Not All Sunscreens Are Created Equal

The question the study did not ask

Here is the part we find more interesting. The study recorded whether people used sunscreen. It did not record which sunscreen.

That is a genuine gap, because sunscreen is not one product. Mineral sunscreens use a physical filter — zinc oxide or titanium dioxide — that sits on the surface of the skin. Chemical sunscreens use synthetic filters that absorb into the skin and convert UV energy there. Same shelf, same SPF number on the front, different formulations behind it. A study that groups them together cannot tell you anything about the difference between them, and this one did not set out to.

Which is why our takeaway is not that you should stop wearing sunscreen. It is that you should turn the bottle over and read what is in it.

What is in ours

3rd Rock Sunblock is a mineral sunscreen. The active ingredient is zinc oxide at 23.5%, giving broad-spectrum SPF 35 coverage across UVA and UVB. The formula is patented and has been independently tested against standard sunscreens.

The rest of the list is short and food-grade: vegetable glycerin, distilled water, jojoba oil, olive fruit oil, aloe vera leaf gel, beeswax with propolis, orange peel wax, coconut oil extract, tocopherol (vitamin E), ascorbic acid (vitamin C), and natural corn and arrowroot starches. No synthetic chemicals. It is water and sweat resistant, hypoallergenic, and gentle enough for sensitive skin. It is CertClean certified, Leaping Bunny approved, PETA certified and made in the USA.

Guerry Grune, who founded the company, is a PhD chemical engineer and a lifelong surfer. He built the formula after a close friend was diagnosed with melanoma, with one requirement: it had to be made entirely from food-grade ingredients he was willing to put on his own skin and carry into the water he surfs in. That requirement is the whole reason the ingredient list reads the way it does.

It comes in unscented, aromatherapeutic and infant formulations, so there is a version for most skin types and most preferences.

What to do with all this

Wear sunscreen. Reapply it after swimming, after sweating and after long stretches in the sun, because that is where most people actually lose their coverage. Then, when you next replace the bottle, spend thirty seconds on the ingredient list the same way you would on a food label.

Not all sunscreens are created equal. That is the part the headlines skipped.

FAQ

Does this study mean I should stop wearing sunscreen? No. It is an observational study and it cannot show that sunscreen caused the cancers it recorded. The most likely explanation for the pattern is that the people most at risk of skin cancer are also the people who use sunscreen most.

What is the difference between mineral and chemical sunscreen? Mineral sunscreens use a physical filter, usually zinc oxide or titanium dioxide, which sits on the skin. Chemical sunscreens use synthetic filters that are absorbed into the skin. 3rd Rock Sunblock is a mineral sunscreen built on zinc oxide.

What SPF is 3rd Rock Sunblock? Broad-spectrum SPF 35, from zinc oxide at 23.5% concentration, covering both UVA and UVB.

How often should I reapply? After swimming, after sweating, and after prolonged sun exposure. Apply it evenly, warming it between your palms first so it goes on smoothly and finishes invisible.

A study of more than 470,000 people has been going around this week, and the headlines built on top of it all say roughly the same thing: people who use sunscreen get more skin cancer. It is an alarming sentence, and it is worth ten minutes to understand what actually sits underneath it.

The short version is that the study is real, the numbers in it are real, and the conclusion most people are drawing from them is not one the study can support. Here is what it found, and what we think the useful takeaway is.

What the study looked at

The research draws on the UK Biobank, a long-running health database covering more than 470,000 adults. Researchers compared how often people reported using sunscreen against how often they were later diagnosed with skin cancer.

People who reported frequent sunscreen use had higher recorded rates of all three main skin cancers — melanoma, basal cell carcinoma and squamous cell carcinoma. The associations were large: close to four times the rate of melanoma, and a little over twice the rate for each of the two carcinomas. The researchers adjusted their figures for a list of the obvious factors, including age, sex, skin type, how easily someone tans or burns, sunburn history, sunlamp use and time spent outdoors.

Why “linked to” is not “caused by”

This is an observational study. It followed what happened to a large group of people over time. It did not assign anyone to use sunscreen or to go without it, which is the only kind of study that can establish cause. The write-up says so directly: it cannot prove sunscreen directly caused cancer.

That distinction matters more than usual here, because there is a straightforward explanation sitting right next to the data. The people who reach for sunscreen most often are, broadly, the people who burn most easily and who spend the most time in strong sun. Those are also the people who are diagnosed with skin cancer most often. Statistical adjustment reduces that overlap. It does not eliminate it. When the main reason someone uses a product is itself a risk factor for the outcome being measured, the two will travel together in the data whether or not one is causing the other.

So this is not a finding that sunscreen causes skin cancer, and the researchers have not claimed that it is. Reading it that way and then going out unprotected would be a poor trade.