Sunscreen and UV filter myth busters – clean sunscreens and coral safe

Welcome to our second blog from the sunscreen and UV filter myth busters. In part 1 we tackled some of the main myths around “nano” and particle science, click here to read.

I have gathered together the same team of solar experts as last time. In this blog we are debunking some of the biggest myths around “clean” sunscreens, “coral safe” and environmental impact.

For each myth we have referenced the key citations where you can find the evidence for our conclusions. The full list of citations can be found in the presentation: Solaveil Myth Busters – Clean Sunscreens.

Mythbusting with Croda

Mineral/inorganic UV filters are better because natural means safer
The derivation of an ingredient tells you nothing about its safety. Natural ingredients can be harmful. This myth comes from a narrative of chemical phobia that is now common on social media, especially in the area of clean sunscreens. In the case of mineral/inorganic UV filters they tick both boxes, safety, and naturalness. They are the only two UV filters that are GRASE category 1 in the US.1 They have a long history of safe use with no adverse reactions and no evidence of allergenicity.2 In addition, they are nature-identical minerals and COSMOS approved.

TiO2 and ZnO are not natural
In the main we see TiO2 and ZnO being claimed to be natural, but occasionally we hear the myth that they aren’t natural. As you can tell, it can be very confusing for consumers.
Both TiO2 and ZnO are nature-identical minerals, ISO define this as “obtained through chemical processing of inorganic substances occurring naturally in the earth, which have the same chemical composition as natural mineral ingredients”.
Titanium is the ninth most abundant element on earth and occurs in the form of ores. TiO2 is its most common compound. Titanium is found in almost all living things, as well as water, rocks and soils. TiO2 as a UV filter is obtained by transformation of titanium compounds mined from the earth, using an aqueous process with saltwater waste streams.
Zinc oxide is a rarer mineral but has a long history of use that is thought to date back to 500 BC where it was used as medicinal ointment. It occurs naturally as the mineral zincite, but commercial ZnO is all produced synthetically by vaporisation of Zn metal at high temperatures.

pouring powder

TiO2 and ZnO production processes and impact on the environment is not neutral
Measuring environmental impact of production of TiO2 and ZnO is a priority for us at Croda, we are working on a full life cycle analysis of our products in collaboration with our raw material suppliers.
In the meantime, we report our sustainability commitment. By 2030 we will be Climate, Land and People positive. Our solar manufacturing sites in Girona, Spain and Ditton, UK source 100% renewable electricity. The carbon footprint associated with manufacturing our products will be reduce by half by 2030. Click here to read more about our sustainability goals.

TiO2 and ZnO are not biodegradable and therefore not safe for the environment
Biodegradable means to be able to decay naturally and without harming the environment.
Biodegradability is a measure of how quickly organic carbons are degraded in the eco-system, and when there are no organic carbons (for examples with minerals such as TiO2 and ZnO) such measurement is not relevant. So, TiO2 and ZnO cannot biodegrade as they are inert minerals, and they already occur naturally in the environment.

Mineral/inorganics are unstable or photocatalytic and need to be chemically treated/coated
Fundamentally TiO2 is a photocatalytic substance, this is what makes it so useful for applications like self-cleaning glass. However, in cosmetics, all TiO2 it is coated or doped to avoid this and to ensure is safe to use, as verified by the Scientific Committee on Consumer Safety (SCCS).3 ZnO is not photocatalytic and can be used uncoated. However, coatings make ZnO easier to formulate and to improve compatibility with other formulation ingredients. Croda offers a range of coated TiO2 products, and both uncoated and coated ZnO grades. To find out more about our range, and to see what SPFs can be achieved with our products try our Solaveil Calculator, click here to access.

Scientists in lab

Alumina found in sunscreen could cause cancer
This myth comes from accusations that aluminum salts play a role in the development of breast cancer and Alzheimer’s disease. However, they are approved safe by the EU Scientific Committee on Consumer Safety up to certain levels. Also, the aluminum used in the coating of TiO2 is chemically different to the soluble aluminum salts of concern. Aluminum based coatings (Aluminum oxide (alumina) and Aluminum stearate) are insoluble compounds which cannot give rise to any soluble aluminum species and are chemically bound to the surface. Also, they are an SCCS approved coating.

Silica coated TiO2 is harmful
This myth comes from confusion around the different types of silica. There is proposed draft legislation to prohibit ingredients silica (nano) and hydrated silica (nano) in EU cosmetics. Silica coated TiO2 however is not impacted as the silica is precipitated onto the core TiO2 and is chemically bound to the surface of the particles. Also, silica is an SCCS approved coating.

Mineral/inorganic UV filters are “chemical-free”
EVERYTHING is a chemical and the broad term “chemical-free” is considered by many to be green-washing as it creates a false impression about the product. However, there are two important definitions that come in to play here that explain why we see this claim a lot in sunscreens:
• Organic UV filters are also known as chemical filters.
• Inorganic UV filters are also known as physical or mineral filters.
Some brands are making “chemical-free” claims for sunscreens to show that they are not based on organic/chemical filters. But all UV filters are fundamentally chemical substances, though inorganic/mineral filters are nature-identical minerals, so preferred by natural and clean sunscreen brands.

Sunscreen is a major cause of coral bleaching
This is one of the biggest myths about sunscreens and it is very widely perpetuated by the media. The truth is that there is actually no direct evidence that sunscreens cause coral bleaching in the wild.4 This is also the conclusion of a recent critical review on organic UV filter exposure hazard and risk to corals.5
In our industry there is concern that this claim is distracting from the real cause of coral bleaching which is climate change and has the potential to undermine sun protection products in general.
However, Oxybenzone (Benzophenone-3) and Octinoxate (Ethylhexyl Methoxycinnamate) are banned in the state of Hawaii. In addition a bill is in progress to also ban Avonebzone (Butyl Methoxydibenzylmethane) and Octocrylene. This is driving the market away from organic UV filters, towards inorganic UV filters, which are not under scrutiny by authorities.

coral reef

TiO2 in sunscreens cause hydrogen peroxide production in the ocean
This myth originates from one study which claims sunscreens are a source of hydrogen peroxide (H2O2) in coastal waters. The study has been discredited by experts who point out that TiO2 UV filters are insoluble and there is no evidence that they are a source of metals found in coastal waters. Furthermore, hydrogen peroxide is naturally occurring in the ocean and the levels found within the study are well within normal levels.

ZnO is aquatoxic and therefore harmful to coral
It is true that ZnO has a hazard label of very toxic to aquatic life with long lasting effects.
However, hazard is not the same as risk, and we must consider the exposure in the marine environment. Based on the current available data it can be concluded that zinc exposure due to ZnO use in sunscreens is not predicted to be of concern for risks to the aquatic environment.6 ZnO remains the most widely used UV filter in products making a coral/reef safe claim according to Mintel GNPD.

TiO2 and ZnO are bioaccumulating
This is another myth related to environmental impact and clean sunscreens. The truth is that mineral UV filters are not known to be bioaccumulating. According to European Chemicals Agency (ECHA) the available data on bioaccumulation of nanosized-TiO2 in invertebrates and fish indicate that it does not appear to bioaccumulate or biomagnify. For Zinc Oxide, ECHA state that zinc is an essential element which is actively regulated by organisms, so bioconcentration/bioaccumulation is not considered relevant for inorganic zinc substances.In our next blog we will be tackling the topic of the health benefits of sunscreens and consumer myths. If you think of any myths that you would like us to debunk, please contact us.