What's inside
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Homosalate
Skin ConditioningEthylhexyl Salicylate
UV AbsorberOctocrylene
UV AbsorberZinc Oxide
Cosmetic ColorantWater
Skin ConditioningGlycerin
HumectantCoco-Caprylate/Caprate
EmollientPropanediol
SolventButyloctyl Salicylate
Skin ConditioningC12-22 Alkyl Acrylate/Hydroxyethylacrylate Copolymer
StabilisingNiacinamide
SmoothingEthylhexyl Methoxycrylene
Skin ConditioningOryza Sativa Bran Wax
Skin ConditioningSteareth-20
CleansingCeramide NP
Skin ConditioningCeramide AP
Skin ConditioningCeramide EOP
Skin ConditioningSorbitan Isostearate
EmulsifyingCarbomer
Emulsion StabilisingTriethoxycaprylylsilane
Cetearyl Alcohol
EmollientBehentrimonium Methosulfate
SurfactantTriethyl Citrate
MaskingSodium Lauroyl Lactylate
EmulsifyingSodium Hyaluronate
HumectantCholesterol
EmollientChlorphenesin
AntimicrobialHydroxyacetophenone
AntioxidantHydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer
Emulsion StabilisingCitric Acid
BufferingCaprylic/Capric Triglyceride
MaskingCaprylyl Glycol
EmollientTrisodium Ethylenediamine Disuccinate
Diethylhexyl Syringylidenemalonate
Skin ProtectingXanthan Gum
EmulsifyingPhytosphingosine
Skin ConditioningPolyhydroxystearic Acid
EmulsifyingPolysorbate 60
EmulsifyingBenzoic Acid
MaskingHomosalate, Ethylhexyl Salicylate, Octocrylene, Zinc Oxide, Water, Glycerin, Coco-Caprylate/Caprate, Propanediol, Butyloctyl Salicylate, C12-22 Alkyl Acrylate/Hydroxyethylacrylate Copolymer, Niacinamide, Ethylhexyl Methoxycrylene, Oryza Sativa Bran Wax, Steareth-20, Ceramide NP, Ceramide AP, Ceramide EOP, Sorbitan Isostearate, Carbomer, Triethoxycaprylylsilane, Cetearyl Alcohol, Behentrimonium Methosulfate, Triethyl Citrate, Sodium Lauroyl Lactylate, Sodium Hyaluronate, Cholesterol, Chlorphenesin, Hydroxyacetophenone, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Citric Acid, Caprylic/Capric Triglyceride, Caprylyl Glycol, Trisodium Ethylenediamine Disuccinate, Diethylhexyl Syringylidenemalonate, Xanthan Gum, Phytosphingosine, Polyhydroxystearic Acid, Polysorbate 60, Benzoic Acid
Homosalate 8.5%
Skin ConditioningEthylhexyl Salicylate 5%
UV AbsorberOctocrylene 8.5%
UV AbsorberZinc Oxide 12.1%
Cosmetic ColorantWater
Skin ConditioningCaprylic/Capric Triglyceride
MaskingPropanediol
SolventGlycerin
HumectantCetearyl Olivate
Polyhydroxystearic Acid
EmulsifyingEthylhexyl Methoxycrylene
Skin ConditioningPotassium Cetyl Phosphate
EmulsifyingLauroyl Lysine
Skin ConditioningPhenyl Trimethicone
Skin ConditioningDimethicone
EmollientSorbitan Olivate
EmulsifyingInulin Lauryl Carbamate
Emulsion StabilisingXanthan Gum
EmulsifyingTriethoxycaprylylsilane
1,2-Hexanediol
Skin ConditioningCaprylyl Glycol
EmollientHydroxyacetophenone
AntioxidantPolyester-8
Skin ConditioningDiethylhexyl Syringylidenemalonate
Skin ProtectingCetearyl Alcohol
EmollientMenthone Glycerin Acetal
RefreshingLactic Acid
BufferingArachidyl Alcohol
EmollientChlorphenesin
AntimicrobialCitrullus Lanatus Fruit Extract
Skin ConditioningNiacinamide
SmoothingSodium Stearoyl Glutamate
CleansingCoco-Glucoside
CleansingBehenyl Alcohol
EmollientTrisodium Ethylenediamine Disuccinate
Aloe Barbadensis Leaf Juice
Skin ConditioningSilica
AbrasiveDimethicone Crosspolymer
Emulsion StabilisingArachidyl Glucoside
EmulsifyingSodium Citrate
BufferingParfum
MaskingSodium Hyaluronate
HumectantMagnesium Aspartate
Skin ConditioningZinc Gluconate
Skin ConditioningPhenoxyethanol
PreservativeCopper Gluconate
Skin ConditioningHomosalate 8.5%, Ethylhexyl Salicylate 5%, Octocrylene 8.5%, Zinc Oxide 12.1%, Water, Caprylic/Capric Triglyceride, Propanediol, Glycerin, Cetearyl Olivate, Polyhydroxystearic Acid, Ethylhexyl Methoxycrylene, Potassium Cetyl Phosphate, Lauroyl Lysine, Phenyl Trimethicone, Dimethicone, Sorbitan Olivate, Inulin Lauryl Carbamate, Xanthan Gum, Triethoxycaprylylsilane, 1,2-Hexanediol, Caprylyl Glycol, Hydroxyacetophenone, Polyester-8, Diethylhexyl Syringylidenemalonate, Cetearyl Alcohol, Menthone Glycerin Acetal, Lactic Acid, Arachidyl Alcohol, Chlorphenesin, Citrullus Lanatus Fruit Extract, Niacinamide, Sodium Stearoyl Glutamate, Coco-Glucoside, Behenyl Alcohol, Trisodium Ethylenediamine Disuccinate, Aloe Barbadensis Leaf Juice, Silica, Dimethicone Crosspolymer, Arachidyl Glucoside, Sodium Citrate, Parfum, Sodium Hyaluronate, Magnesium Aspartate, Zinc Gluconate, Phenoxyethanol, Copper Gluconate
Reviews
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
Caprylic/Capric Triglyceride (aka MCT Oil) is a lightweight emollient, solvent, and texture enhancer. It is considered a skin-softener by helping to prevent moisture loss.
Though it behaves like an oil, it is not technically one due to its chemical composition. One perk of this ingredient is that it is very stable, resistant to oxidation, and unlikely to go rancid.
In practice, that translates to a long shelf life and a consistently elegant skin feel.
While there is an assumption Caprylic Triglyceride can clog pores due to it being derived from coconut oil, there is no research supporting this. Just patch test if you have concerns.
Fractionated coconut oil and MCT Oil are both listed as Caprylic/Capric Triglyceride according to INCI. This is because INCI names are based on the ingredient’s final chemical composition and not its marketing name or source.
This ingredient is treated as the gold standard fungal acne safe oil. Even though it is coconut derived, the problematic lauric acid is stripped out.
This leaves just caprylic (C8) and capric (C10) acid. These chain lengths actually trend antifungal; a 2020 study found caprylic acid was enough to disrupt Malassezia furfur cell membrane, with a caprylic acid derivative damaging membrane structures at concentrations as low as 0.2%.
Learn more about Caprylic/Capric TriglycerideCaprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.
Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.
Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).
Learn more about Caprylyl GlycolCetearyl alcohol is a waxy mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is an emollient and emulsifier.
Despite having "alcohol" in its name, it has nothing to do with drying solvent alcohols; the FDA also allows "alcohol-free" products to contain fatty alcohols like this ingredient.
It plays several roles in a formula:
Typical use levels for this ingredient sit around 1-10% and the Cosmetic Ingredient Review Expert Panel has affirmed safety at concentrations up to 25% in leave-on products.
Multiple assessments have found it to be non-irritating and non-sensitizing to most people.
However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.
Cetearyl alcohol has a comedogenic rating of 2 and irritancy rating of 1. Both of these numbers come from the 1989 study that used rabbit ears; a "2" means mildly comedogenic and a "1" means low irritancy.
Here's the catch: rabbit skin is more sensitive than human skin and throws a lot of false positives. A 1996 reappraisal found that ingredients rated 1-2 in the rabbit ear tests are generally safe for humans.
Remember comedogenic ratings are unable to assess the entire formula of a product or how it will react on your skin. Just be sure to patch test if you are unsure about certain ingredients.
This ingredient is not fungal acne safe. Cetearyl alcohol is a fatty alcohol with chain lengths that fall within the range that Malassezia can metabolize.
A 2019 study has also observed Malassezia growth in the presence of this ingredient, confirming it to be not-fungal acne safe.
Learn more about Cetearyl AlcoholChlorphenesin is a synthetic preservative. It helps protect a product against bacteria in order to extend shelf life. In most cases, Chlorphenesin is paired with other preservatives such as phenoxyethanol and caprylyl glycol.
Chlorphenesin is a biocide. This means it is able to help fight the microorganisms on our skin. It is also able to fight odor-releasing bacteria.
Chlorphenesin is soluble in both water and glycerin.
Studies show Chlorphenesin is easily absorbed by our skin. You should speak with a skincare professional if you have concerns about using Chlorphenesin.
Learn more about ChlorphenesinDiethylhexyl Syringylidenemalonate (DESM) is a photostabilizer, antioxidant, and SPF booster.
One of DESM's main roles is stabilizing UV filters, especially avobenzone. Avobenzone is notoriously unstable when exposed to sunlight. By enhancing the stability of these filters, DESM helps maintain the sunscreen's effectivess through wear. It also helps improve protection against long-wave UVA rays by increasing the wavelength of the formula.
Besides enhancing UVA protection, DESM can boost the SPF of high-SPF formulations by up to 5 units.
DESM also preserves the color integrity of cosmetic products and helps reduce the chance of yellowing of fading due to light exposure.
This ingredient is typically found in concentrations between 0.3% - 0.5%. There are currently no maximum usage limits by regulatory bodies.
Though this ingredient is a chemical UV filter, it can often be found in "100% mineral" sunscreens. This is due to regulatory loopholes.
Learn more about Diethylhexyl SyringylidenemalonateThis ingredient is a photostabilizer and a chemical UV booster. It is marketed as an alternative to octocrylene.
You'll most likely find it in sunscreens to enhance stability and effectiveness of UV filters, antioxidants, and vitamin A derivatives. According to the manufacturer, this ingredient is better than octocrylene at stabilizing avobenzone.
Due to regulation loopholes, you'll likely see this ingredient in "100% mineral" sunscreens.
Learn more about Ethylhexyl MethoxycryleneEthylhexyl Salicylate (also called Octisalate or Octyl Salicylate) is an oil-soluble organic UV filter that's been used in sunscreen since the 1950's.
It absorbs UVB light in the 280-320 nm range with a peak absorbance around 306 nm.
You'll often see it paired with other UV filters to boost overall SPF because octisalate is a fairly week filter on its own.
The reason you'll see it so often is because it can help solubilize and stabilize the trickier filters like oxybenzone and avobenzone.
Unlike these filters, octisalate has pretty good photostability and doesn't create skin-damaging free radicals when exposed to sunlight.
The fatty-alcohol part of the molecule also gives it a light, emollient feel so it doubles as a nice texture enhancer.
Usage levels vary around the world:
Safety-wise, this ingredient has a pretty reassuring track record. The EU's Scientific Committee on Consumer Products (SCCP) found very low skin penetration in human skin tests and negative results for irritation, phototoxicity, and photoallergy.
The real-world allergy risk is pretty low too; a 2012 European study of 1,031 people recorded only 2 reactions to it (a rate of 0.19%).
You might have seen scary headlines about sunscreen getting into your blood.
In 2019, the FDA found that several chemical filters can absorb through the skin and show up in the bloodstream at small but measurable levels.
Here's the important part: these tiny levels are just a cutoff the FDA uses to decide which ingredients need more testing and doesn't mean anything harmful was found.
The researchers were clear that the results are no reason to stop wearing sunscreen.
Learn more about Ethylhexyl SalicylateGlycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.
Topically, glycerin does several things at once:
Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.
Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.
This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.
Just know very high concentrations (>40%) can feel tacky in low humidity.
Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.
Learn more about GlycerinHomosalate is an oil-soluble organic UVB filter that has been a sunscreen staple for decades. Its job is to absorb UVB rays (~295-315 nm) and protect your skin against sunburn,
This is one of the more photostable organic UV filters; it holds up pretty well under UV and a 2022 quantum-chemistry study found it stays stable in sunlight.
It's actually so reliable that formulators often pair it with shakier ingredients like oxybenzone and avobenzone. Formulators also use it to help dissolve the other UV filters into the oil phase.
One thing to keep in mind: "stable" isn't the same as "strong". On its own, homosalate is actually a pretty weak UV filter so it's better off as a helpful team player that helps boost overall SPF protection.
The safety picture is a bit nuanced but not scary.
This ingredient has a long track record of being gentle and regulators agree it isn't an irritant; EU's Scientific Committee on Consumer Safety found that homosalate is not considered a skin irritant and doesn't raise eye-irritation flags either.
There's talk about homosalate because your skin absorbs a little bit of it into your bloodstream. A 2020 FDA-backed study found homosalate showed up in people's blood levels at the level where the FDA decides to double check.
The EU's Scientific Committee on Consumer Safety (SCCS) also found small amounts in blood and breast milk. They estimated that about 5% of what you apply gets absorbed through the skin.
Due to the debate about whether it might mess with hormones, the SCCS recommended a maximum limit of 0.5% in most products of 7.3% in face creams/pump sprays.
One important thing to keep in mind: in the US, Homosalate is currently labeled "non-GRASE" by the FDA. This sounds alarming but really just means the FDA wants more data to confirm it's safe. It's not confidently saying this ingredient is harmful.
As of now, homosalate is still completely legal and widely used while that research gets done.
The current maximum limits are:
Learn more about HomosalateHydroxyacetophenone is a small phenolic molecule that earns its place in a formulas as an antioxidant and preservative booster.
As a phenol, it is able to neutralize free radicals to protect both the product and the skin from oxidative stress.
Though it can't kill microbes on its own, it works as a good supporting agent when combined with other preservatives like Phenoxyethanol or 1,2-Hexanediol.
This ingredient naturally occurs as piceol in Norwegian spruce needles (~0.4-1.1% dry weight and in cloudberries). Though the cosmetic-grade material is synthesized for purity and consistency.
You'll usually see it used at low levels and suppliers recommend up to 1% added to a water phase.
Safety testing was done at concentrations like 0.05% in SPF products and 0.5% in a Human Repeated Insult Patch Test. The safety evidence is assuring; this ingredient is safe for cosmetics in current use and also holds safety status as a food flavoring as well.
An honest caveat: the "soothing" and "anti-inflammatory" claims come mostly from supplier marketing rather than published clinical trials. The Cosmetic Ingredient Review's own literature search found no useful efficacy studies on this ingredient.
So the antioxidant and preservative-boosting roles are the well supported ones while the calming benefit is plausible but thinly evidenced.
Overall, this is a well-tolerated, low-irritation multitasker that quietly helps a formula stay fresh and stable.
Learn more about HydroxyacetophenoneNiacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.
And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.
You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.
In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.
If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.
When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.
When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.
In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).
Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.
Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.
The type of niacinamide used in skincare is synthetically created.
Learn more about NiacinamideOctocrylene is an oil-soluble organic UV filter that mainly absorbs UVB and short wave UVA II light.
Its real superpower is teamwork: octocrylene is remarkably photostable and is most famous for stabilizing avobenzone (the workhorse UVA filter).
This ingredient is commonly used to enhance both UVB and UVA protection due to its unique property in stabilizing avobenzone. It also pulls double duty by boosting water resistance and giving formulas a smooth, spreadable feel.
The EU's Scientific Committee on Consumer Safety (SCCS) has deemed octocrylene to be safe as a UV-filter at concentrations up to 10% (capped at 9% in propellant sprays). The US also permits it up to 10%.
Two things worth knowing:
You'll usually see this ingredient used in concentrations between 2-10% (higher amounts when used as a stabilizer for avobenzone).
Learn more about OctocrylenePolyhydroxystearic Acid is a vegetable-derived soft wax made from castor oil. It's an emulsion stabilizer, thickener, and film former.
You'll likely see it in sunscreens because it helps disperse pigments and UV-reflecting minerals like titanium dioxide and zinc oxide evenly.
Depending on the concentration, it can drastically change the texture of a product from pasty solid (like lipstick) to sprayable liquid.
The CIR Expert Panel for Cosmetic Ingredient Safety has concluded this ingredient to be safe in cosmetics. The highest reported use concentration is 14.2% in lipsticks.
Learn more about Polyhydroxystearic AcidPropanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.
It’s often used to:
Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.
Learn more about PropanediolSodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.
In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.
Interestingly, the size of the molecule affects its behavior:
Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.
Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.
You'll typically see concentrations between 0.1-2% for this ingredient.
Learn more about Sodium HyaluronateTriethoxycaprylylsilane is a silicon-based surface modifier that makes sunscreens feel silky and makeup stay put.
Its main job is to coat mineral particles like titanium dioxide, zinc oxide, and color pigments in a thin, oily layer so they spread smoothly, don't clump, and stick to skin better.
This ingredient is typically used at low levels (up to 2.5% in eyeshadow and 1% in lipstick).
Learn more about TriethoxycaprylylsilaneTrisodium Ethylenediamine Disuccinate is used to help stabilize a product.
It is a chelating agent, meaning it helps prevent metal ions from binding to other ingredients. This prevents unwanted reactions in products. Metal ions can come into a product via the water ingredient. They are found in trace amounts and are not known to be harmful.
Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.
So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.
You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!
Learn more about WaterXanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.
On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.
Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.
Learn more about Xanthan GumZinc Oxide (ZO) is a mineral broad-spectrum UV filter and the broadest-spectrum filter recognized by the FDA. It covers everything from UVB through to long-wave UVA.
On top of sun protection, it has skin protectant and skin-soothing properties too.
Here's a myth worth busting: mineral filters are usually described as working by "reflecting" or "bouncing" UV off your skin.
That's mostly not true: when researchers actually measured it, ZO and Titanium Dioxide reflect only about 4-5% of UV (less than SPF 2 worth of protection).
The vast majority of the work (~95%) is done by absorption, similar to chemical UV filters. ZO is a semiconductor that absorbs UV photos through its energy band gap.
So the old "physical blocker vs. chemical absorber" framing is really an oversimplification.
Zinc Oxide is one of the most effective broad-spectrum UV filters out there. It protects across UVB, UVA2, and UVA1 with a flat, even absorption curve across the whole UVA-UVB range.
That uniform UVA coverage is its standout feature; titanium dioxide skews more toward UVB as its particle size drops so ZO gives more consistent and extended UVA protection.
It's also very photostable. As an inorganic oxide, ZO doesn't break down in sunlight the way some organic filters can, so it holds up over a day of wear.
This ingredient is gentle and soothing, making it go-to for sunscreens aimed at sensitive skin, rosacea, or ecezma-prone skin, babies, and children.
It's also unlikely to cause the "eye sting" that some sunscreen ingredients are known for, and regulatory agencies broadly consider it non-toxic and safe for topical use.
Beyond sun protection, ZO is also a recognized OTC skin protectant. It forms a breathable barrier that shields skin from moisture and irritation while supporting healing. This is why you'll see it as a classic active in diaper rash creams.
The only downside to ZO is that it can leave a visible white cast, especially on deeper skin tones. This is the main reason mineral sunscreens have historically felt less cosmetically elegant than chemical or hybrid formulas.
Zinc Oxide comes in both non-nano and nano forms. The dividing line is 100nm and anything under is classified as a nanomaterial by the EU.
The nano version scatters less visible light which cuts down white case and gives a lighter, more wearable texture.
Another thing worth understanding about formulation:
Uncoated ZO has some inherent photocatalytic activity. This just means it can generate reactive oxygen species under UV. It's exactly why cosmetic-grade ZO is almost always surface-coated; this coating suppresses that reactivity and improves how the powder disperses and feels.
A well-formulated coated ZO largely sidesteps this issue.
Zinc Oxide is commonly used anywhere from 10% up to the regulatory maximum in sunscreens (25%).
Mineral-only broad-spectrum products often land in the 15-25% range to hit higher SPF and UVA values. Keep in mind SPF performance depends heavily on particle size, dispersion, and the rest of the formula, and not just the percentage.
As an OTC skin protectant like diaper creams, ZO typically runs higher at roughly 10-40%.
This ingredient is generally easy to work with and doesn't photodegrade.
The only thing to know is that uncoated ZO can be a bit reactive in a formula.
Under UV, it can break down sensitive ingredients like other actives or UV filters. This is another reason coated versions are standard. ZO can also react with very acidic ingredients or throw off stability of some creams. A good formula will get around this with the right coatings and dispersion.
The EU's Scientific Committee on Consumer Safety has concluded that ZO nanoparticles "can be considered to not pose any risk of adverse effects in humans after application on healthy, intact or sunburnt skin".
You might hear that ZO is "toxic"; this is because an in-vitro (test tube) study suggested micronized ZO had potential phototoxicity. In vivo (human) investigations have disputed this and the results have come back reassuring.
So does ZO penetrate skin? The short answer is no, not in any way that matters.
The most relevant evidence comes from real-world human studies: in one, volunteers applied ZO nanoparticle sunscreen hourly for six hours and daily for five days. The advanced imaging showed the particles stayed on the surface and never reached the living epidermis, and no cellular toxicity was found.
Other in-vivo and ex-vivo work agree; ZO nanoparticles don't cross the stratum corneum, even on flexed, massaged, or barrier-impaired skin.
A small amount of solubilized zinc ions can dissolve off the particles and enter the upper skin. But the quantities are tiny compared to the zinc already naturally present in your body, and studies haven't found this to cause local toxicity.
The sunscreen bans you've heard of (like Hawaii's) are aimed at two chemical filters, Oxybenzone and Octinoxate. ZO itself it not banned and is often recommended instead.
So far, there's no solid evidence that any form of ZO harms reefs. It is an ongoing and active area of study, and worth keeping an eye on.
If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.
Learn more about Zinc Oxide