The SPF Series: Everybody Loves Radiation

Can you guess which side of the road this guy has been driving on for the last 30 years?

I am sorry that I just unleashed that pun upon you. It is my sincerest hope that by the end of this absurdly long series on SPF, that horrible pun will be but a memory, like Ray Romano's career should be.

Seriously, kids, this is going to be a long ride. Like, watching The Lord of the Rings series in one sitting long. And rightfully so, because oh my goodness is SPF a massively important, albeit complicated, cookie. How so, you ask? Well, according to the most recent estimates, "40-50 percent of Americans who live to age 65 will have skin cancer at least once," and furthermore, UV rays (ultraviolet rays found in sunlight) constitute perhaps the largest extrinsic aging force. Keep in mind, too, that our understanding of skin cancer development and photoaging is constantly evolving - for example, it's only within the last two decades that researchers have come to suspect that UVA rays contribute to the development of skin cancer; previously, it was widely accepted that only UVB rays played a role in the development of skin cancer and -

HOLD UP.

I suppose it is prudent to first provide some sort of framework for whatever the hell it is I am rambling about - please excuse me, I am easily excitable (and I need to get this information in writing before it leaves my brain and is replaced with the Real Housewives of New Jersey's season premiere).

These UV rays, what are they? Why are they divided into two categories?






That's an excellent question, friend. Ultraviolet radiation is a bit of the light (meaning it's on the electromagnetic spectrum, but let's avoid layman's terms) produced by the sun that actually reaches the earth, but it is not the light we experience with our eyes. UV rays are invisible to the human eye because they possess wavelengths shorter than visible light. Unfortunately, like an expulsion of silent gas, UV rays can be deadly. UV radiation can damage cellular DNA, causing mutations which potentially could lead to skin cancer.

UV rays are subdivided into several categories based on wavelength, though let's only concern ourselves with two, A and B (this shit's already too complicated).

UVA vs. UVB?

UVA rays comprise the majority of UV radiation that reaches the planet's surface, and therefore are the rays to which we are most exposed. UVA rays are less intense than their B counterparts, but are present in relatively similar intensities throughout the year, rain or shine; January or May, you gotta watch out for that UVA (someone stop me). UVA rays have a long association with photoaging, yet only recently has research emerged suggesting a connection between UVA and skin cancer.

That said, when we think of sun damage, UVB rays are what come to mind. UVB visibly affects the epidermal layers, causing reddening and burning of the skin. Scientists have long accepted that UVB exposure greatly increases the risks of skin cancer.

I thought this series was on sunscreen.

Nothing gets by you, oh sweet, gentle readers. You're right, of course, this is about SPF, I just have a roundabout, confusing, and unnecessary way of getting to a point. We're almost there!

Sunscreen and sunblock (yup, there's a difference!) are products, most commonly lotions, formulated to provide protection against those harmful UV rays. Sunscreen filters UV rays, allowing some to penetrate the skin - generally, sunscreens leave less of a white film and more readily absorb into the skin. Sunblock, as the name implies, physically reflects sunlight, and as you might imagine, goes on thicker.

Are you ready to hate me?

Sunscreen and sunblock are dated terms; I prefer chemical and physical SPFs. More on this next post, though.

Do I even want to ask you about SPF? I stopped caring at Ray Romano.

One last answer, I promise! It'll be brief! Stay, don't go!

I'll pay you!

... in SPF knowledge! Sun protection factor (SPF) is how we measure the effectiveness of a product against UVB rays. I'm using the royal We here, because obviously I'm doing zero measuring myself - it's better for everyone that way. Essentially, human volunteers are spot tested with a product, subjected to machines that simulate sunlight, and our good scientist friends record the results. Based on those results, a numerical value can then be assigned to the product. Unfortunately, those values are rather misleading, being highly dependent on subjectivities. That said, I promised that I would be brief.

Stay tuned for more information on SPF testing, formulation, and variations!

-Pseudonate