The Science Behind White Cast and Sunscreen Inclusivity with AJ Addae

0:00Ekta Yadav:Hey guys, welcome back to Skin Anarchy. This is a very, very special episode. We are going to be learning a lot today, and especially in the realm of sunscreen and understanding why things are not inclusive in the sunscreen space and how do we make them inclusive. So our guest today is a true expert in this field. She is an innovator. She is a trailblazer, and I am so honored to host her. So please welcome AJ Addae, who's an award-winning cosmetic chemist and clinical researcher and now soon-to-be doctor Addae. So welcome, AJ. Oh my goodness. Thank you for that introduction. Like I'm flattered.

0:32Ekta Yadav:Oh no, it doesn't do you justice, please. I was like really brief with that, you know, but I could, I could rave about you for hours. I mean, you're so impressive. I want you to tell your story because I don't want to miss anything. I want you to tell us about what got you into science. Like honestly, I really want to know, like, where did you realize, when did you realize in your life, I want to do chemistry. I want to go into science. Walk us down memory lane. Okay. So I'm glad that your question is what got you into science and not necessarily what got you into beauty, because I've worked in cosmetic science labs where there's men, right?

1:03No one ever asked them like, what got you into beauty, right? Like they see them as scientists. And that's kind of the lens that I think I approach this love beauty though. I think I've always had ever since I was little, like kind of a love hate relationship with beauty where I liked the idea of, you know, cosmetics and everything like that. But I think it came from a perspective of I'm a darker skinned woman. I have very like kinky, coily hair. You know, there are these things that you grow up with as a dark skinned, you know, first generation immigrant child that just you don't feel like you're tapped in sometimes.

1:37And beauty is one, I think, area where a lot of us kind of feel like we aren't immediately included or tapped in. So that's where my love hate relationship started. Even like, honestly, to a point where when I was 11, I was writing articles on back when wiki how was was a little early i was writing articles on wiki how about like how to make a you know lip balm that compliments to duotoned lips and stuff like that and those would get hundreds of thousands of views they had no idea that an 11 year old was writing so i think where the story really begins is you know we were just talking about our backgrounds you're saying that you grew up with your dad as a professor my dad was also a professor and still is.

2:19Yeah. He's, I mean, like, to be honest, like dad, if you're listening, you already know this. So I'm going to say it anyway. It's like, I feel like I don't quite understand what feels my dad's in, but you know, it was cool. I enjoy, I grew up close to the academy and one expectation that my parents had for me was you're going to go to school and you're going to be an MD, you're going to be a doctor. And that was just so not my vibe. And it still is not my vibe. You know, no, no offense to doctors. Like y 'all are great, but I feel like It's just not my calling. That just wasn't where I felt called.

2:49And I'm the type of person where my heart has to be in it for me to show up every day.

2:52Ekta Yadav:You know, I went, I still went to college. I got a biology major. I honestly didn't like most of it. But I went to Northeastern University and like they have this thing called a co-op program where you have to take six months off at a time, you know, once or twice in your whole time there for you to go work a full time job. And I was panicking because everyone around me was doing research and all these things. Meanwhile, I was more artistic. I was a writer. I wanted to be an English major. And I had actually written at the time in college an article called Why the Beauty Industry Has Failed Darker Women.

3:23And I didn't think anything was going to come of it. But when it came time to do my co-op, I ended up thinking like, what is a way for me to merge my biology major and like my artistic endeavors and just things that I'm interested in and care about? And this was like at the height, maybe the height of like Glossier. So that was like what was really popping at the time. And I was like, beauty is actually a really great place to be doing that. So I took a stab at it. I ended up doing my co-op at a skincare company. They've since been acquired. And it was really cool seeing the R &D in the background and everything like that.

3:56Living proof, by the way, if you are listening, I did apply to a co-op at your company and I got rejected. And I'm still salty about that to this day.

4:03Ekta Yadav:Why would you get rejected? Why would y 'all reject? No, I'm just kidding. We love living proof. I'm calling you out too. We love living proof. But so really what ended up happening there is I fell in love with the R &D behind beauty and that I wanted to immerse myself in it fully. I started working at Credo, like picking up shifts there. I started learning about products, CPG. I started learning about startups and just kind of the rush that you get from running so lean and scrappy and like still having a lot of success and reach. You know, we did a lot of partnerships at the brand that I was working with where I got to learn brands like, you know, all the indie beauty companies that were really rising at this time, like the late 2010s.

4:42And then after I graduated from college, actually a little bit early, I started working at a medical grade, you know, whatever that means, a skincare company and their partner contract manufacturer, where I was making things like sunscreens, like emulsions, you know, all types of formulator things. And before that, I was actually doing academic research at Northeastern, you know, formulating sunscreens as well. So formulation just kind of became the thing that I thought I was pretty good at. I liked being able to put things together, understand the impact that it had on skincare and haircare. But ultimately I kind of hit a wall where one of my biggest projects that I was working on was a sunscreen when I was working at the manufacturer and the medical grade skincare company.

5:24And it was a sunscreen that was meant to not have a white cast and still includes zinc oxide, titanium dioxide. Now, as we know, that is very hard. And I was pretty immersed at this point. Like I was doing, I was running clinical research. I was writing papers with the company. Like I was really into the research world. And every single paper that I came across was like, this is hard. Every single supplier that I came across, this is hard. And what kind of made it difficult for me as well was when it came time to approve formulations, people would spread it on their skin and they were Fitzpatrick one and two.

5:59I'm a Fitzpatrick six. And things would be getting approved because they're like, see, no white cast. And I'm like, no, no, no, we got to take that to the bench. Well, it matches your skin tone. What do you mean? Right. Exactly. So what ultimately really helped at the time was using a dispersion from a supplier that what they did was they like, you know, it was interesting. They improved the size of zinc oxide and titanium dioxide in such a way where it reflected light advantageously to a point where you saw less of a white cast. You didn't see like no white cast, but it was really playing around with the optics of the material.

6:32And that really stuck with me because it's the formulation as much as it is the actual optical properties of the zinc oxide, titan dioxide, iron oxides, maybe even if you're using them in the formula.

6:42Ekta Yadav:So, you know, I didn't really like the idea that a lot of things that are being passed, approved in formulations weren't really that inclusive. I could tell that the whole tested on all skin tones thing wasn't really that pursued, even in a medical grade setting, even in, and I'm talking, I was working with people that really knew what they were doing, but to me, I just felt so unreal. Like it just didn't really feel like it aligned with the calling that I had considering I'd written that article, like about beauty industry, failing darker skin women. So I had left the company and I actually came across the research grant serendipitously where it's like pick a project that Mary Stem and social justice will fund it a little bit.

7:19So they funded like$5 ,000. That was enough for me to, you know, secure small space and some materials and some hot plates and things like that. And I didn't really mean to start a business. You know, someone was asking me, hey, you work in this field. Could you make me a formula? And that turned into a client. And then one client turned into two, and then two turned into 10. And now Sula Labs is the company that started in 2021. And here we are almost five years later.

7:44Ekta Yadav:That's incredible. And you know, what's like, I think for me, what stood out so just obviously with your story, when I first learned about, I was telling you on on social media, I found a reel that was discussing your work and like your contributions to the space. And what struck me was like, this is a perfect example of how science first, and it leads to so much untapped innovation in a space like beauty. You know what I mean? Like you're absolutely right when you say it's not about the beauty. It's about where do we innovate in science to where it's translatable. And that's something I feel like we're missing.

8:17Ekta Yadav:We missed the mark there, you know? Absolutely. You know, and I see this a lot right now. I don't know if you agree in regenerative medicine. Take regenerative medicine as an example. I love regenerative medicine. I've been doing wound healing research for decades at this point. And now I'm looking at the space and I'm like, guys, this is not skincare. This comes from serious burn victim, injury related, you know, like research. We just do that in this industry. And there's nothing wrong with learning, but it's like we still have to acknowledge like science first. Exactly. And similar to you, like along the way, I realized that if I wanted to contribute to this industry the way that I know I can, like to my fullest potential, as well as my company contributing to its fullest potential.

8:54I was like, why not get a PhD in chemistry? So yeah, I've been doing that for the last four years. I'm actually graduating early because I just kind of have to do that. And I'm grateful to have made the progress that I've made. And actually a majority of my dissertation is everything sunscreens, formulations, white cast, interaction with the skin microbiome, you know, film forming, even challenging the theory of how we calculate sun protection factor and uva protection factor like it's very much i i'd be in the lab guys yeah that's that's so freaking cool i love that

9:27Ekta Yadav:because i honestly you know aj i'll tell you what sunscreen i mean obviously it's a major problem for like what you mentioned like the fitzpatrick's like the numbers that are later on but for everybody there's no reason at this point that we haven't figured this out like there's no reason why we should be stuck. And I feel like you're a perfect example of a young innovator that I'm like, why are we not pouring, like you said,$5 ,000? Why did a company not step up and be like, AJ, take this$5 million grant and run with it and go figure this out? You know what I mean? And we'll fund you, we will pay you, you do what you know you can do.

10:04Ekta Yadav:I mean, this is where I get stuck. Very early in this podcast, I brought this up and I feel like you're going to understand where I'm coming from. I literally was interviewing like a major executive and I said, why is there not a grant type of setup in the beauty industry that is funding emerging scientists that can actually innovate? Like, NH does this. Everybody's doing it. We have billions of dollars floating around in this industry and nobody wants to do it. I think a part of it is really that, and this isn't the case in every single industry, but beauty is very much dominated by market. Like, everybody wants their share, their exclusivity and this and that.

10:40And so when And there is actually really great emerging research. Take Celescence as example, which if you aren't aware of Celescence, they are a contract manufacturer that really focuses on sunscreens and making cosmetically elegant solutions. But, you know, they own everything that they've made, which is great, right? Like they started with a chief scientific officer and he does really great work. I also sometimes wonder what it would look like if we ran as fast as a company like Celescence does and made a lot of that research open access and publishing a lot more and a lot more rigorously than the beauty industries used to and really just improving the rigor of, you know, a lot of the fundamental science that governs how we, you know, substantiate claims and governs how we formulate, how we do things like stability testing, right?

11:24There's no major consensus on a lot of things. Beauty is unregulated in many ways, but I do definitely see a push towards aligning more with, you know, paint and coating industry and their academic rigor and nutrition, even though nutrition is a whole, that's a whole different episode guys. But yeah. So companies like Sula

11:45Ekta Yadav:Labs are part of the reason why. That's right. No, I want to actually dive into this because you had mentioned like in the beginning of the optics matter, you know, when it comes to these, like these molecules, understanding how they perform. And I would love for you to do a deep dive and understand like, what is it that you observed in the lab that you were like, this is how we need to shift our thinking. So basically sunscreens made with zinc oxide and titanium dioxide, for some reason, are preferred by consumers generally. I don't completely know why considering the fact that they leave a white cast, but I think a lot of it really has to do with people's safety concerns and how they interpret how organic filters, so things like ibibenzone, octisylate, homosylate, how those might possibly be less advantageous in maintaining sensitive skin claims and taking care of sensitive skin.

12:33We see an overwhelming preference towards zinc oxide, titanium dioxide. The difference, I guess, between zinc oxide, titanium dioxide and organic filters. So what people refer to as chemical filters, but they're both chemicals. So I refuse to refer to things as chemical filters. I'm glad you said that. The real difference is that zinc oxide and titanium dioxide are minerals, right? They're metal oxides. They are particles that don't naturally dissolve in emulsion systems. So they're really suspended, kind of like how glitter can suspend in a makeup. It's really just a suspension at the end of the day.

13:10The thing about zinc oxide and titanium dioxide, though, is that when they are in powder form, they like to form aggregates and those aggregates form agglomerates. You ever see like a sunscreen where there's settling at the bottom or maybe it's a little bit. That is the nature of what zinc oxide and titanium dioxide like to do. They just will one day not be suspended due to the nature of Brownian motion and all those things. So what we see when it comes to those particles is because they also reflect a lot of visible light, just as much as they absorb visible light, you see them. Anything that reflects visible light, we perceive as a color.

13:46Whereas organic filters, I'm sure they do reflect visible light, but just not to the same extent as you would typically see from zinc oxide and titanium dioxide. They are literal minerals for that reason. So when you put them in a sunscreen, you have two problems, right? One of which they're prone to aggregation and agglomeration. And the second one is because they reflect visible light, when they aggregate and agglomerate more, that visible light scattering increases significantly. So that's where you see pasty colors of that white cast when you rub it on the skin. So I published a paper a few years ago about like, okay, formulators, these are the properties of zinc oxide and titanobre oxide.

14:22Here's how you can reduce white cast. Maybe you should not use it as a free powder, you should put it in a dispersion so it can disperse really nicely into a formula. And that does take care of some of the aggregation and agglomeration. Maybe you could choose a smaller particle size because that smaller particle size scatters light differently in such a way that you don't see it as much. But then of course you run into things where you don't get non-nano claims, which honestly, I think those claims are BS, but you don't get

14:47Ekta Yadav:non-nano claims. There are all types of drawbacks and trade-offs when you're working with zinc oxide and titanium dioxide. But what I was interested in was thinking back to what made those sunscreens, and I was working at the medical grade skincare manufacturer, what made those dispersions that the supplier had sent me so successful? And part of it was a change in particle size. But what I've always been interested in is what about a change in particle shape? Because, you know, the particles aren't very uniform. They're not like perfectly spherical. They're just tiny little rocks that bump up against each other.

15:19So I had been really interested in some work from, shout out to Dr. Yogedra Mishra Kumar at the University of Southern Denmark. He spent the majority of his career synthesizing a particular shape of zinc oxide called a tetrapod. There's a core, and then there's kind of three spikes pointing out of that core in such a way that, you know, they're kind of needle-like spikes. And what's interesting about the tetrapod shape is instead, when you have two tetrapods that come near each other, they never fully touch because they're kind of like, you know, no pun intended, but an arm's length distance. So they don't aggregate and agglomerate the way that conventional zinc oxide shapes do.

15:54What they do is they form these networks that are kind of, they introduce like porosity into the formula, which is really helpful for the rheology of the formula. So what that means is it won't settle as much and the colloidal suspension remains really nicely intact for longer. But what I found the most interesting was I didn't see as much of a white cast when I formulated sunscreens using tetrapods. So I took it upon myself to kind of invent a dispersion that allows the tetrapods to settle really nicely into a formulation. And then I tested it in different sunscreen formats, water and oil, oil and water, so sprays, liquids, gels, all those.

16:32And I found that every single time the white cast was reduced in comparison to conventional zinc oxides that I was formulating with. And ultimately when I did some tests further in the lab, and this is, I guess I should mention, this is part of my PhD research. So when I did some tests in the lab, I found that it's because the way the light scatters and reflects with that type of zinc oxide synthesis, it's much more favorable in the sense that it reflects more warmer light versus just that white pasty light that you typically see with zinc oxide. So that made it closer to, I guess, the warmth that is more analogous to human skin tones.

17:12And then also the lessened aggregation agglomeration, as well as the particle size, was really advantageous for the spreadability and the longevity of the formula itself. So yeah, that work is published and y 'all can go read more about it.

17:26Ekta Yadav:That's so freaking cool. So like, essentially like what you were saying, like the appendages that are coming off, like the spikes, are they creating kind of a mesh then? Like it's like more of like a mesh-like configuration they lay down in? Is that what it is? it's not necessarily fully laid because you're always going to have some tetrapod arm that's pointing upward or like outward direction but for the most part it does follow that logic in the sense that it's like more spread over a surface really evenly it's more porous so yeah one could think of it like a mesh surface so like i want to go back to like what you were talking about with like chemical sunscreens like even though i agree with you with the word chemical please stop using that word.

18:07Ekta Yadav:I mean, I would love to understand where does this really fall in that efficacy part? Does this impact the efficacy of a sunscreen in the sense of like, is it better? Is it altered? I mean, what are your thoughts around that? I brought the chemical thing in because people always use that claim of like with chemical sunscreens and mineral sunscreens, they're talking for some reason, I always hear the efficacy argument between the two, which I never does this kind of new way of like chemically thinking about it, does it affect the long wear of a sunscreen, like sun protection factor? Like does that get impacted with this type of chemistry?

18:42Yeah. So whenever you are formulating a sunscreen, the sun protection factor, of course, has a lot to do with the UV filters, but it also honestly has a lot to do with the film formation and the adhesions. And I got a lot to say about the sun protection factor calculation. So I guess let's take a step back and talk about how sun protection factor is even made. And then we'll come back around. So SPF, you come to the claim of an SPF through an in vivo test, so a clinical test. And what happens is that there are about 10 volunteers that come into the clinic and then they get irradiated with UV light on different sites of their backs, specifically UVB light, because that light wavelength is more analogous to where sunburn comes from.

19:20And they get irradiated at different sites of their backs. Some have sunscreen applied, some have sunscreen not applied in the dosage and time scale of the UV radiation increases like over time.

19:30Ekta Yadav:So all SPF is, is really a measurement of minimal erythema dosage. So how long it takes for UV light, UV irradiation to turn the skin red, the ratio of MED of, you know, unprotected skin versus sun protected skin with the sunscreen. There's a lot wrong with this. One of which I know that I'm good. It's going to take a lot longer for me to turn red. So, you know, take that, which you will. I feel like that does kind of skew how SPF could be seen across, you know, a sample size. And then also like, it's a visual endpoint like MED, but also UVB specifically is all that is evaluated. Right. So when you think of UVA, that's where UVA PF comes up.

20:12That is a completely different type, not that different, but it's a different type of test. So when I think of SPF in general, I honestly think that there's a lot more work to be done on communicating to the public how efficacious their sunscreen is, because it's not just the protection absorption against UVB light. It's also against UVA light that needs to be taken to account, which is communicated through VAPF. There's also visible light protection that needs to be taken to account, which is almost in no way, you know, communicated through the SPF value. So going back to what you said. When we tested the zinc oxide tetrapod sunscreen, you know, dispersion versus others, we saw an interesting effect where UVB light was absorbed, UVA light was absorbed, but a lot of UVC light was absorbed versus typical zinc oxide types.

21:01Now, again, that's great, but it doesn't necessarily improve the sun protection factor by doing so, right? Even if you absorb more visible light, it doesn't improve the sun protection factor. So when we tested with different shapes of zinc oxide, we saw that ours was comparable to one specific shape of zinc oxide, which was made by French process or by Solgel synthesis. But when we look at French process zinc oxide, which is used really widely in the sunscreen industry, that was testing at about SPF 50 at the exact same concentration versus what we got from the tetrapod sunscreen and the Solgel zinc oxide at SPF 30-ish in a 20 % weight-by-weight formula.