from UVA & UVB while Titanium dioxide provides better UVB protection.

Physical filters are generally recommended for people with sensitive skin or conditions such as rosacea or acne.

Physical filters are banned in spray applications in the EU due to concern over their effects on the lungs when inhaled.

When used on the skin in sunscreen creams & lotions, as you have probably experienced, these mineral filters can give a white ‘cast’ across the skin & have historically been thick & opaque, but the industry has found a solution to this in the form of nano.

Zinc oxide & Titanium dioxide, when broken down into smaller ‘nano’ particles, are then much easier to rub in & no longer opaque. You will see some sunscreen brands using terms like ‘clear’ or ‘micron-sized’ zinc, which indicate that the ingredient is made from smaller particles, whereas nano are even smaller: “so small, in fact, that “they are undetectable by conventional microscopes.”[2] (Wiley online library)

Here’s how nanoparticles work with physical filters:

“Titanium dioxide is effective for protection against UVB (and some UVA) rays, however, it should always be used in combination with zinc oxide to attain true broad-spectrum protection. Zinc oxide can provide greater protection from UVA rays, and amongst all sunscreen actives, Zinc oxide is unique in that it is a true broad-spectrum blocker protecting from UVA, UVB and even UVC light. Bulkier particles of zinc oxide and titanium dioxide have been used in sunscreens for decades. Those sunscreens look white when rubbed onto the skin because particles of this size reflect visible light. But when these sunscreen ingredients are manufactured into nanoparticles – usually 25 to 50 nanometers wide – this is different. Despite clumping together when mixed into sunscreen, nanoparticles of titanium dioxide and zinc oxide not only retain their highly effective UV light-absorbing capacity but also absorb and scatter visible light, rendering them transparent on the skin.” [3](in-cosmetics®)

While a “single internationally accepted definition for NMs does not exist”, in the EU:  

“In cosmetic products, 'nanomaterial' refers to an insoluble or bio-persistent and intentionally manufactured material. A nanomaterial has one or more external dimensions, or an internal structure, on the scale from 1 to 100 nm. EU legislation provides a high level of protection of human health where nanomaterials are used in cosmetic products."[4] (European Commission)

Both physical & chemical sunscreen filters are made from nanoparticles. Sunscreen brands don’t have to reveal the size of nanoparticles in their products, but you’ll see (nano) after the ingredient on the Ingredients list (INCI). This has to be explicit by law.

In some formulas, nano ingredients are “coated” while in others, “uncoated”. 

More on this later.

SPF Boosting Ingredients

You will also see sunscreen products that are formulated with natural SPF-boosting ingredients, for example, certain plant oils. A 2020 study looked at this more closely:

“It can be observed that the SPF values found for nonvolatile oils were between 2 and 8; and for volatile oils, between 1 and 7. Among the fixed oils taken, SPF value of olive oil was found to be the highest. Similarly among essential oils, SPF value of peppermint oil was found to be the highest. The study will be helpful in the selection of oils and fragrances to develop sunscreens with better safety and high SPF. Oily vehicles are more effective for producing a uniform and long-lasting film of sunscreen on the skin, and their emollient properties protect the skin against the drying effects of exposure to wind and sun.“[5] (Kaur CD, 2020) It should be noted that these oils are not categorised as UV filters in their own right. 

New Generation Hybrids & Combinations

Some sunscreens contain a mixture of both physical & chemical UV filters.

With ongoing development in the area of nano in cosmetics, ‘new generation’ ‘hybrid’ nano-sized sunscreen agents are increasingly in circulation. These include both chemical & physical agents to give broad-spectrum protection & include nano & non-nano. Examples of these in EU cosmetics:

-           Bemotrizinol (INCI: Bis-ethylhexyloxyphenol methoxyphenyl triazine) (brand name Tinosorb® S)

-           Bisoctrizole (INCI: Methylene bis-benzotriazolyl tetramethylbutylphenol) (brand name Tinosorb® M)

-           Tris-biphenyl triazine (nano) (brand name Tinosorb® A2B)

The latter is considered to be a breakthrough:

“Still the most important thing is to ensure that there is protection across the UVA and UVB radiation spectrum. Thus a high level of UVA protection, in proportion with the SPF (UVB protection) is important.
The newest filter registered in the EU is Tinosorb A2B, which helps to ensure a more complete protection across the UV spectrum as there used to be a gap between the UVA and B peaks of absorption in sunscreens.” [6] (Altruist)

While I have seen ‘Bisoctrizole’ in the INCI list of an ‘environmentally-friendly’ sunscreen, Cosmetics Business reports:

“Bisoctrizole compound methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) can now be used in its nano form as a UV-filter and at a concentration of 10%… Despite its success in sun care the SCCS has issued a warning about the compound’s potential long-lasting harmful effects to aquatic life, as the compound has been classified as Aquatic Chronic 4 H413 according to CLP regulation.”[7]

If this is correct, it seems we have a long way to go until scientific reports are conclusive.

Zinc & Titanium are minerals found in the earth, so these UV filters are often called ‘natural’. However, some would argue that the filters are so far from the original source that they are no longer natural in any sense, simply derived from a natural material originally & then created in a laboratory.

Physical filters are favoured by the more natural & organic skincare brands & are accepted by certain certification bodies such as COSMOS in the EU.  This is because they are generally more gentle, as they sit on top of the skin, rather than causing a chemical reaction within the skin.  

‘Natural’ and ‘organic’ cosmetics are a growing sector, often considered to be more eco-friendly & better for human health, purer or closer to nature than their counterparts. But the term can also be exploited & natural isn’t always better. It may be that sometimes the more sustainable option is made in a lab.

So we need to be savvy. We need to understand more about natural ingredients – where they come from, how they are harvested, whether they are really sustainable. For example, Indian Sandalwood has been so over-used over the years, in many industries including cosmetics, that it is now endangered. 

Another issue with ‘natural’ is that we may assume that this is synonymous with ‘botanical’, but this isn’t the case. For example, carmine, a popular colourant used in make-up such as lipstick, is derived from (natural) crushed insects.

Another problem is that some companies use “greenwashing” to appeal to consumers, using misleading marketing to suggest they are more eco-friendly or natural than they really are.

That being said, my own personal preference generally is to choose cruelty-free products derived from botanicals & with as few synthetics as possible. I trust the European COSMOS standard[8] & also like to use some independent brands which are authentic & have strong ethical standards but may be unable to afford certification.

MYTH: All Sunscreens are Made Equal

There is no global standard for sunscreens:

“…in many countries and regions around the world, a major ongoing divergence remains on the classification of sunscreen as either a cosmetic product or a form of medical therapy, which in turn affects the consumers' attitudes towards the use of sunscreen. This is also affected by the increasing use of the internet, which has made the purchasing of products internationally convenient and easy for consumers worldwide, including sunscreen products, which are frequently marketed online. There is variation between each country or region and their regulations of sunscreen affect the consequent labelling claims of sunscreen products. This affects the unsuspecting consumer's choices in purchasing sun protection, which may be misinformed. Australia, Canada, and the US are the only countries to classify sunscreen as a form of medical therapy.”[9] (National Library of Medicine)

This disparity can cause issues for the unsuspecting consumer & is something to bear in mind when you are buying products online or when you are abroad. Here are some examples:

-           EU                   ‘cosmetic products’ 

-           USA                 ‘over-the-counter drugs’ (OTC)

-           Australia           Primary sunscreens are called ‘therapeutic goods’ (medicines/drugs).

Secondary sunscreens e.g. moisturiser with SPF (but not a broad-spectrum sunscreen) - ‘cosmetics’

-           Canada             ‘over-the-counter drugs’ (OTC) or ‘Natural Health Products’

-           China               ‘Special Use Cosmetics’ (SUC)

Choosing a sunscreen manufactured outside the EU, therefore, may be problematic unless the differences are understood. You may find that products made in the US, for example, are not as stringently formulated as those in the EU, despite being called ‘drugs’:

“A long list of potentially harmful ingredients banned in the EU are legally allowed in the US due to historically relaxed regulations” & “In cosmetics alone, the EU has banned or restricted more than 1,300 chemicals while the US has outlawed or curbed just 11.”[10] (The Guardian, 2019)

Here in the EU, we are protected by Colipa[11], the European Trade Association which governs all cosmetics. The EU Cosmetics Database, CosIng[12], publishes information on cosmetic substances & ingredients, including those which are banned. Every sunscreen formulation on the market in the EU must have passed tests, to ensure that it offers the correct levels of UVA & UVB protection that it states on the bottle. If a product states that it is ‘clinically proven’ then it also has to show supporting evidence that it has been tested on humans at different time points. 

A word of caution - don’t fall for amateur sunscreens you can buy online or attempt to make your own. Only buy from reputable brands & reputable websites. Here’s why: when I typed ‘Sunscreen’ into the search engine of a well-known online marketplace for handmade goods, there were over 2,000 results. But how many of these are compliant with Cosmetic Regulations & therefore safe to use & to trust to protect you? Producing a protective sunscreen is a lengthy & expensive process & needs science to ensure its efficacy.  

So, no, not all sunscreens are made equal. I recommend choosing a broad-spectrum sunscreen from a reputable company that is manufactured in the UK or EU.

Ingredients, Human Health & The Environment

Increasingly, personal care products & their ingredients are under scrutiny by consumers. So is one type of UV filter ‘better’ for us than the other? And/or better for the environment? While both Chemical & Physical filters protect us, there are questions surrounding both in relation to human health & the environment. To help you consider these questions, let’s start by taking a look at our skin.

 The skin is our largest & heaviest organ:

“Skin has a lot of different functions. It is a stable but flexible outer covering that acts as barrier, protecting your body from harmful things in the outside world such as moisture, the cold and sun rays, as well as germs and toxic substances.”[13] (NCBI)

In cosmetic products, ingredients are designed to stay on the superficial layers. However, we do know that the skin has absorption ability – think nicotine patches, for example. Tiny molecules from ingredients may reach the bloodstream & internal organs through the skin. This is why:

“The assessment of dermal permeation is a primary procedure for evaluating a substance and classifying it as hazard, particularly in the cosmetics and pharmaceuticals industries.”[14] (Science Direct) 

The European Commission monitors ingredients through scientific testing. Thankfully, animal testing is now banned in Europe (although many common ingredients historically have been tested on animals). In the EU:

“Changes in regulatory requirements and social views on animal testing have incremented the development of reliable alternative tests for predicting the skin absorption potential of new compounds and evaluating dermal permeability.”[15] (Science Direct)

So, dermal permeation is a reality. Exactly what & how much absorbs & whether this is then a threat to human health, is an ongoing area of research: 

“…one thing is absolutely clear: it is impossible to put a figure on this absorption rate and it is impossible to estimate how much ends up in our bloodstream. Every person is different and every chemical is different. It is always good to question what you put on your skin but your body’s response will be individual.”[16] (Herb & Hedgerow)

A 2020 report highlighted the gaps in current scientific data in relation to sunscreens & human health:

“Understanding positive and negative sunscreen effects on skin homeostasis is also challenging. The results in this field, especially in vitro testing, are controversial and experimental design varies widely which further supports disparities between some findings.”[17] (Yamada et al. Science Direct) 


Despite legal frameworks to protect our health, people still have concerns about certain accepted ingredients. Why? Reports in the media, conflicting scientific studies, marketing, ingredients being banned by organic certification bodies… the list goes on.

A prime example of a group of ingredients that is constantly under the spotlight is parabens:

“a group of chemicals that are widely used as preservatives in cosmetics and personal care products such as deodorants, shower gels and body creams.”[18] (European Commission)

The debate continues to rage within the industry about whether or not some or all are harmful. Some blame the media for damaging parabens’ reputation, by over-exaggerating a scientific study that showed parabens from deodorants had absorbed into tissue. Others believe that we should be aware of the potential risks:

“There is growing evidence that parabens and parahydroxybenzoic acid can act as oestrogenic endocrine disrupting chemicals, interfering with our hormone system, in particular with the hormone oestrogen. At high concentrations, parabens may increase breast cancer risk, and may also be implicated in the proliferation of breast cancer.”[19] (Breast Cancer UK)

Parabens is used as a ‘blanket’ term, but there are several different types & in the EU, not all are allowed in cosmetics:

Banned: Isobutylparaben, Isopropylparaben, Phenylparaben, Benzylparaben and Pentylparaben.

Restricted: Propylparaben, Butylparaben

Allowed: Methylparaben, Ethylparaben  

(European Commission)[20]

Because of the bad press, manufacturers sought alternative preservatives to parabens, to appeal to consumers by being able to use the term ‘paraben-free’. Phenoxyethanol thus became a widely-used synthetic preservative - originally accepted by the Soil Association’s organic certification in the UK, it has since been withdrawn from COSMOS organic certification. As with Parabens, the scientific data surrounding Phenoxyethanol is conflicted.

It is often in the media where we first hear about controversial ingredients.

NHS UK, in January 2020, criticised the Mail Online for an “unnecessarily alarming”[21] headline:

“Sunscreens leach up to 360 times more toxic chemicals into the blood than the FDA allows, raising risks for liver and kidney failure, study finds.”[22] (Daily Mail)

The story was about a Randomized Clinical Trial by US Food and Drug Administration (FDA) researchers:

“In this study conducted in a clinical pharmacology unit and examining sunscreen application among healthy participants, all 6 of the tested active ingredients administered in 4 different sunscreen formulations were systemically absorbed and had plasma concentrations that surpassed the FDA threshold for potentially waiving some of the additional safety studies for sunscreens. These findings do not indicate that individuals should refrain from the use of sunscreen.”[23] (JAMA Network)

In response to the controversy, the American Academy of Dermatology published this:

“A recent study by the FDA looked at four sunscreen ingredients and concluded that absorption of these ingredients into the body supported the need for additional safety data. However, the study noted that the data do not conclude that there are any effects on a person’s health and more research would be needed before it that can be determined.  Importantly, the study authors stated that individuals should continue to use sunscreen.”[24]

The critical element here is that the study showed levels of absorption - it did not prove that this absorption was harmful, which is what the Mail headline had implied.

In the EU, The Scientific Committee on Consumer Safety (SCCS)[25] provides opinions to the European Commission on health and safety risks of cosmetic products & their ingredients. Concerns about Endocrine Disruptors (ECs) led to the European Commission calling for a review[26] in 2019 to establish:

“…a priority list of potential EDs not already covered by bans or restrictions in the Cosmetics Regulation for their subsequent safety assessment.”[27] (European Commission)

Among 28 potential Endocrine Disruptors in cosmetics were these sunscreen ingredients:

-           Benzophenone-3 (Oxybenzone)

-           4-methylbenzylidene camphor (Enzacamene)

-           Octocrylene

The outcome of the review has yet to be published:

 “The European Parliament voted in favour of this resolution on 18 April 2019 by an overwhelming majority. Considering that “there is no valid reason to postpone effective regulation,” MEPs ask the Commission to make, by June 2020 at the latest, legislative proposals to insert specific provisions for endocrine disruptors, similar to those applicable to CMRs, into the Cosmetics Regulation.”[28] (Cosmeticobs)

So we know that our cosmetics are regulated & monitored, but how do we, as consumers, find out which ingredients are considered a risk?

The SIN (Substitute it Now) list[29] is a database by the non-profit organisation International Chemical Secretariat (ChemSec) in Sweden, which lists substances of ‘very high concern’ (SVHC). These substances are evaluated on the criteria defined within the EU’s regulation known as REACH, which “aims to improve the protection of human health and the environment through the better and earlier identification of the intrinsic properties of chemical substances. This is done by the four processes of REACH, namely the registration, evaluation, authorisation and restriction of chemicals. REACH also aims to enhance innovation and competitiveness of the EU chemicals industry.”[30] (European Commission)

Being on the SIN list, substances currently in use are under scrutiny & likely to be restricted, or banned. Restriction of an ingredient means that it is safe, when used within certain limits, while banned substances have been proven to be harmful. The chemical sunscreen filters most often questioned in relation to marine life, oxybenzone & octinoxate, appear on the list:  


“Benzophenone-3 (BP-3) is an endocrine disruptor with estrogenic, antiandrogen and thyroid activity, affecting several body functions including development and immune function. The substance has been found in biomonitoring studies and in human milk and urine.  It is categorized as an endocrine disruptor in the EU Commission Database.”[31] (ChemSec)

It records that is has been found in “surface waters, fish as well as wastewater”.[32] (ChemSec)


“Substance is an endocrine disruptor with estrogenic and thyroid activity, affecting several body functions including development, brain and metabolism. The substance has been found in biomonitoring studies and in human milk. It is categorized as an endocrine disruptor in the EU Commission EDC database.”[33] (ChemSec)

It records that this ingredient has been found in “natural waters”, “biota2 & “human milk samples”.[34] (ChemSec)

Homosalate, another ingredient in some sunscreens, is currently under assessment as a potential ED by the Scientific Committee on Consumer Safety (SCCS).[35] (European Commission) Its current status:

“According to the notifications provided by companies to ECHA in REACH registrations no hazards have been classified.”[36] (European Chemicals Agency ECHA)

Currently, the amounts of each of these ingredients in sunscreens are restricted in the EU, to safeguard human health & the environment. 

Oxybenzone & octinoxate are both now banned in some countries because of concerns about their detrimental impact on ocean life. Marine & environmental organisations continue to highlight threats to the environment from these & many more ingredients (see the Appendix for examples).

You may have noticed terms such as ‘Reef-Safe’ & ‘Marine Positive’ appearing on sunscreen products. This is a growing area, as brands realise that consumers care but there is no umbrella certification for a marine-friendly product & so the term may be open to interpretation. For one brand it may simply mean that their products do not contain oxybenzone & octinoxate. For another, it may be that they exclude a whole raft of ingredients considered to be a threat & also create eco-friendly packaging.

In 2008, an article was published by leading marine scientists entitled:

“Sunscreens Cause Coral Bleaching by Promoting Viral Infections”.[37] (NCBI, Roberto Danovaro)

This study concluded that “sunscreens containing parabens, cinnamates, benzophenones, and camphor derivatives can contribute to hard-coral bleaching if released into natural systems”.[38] (NCBI, Roberto Danovaro)

So what is coral bleaching & why is it a problem? The World Wildlife Fund (WWF)[39] explains:

“Coral bleaching matters because once these corals die, reefs rarely come back. With few corals surviving, they struggle to reproduce, and entire reef ecosystems, on which people and wildlife depend, deteriorate.”[40]  (WWF)

While global warming is generally recognised as the main reason for coral bleaching[41] (National Ocean Service US), the impact of certain ingredients is also a real concern.

The Centre for Biological Diversity in the US[42] petitioned the US Food & Drug Administration in 2018 to ban oxybenzone & octinoxate:

““Lab studies have shown that even a minute amount of oxybenzone in the water is toxic to corals. Just 62 parts per trillion — the equivalent of three drops mixed into an Olympic-sized swimming pool — has been found to damage coral larvae. Scientists have found high concentrations of oxybenzone in many areas popular with sunscreen-slathered tourists, including Waikiki Beach in Hawaii, the Florida Keys and the U.S Virgin Islands.”[43] 

The Republic of Palau in the Pacific Ocean has already taken action to protect its coral reefs:

“Palau is the first country in the world to ban all active sunscreen ingredients and preservatives known or suspected to be reef-toxic.”[44] (palaugov January 2020)

This approach is one which I suspect resonates with many consumers of cosmetic products:

“The new regulations also adopt a groundbreaking regulatory approach for sunscreens based on the precautionary principle. Instead of waiting for scientific studies to conclusively prove an ingredient is reef-toxic before banning it, MNRET has decided to prohibit any sunscreen ingredient suspected of being reef-toxic. Furthermore, to ensure that the new regulations remain responsive to scientific advancements, MNRET may also amend the list to remove banned ingredients if scientific research studies definitively reveal that ingredients prohibited by these regulations are not reef-toxic.”[45] (palaugov January 2020)

Hawaii made headlines recently, too, having passed a ban on the sale of sunscreen containing oxybenzone & octinoxate, which comes into force in January 2021:

“Gov. David Ige signed SB 2571, Act 104 — prohibiting the sale, offer of sale, and distribution of sunscreens that contain the chemicals oxybenzone and octinoxate in Hawai‘i, beginning Jan. 1, 2021.

The purpose of this law is to preserve marine ecosystems, including coral reefs. Scientific studies have shows that oxybenzone and octinoxate are toxic to corals and other marine life.” [46] (

Bonaire in the Caribbean followed suit, with a ban coming into place in 2021.[47] (infobonaire)

Other countries which have implemented measures to protect their oceans from certain sunscreen ingredients are the US Virgin Islands:

“The ban on the sale and possession of certain types of sunscreens will take effect in the U.S. Virgin Islands on March 30.

These sunscreens contain ingredients such as oxybenzone, octinoxate and octocrylene, which are said to threaten the health of coral reefs when they wash off swimmers' bodies and cause coral bleaching.”[48] (Travel Weekly)

But while Key West, Florida, was the first place on the mainland U.S. to approve a sunscreen ban, this was nullified in March 2020:

“Florida lawmakers approved legislation Tuesday that prevents local governments from regulating any over-the-counter drugs or cosmetics - like sunscreen.” [49] (  The Florida senate overruled the ban, questioning the science & concerned that a ban could send the wrong message about sun protection in a state where skin cancer is high.[50] 

In addition to the ingredients already discussed, questions are also being asked about nano-ingredients. With nano being a relatively new departure in cosmetics, when they were introduced, there were concerns among consumers regarding whether nano-particles penetrate the skin.

In 2020, one review of recent studies concluded that:

“In vivo human skin penetration studies showed ZnO nanoparticles (ZnO-NP) did not penetrate the stratum corneum. Limited quantities of TiO2-NP may be absorbed systemically”[51] (Adler, DeLeo. 2020 Springer)

Another suggests:

“…the need for further investigation into the health implications of these skin applications rather than being complacent just in the commercially viable cosmetic space.”[52] (Effiong. 2020 Researchgate)

A paper examining at recent updates on nanomaterials in cosmetics, published 20 May 2020, highlights innovations in the field:

“If the presented cosmetic nanomaterial development is allowed to bloom after the currently ongoing nanotoxicity and safety research incentives have had a chance to affect regulations and guidelines for production and use of nanomaterials, and if the necessary commercial support is in place to carry the materials presented in recently published scientific articles and granted patents to the market, we can soon expect to see a range of new nanotechnology-based cosmetic products on the shelves of the nearest drug store.”

It goes on to conclude:

““The cost is not the only important issue, safety and the application of alternative testing methods for toxicity are of crucial importance as well”.”[53] (Fytianos et al. MDPI)

A recent study by The European Union Observatory for Nanomaterials (EUON) has analysed existing research on “whether nanomaterials used in consumer products and at workplaces are absorbed through the skin.”[54] It summarized that “the lack of standardised, validated methods and the use of varying testing protocols makes it difficult to compare results and evaluate whether nanomaterials can penetrate the skin.

Based on the findings, nanomaterials rarely absorb through intact skin, except for silver that is likely to partly penetrate in ionic form. Silver is used for its anti-bacterial properties in textiles and can be found in other consumer products such as pharmaceuticals and cosmetics.

Some of the analysed studies suggest that absorption through damaged skin is higher than through intact skin.”[55] (EOUN May 2020)

New European guidance on nano, from the Scientific Committee on Consumer Safety, is contained in a document over 100 pages long, published in October 2019[56]. This concludes:

“The use of NMs as cosmetic ingredients requires thorough safety evaluation because of the potential for size-related changes in physicochemical properties, biokinetic behaviour, and/or toxicological effects of materials at the nano-scale. Exposure to NMs through the use of cosmetic products may pose a risk of harmful effects from insoluble and persistent nanoparticles that may reach unintended sites in the body and interact with biological entities close to the molecular level.”[57] (European Commission)

Nano-sized physical sunscreen filters Zinc oxide & Titanium dioxide are found in both coated & uncoated forms. There is some evidence that uncoated physical sunscreens may be detrimental to marine life. Here are a few examples:

“…uncoated ZnO induces a severe and fast coral bleaching due to the alteration of the symbiosis between coral and zooxanthellae. ZnO also directly affects symbiotic dinoflagellates and stimulates microbial enrichment in the seawater surrounding the corals.”[58] (Corinaldesi, 2018. Science of the Total Environment).

“Noncoated nanoparticles (less than 35 nanometers in diameter) of zinc oxide and titanium dioxide (referred to as “mineral-based” sunscreens) can be toxic to corals, fish and other reef organisms.”[59] (Marine Safe UK)

“The researchers have found that in water, the nanoparticles tend to lose their protective coating under the influence of UV light or seawater composition, which exposes the more toxic TiO2 to the aquatic environment.”[60] (

So it appears that it is the coating of the nano-ingredient that makes the difference. With such little information available to the consumer, the only way to really find out how a nano ingredient has been formulated is to contact the brand or the manufacturer & hope for a detailed response.

In the meantime, scientists are continually looking for new ingredients to solve problems, such as “a UV-absorbing ingredient harvested from algae” & “biodegradable beads that could soak up oxybenzone from oceans”.[61] (Smithsonian magazine)

So where does that leave us? Which ingredients are ‘better’? Should we stick to Zinc oxide & Titanium dioxide? Not necessarily. When I contacted a UK sunscreen manufacturer about this, their cosmetic scientist explained that Zinc oxide, too, has its drawbacks:

“Zinc oxide is relatively harmless and has not been shown have toxicity towards aquatic organisms.  However, Zinc ions (i.e. isolated Zinc molecules unassociated with other elements) are extremely toxic to aquatic life forms including coral polyps.  Although Zinc oxide should not contain isolated Zinc ions, there is a risk that some may be present as a result of incomplete reactions taking place during its production.  There is also a risk of Zinc oxide releasing unassociated zinc ions as the result of reactions taking place in the aquatic environment in the presence of volatile reagents triggered by high energy inputs such as heat and UV radiation from strong sunlight.  Whilst this has yet to be scientifically confirmed, there are some concerns amongst environmentalists that this could contribute to the toxic load already affecting simple aquatic lifeforms.” (By email, Green People May 2020)

Lastly, if you’re concerned about the environment, once you’ve figured out which ingredients are OK, you may also wish to ask questions about your cosmetics packaging. But that’s another topic entirely! 

Summary & Conclusions

Regulations in the EU are there to safeguard consumers, but as we all know, data takes time to accumulate:

“One of the main reasons for developing and adopting the REACH Regulation was that a large number of substances have been manufactured and placed on the market in Europe for many years, sometimes in very high amounts, and yet there is insufficient information on the hazards that they pose to human health and the environment. There is a need to fill these information gaps to ensure that industry is able to assess hazards and risks of the substances, and to identify and implement the risk management measures to protect humans and the environment.”[62]  (European Commission, Environment)

In the EU, there are currently 31 UV filters listed on the CosIng database (including some banned or restricted). Of the UV filters/absorbers that are allowable in cosmetics in the EU, based on the reports I have read online, the two most controversial are:

  1. Oxybenzone (BENZOPHENONE-3)

According to the Outdoor Swimming Society, the “Awful Eight” in Reef terms are:

  3. Ethoxylated Ethyl-4-Aminobenzoate (PEG-25 PABA)
  4. Homosalate (HOMOSALATE)
  5. Octinoxate
  7. Octocrilene (OCTOCRYLENE)
  8. Oxybenzone

Others which have also been questioned in the reports I have read about health and/or the environment are below (A-Z).

-           Amiloxate (ISOAMYL P-METHOXYCINNAMATE)




-           CINOXATE

-           ZINC OXIDE

-           Uncoated ZINC OXIDE (NANO)

-           Uncoated TITANIUM DIOXIDE (NANO)

This is not a definitive list by any means. For me, it’s start. I’ll choose sunscreens carefully & try to avoid some of these ingredients, but it’s almost inevitable that some of them will crop up. As always, my number one priority is to protect my skin.

My conclusion, from this research, is that we are right to continue to ask questions & to be mindful of emerging scientific evidence about potentially harmful effects of certain substances in relation to our health & also if we care about preserving the environment (which is, in effect, also vital for health). You can wait for absolute proof, or choose to avoid ingredients you are unsure of in favour of something gentler or less controversial. It isn’t hard, for example, to avoid oxybenzone & octinoxate in sunscreen.

I am mindful of the argument that we are exposed to a “cocktail” of potentially harmful substances within our environment on a daily basis. To reduce this exposure, perhaps it is preferable to try & avoid potentially questionable ingredients as much as we can. 

You can find any number of websites with lists of ingredients to avoid. I like to read everything & to hear all of the arguments, from both sides. I like to read information from skincare brands that I trust, to learn about their reasons for using certain ingredients & avoiding others.

To make your choice of which broad-spectrum sunscreen to use, here are some of the criteria I use:

What am I looking for? Do I want a basic broad-spectrum sunscreen formula? Or do I want it to be more sophisticated & benefit my skin in other ways too?

  • Is it made in the EU?
  • Is it a reputable brand from a reputable website/shop?
  • Are the ingredients acceptable to me? Or does it contain something I wish to avoid?
  • Is it a good brand, with strong ethics?
  • Can I afford it? Will it do what I want it to do?

And of course, once you’ve made your purchase, you must enjoy using the product to ensure that you apply it as instructed, regularly, to protect your skin. Choose something to become a staple in your skincare regime that you enjoy using, otherwise it’s likely that it will languish at the back of the cupboard, unused, leaving you unprotected.

So read, research, question & make decisions on which ingredients & brands to trust, based on your budget, your ethics/values & your skin – but don’t scrimp on sunscreen because of your principles, or you will put your health at risk & your skin will age faster.

For more information about SPF, UVA & UVB, dig into Part 1  – Decoding Sunscreen & Debunking Myths.

Have Your Say

Did you enjoy the read? Have we delved into all the important questions? What are your thoughts? Please let us know in the comments (:

Disclaimer: All opinions are my own & there are no affiliate links. References are correct at the time of writing to my knowledge and are cited in the footnotes which are filed elsewhere. Information provided by this blog is subject to change. We recommend that you do not take any information held within as a definitive guide to the matter being discussed. You are advised to seek legal or professional advice where necessary rather than relying on the content supplied by the author. There is an Appendix & over 60 references to accompany this article. If you're interested, do get in touch. Lucy Stevens May 2020 (intro updated September 2020).

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