Wait, what’s the deal with sunscreen? Whether it works

But for skin cancer, this picture is a bit cloudy.

There are two basic types of skin cancer: melanoma and nonmelanoma. The majority of skin cancers are nonmelanoma and can be further classified as either squamous cell carcinoma (SCC) or basal cell carcinoma (BCC). If you Had If you are likely to choose the type to get cancer, you might choose BCC. BCC grows very slowly and rarely metastasizes. Melanoma, on the other hand, is often much more severe. It accounts for the few cases of skin cancer, but causes most deaths.

We have the sun Cause Skin cancer. The question is whether to use sunscreen protect On the other hand. Intuitively, it seems like that. It is known to absorb the UV photons that cause sunburn. However, cancer researcher John DiGiovanna said: “Sunscreens are not protective clothing. They can be overcome by too much sun.” Some sun photons can reach your skin perfectly, unless you soak yourself in a sunscreen pool. This is one reason why the FDA doesn’t allow manufacturers to use the word “sunscreen.” But there is also this:

1. Photons have different energies

2. Photons of different energies can do different things on your skin

3. Different sunscreens may absorb photons of different energies differently.

It’s a bite. Let’s break it down.

In Copenhagen, 1932, many physicists drunk and created arbitrary divisions in the UV at the Second International Light Congress, which sounds like a gathering of some sort of Illuminati. Any of these categories will almost certainly have been seen before. They are called UVA and UVB and are probably described roughly by dermatologists as follows:

UVB causes sunburn (and some cancers).

UVA causes wrinkles (and some cancers).

This isn’t exactly the case, but it’s a completely fine simplification for our purposes. Early sunscreens absorbed UVB photons very well and UVA photons. . . These bad sunscreens may be called “narrow spectrum”. The narrow spectrum is also great for shielding from UVB photons that cause sunburn, but it must also absorb UVA photons to protect against a wider range of sun photonic attacks. Therefore, the label “broad spectrum”.

The FDA allows any sunscreen with an SPF of 15 or more to pass its broad-spectrum test and declare that it “reduces the risk of skin cancer.” . . Caused by the sun What is the proof of that claim?

Uh. . .

Good . .

It’s a bit embarrassing to admit this, but so far 1 A randomized, controlled trial that tested whether sunscreen could reduce the risk of skin cancer, which was primarily focused on nonmelanoma skin cancer. It turns out that sunscreen did not change the number Man I have had squamous cell carcinoma or basal cell carcinoma number Number of squamous cell carcinoma tumors diagnosed per person. This isn’t exactly the type of evidence you want, but I would like to point out two elements in the defense of this case. First, it was implemented in the 1990s. In other words, they used pretty old sunscreen technology. If you try again with modern sunscreen you can expect more dramatic results. Second, the control group of the test did not prevent the use of sunscreen. It would have been unethical. They were allowed to use sunscreens, but they used less than full sunscreen groups. We also expect more dramatic results if people in the control group are prevented from using sunscreen.^Five

How about melanoma? Again, here is the evidence. . . Not ideal. The only randomized controlled trial for adult melanoma was, in fact, a continuation of the study I just discussed. Both this trial and some cohort studies suggest that sunscreen has a protective effect.

Data on the incidence of melanoma show some paradox. Many whites around the world use sunscreen, but the incidence of melanoma has not declined or leveled off. In fact, in the last 30 years They are almost Three times. If sunscreen prevents skin cancer, why is the melanoma rate increasing?

One of the explanations is that even though people use sunscreen, people are enjoying sunburn and burning crap more than ever before. Way More sun than they used before. The hypothesis is that people would have an even higher incidence of melanoma if they didn’t use sunscreen.

But there is another hypothesis. This has been controversial, although it was facilitated by a Belgian epidemiologist named Philippe Autier and supported by two (small) randomized controlled trials that helped him conduct it. Autier believes in the use of sunscreen among white people who actually want to sunbathe To increase Total exposure to UV light that can lead to melanoma. His idea goes as follows. Whites intentionally like to get sunburn and tan, but they don’t like to burn. So they buy an ultra-high SPF sunscreen that effectively absorbs most of the photons that cause sunburn. But they Absent Tanning, these whites stay in the sun for much longer than they otherwise would have their bodies.

Basically, Autier believes that sunscreens can help you avoid the biochemical “Solar GTFO”. Warnings, and thus exposure to the sun, can be overdose. In a 2011 paper, he even said the recommendation recommending reapplying sunscreen, as required by US law, “probably represents a form of abuse.”