The Sunscreen Trials Were Run in Queensland

The evidence that sunscreen prevents skin cancer is good. I want to say that first, because the rest of this piece gets quoted out of context by people I would not like to be quoted by.

It is good, and it comes from Nambour, a town in subtropical Queensland, where researchers ran a randomized trial through the 1990s on a population of overwhelmingly fair-skinned Australians living under some of the most punishing ultraviolet on earth. It worked. Daily sunscreen reduced squamous cell carcinoma and, in longer follow-up, melanoma. That trial is the backbone of almost every confident sentence written about sunscreen since.

Now go looking for its counterpart in a Black, South Asian, East Asian or Latina cohort.

There isn’t one.

What “unknown” is doing here

There are two bad ways to read this and I want to close both of them before anyone gets there.

The first is the one that has already been made into a thousand posts: the trials weren’t done on us, therefore sunscreen is a scam sold to people who don’t need it. That does not follow. Ultraviolet radiation damages DNA by a mechanism that is not negotiable by ancestry. Melanin reduces UV penetration by roughly a factor of three, which is real and which is not thirty. Photoageing happens in richly pigmented skin, later and less visibly, but it happens. And acral melanoma — the subtype that accounts for a hugely disproportionate share of melanoma diagnoses in patients of color — turns up on the palms and soles, where pigment is not doing you any favors anyway.

The second bad reading is the professional one: this is a technical quibble, the mechanism is obviously sufficient, stop making trouble. I have less patience with this one, because the same field that considers mechanistic extrapolation adequate here demands randomized evidence for essentially everything else it sells.

The honest position is in the middle and it is uncomfortable, which is presumably why so few people occupy it. We have excellent mechanistic reasoning and no direct outcome data. Two 2026 reviews say exactly this, in print, framing it as an open gap rather than settled science. That framing is correct and it is roughly forty years overdue.

The vitamin D problem has the same shape

Watch this happen twice.

In 2019, an international consensus panel led by Passeron examined whether sunscreen use compromises vitamin D status. Their answer was clear: it does not. Real-world sunscreen use, even under optimal application conditions, did not meaningfully reduce serum vitamin D in the studies available. A holiday-UV study in Tenerife found SPF 15 users still achieving considerable vitamin D production.

Then the panel added a sentence that almost nobody quotes alongside the reassurance. Studies to date, they wrote, have been done with lighter-skinned individuals, and the conclusions may not apply to those with skin types IV to VI who use sunscreens. In such cases, oral supplementation may be advisable.

That is the panel telling you the reassurance does not extend. In the same document. Under the same heading.

Vitamin D deficiency is markedly more prevalent among African Americans than white Americans — that much is well documented in the NHANES literature. So the population with the most deficiency to begin with is the population the reassuring studies excluded, and the advice they get is the reassurance without the caveat.

Why I am telling you this rather than just saying wear sunscreen

Because the version without the gap in it does not survive contact with a skeptical reader, and it should not.

Somebody with deep skin who has been told her whole life that sunscreen is non-negotiable, then finds out the trials were run on fair Australians, has been handed a reason to disbelieve everything else in the same sentence. That is what happens when an industry oversells its certainty: the first crack takes the whole wall.

The stronger argument is the true one. We know what ultraviolet does. We know melanin helps and by roughly how much. We know it helps least exactly where the dangerous subtype appears. We know the pigment problem — the marks, the melasma, the shadow that outstays the spot — runs on visible light that no sunscreen is tested against and that a tint partially addresses. And we know nobody has run the trial that would close the loop, which is a failure of the research enterprise and not a reason for you to make a decision in the dark.

Use it for the marks. Use it on your hands and your chest and the side of your face that faces the window. Check your soles and your nail beds, because that is where the thing that kills people actually shows up in your skin, and no sunscreen was ever going to help with that.

And if a brand tells you their product is clinically proven to reduce skin cancer risk in all skin tones — ask which trial. There is a very short answer.

And treat the number on the front with the same skepticism. Seven laboratories testing the same SPF 50+ product returned answers from 62.4 down to 5.5, and the endpoint all of them were measuring is how pink a panel of skin goes.

This article is educational and is not a substitute for care from someone who can look at your skin. Anything new, changing, painful or spreading should be assessed rather than researched.