Chemical vs Mineral Sunscreen: Skin + Ocean Facts

I had a buddy who'd been holding out on switching from chemical to mineral sunscreen. Then the other day he paddled out, and I saw it right away: full face of white. When he came in, I asked what changed. He told me he'd been seeing the headlines about sunscreen ingredients showing up in blood samples and the stories about reef damage. Same beach, same routine, but now he was looking at that bottle like it was a question he'd been dodging.

So let's treat it like a real question and go through the facts.

Step zero: sunscreen is not optional

Before we argue mineral vs chemical, it helps to remember what we're actually trying to avoid.

• 1 in 5 Americans will develop skin cancer by age 70, and five or more sunburns can double melanoma risk.
• In the U.S., nearly 6 million people are treated for skin cancer each year.

That means the worst move is skipping protection altogether because the ingredient debate feels messy. The goal is to find something you will use consistently.

What "chemical sunscreen" means, and why people are uneasy about it

Chemical sunscreens rely on UV filters like oxybenzone, octinoxate, octocrylene, avobenzone, homosalate, and octisalate. The promise is simple: thin feel, easy rub-in, no white cast.

Under real-world use, the assumption many people make is that these ingredients mostly stay on the skin. But the research suggests they can be systemically absorbed.

In an FDA-led clinical trial, participants applied sunscreen over most of their body multiple times per day. Researchers then measured sunscreen active ingredients in blood. The study was designed around a key FDA screening concept: 0.5 ng/mL in plasma. This number is not a "safe vs unsafe" line. It's a trigger point the FDA uses to decide whether an ingredient needs more safety testing because measurable absorption is occurring.

In that trial, blood levels exceeded 0.5 ng/mL for all tested products after the first day. Some ingredients were multiple times higher than the screening level. Most notably, oxybenzone reached peak levels around 169 to 209.6 ng/mL, which is about 339 to 419 times higher than the FDA trigger point.

Why does this matter? Because sunscreen use is not a once-a-summer thing anymore. National survey tracking shows a large share of adults report using sunscreen regularly, and the trend has been rising over the long run. For example, the NCI's Cancer Trends Progress Report (NHIS data) reports 36.5% of U.S. adults used SPF 15+ sunscreen "always or most of the time" in 2020.

So if you're weighing "FDA-allowed" versus "fully understood," a reasonable takeaway is: absorption is real, and long-term certainty varies by ingredient, so it's fair to question whether you want those filters as a frequent habit.

What are the potential harms of these chemicals?

If our bodies are absorbing chemical sunscreen filters systemically, the next question is simple: what harms can they cause?

One concern is endocrine disruption. A 2023 review and meta-analysis in Environment International concluded that benzophenones (a class that includes oxybenzone) have evidence consistent with endocrine-disrupting properties. Endocrine disruptors interfere with your hormone system by mimicking, blocking, or altering hormone signals, which matters because hormones help regulate reproduction, thyroid function, metabolism, and development.

Another concern is what happens over time in real life. If you leave sunscreen in your car all summer, a 2021 study in Chemical Research in Toxicology reported that octocrylene can degrade into benzophenone in sunscreen products. Benzophenone is classified by IARC as "possibly carcinogenic to humans."

And it's not always "totally safe on skin," either. A case series in JAMA Dermatology reported photoallergic contact dermatitis linked to octocrylene exposure, meaning some people can develop a sun-triggered allergic reaction after using it.

Put together: if a product can be absorbed, can form a potentially carcinogenic breakdown product, and has documented allergy reactions, it's reasonable to question whether you want to use it every day.

Chemical sunscreens and the ocean: what's the evidence?

Sea life and coral reefs are already under major pressure from warming oceans, and sunscreen pollution is adding to that stress, especially in shallow, heavily visited areas where concentrations can build up.

• Coral: In lab tests, the UV filter oxybenzone has been shown to harm early coral life stages. Researchers observed things like bleaching and deformities in coral larvae, and the effects were stronger when the corals were exposed to light.
• Fish: In fish embryo studies, oxybenzone exposure has been linked to development problems and lower survival and hatching success, meaning fewer embryos successfully develop and make it to hatch.
• Dolphins: Researchers have detected sunscreen UV filters in dolphins, and there's evidence of mother-to-baby transfer because UV filters have been found in dolphin milk/placenta samples in field studies.

One of the clearest "this is not just internet noise" signals is policy: Hawaii made it unlawful (starting January 1, 2021) to sell sunscreens containing oxybenzone or octinoxate without a prescription.

You do not pass laws like that because the science is perfectly settled. You pass them because the risk, combined with the stakes, is high enough to justify acting before every last question is answered.

Why mineral sunscreen looks like the safer bet for cautious people

Mineral sunscreens use zinc oxide and titanium dioxide. Instead of relying on organic filters that may absorb and circulate, minerals are used as inert particles that primarily remain on the skin's surface to block and scatter UV.

From a regulatory standpoint in the U.S., these two mineral actives are also in a different category than most chemical filters. The FDA has repeatedly pointed to zinc oxide and titanium dioxide as the actives with the safety data needed for "generally recognized as safe and effective" status in its sunscreen framework, while requesting additional data for many other ingredients.

From a dermatologist perspective, mineral sunscreens are commonly recommended for sensitive skin because they tend to be less irritating.

From an ocean-impact perspective, NOAA notes mineral sunscreens are often considered a better option because they do not use the same chemical UV filters that have shown more effects in aquatic organisms.

If your personal decision rule is "minimize uncertain exposures for me and minimize questionable additives washing into the water," mineral is the straightforward answer.

The only real downside: mineral sunscreen can be a pain to remove

Mineral sunscreens work because they stay put. That is also why they can leave a white cast, cling to hairlines and eyebrows, and linger after a quick shower. If you have ever searched for how to get that zinc film off your face without scrubbing your skin raw, you are not alone.

This is where people quit mineral and go right back to the "invisible" chemical formulas, even if they do not feel great about it.

The fix is not more friction. It is better chemistry.

Oil-based cleansing (balms, oils, and emollient removers) is a common approach for breaking down stubborn sunscreen films before a gentle rinse. The core idea is simple: dissolve first, then wash away, instead of abrading your skin barrier.

And if you want a purpose-built option designed specifically around that mineral residue problem, Kook-Off is made to break down mineral sunscreen and lift that leftover film so you can actually stick with the sunscreen choice you feel best about.

Conclusion

If you came here because you heard chemical sunscreens might be "bad," the more evidence-based takeaway is that some chemical UV filters raise enough unanswered questions, including systemic absorption findings and environmental concerns, that a precautionary beachgoer may reasonably decide the risk is not worth it when mineral options exist.

Mineral sunscreens have the cleanest regulatory footing in the U.S., tend to be friendlier for sensitive skin, and are generally the more reef-conscious direction, with the one catch being removal.

If the only thing holding you back is that stubborn zinc layer, would switching to mineral feel like an easy call if you knew you could wipe it off clean after the session with Kook-Off?