Indermeet Kohli

Background: Photoprotection has traditionally focused on ultraviolet (UV) radiation, particularly UVB and UVA. Recent evidence highlights the significant role of long‐wavelength UVA1 (LW‐UVA1, 370–400 nm) and visible light (VL; 400–700 nm) in inducing pigmentation, erythema, and photoaging. This review study summarizes recent advances in LW‐UVA1 and VL photoprotection and discusses emerging UV‐filter formulations, non‐filtering protective ingredients (PINGs), personalized photoprotection, skin microbiome, and environmental considerations. Methods: A literature review was conducted using PubMed and Google Scholar online databases to identify recent studies on LW‐UVA1 and VL‐related photoprotection. Studies were screened for direct relevance to VL and LW‐UVA1 and excluded if not available in English, lacked relevance, or had insufficient methodological detail. This review represents a narrative synthesis without formal systematic quality assessment. Results are summarized. Results: LW‐UVA1 and VL exert synergistic effects on the skin, resulting in erythema and sustained pigmentation. Advances include tinted mineral sunscreens with expanding shade ranges, newer UV filters with broader coverage (e.g., Mexoryl 400, TriAsorB), and oral and topical PINGs to be used as potential adjuncts. Environmental concerns for currently used UV filters persist, however. Skin microbiome has also emerged as a target and potential source for novel photoprotective agents. Personalized photoprotection recommendations now provide an individualized approach, taking skin phototype, lifestyle, and risk profile into consideration. Conclusion: Photoprotection is expanding to include a broader‐spectrum coverage, including LW‐UVA1 and VL with new filters, formulations, and adjuncts. These innovations enhance UV protection, but environmental and long‐term safety concerns highlight the need for continued research to ensure safe, effective, and inclusive photoprotection.

Sunlight is an important environmental determinant of human physiology, though its effects on health have been studied predominantly in the context of skin disease. While ultraviolet (UV) radiation is a well‐established risk factor for skin cancer, evidence suggests that it may also have beneficial systemic effects. This narrative review synthesizes evidence from the past decade on the associations between sunlight and UV radiation exposure and mortality‐related outcomes, with a focus on internal malignancies, cardiovascular disease and infectious diseases. A comprehensive search of PubMed and Embase was conducted for English‐language articles published between January 2015 and June 2025. Of 148 articles identified, two duplicates were removed. After title and abstract screening, 64 full‐text articles were assessed for eligibility; a total of 28 studies met the inclusion criteria and were included in the final review. Among the included studies, four examined cardiovascular outcomes, 12 evaluated infectious diseases, six focused on malignancies and six assessed all‐cause mortality. Overall, most studies reported inverse associations between UV exposure and adverse health outcomes, suggesting potential protective effects. For example, a large cohort study found that individuals with 2000 kJ/m ² higher annual solar radiation exposure had a 12% lower risk of all‐cause mortality. The comparator group had an average of 26 days of life lost over the 15.7‐year follow‐up period. This review identifies a pattern of potential beneficial associations between UV radiation exposure and systemic health outcomes, although confounding by various parameters including the healthy user effect and socioeconomic differences. When the benefits are considered alongside the well‐established deleterious cutaneous effects of UV exposure, these findings underscore the need for balanced public health messaging that acknowledges the risks and potential benefits of sunlight exposure.

Background: There is concern among consumers and researchers about the potential risk of cutaneous malignancy associated with ultraviolet (UV) nail polish dryer lamps used to cure gel nail polish. In this review, we analyze the current literature on the safety of UV gel nail polish dryer lamps and their potential for cutaneous carcinogenesis. Methods: A review of the literature from OVID Medline, PubMed, EMBASE, and Web of Science databases was performed from inception to April 4, 2023 to identify studies pertaining to UV nail polish dryer lamps and cutaneous malignancies. Results: A total of 14 articles were included. Squamous cell carcinoma was described in 5 patients with a history of UV nail polish dryer lamp use. There were 2 in vitro studies on UV lamp effects on cultured primary cells and cell lines: 1 study found an increased risk of cytotoxicity and mutagenicity, and 1 study found negligible reductions in cell viability when exposed to irradiation appropriate for gel manicures. One study using the Surveillance, Epidemiology, and End‐Results national cancer registry found no cases of melanoma associated with UV nail polish dryer lamps. Mathematical models were used to estimate the risk of carcinogenesis associated with using UV nail polish dryer lamps in 7 studies; 6 of 7 studies calculated minimal to no risk. Conclusion: There is a lack of compelling evidence to support the carcinogenic potential of UV nail polish dryer lamps. Based on current evidence, we recommend photoprotection for individuals who anticipate using UV nail polish dryer lamps long‐term.

Background: Tinted sunscreens not only shield against UV rays but also provide protection against visible light, as opposed to traditional sunscreens. Universal tinted sunscreens are marketed to complement all skin tones.Objective: To assess color match and subject satisfaction for 7 universal tinted sunscreens across various price ranges in all Fitzpatrick skin phototypes (SPT).Methods: Products A‐G were applied at concentrations of 1 and 2 mg/cm² on the dorsal arms of 30 subjects spanning SPT I–VI. Photography, colorimetry, and subject and investigator surveys were utilized to determine color match.Results: Using colorimetry analysis at the recommended 2 mg/cm² concentration, two of seven products were identified as suitable matches for SPT I–II, while six out of seven were determined to be a good match for SPT III–IV. However, only one product was found to be a good match for SPT V–VI at the recommended concentration according to colorimetry results.Conclusion: Universal tinted sunscreens do not provide an adequate color match for all skin phototypes, especially for individuals with very fair or very dark skin tones.

Background: The combination of long wavelength ultraviolet A1 radiation (LWUVA1) and visible light (VL) has been shown to produce photodamage and the majority of organic sunscreens lack protection against this spectrum. Currently, established testing protocols for VL photoprotection are lacking.Objective: To compare pigmentation assessment methods, including Investigator’s Global Assessment (IGA) scoring, Diffuse Reflectance Spectroscopy (DRS), and immunohistochemistry, to assess the utility of each in evaluating VL + LWUVA1 induced pigmentation.Methods: Anonymized IGA, DRS, and immunohistochemistry data for 37 subjects (Fitzpatrick skin phototypes IV-VI) was retrospectively analyzed for pigment evaluation. Pigmentation was induced on the subjects’ backs with VL + LWUVA1 (0%–0.5% UVA1) irradiation at a dose of 480 J/cm². Comparisons were made for all three assessment techniques between non-irradiated skin and VL + LWUVA1 irradiated skin, as well as between pure VL (0% UVA1) and VL + LWUVA1 (0.5% UVA1) irradiated sites. All comparisons were made for data collected approximately 24 h after irradiation to evaluate persistent pigment darkening (PPD).Results: Among all 37 subjects, both IGA scores and DRS detected a statistically significant difference in PPD between irradiated and non-irradiated sites, as well as between VL + LWUVA1 and pure VL irradiated sites. However, MART-1/Melan-A did not indicate a statistically significant difference in PPD between irradiated and non-irradiated sites or between VL + LWUVA1 and pure VL irradiated sites.Conclusion: Subjective and objective noninvasive assessments were more sensitive in detecting VL + LWUVA1 induced pigmentation and should be preferred over invasive methods. Researchers are advised to initiate assessments with IGA and subsequently incorporate DRS for more objective and comprehensive insights in pigment evaluation.

Background: The human skin microbiome is a dynamic ecosystem that plays an important role in skin health. The skin microbiome has been implicated in numerous diseases, and our knowledge surrounding it continues to evolve. A better understanding of the interactions between the environment and the skin microbiome will lead to improvements in skin health.Methods: This article reviews the published literature surrounding the impact of ultraviolet radiation (UVR) and sunscreen on the skin microbiome.Results: Skin microbes are differentially impacted by UVR, and alterations in the microbiome can be detected following UVR exposure. These changes are related to direct bactericidal effects, alterations in the cutaneous metabolome, and changes in the cutaneous immune system. UV filters used in sunscreen have been shown to have bactericidal effects, and many compounds used in sunscreen emulsions can also negatively impact cutaneous microbes.Conclusion: A healthy microbiome has been shown to produce compounds that help protect the skin from UVR, and sunscreen has the potential to reduce the diversity of the skin microbiome. This indicates that designing sunscreen products that both provide protection against UVR and preserve the skin microbiome may offer additional benefits to skin health when compared with traditional sunscreen products.