The Face Shop Air Cotton Makeup Base SPF 30 PA++ Versus Dr. Jart+ Cicapair Tiger Grass Color Correcting Treatment SPF 30
What's inside
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Skin ConditioningCyclopentasiloxane
EmollientCyclohexasiloxane
EmollientTitanium Dioxide
Cosmetic ColorantDipropylene Glycol
HumectantZinc Oxide
Cosmetic ColorantButylene Glycol
HumectantCetyl PEG/PPG-10/1 Dimethicone
EmulsifyingButylene Glycol Dicaprylate/Dicaprate
EmollientNiacinamide
SmoothingSodium Chloride
MaskingPEG-10 Methyl Ether Dimethicone
EmulsifyingMica
Cosmetic ColorantGossypium Herbaceum Extract
Skin ConditioningAnthemis Nobilis Flower Water
MaskingVolcanic Ash
AbrasiveChenopodium Quinoa Seed Extract
Skin ConditioningRosa Damascena Flower Water
MaskingDimethicone
EmollientDisteardimonium Hectorite
StabilisingAluminum Hydroxide
EmollientStearic Acid
CleansingDimethicone/Vinyl Dimethicone Crosspolymer
Skin ConditioningTriethyl Citrate
MaskingHydrogen Dimethicone
Adenosine
Skin ConditioningHydrogenated Lecithin
EmulsifyingDisodium EDTA
Phenoxyethanol
PreservativeCaprylyl Glycol
EmollientEthylhexylglycerin
Skin Conditioning1,2-Hexanediol
Skin ConditioningParfum
MaskingCitric Acid
BufferingSodium Benzoate
MaskingPotassium Sorbate
PreservativeChromium Oxide Greens
Water, Cyclopentasiloxane, Cyclohexasiloxane, Titanium Dioxide, Dipropylene Glycol, Zinc Oxide, Butylene Glycol, Cetyl PEG/PPG-10/1 Dimethicone, Butylene Glycol Dicaprylate/Dicaprate, Niacinamide, Sodium Chloride, PEG-10 Methyl Ether Dimethicone, Mica, Gossypium Herbaceum Extract, Anthemis Nobilis Flower Water, Volcanic Ash, Chenopodium Quinoa Seed Extract, Rosa Damascena Flower Water, Dimethicone, Disteardimonium Hectorite, Aluminum Hydroxide, Stearic Acid, Dimethicone/Vinyl Dimethicone Crosspolymer, Triethyl Citrate, Hydrogen Dimethicone, Adenosine, Hydrogenated Lecithin, Disodium EDTA, Phenoxyethanol, Caprylyl Glycol, Ethylhexylglycerin, 1,2-Hexanediol, Parfum, Citric Acid, Sodium Benzoate, Potassium Sorbate, Chromium Oxide Greens
Water
Skin ConditioningCentella Asiatica Leaf Water
Skin ConditioningIsononyl Isononanoate
EmollientCyclopentasiloxane
EmollientButylene Glycol
HumectantDimethicone
EmollientPhenyl Trimethicone
Skin ConditioningMethyl Methacrylate Crosspolymer
Cera Alba
EmollientGlycerin
HumectantDiethylhexyl Carbonate
EmollientPolyglyceryl-3 Polyricinoleate
EmulsifyingNiacinamide
SmoothingPolymethylsilsesquioxane
Cyclohexasiloxane
EmollientPanthenol
Skin ConditioningDiglycerin
HumectantIron Oxides
Polyglyceryl-4 Diisostearate/Polyhydroxystearate/Sebacate
EmulsifyingIsododecane
EmollientEthylene/Methacrylate Copolymer
Cetearyl Alcohol
EmollientPolyglyceryl-2 Triisostearate
EmulsifyingAluminum Hydroxide
EmollientStearic Acid
CleansingDisteardimonium Hectorite
StabilisingAcrylates/Ammonium Methacrylate Copolymer
Sclerotium Gum
Emulsion StabilisingSodium Benzoate
MaskingAcrylates/Dimethicone Copolymer
Skin ConditioningHydrogen Dimethicone
Chromium Oxide Greens
Triethyl Citrate
MaskingPotassium Sorbate
PreservativeFragaria Vesca Leaf Extract
AstringentDisodium EDTA
BHT
AntioxidantAlcohol
AntimicrobialAsiaticoside
AntioxidantAdenosine
Skin ConditioningTriethoxycaprylylsilane
Lavandula Angustifolia Oil
MaskingBoron Nitride
AbsorbentAsiatic Acid
Skin ConditioningMadecassic Acid
Skin ConditioningCitrus Grandis Peel Oil
MaskingRosmarinus Officinalis Leaf Oil
Masking1,2-Hexanediol
Skin ConditioningAnthemis Nobilis Flower Oil
MaskingHouttuynia Cordata Extract
Skin ConditioningPropanediol
SolventCentella Asiatica Extract
CleansingGentiana Lutea Root Extract
Skin ConditioningArtemisia Absinthium Extract
Skin ConditioningAchillea Millefolium Extract
CleansingArnica Montana Flower Extract
MaskingPolysorbate 20
EmulsifyingAniba Rosodora Wood Oil
AstringentSodium Glycerophosphate
Selaginella Lepidophylla Extract
EmollientPotassium Magnesium Aspartate
BufferingCitric Acid
BufferingCalcium Gluconate
HumectantMadecassoside
AntioxidantMagnesium Gluconate
Skin ConditioningCentella Asiatica Meristem Cell Culture
AntioxidantXanthan Gum
EmulsifyingTitanium Dioxide
Cosmetic ColorantZinc Oxide
Cosmetic ColorantWater, Centella Asiatica Leaf Water, Isononyl Isononanoate, Cyclopentasiloxane, Butylene Glycol, Dimethicone, Phenyl Trimethicone, Methyl Methacrylate Crosspolymer, Cera Alba, Glycerin, Diethylhexyl Carbonate, Polyglyceryl-3 Polyricinoleate, Niacinamide, Polymethylsilsesquioxane, Cyclohexasiloxane, Panthenol, Diglycerin, Iron Oxides, Polyglyceryl-4 Diisostearate/Polyhydroxystearate/Sebacate, Isododecane, Ethylene/Methacrylate Copolymer, Cetearyl Alcohol, Polyglyceryl-2 Triisostearate, Aluminum Hydroxide, Stearic Acid, Disteardimonium Hectorite, Acrylates/Ammonium Methacrylate Copolymer, Sclerotium Gum, Sodium Benzoate, Acrylates/Dimethicone Copolymer, Hydrogen Dimethicone, Chromium Oxide Greens, Triethyl Citrate, Potassium Sorbate, Fragaria Vesca Leaf Extract, Disodium EDTA, BHT, Alcohol, Asiaticoside, Adenosine, Triethoxycaprylylsilane, Lavandula Angustifolia Oil, Boron Nitride, Asiatic Acid, Madecassic Acid, Citrus Grandis Peel Oil, Rosmarinus Officinalis Leaf Oil, 1,2-Hexanediol, Anthemis Nobilis Flower Oil, Houttuynia Cordata Extract, Propanediol, Centella Asiatica Extract, Gentiana Lutea Root Extract, Artemisia Absinthium Extract, Achillea Millefolium Extract, Arnica Montana Flower Extract, Polysorbate 20, Aniba Rosodora Wood Oil, Sodium Glycerophosphate, Selaginella Lepidophylla Extract, Potassium Magnesium Aspartate, Citric Acid, Calcium Gluconate, Madecassoside, Magnesium Gluconate, Centella Asiatica Meristem Cell Culture, Xanthan Gum, Titanium Dioxide, Zinc Oxide
Reviews
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
1,2-Hexanediol is a synthetic liquid and another multi-functional powerhouse.Â
It is a:
- Humectant, drawing moisture into the skin
- Emollient, helping to soften skin
- Solvent, dispersing and stabilizing formulas
- Preservative booster, enhancing the antimicrobial activity of other preservativesÂ
Adenosine is a purine nucleoside that your body already makes in every cell. In skincare, it acts mainly as a skin conditioning and anti-aging agent.
The way it works is fairly well mapped out:
Your skin has cells called fibroblasts that build collagen (the stuff that keeps skin firm and smooth). Adenosine basically flips a switch on these cells that tells them to get to work making more collagen and other proteins. These cells slow down on their own as skin ages, so Adenosine helps give them a little nudge to keep going.
The clinical backing is pretty solid too.
A blind, randomized, placebo-controlled trial of 126 women aged 45-65 tested a 0.1% cream twice daily and found real improvements in crow's feet and frown lines using a precise 3D skin-mapping technique; these changes showed up by week 3 and held at 2 months.
A later study using Adenosine-loaded dissolving microneedle patches reported gains in wrinkle depth, dermal density, elasticity, and hydration.
On concentrations, South Korea's Ministry of Food and Drug Safety has set 0.04% as the approved functional anti-wrinkle level. You'll typically see this ingredient used somewhere in the 0.04-0.1% range since it works at low doses.
This ingredient has been found safe for cosmetics with the data showing no irritation or sensitization.
Overall, this is a great ingredient for any anti-aging routine and has no photosensitizing effect, so it suits both AM and PM use.
Learn more about AdenosineAluminum Hydroxide is a form of aluminum. It can be naturally found in nature as the mineral gibbsite. In cosmetics, Aluminum Hydroxide is used as a colorant, pH adjuster, and absorbent.
As a colorant, Aluminum Hydroxide may add opacity, or reduce the transparency. Aluminum hydroxide is contains both basic and acidic properties.
According to manufacturers, this ingredient is an emollient and humectant. This means it helps hydrate the skin.
In medicine, this ingredient is used to help relieve heartburn and help heal ulcers.
There is currently no credible scientific evidence linking aluminum hydroxide in cosmetics to increased cancer risk.
Major health organizations allow the use of aluminum hydroxide in personal care products and have not flagged it as a carcinogenic risk at typical usage levels.
Learn more about Aluminum HydroxideButylene Glycol (or BG) is used within cosmetic products for a few different reasons:
Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.
Learn more about Butylene GlycolThis ingredient adds a green color to formulations.
You'll likely see this ingredient as part of the blend that makes up 'emerald powder'.
The other ingredients that make up emerald powder include: mica, titanium dioxide, chromium oxide, and ferric ferrocyanide.
Learn more about Chromium Oxide GreensCitric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.
Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.
However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.
Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.
In skincare formulas, citric acid can:
While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.
Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.
Read more about some other popular AHA's here:
Learn more about Citric AcidCyclohexasiloxane is a type of silicone more commonly known as D6. It is an emollient and solvent.
Cyclohexasiloxane is used to evenly distribute ingredients throughout the product. When applied to the skin, Cyclohexasiloxane evaporates and leaves behind a silky feel.
As an emollient, it can help the skin feel soft and hydrated. It is also used to reduce frizz in hair products.
Learn more about CyclohexasiloxaneCyclopentasiloxane (D5) is a lightweight silicone that mostly acts as an emollient and solvent in cosmetics. Its the reason your products feel silky, fast-spreading, and non-greasy.
Since D5 is volatile, it does its thing and then evaporates off the skin quickly.
The safety profile of this ingredient is reassuring; the US CIR Expert Panel concluded D5 is safe as used in cosmetics and Health Canada concluded that D5 is not harmful to human health or the environment as currently used in cosmetics
There's a study that people mention about D5 in a rat study showing tumors. This study is related to long-term inhalation of high D5 levels.
Regulatory bodies have judged this study to be not applicable in topical skincare since skin absorption of D5 is very low and we're not really inhaling huge amounts of D5.
The only restriction for this ingredient is environmental. The European Chemicals Agency (ECHA) restricted D5 in wash-off cosmetics at or above 0.1% due to their persistence in water.
Learn more about CyclopentasiloxaneDimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.
What it does:
Dimethicone comes in different viscosities:
Depending on the viscosity, dimethicone has different properties.
Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.
This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.
Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.
Learn more about DimethiconeDisodium EDTA is a chelating agent. It grabs onto and deactivates metal ions that sneak into your products from water, packaging, or air.
This ingredient mainly works behind the scenes and helps with:
On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.
One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).
Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.
You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.
Learn more about Disodium EDTADisteardimonium Hectorite comes from the clay mineral named hectorite. It is used to add thickness to a product.
It can also help stabilize a product by helping to disperse other ingredients.
Hectorite is a rare, white clay mineral.
Learn more about Disteardimonium HectoriteHydrogen dimethicone is a silicone-based ingredient. It is mainly used to alter the texture and spread of a product without adding "stickiness".
Niacinamide 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 NiacinamidePotassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.
This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.
Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.
You'll often find this ingredient used with other preservatives.
Learn more about Potassium SorbateSodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.
Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.
Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.
It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.
Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.
We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.
Learn more about Sodium BenzoateStearic Acid is a fatty acid that is already found in your skin. It's one of the free fatty acids that works alongside ceramides and cholesterols to maintain your barrier.
In cosmetics, it is a multitasker:
Safety-wise, the CIR Expert Panel has concluded it to be safe in cosmetics when formulated to be non-irritating and non-sensitizing.
Free stearic acid is a C18 fatty acid that the Malassezia yeast can substrate, so this ingredient may not be fungal acne safe.
Learn more about Stearic AcidTitanium Dioxide (TD) is a mineral UV filter widely used in sunscreens and cosmetics.
It's one of only two UV filters officially classified as "mineral" by regulatory agencies (the other being Zinc Oxide).
A really common myth is that mineral filters work by reflecting UV light off your skin like tiny mirrors.
They don't only do that; modern research shows TD protects mostly by absorbing UV radiation, the same way chemical filters do.
When researchers measured this, reflection accounted for only about 4-5% of the protection (and less than SPF 2 on its own). The other ~95% comes from absorption: the UV photons hit the particle and their energy gets soaked up by its semiconductor band gap rather than bouncing off.
So "reflects vs. absorbs" was never really the right way to split mineral from chemical filters.
TD gives broad-spectrum protection that's strongest in the UVB and UVA-2 range and weaker in the UVA-1 range. Its UVA protection isn't quite as strong as Zinc Oxide's which is why you'll often see the two paired together.
Together, they make a solid broad-spectrum system.
TD is a great pick for sensitive, acne-prone, or redness-prone skin because it's non-irritating and chemically inert. Regulatory reviews classify it as a non-sensitizer and mild-to-non-irritant.
It's also unlikely to cause the "eye sting" some chemical filters are known for.
The main trade-off is cosmetic; TD can leave a white cast and has a thicker texture. This is why mineral sunscreens are often less cosmetically elegant than chemical or hybrid formulas (and harder to shade-match on deeper skin tones).
Formulators often use micronized or nano-sized TD to cut down on white case and improve spreadability. Smaller particles scatter less visible light so the formula looks less chalky while still filtering UV.
TD is almost always bundled with coatings like Alumina, Silica, Stearic Acid, or Dimethicone. These coatings do two important jobs:
TD can be used at up to 25% in a finished sunscreen; this is the regulatory ceiling in both the US and the EU.
In practice, the amount in any given product varies a lot depending on the target SPF and whether it's paired with other UV filters.
TD is one of the most heavily vetted sunscreen ingredients out there. It is approved as a UV filter in all major markets worldwide, including the US, EU, UK, Japan, Korea, China, Australia, and Canada.
The safety evidence is solid. There was an old worry that nano particles might absorb through skin into the body but multiple studies (including on damaged, sunburned, and UV-irradiated skin) have shown that TD stays on the surface and the layer of dead skin cells on top of everything else.
There's also no evidence of carcinogenicity, mutagenicity, or reproductive toxicity from dermal exposure of this ingredient.
For those who have seen the headline about a 2022 EU ban on TD, that was on TD as a food additive (a complete separate use from topical sunscreen).
There are ongoing questions about how nano-TD might affect marine ecosystems. As of now, there has been no conclusive evidence that any form of TD (or any other sunscreen filter) harms coral reefs or marine life.
The science is still developing and it's a space worth watching rather than packing over.
However, several destinations have reef-safety sunscreen rules that restrict certain chemical filters and steer visitors toward mineral, non-nano options. If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.
Learn more about Titanium DioxideTriethyl Citrate comes from citric acid. It has masking, perfuming, and solvent properties. As a solvent, this ingredient helps disperse ingredients evenly in skincare.
One manufacturer claims this ingredient can:
According to perfume manufacturers, this ingredient is almost odorless but has a mild fruity, wine and plum scent. It can be used to mask the scent of other ingredients.
This ingredient can be plant-sourced or synthetic; it can naturally be found in cabbage and white wine.
Learn more about Triethyl CitrateWater. 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 WaterZinc 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