Chemical vs. mineral sunscreens: Which one should you choose?
By Vallary Akinyi, July 26, 2025The raging debate between chemical and mineral sunscreens has intensified in recent years, driven by growing concerns over skin health, environmental impact, and potential toxicity.
More people have become conscious of what they apply to their skin and how it affects the planet.
Amid concerns that the so-called chemical sunscreens may be bad for our bodies, brains, and even coral reefs, mineral-based formulations have become the fastest-growing share of the global sunscreen market.
But debates over “chemical” versus “mineral” sunscreens are riddled with misconceptions.
The confusion begins with terminology.
“Everything is a chemical,” points out Brian Diffey, emeritus professor of photobiology in dermatological sciences at the UK’s University of Newcastle and inventor of sunscreen’s UVA star rating.
What people call “chemical” filters are more accurately termed organic, since they contain carbon-hydrogen bonds, says Diffey.
Inorganic filters, often called mineral, primarily titanium dioxide and zinc oxide, lack those bonds. All are chemicals.
Seeking to protect our skin and bodies from the sun is not a new trend, nor are sunscreens, organic or inorganic.
From Ancient Mesopotamians’ umbrellas to the use of ochre-based pastes as sunscreen in Namibia, it dates back at least 285,000 years.
Ultraviolet radiation discovery
It wasn’t until the 19th Century, however, that scientists discovered ultraviolet radiation (UVR) and realised that some ingredients, like quinine sulphate derived from a tree bark, could absorb it.
Scientists duly recommended it as a sunscreen. By 1930, researchers had found a number of other ingredients that absorbed UVR, including aesculin from trees such as horse chestnut and larch bark tannin.
Later, dozens of other ingredients were added to this list, including those produced by mixing together different substances in a laboratory to induce a chemical reaction.
Often referred to as “synthetic chemicals”, these types of ingredients have been found to absorb UV rays far more effectively than their predecessors.
Another type of sunscreen came to market, too: “mineral” sunscreens.
While they might seem more “natural”, the titanium dioxide and zinc oxide in today’s sunscreens are usually lab-produced.
At first, it was thought that organic sunscreens absorbed UVR, while inorganic sunscreens physically reflected and scattered UVR away from the skin – a belief that was perpetuated further in a 1970s United States Food and Drug Administration (FDA) monograph.
Concerns around skin penetration
This idea is still commonly heard today, including from seemingly authoritative sources. It is also partly why inorganic sunscreens are sometimes also called “physical sunscreens”, implying that they block out UV rays like an umbrella deflects raindrops.
“People say that mineral or inorganic sunscreens reflect ultraviolet radiation,” says Antony Young, professor emeritus of experimental photobiology at King’s College London and a lifelong researcher of sunscreen efficacy.
“And that’s not true.”
Scientists have been aware that inorganic sunscreens absorb UV since the 1980s, so much so that the authors of the 2015 study already seemed exasperated with having to provide even further proof.
Their study emphasised “yet again”, they wrote, “that the true function of these insoluble ‘physical’ or ‘mineral’ UV filters is in fact identical to that of the soluble ‘chemical’ UV filters.
These data indicate clearly that these filters act primarily as UV-absorbing materials, and not as UV-scattering or UV-reflecting materials.”
Most organic filters are soluble, meaning their active ingredients can be dissolved in a medium like water or oil. Inorganic sunscreens are not: their particles remain intact.
As a result, inorganic sunscreens can feel thicker and give a white cast, while organic filters can provide smoother, clearer formulations.
As chemistry advances have shrunk inorganic particle sizes down, the white-cast effect has decreased.
These “nanoparticles” (less than 100nm in size) of titanium dioxide and zinc oxide have led to their own set of concerns around skin penetration.
But even this minuscule particle size doesn’t penetrate more than the outermost skin layer – thus preventing systemic absorption.
So far, the threshold at which the ingredients pose a risk seems to be many times higher than the quantity in which people are using them.
One scientific review published earlier this year found no evidence that UV filters like avobenzone and homosalate can damage DNA or cause cancer in humans, and that blood levels of these chemicals from topical sunscreen are far below the amount at which they might have an effect.
While scientists haven’t yet proven any concrete, adverse effects to humans of using organic or inorganic sunscreens, aside from occasional side effects like allergic reactions, we can’t say the same of excessive UV exposure.
At worst, it can lead to skin cancer, the most common type of cancer. If it spreads, the deadliest type, melanoma, has only a 35 per cent five-year survival rate.
This is why the best sunscreen, experts say, is one you are happy to use. For some people, that is a sunscreen that is smoother, clearer and absorbs more quickly.
For others, that might be a sunscreen that has fewer toxicology concerns, no matter how theoretical.