Latest / The Science of Skin / Dr. Henry Lim: Expertise in photobiology, and state of the art photoprotection

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Dr. Henry Lim: Expertise in photobiology, and state of the art photoprotection · The Science of Skin

• 0:09
  SPEAKER_01: Hi, I'm Dr.
• 0:10
  SPEAKER_01: Patty Ferris.
• 0:11
  SPEAKER_01: I'm a board certified dermatologist and I'm your host for this episode of Skin Care Confidential.
• 0:16
  SPEAKER_01: Dr.
• 0:17
  SPEAKER_01: Ted Lane and I started the podcast as an outreach of our medical meeting, the Science of Skin Care Summit, so we could bring educational information about skincare products to a wider audience.
• 0:28
  SPEAKER_01: The summit will be held in Austin, Texas this year, September 22nd through the 23rd.
• 0:33
  SPEAKER_01: It's coming upon us.
• 0:34
  SPEAKER_01: We're six weeks out.
• 0:36
  SPEAKER_01: I'm not sure this episode will air before the summit, but I hope that it will.
• 0:40
  SPEAKER_01: I'm really excited today to have one of my very esteemed colleagues, Dr.
• 0:44
  SPEAKER_01: Henry Lim, with me.
• 0:46
  SPEAKER_01: His bio is pretty extensive here, but I'm going to hit the high points.
• 0:51
  SPEAKER_01: He is the former Clarence S.
• 0:52
  SPEAKER_01: Living Good Chair and Chairman of the Department of Dermatology at Henry Ford Health Hospital in Detroit, Michigan, and you held that position for 20 years, Henry, from 1997 to 2017.
• 1:05
  SPEAKER_01: He received his medical degree from SUNY Down State and completed his dermatology residency at NYU.
• 1:12
  SPEAKER_01: He is a past president of the American Academy of Dermatology, the American Board of Dermatology, the American Dermatologic Association, the American Society for Photobiology, and the International Union of Photobiology.
• 1:25
  SPEAKER_01: That's exhausting, Henry.
• 1:28
  SPEAKER_01: He was elected in 2019 as a board member of the International League of Dermatological Societies.
• 1:34
  SPEAKER_01: And now I think you've taken the presidency of that organization.
• 1:38
  SPEAKER_01: So you'll have yet another presidency under your belt.
• 1:42
  SPEAKER_01: He was awarded an honorary membership, which is a very high honor from the American Academy of Dermatology in 2020.
• 1:49
  SPEAKER_01: You have a long list of accolades here, and I'm just going to tell everybody that they're impressive, that they would take me a long time to read.
• 1:56
  SPEAKER_01: He's published more than 570 articles, edited 11 textbooks.
• 2:01
  SPEAKER_01: You're going to have to tell me how you get people to submit their chapters, because that's the challenge of editing a textbook, right?
• 2:07
  SPEAKER_01: And he has also been voted by Expertscape as the world's top-rated sunscreen expert.
• 2:13
  SPEAKER_01: So no surprise that today I'm going to talk to Dr.
• 2:16
  SPEAKER_01: Lim about sunscreen, about photo protection.
• 2:20
  SPEAKER_01: And Henry, I'd love to start these episodes, especially with friends and people I know like you, but I don't really know the answer to this question.
• 2:27
  SPEAKER_01: How did you get interested in photobiology?
• 2:30
  SPEAKER_00: Patty, that is a very, very good question.
• 2:32
  SPEAKER_00: First of all, thank you very much for inviting me to participate in this podcast.
• 2:38
  SPEAKER_00: You know, we have known each other for a long time.
• 2:39
  SPEAKER_00: You are one of my favorite persons for sure.
• 2:41
  SPEAKER_00: It's definitely a pleasure to be on the screen with you here.
• 2:45
  SPEAKER_00: So coming back to your question about photobiology, actually, is by chance, really.
• 2:51
  SPEAKER_00: You know, I have never planned my career path uh very, very clearly from the very beginning.
• 2:56
  SPEAKER_00: All I knew was that when I was in residency, I wanted to be in academic dermatology.
• 3:03
  SPEAKER_00: Primarily, I like the intellectual stimulation.
• 3:06
  SPEAKER_00: So I was asked by my chair at the time, Rudy Baer, whom you probably know, he passed away, of course, but he knew Dr.
• 3:13
  SPEAKER_00: Baer.
• 3:13
  SPEAKER_00: So he said, well, you know, go work in a laboratory because at that time he wanted to be an academician.
• 3:20
  SPEAKER_00: You know, having spent time in the laboratory is definitely one of the paths to get there.
• 3:24
  SPEAKER_00: So it happened to be that the laboratory that I worked in, uh, which is led by Irma Gili, who became the chief of dermatology at UC San Diego, uh, had a project on the activation of the complement system.
• 3:37
  SPEAKER_00: Again, keeping in mind this was in the 70s, so the complement system was quite a hot topic of research at the time.
• 3:44
  SPEAKER_00: The activation of the complement system by porphyrin and light.
• 3:48
  SPEAKER_00: So that's how I got started in the laboratory, and then I expanded from there to uh seeing patients with porphyria, and then at NYU as I established the photodermatology unit.
• 4:00
  SPEAKER_00: I worked with Nick Soder in phototherapy unit, and then subsequent to that, I get more interested in not only photodermatology, photodermatosis, phototherapy, but expanded into photoprotection.
• 4:14
  SPEAKER_00: So that's how, in a long story, but in a in a short three minutes, that's how the synopsis of my interest in photodermatology.
• 4:22
  SPEAKER_01: It's so interesting, and you're right.
• 4:23
  SPEAKER_01: It's like you don't plan it, but it's those interesting twists and turns of your career that take you in in certain directions.
• 4:30
  SPEAKER_01: Um let's start with sort of simple sunscreen and maybe starting with UV protection.
• 4:38
  SPEAKER_01: I want to go on to visible light and other wavelengths because I know you're an expert in that as well.
• 4:42
  SPEAKER_01: But really for our audience, some just sort of basics on sunscreen and UV protection and all the different filters that are out there and sort of what's new and what's happening in that arena.
• 4:55
  SPEAKER_00: Well, I think the uh part, you know, speaking to the very sophisticated audience of dermatologists and other healthcare providers uh on this podcast here, we know that the sunscreen is one of the components of photoprotection.
• 5:09
  SPEAKER_00: Sunscreen uh is was designed and is uh still a very, very good photoprotector for UVA and UVB spectrum.
• 5:18
  SPEAKER_00: UVB is reflected by a sun protection factor because that testing primarily is looking at UV-induced erythema, which is primarily the effect of UVB, a little bit of the effect of UVA2, the shorter wave than UVA.
• 5:32
  SPEAKER_00: But primarily is the effect of UVB.
• 5:35
  SPEAKER_00: So the SPF reflects the protection primarily against erythema, which is UVB.
• 5:40
  SPEAKER_00: On the other hand, the FDN now requires the broad spectrum classification of sunscreen or labeling of sunscreen.
• 5:47
  SPEAKER_00: So broad spectrum covers essentially the UVA spectrum because we do know UVA acts synergistically with UVP and many of the photobiologic effects of UV, including photocarcinogenesis, but as importantly, uh UVA also is the main spectrum that induces uh photoaging changes, but also the photo uh pigment, photoinduced pigmentation, pigmentary alteration on the skin.
• 6:13
  SPEAKER_00: So that is how the sunscreen was developed.
• 6:16
  SPEAKER_00: I mentioned before that sunscreen is just one of the important components of photoprotection.
• 6:22
  SPEAKER_00: Clearly, we all know photoprotection includes you know behavioral modification when we go outdoors, stay in the shade, and then wearing uh white brim hat, clothing, and sunglasses.
• 6:32
  SPEAKER_00: And sunscreen should be applied on otherwise exposed sites.
• 6:37
  SPEAKER_01: So talk a little bit about some of the filters.
• 6:41
  SPEAKER_01: I mean, we've we've seen, I think, what we might call a backlash against the bad chemical sunscreens.
• 6:47
  SPEAKER_01: You know, they've been vilified so much in the press.
• 6:50
  SPEAKER_01: And now people are really moving more into the mineral sunscreens or the inorganic sunscreens.
• 6:55
  SPEAKER_01: And I guess you and I've been around long enough to remember when they used to be worried about the nanoparticles that were in the mineral sunscreens.
• 7:03
  SPEAKER_01: So where do we kind of stand with all of those right now, the ingredients?
• 7:08
  SPEAKER_00: The ingredients, and as you all know, that the sunscreen ingredient in the US is regulated by the FDA as an over-the-counter drugs.
• 7:17
  SPEAKER_00: So it is classified into two broad categories that uh you, Patty, had mentioned, that in one side is a so-called chemical, also known as organic filters.
• 7:27
  SPEAKER_00: Uh, those are the vast majority of the filters.
• 7:30
  SPEAKER_00: And then the other one is the mineral or inorganic filter.
• 7:33
  SPEAKER_00: You all sometimes is called also physical sunscreen.
• 7:36
  SPEAKER_00: So those are the titanium dioxide and zinc oxide, the only two of them uh that is used by the FDA.
• 7:42
  SPEAKER_00: FDA classification uh uh is that both of them are completely uh safe, so then they have no question about the use and the uh the use and also the marketing of the mineral sunscreen.
• 7:56
  SPEAKER_00: What FDA has been asking the industry to look at is uh the mineral sunscreen.
• 8:02
  SPEAKER_00: There's a group of mineral sunscreen that FDFL, there is just not enough data in terms of the safety, not so much in the efficacy, but in terms of the safety.
• 8:11
  SPEAKER_00: So they wanted to get more data on that, primarily because of the newer data showing that there is uh uh uh absorption of UV filters, organic filters, into the uh bloodstream.
• 8:23
  SPEAKER_00: That's the reason that the question has been asked.
• 8:25
  SPEAKER_00: Having said that, FDA currently still stands behind the not only the efficacy but the safety of all the UV filters.
• 8:34
  SPEAKER_00: That's the reason there is no uh uh sunscreen that has been pulled from the market.
• 8:38
  SPEAKER_00: But uh, but you know, clearly the FDA is still negotiating and discussing, discussing with the with the industry specifically what type of uh UV testing that needs to be done uh in order to be able to satisfy the FDA requirement on this particular aspect.
• 8:54
  SPEAKER_00: That's where the controversy comes in.
• 8:56
  SPEAKER_00: That is the reason that Patty, as you have mentioned, you know, many of the um uh public has moved on to using mineral sanskrit.
• 9:04
  SPEAKER_00: So let me mention about mineral sunscreen.
• 9:06
  SPEAKER_00: Mineral sunscreen nowadays it is used as nanoparticles, meaning the particle size is less than 100 nanometers.
• 9:13
  SPEAKER_00: The reason it is used as a nanoparticle is that because it would increase the cosmetic uh uh acceptance of the sunscreen because it makes it less chalky and less white.
• 9:25
  SPEAKER_00: Because if the particle gets larger, then it reflects more of the visible light into our retina, so our retina would then uh pick it up as a whitish discoloration on the skin.
• 9:34
  SPEAKER_00: With nanoparticles, then there's there's less of that reflection of the visible light.
• 9:39
  SPEAKER_00: That's the reason it is used primarily as nanoparticles.
• 9:42
  SPEAKER_00: Based on the current data, nanoparticles actually is very, very safe.
• 9:47
  SPEAKER_00: Uh there is uh practically no absorption at all into the skin beyond the epidermis, which is where you want the sunscreen to be.
• 9:55
  SPEAKER_00: So it is it is definitely very safe.
• 9:58
  SPEAKER_00: There are some drawback, of course, you know, no matter how fine the nanoparticles are, there's still sometimes a little bit of whitish discoloration.
• 10:05
  SPEAKER_00: Even though I must say that the industry has done a great job.
• 10:08
  SPEAKER_00: Now there are many uh mineral sunscreens, they're very, very elegant, that is almost transparent.
• 10:15
  SPEAKER_01: I agree.
• 10:16
  SPEAKER_01: They've come out with some really beautiful mineral sunscreens in the last year or two.
• 10:20
  SPEAKER_01: Talk for a minute about the environmental dangers of chemical sunscreen.
• 10:24
  SPEAKER_01: I've heard you eloquently discuss it on the podium, and I think in a way that many people can't.
• 10:31
  SPEAKER_00: Yeah, it is it is the the sort of the rationale on this, is there two.
• 10:36
  SPEAKER_00: One, the one that I'd mentioned before, that there is uh uh evidence of absorption of mineral of uh organic sunscreen into the skin, uh resulting in questions about the health effect.
• 10:48
  SPEAKER_00: But in terms of the environmental effect, it's primarily based on in vitro studies, laboratory studies.
• 10:55
  SPEAKER_00: What had been shown is that if you put corals in a laboratory setting and put uh UV filters in there, there is an increased probability of coral reef bleaching by measures that they use in a laboratory setting.
• 11:10
  SPEAKER_00: So that had generated a lot of discussion as to, you know, we do know they're bleaching of coral reefs in in uh many parts of the world.
• 11:19
  SPEAKER_00: The question is that what is the role of UV filters?
• 11:23
  SPEAKER_00: And what has been studied now is that one, there have been a number of studies to look at the concentration of UV filters in actual seawater, specifically in areas that there are a lot of tourists, for example, whatever the study was done in Hawaii.
• 11:39
  SPEAKER_00: What they found is that indeed you can detect UV filters in the seawater, but the important part is that the concentration is significantly less, a thousandfold less than what is used in the laboratory setting.
• 11:54
  SPEAKER_00: So that so that that is something that I think we need to keep in mind.
• 11:57
  SPEAKER_00: You know, as we know, many of the quote-unquote in vitro studies for whatever it is, uh it is uh it is a big jump to convert it into in vivo clinical setting.
• 12:08
  SPEAKER_00: So that's something that we need to keep in mind about that.
• 12:11
  SPEAKER_00: Number two is that we do know that you know sunscreen or UV filters from sunscreen is just one of the sources of UV filter in the water because wastewater removal is one, you know, it's uh a lot of the UV filters is used in the industry to prevent fading of the furniture paint and so on and so forth.
• 12:28
  SPEAKER_00: So there are other sources in the uh in the seawater of the UV filters.
• 12:33
  SPEAKER_00: Thirdly, there are a lot of studies to show that actually the major cause of coral reef bleaching is not so much of the UV filters, but the major cause is the ocean warming.
• 12:45
  SPEAKER_00: Uh the warming of the ocean water causes obviously the coral reef, which is very, very delicate uh being uh to be bleached.
• 12:53
  SPEAKER_00: So they are multifactorial.
• 12:55
  SPEAKER_00: In fact, because of this controversy, uh AAD and many organizations had asked uh the EPA to look into that, and EPA subsequently had asked the National Academies, uh the independent body, uh, to look at this particular issue.
• 13:11
  SPEAKER_00: They spent about a good six months, about a good eight months, I think, to look at it with individuals, dermatologists, but also a lot of other scientists uh to look at this particular issue.
• 13:22
  SPEAKER_00: All of them have been vetted very carefully for being non-conflicted in uh uh scientists and individuals.
• 13:29
  SPEAKER_00: And essentially what they found is that they more studies need to be done because they they acknowledge the very complexity of the factors, the different factors that is in there, and there is no standardized method, for example, to measure many of the endpoints that is to be done.
• 13:45
  SPEAKER_00: So their bottom line is that essentially, uh, based on what their review is, uh, more studies need to be done.
• 13:51
  SPEAKER_01: Isn't that always the way?
• 13:52
  SPEAKER_01: It is unfortunately.
• 13:54
  SPEAKER_01: Another big scare we had, I think it was last summer or the summer before, was the benzene that was found in some sunscreen.
• 14:00
  SPEAKER_01: So maybe you could speak to that.
• 14:02
  SPEAKER_01: We're gonna get all the bad things out of the way.
• 14:05
  SPEAKER_00: Yeah, indeed, that that was a concern, of course, because benzene is known as a carcinogen.
• 14:10
  SPEAKER_00: Uh, that was apparently a supply chain issue.
• 14:14
  SPEAKER_00: And uh, because of that, actually, there was some sunscreen product that was pulled from the market because of this concern about contamination of benzene.
• 14:22
  SPEAKER_00: But to my knowledge, you know, everything is well resolved.
• 14:24
  SPEAKER_00: You know, the AD industry had to act very aggressive and correctly so to make sure that that doesn't happen.
• 14:30
  SPEAKER_00: And uh death had pretty much been uh been resolved on that part.
• 14:35
  SPEAKER_01: Interesting.
• 14:35
  SPEAKER_01: So let's move on a little bit to visible light, because I know you've done a lot of work in this area, and it's getting a lot of attention among dermatologists.
• 14:43
  SPEAKER_01: You know, we didn't talk about visible light not all that long ago, and now we're talking about visible light and even beyond with infrared.
• 14:51
  SPEAKER_01: So tell us a little bit about visible light.
• 14:54
  SPEAKER_01: We all know we get visible light from sun exposure, but also from devices.
• 14:58
  SPEAKER_01: So how does that all influence our skin and skin biology?
• 15:03
  SPEAKER_00: You're absolutely correct, Patty, that the visible light has been around for a long time, and for the long actually, we all need visible light for uh to live, right?
• 15:11
  SPEAKER_00: Uh in what what uh uh has been understood for the longest time is that visible light is biologically inert.
• 15:18
  SPEAKER_00: Uh however, in the past 10, 12 years or so, you know, our group as well as others had shown that indeed visible light has biologic effect.
• 15:27
  SPEAKER_00: You know, our group was one of the first that showed that uh using visible light, uh exposing visible light on the skin of darker skin individuals would result in fairly significant and very intense pigmentation that is longer lasting as compared to the pigmentation induced by UVA, because we know UVA classically is considered to be the spectrum that would induce pigmentary alterations, and that is the case, but what we've shown is that visible light is even more intense in terms of the pigmentation and also would last longer.
• 16:01
  SPEAKER_00: So the clinical implications, there are several folds though.
• 16:04
  SPEAKER_00: One is that clearly, and this only occurs in darker skin individuals when the study was done using skin type 2 individual, skin type 2 subject, nothing happened.
• 16:14
  SPEAKER_00: That is no pigmentary alteration.
• 16:17
  SPEAKER_00: So the implications on that is that obviously, you know, we know that a lot of the uh pigmentary alterations occurs in darker skin individuals.
• 16:26
  SPEAKER_00: Clinically, we know melasma, for example, tends to occur in darker skin individuals, post-inflammatory hyperpigmentation likewise.
• 16:33
  SPEAKER_00: So that is a clinical implication that we all know clinically.
• 16:37
  SPEAKER_00: We know with a lot of patients, our patients with melasma, they say, well, doctor, and I put on my sunskin all the time, but my uh melasma continue to get darker in the summertime, and it is possibly the the role of the additional role of visible light in addition to UV that is causing that uh darkening of the melasma.
• 16:56
  SPEAKER_00: The other implication of that is that in terms of photoprotection, because we mentioned before that currently sunscreen, specifically the UV filters that is approved by the FDA in a sunscreen, is meant to protect against UV, UVB or UVA.
• 17:13
  SPEAKER_00: But it's not meant to protect against visible light.
• 17:16
  SPEAKER_00: Because in order to protect against visible light, at least on a topical level, it has to be visible because visible light is visible, right?
• 17:23
  SPEAKER_00: So you you unless you have something that is visible that would reflect the visible light back to our retina, you're not going to be able to protect well again against visible light.
• 17:33
  SPEAKER_00: So there comes the challenge, and unfortunately, there are now uh new developments that help to protect against visible light, and uh that but so it is an active area of uh of research and investigation.
• 17:47
  SPEAKER_01: It's a challenge.
• 17:49
  SPEAKER_01: It is for sure.
• 17:50
  SPEAKER_01: Um talk a little bit about antioxidants.
• 17:53
  SPEAKER_01: I know you've recently published some things on um papers on using antioxidants with sunscreens or sunscreens that contain antioxidants and how that plays into visible light protection in particular.
• 18:06
  SPEAKER_00: Yeah, so the the protection against visible light, you know, either topical, and I'll come back to the topical aspect of the visible light protection, but there are some new developments on that.
• 18:15
  SPEAKER_00: But the other way is that true antioxidants, because we do know just like UV, visible light can induce production of reactive function species.
• 18:25
  SPEAKER_00: Clearly, when you know we we studied by based on UVA, UVB, and visible light, but in real life, when you go at second, there's always uh a sort of crossover between UV and visible light.
• 18:39
  SPEAKER_00: So reactive function species likewise is generated definitely by UVA, but also by visible light.
• 18:45
  SPEAKER_00: So the the rationale of using topical uh antioxidants is that by having antioxidants, it would help to downregulate the effect of visible light.
• 18:55
  SPEAKER_00: Indeed, you know, the studies that you have mentioned that we have done uh show that indeed if the product the products contain biologically active antioxidants, it can downregulate.
• 19:06
  SPEAKER_00: It would not completely suppress, but it would help to downregulate visible light-induced pigmentary alteration in darker skin individuals.
• 19:13
  SPEAKER_00: So that is one aspect that we could use to help to protect the pigmentary alteration induced by visible light.
• 19:21
  SPEAKER_00: I must say also that industry has developed quite well in terms of biologically active antioxidants because you probably remember, probably about 10 years ago, there's been a study to show that in a lot of the topical antioxidants is not biologically active, but nowadays, I think uh the technology had advanced many, most of the antioxidants on the in sunscreen is biologically active.
• 19:43
  SPEAKER_00: So that's one aspect.
• 19:45
  SPEAKER_00: The other aspect in terms of protection of visible light is to use tinted sunscreen.
• 19:50
  SPEAKER_00: So tinted sunscreen is essentially a sunscreen that contains iron oxides, which comes in three different colors, and usually their manufacturer would mix and match that.
• 19:59
  SPEAKER_00: Sometimes they put the non-pigmentary, uh non-nadonized, so pigmentary, uh titanium dioxide also to again mix and match the color.
• 20:09
  SPEAKER_00: And because they're colored, because of that, it would help to protect against visible light.
• 20:13
  SPEAKER_00: Clearly, the limiting factor is that, as we all know, you know, you have to tell the patient, get several samples to see which one would match with your natural skin tone so that it would be acceptable for the patient to use.
• 20:26
  SPEAKER_00: The other limiting factor with tinted sunscreen, obviously, it does uh just like tinted makeup, it does color, uh it does sort of uh color to your clothing, so you have to be careful about that.
• 20:38
  SPEAKER_00: In Europe, there are two uh new uh filters that protect against the visible light range.
• 20:46
  SPEAKER_00: One is not so much an invisible light but in a very long wave UVA, which we know that it would induce uh pigmentary alteration.
• 20:53
  SPEAKER_00: So that is the MaxRail 400, uh that is a L'Oreal product.
• 20:58
  SPEAKER_00: It covers essentially the very long spectrum of UVA1, so from 360 to 380, even to 390 range.
• 21:06
  SPEAKER_00: So it is quite uh good in helping to suppress the uh pigmentary alteration on the skin.
• 21:12
  SPEAKER_00: Another one, which is a PRFAR product, uh uh triopsol, and both of them are marketed in Europe and available in Europe.
• 21:20
  SPEAKER_00: The triops rope it covers is a broad spectrum, so it covers UVB, UVA, but also this one covered visible light spectrum.
• 21:27
  SPEAKER_00: But because of that, that particular one is pigmented, so they have to match it with the uh different type of pigments to make sure that it is acceptable to patients.
• 21:37
  SPEAKER_00: So those are the developments that have uh occurred, at least uh for protection against visible light.
• 21:42
  SPEAKER_00: Two of the products are now available in Europe.
• 21:45
  SPEAKER_00: A third one is being developed and probably uh uh is going to be available in Europe uh fairly soon.
• 21:51
  SPEAKER_01: This is why dermatologists are bringing sunscreen back every time they go to Europe because they have such great filters there that we don't have.
• 21:58
  SPEAKER_00: Correct, yeah.
• 21:59
  SPEAKER_01: Unfortunately.
• 22:00
  SPEAKER_01: I wish we could get some of these into the States.
• 22:02
  SPEAKER_01: This would make a big difference.
• 22:03
  SPEAKER_01: Talk for just a minute about uh infrared, because that's our sort of longer wavelength of light beyond visible.
• 22:11
  SPEAKER_01: Yeah.
• 22:12
  SPEAKER_01: And I think again, it's being implicated in photo aging for sure.
• 22:16
  SPEAKER_00: Yes, yes.
• 22:16
  SPEAKER_00: You know, we just uh uh published a paper, a review paper actually on this particular aspect uh in photodramatology for the immunology photo medicine journal.
• 22:25
  SPEAKER_00: But essentially, you're absolutely right.
• 22:26
  SPEAKER_00: You know, infrared, you know, we all I think recognize infrared being the one, the source of when when you go outside to get the heat from sunlight, that is the effect of infrared, right?
• 22:35
  SPEAKER_00: But the one that is that is most biologically relevant is the infrared A, which is happened to be the shortest wave of infrared.
• 22:43
  SPEAKER_00: And uh it is indeed uh or has been shown to induce photoaging changes.
• 22:49
  SPEAKER_00: Initially it was done way back uh by uh in animal models, but definitely I think it's now known.
• 22:55
  SPEAKER_00: Also in human, it can uh induce photoaging changes.
• 22:58
  SPEAKER_00: But infrared is an interesting spectrum because depending on the dose, depending on the amount that is exposed that the skin is exposed to, they are beneficial effects.
• 23:09
  SPEAKER_00: Even though the beneficial effect of uh infrared, there have been a lot of studies on that, the data is not yet quite strong, but the indication, the signals there.
• 23:18
  SPEAKER_00: We all know that infrared has been used for the treatment of uh various types of hair loss, for example, the various caps, right?
• 23:26
  SPEAKER_00: Uh there are studies on that.
• 23:27
  SPEAKER_00: Uh, most of the studies are sponsored by industry, but nonetheless, you know, there are some data on that.
• 23:33
  SPEAKER_00: It is used also for wound healing.
• 23:35
  SPEAKER_00: Uh, a lot of uh leg ulcers, for example, the infrared, they have the data to show that it can be helpful for wound healing.
• 23:41
  SPEAKER_00: Uh sometimes it is used even for sclerodermoid skin changes.
• 23:45
  SPEAKER_00: Uh again, it seems to be depending on what dose you use.
• 23:49
  SPEAKER_00: Clearly, more studies need to be done, but I think there are quite a bit of signal to show that this is quite helpful, potentially could be very helpful.
• 23:57
  SPEAKER_00: So I think this is another exposure.
• 23:59
  SPEAKER_00: That's a double-edged sword.
• 24:00
  SPEAKER_00: Yes.
• 24:00
  SPEAKER_01: A little bit of a double-edged sword at this point.
• 24:02
  SPEAKER_00: It is, yes.
• 24:03
  SPEAKER_01: Maybe just in closing, speak for just a minute about some of the other exposomal factors, maybe pollution and some of the other things that we also now know are contributors to uh sun dam, I mean not sun damage, but skin damage and environmental damage.
• 24:19
  SPEAKER_00: Absolutely.
• 24:20
  SPEAKER_00: That that is an another new area, uh relatively new area within photobiology, within photoprotection.
• 24:27
  SPEAKER_00: Pollutants is is is a significant factor.
• 24:30
  SPEAKER_00: Uh, you know, there are some suggestions that you know when you are living in a highly polluted environment, the photo aging changes would be more accelerated.
• 24:39
  SPEAKER_00: Again, you know, there are a lot of data, but still not uh more studies again needs to be done.
• 24:43
  SPEAKER_00: But I think something that we should continue to watch out for.
• 24:46
  SPEAKER_00: The other one new area in this is uh microbiome, the skin microbiome.
• 24:50
  SPEAKER_00: Again, there's a lot of studies now.
• 24:52
  SPEAKER_00: There is a trickier one to study because uh it is uh a lot of study has been done with gut microbiome, but now the screen microbiome is being studied.
• 25:00
  SPEAKER_00: The challenge with microbiome is that because each one of us has different microbiome, even on different parts of the body, the the population of microbiome is very, very different.
• 25:10
  SPEAKER_00: So, you know, the we need we need to continue to be able to standardize and come with a with a conclusion that microbiome is helpful or hurtful.
• 25:18
  SPEAKER_00: There are some suggestions that some microbiome is photoprotective.
• 25:21
  SPEAKER_00: It serves as a photoprotective environment uh mechanism.
• 25:25
  SPEAKER_00: But at this moment, I think it's still relatively early, but there are a lot of new data coming out on that.
• 25:30
  SPEAKER_01: So interesting.
• 25:31
  SPEAKER_01: We've come a long way, haven't we?
• 25:33
  SPEAKER_00: Yes, we have.
• 25:34
  SPEAKER_01: So many developments.
• 25:35
  SPEAKER_01: I'm going to wrap it up here, and I'm so appreciative of your time and your expertise and for you joining us today on the podcast.
• 25:44
  SPEAKER_01: Thank you for everything, Henry, and all your contributions to dermatology and to the world of photobiology.
• 25:50
  SPEAKER_01: I'll keep reading your articles and attending your lectures and hopefully learning more.
• 25:55
  SPEAKER_00: Thank you very much, Betty, for having me.
• 25:56
  SPEAKER_00: Thank you for the kind words, and it's a pleasure to continue to work with you.