how to use sunscreen effectively

by crumpetsandt

hope everyone had a wonderful weekend! on saturday temperatures reached 90 degF in norcal…boy was it HOT! the sun was shining beautifully and i was starting to feel the sizzle of the sun’s rays on my skin.  appropriately, right before the weekend i had a convo with my good friend c. f. c. about spfs and i decided that it is now an apt time to climb onto my soapbox and talk about sunscreen =D

a super clear and sunny day in boston (the boston skyline...awwww memories)

a super clear and sunny day in boston (the boston skyline…awwww memories)

how fitting that my first post on beauty should be on sunscreen–most who know me know that i’m a big sunscreen advocate/enthusiast/patroness (haha). you name the sunscreen and i’ve probably obsessed over it extensively and/or tried it. as an organic/organometallic chemist, i would like to assert i have some extra insight into sunscreens that i believe the general public does not have, mainly that i (1) understand what chemicals are put in there (and believe me, all sunscreen contain chemicals which block the sun’s UV rays albeit via different means, despite company claims of “chemical-free” products), (2) know what the chemical structures of the ingredients look like, and (3) can discern, after reading all the technical papers and whatnot, what chemicals will provide superior “burn protection” from the sun. i’ll attempt to break down the technical jargon a bit and provide as little technical detail needed for the normal reader to understand. DISCLAIMER: i am a phd (in chemistry from a very reputable institution) and not an M.D. which means i can’t give medical advice (e.g. how to prevent skin cancer, what to do in case of an allergic reaction to a beauty product, etc.) BUT can help demystify what makes a sunscreen effective chemically.

a beautiful california day =)

a beautiful californian day =)

firstly, let me say that there is a growing chemophobia in the general public and this often translates into blind fear and irrational aversion of chemicals. chemicals are apparently “very, very bad” in the public eye right now, with the fear of parabens and sulfates (ALS, SLS and others) being two of the more publicly discussed ones. whether these two particular chemical classes actually cause bad things to happen (health problems) has not been definitively established in the scientific community but has been, in my opinion, more of a marketing ploy by cosmetic companies and others to sell a new class of products to the public. i personally still use sulfate-based shampoos just because, well, they clean my hair REALLY effectively and because most cleaning agents chemically “look” similar and clean because they have a fatty end (to trap oils, dirt, ewww-y stuff) and a charged, anionic [negatively charged] end (to allow the cleaning agents to be washed away with water). so, we therefore must keep a sober, rational air when dealing with chemicals and not let hysteria dictate our chemical judgment.

so back to sunscreens…we need sunscreen ourselves to keep the unclothed parts of our body from “burning” from prolonged sun exposure because the sun emits UV rays which in turn do crazy damaging things to our cells and if we’re unlucky, to our DNA. nice, right? i would classify the “active ingredients” in sunscreens into two categories by the means of sun protection: (A) via absorbing the UV rays with the “active ingredient,” commonly and [wrongly, see discussion above] known as “chemical sunscreens” OR (B) via physically blocking the UV rays, commonly and [wrongly, see discussion above] known as “non-chemical sunscreens” or better known as “physical sunscreens” [okay nomenclature here]. sunscreens can contain chemicals that are of (A) nature only or (B) nature only OR a mixture of multiple chemicals that each acts as (A) or (B).

let’s just make this clear right now: BOTH (A) and (B)-acting active ingredients are CHEMICALS. everything on the planet is made of chemicals: water (H2O), salt (NaCl), air (dinitrogen, dioxygen, etc.) so you now know why i get really frustrated when people call products “chemical-free”!  the chemicals used in (A) normally are aryl-type chemicals, meaning their chemical structure is based off a 6-carbon ring with alternating single and double bonds between the carbons. the chemicals used in (B) are typically transition metals bonded to oxygen atoms such as zinc oxide or titanium dioxide. ironically the public scare about sunscreen demonizing the chemicals of (A) and supporting the chemicals of (B) uses the reason that (B) is more “natural” (my hackles are rising, haha) and is COMPLETE B.S. (speaking to the rationale, not the conclusion that (B) is superior).  because realllllllly, how “natural” is (B) if you’re slathering yourself with metal oxides versus carbon-based material? METALS! *sighs and shakes head* okay…back to the topic of which type of active ingredient is superior…while the ingredients of (A) ARE carbon-based, they tend to cause dermatitis (skin rashes, allergic reactions…something that i’ve often experienced with certain (A)-sunscreen type chemicals) and some are implicated in small animal (think mice and rats) toxicity in studies. because i have sensitive, eczema-prone skin, the only two (A)-type chemicals that i’ve not had a problem with (gotten a rash from) are octinoxate and octisalate. i’m sure tolerance to (A)-type sunscreen chemicals will differ from person to person so these sunscreen active ingredients shouldn’t be tossed out as possible options (caveat: see below for final verdict and rationale).

so, the verdict? suncreens that have (B)-acting sunscreen chemicals OR a combination of (A) and (B)-acting sunscreen chemicals are superior. why? because (A)-type chemicals tend to decompose over time and especially when they are in contact with UV rays. they are not “photostable” meaning that if they absorb UV rays, over time the active ingredients will break down. if you use sunscreens that only have (A)-type chemicals, you’re screwed once those molecules decompose because now you have nothing to absorb those pesky UV rays. also the idea of my body absorbing molecules of type (A) that absorb UV light kind of grosses me out and also makes me literally rashy (see above paragraph). i’m more of a “let’s keep the sunscreen chemicals on top of my skin as a thin layer” aka (B)-type of girl. (B)-based suncreens use chemicals to physically “screen” out the UV rays and sit on top of your skin until you wash it off. (B) is not without its drawbacks though; it is often white and pasty to put on (makes sense, titanium dioxide and zinc oxide are both opaque, white chemicals). good news though: sunscreens have come very far in cosmetic elegance and there are a few good aesthetically pleasing options which don’t skimp on the sun protection. i will list them at the end of the post.

as for how high of an spf, is it really true that the higher the spf (like 70, 100) is better than lower spf values (like 15 or 30)? this is where my expertise is lacking BUT after reading quite a bit from reputable resources [see here, here, here for some general readership-friendly examples], the consensus is NO. it turns out that spf 15 blocks about around 93% of UVB rays (a class of UV rays), spf 30 blocks out around 97% of the UVB rays while spf 50 blocks out 98% of the UVB rays with minimal increase in UVB blockage with spfs higher than 50. additionally, it was found that people who use those higher spfs often don’t put on enough sunscreen AND/OR don’t reapply often enough and thus are lulled into a false sense of security and end up getting way less than the label’s worth of spf protection. i’ve heard that the golden rule for an adult is to use at least one shot glass full of sunscreen for one’s whole body.

okay now for the fun part! which ones do i like and recommend to use?

for the face: cosmetic elegance is really important here. no white casts please! note that i have really fair skin but some of my tanner friends have used these without scary ghost face. i’ve used laura mercier’s flawless face daily skin shield, shiseido’s urban environment oil-free UV protector spf 42, as well as origins’
out smart spf 25 (i think now discontinued) all before and they are all very cosmetically elegant, non-oily feeling, non-shiny, and pretty standalone or under makeup. i personally use badger aloe sunscreen spf 16 because i really like the consistency, application, and look standalone and the price is much, MUCH better (read: wayyyy less expensive) than the previous ones i listed (but may be too white cast-ish for tanner skin tones). i’ve read that the coppertone’s sensitive skin faces spf 50 is pretty nice too (don’t know why it was formulated with so high of an spf…*rolls eyes*) but i haven’t tried it out yet.

for the body: cosmetic elegance is less important here and cost effectiveness is much, much more important. i think coppertone’s pure and simple spf 50 (once again, haha, a higher spf probably formulated and marketed for buyers) is a good choice and comes in a pleasant scent. note that some reviewers of sunscreens complain about sunscreens not being “waterproof” and i would just like to say serves their own [scientific] stupidity. ANY company that says their sunscreen is “waterproof” (and buyer believes it) should get their butts kicked as there is only WATER-RESISTANT sunscreens and frequent reapplication is a necessary process, after water immersion (depending on the brand, but often after 30 mins) and after a couple of hours if you’re on dry land (albeit sweating like a pig in the sun haha). i’m sure there are other good body sunscreens but i recommended the coppertone pure and simple one because of the kick-ass chemical safety ratings it received (use of low “toxicity” chemicals if you’re concerned about things like that).

okay this has been a reallllly long post but i hope it has been a helpful and informative one. practice safe sun everyone!