Filling in the Evidence About Sunscreen

Ultraviolet Filters: Dissecting Current Facts and Myths

Skin cancer is a global and increasingly prevalent issue, causing significant individual and economic damage. UV filters in sunscreens play a major role in mitigating the risks that solar ultraviolet ra-diation poses to the human organism. While empirically effective, multiple adverse effects of these compounds are discussed in the media and in scientific research. UV filters are blamed for the dis-ruption of endocrine processes and vitamin D synthesis, damaging effects on the environment, induction of acne and neurotoxic and carcinogenic effects. Some of these allegations are based on scientific facts while others are simply arbitrary. This is especially dangerous considering the risks of exposing unprotected skin to the sun. In summary, UV filters approved by the respective governing bodies are safe for human use and their proven skin cancer-preventing properties make them in-dispensable for sensible sun protection habits. Nonetheless, compounds like octocrylene and ben-zophenone-3 that are linked to the harming of marine ecosystems could be omitted from skin care regimens in favor of the myriad of non-toxic UV filters.

Photoprotective effect of 18β-glycyrrhetinic acid derivatives against ultra violet (UV)-B-Induced skin aging

Excessive exposure to sun can harm the skin, causing sunburn, photo-aging, and even skin cancer. Different benzylidene derivatives (A02-A18 and A19-A34) of 18β-Glycyrrhetinic acid (A01) were designed and synthesized in an effort to discover photo-protective compounds against UV-B -induced skin aging. The synthesized derivatives were subjected to cellular viability test using MTT assay in primary Human Dermal Fibroblasts (HDFs). The results indicate A01, A05, A15, A22, A23, A25, A26, A28, A29, A32, A33, and A34 significantly enhanced cell viability of HDFs. Compound A33 at 10 and 25 μM showed a significant photo-protective effect against UV-B (10 mJ/cm²) -induced damage in HDFs. A33 at 25 μM significantly restored the UV-B -induced damage via its potent anti-oxidant, anti-apoptotic effects and ability to prevent collagen degradation. These findings pave the way for further development of A33 as a photo-protective skin agent.

"She'll Be Right, Mate": A Mixed Methods Analysis of Skin Cancer Prevention Practices among Australian Farmers-An At-Risk Group

This study examined Australian farmers’ engagement with skin cancer prevention behaviours and explored what made it hard for them to be ‘SunSmart’ (barriers), and what could be done to make prevention easier (facilitators). In total, 498 farmers (83.1% male, 22–89 years, 50.8% grain, sheep, or cattle farmers) participated. The least frequently performed SunSmart behaviours (reported as never practiced during summer) were using SPF 30+ sunscreen (16.6%), wearing protective sunglasses (10.5%), and wearing protective clothing (8.6%). Greater engagement (i.e., higher scores on scale from Never to Always) with SunSmart behaviours was explained by gender (female), educational attainment (trade or technical college certificate vs. high school), personal skin cancer history, and skin sun sensitivity. Barriers reported by farmers related to personal preferences (e.g., short-sleeved rather than long-sleeved clothing), comfort, and perceived impracticality of sun protection. Farmers’ solutions included making protective clothing and sunscreen more appropriate for farm work (e.g., by making clothing more breathable). A personal health scare was the most reported motivation for skin cancer prevention. Findings highlight the need for increased access to sun-protective clothing and sunscreen that is suitable for wearing when working on farms, complemented by culturally appropriate health education messaging, to encourage more farmers to perform SunSmart behaviours.

Suppression of Sunscreen Leakage in Water by Amyloid-like Protein Aggregates

A sunscreen offers indispensable skin protection against UV damage and related skin diseases. However, due to the poor interfacial stability of sunscreen coatings on the skin, the synthetic ingredients in sunscreen creams easily fall off and enter aquatic environments, causing large ecological hazards and skin protection failure. Herein, we tackle this issue by introducing amyloid-like protein aggregates into a sunscreen to noticeably enhance the interfacial robustness of sunscreen coatings on the skin. The synthesis of such an agent to suppress sunscreen leakage can be achieved by manipulating the phase transition of bovine serum albumin (BSA) in a mild aqueous solution at room temperature. The resulting phase-transitioned BSA (PTB) aggregates effectively entrap the sunscreen ingredients to generate a uniform cream coating on the skin with robust amyloid-mediated interfacial adhesion stability. With continuous flushing in aquatic environments, such as salt water and seawater, this PTB-modified sunscreen (PTB sunscreen) coated on the skin maintains a retention ratio as high as >92%, which is 2-10 times higher than those of commercially available sunscreen products. The high retention ratio of the PTB sunscreen in aquatic environments demonstrates the great potential of amyloid-like protein aggregates in the development of leakage-free sunscreens with low ecosystem hazards and long-lasting UV protection in aquatic environments.

Understanding sunscreen and photoprotection misinformation on parenting blogs: A mixed-method study

BACKGROUND/OBJECTIVES

Sun exposure during childhood is a modifiable risk factor for skin cancer. Social media (including parenting blogs) represent promising platforms for understanding misinformation about pediatric photoprotection. This study's objective was to qualitatively and quantitatively evaluate the digital social context of parenting blogs that shape parents' decisions about children's photoprotection.

METHODS

Mixed-method analysis was conducted of the 25 most popular parenting blogs in the USA, including 56 blog posts addressing photoprotection and 2661 comments. An inductive method was used to code and identify key themes associated with blog post categorization as sunscreen-encouraging, -discouraging, and -ambivalent. The qualitative analysis program NVivo was used to calculate descriptive statistics for comment codes based on co-occurrence with blog post category.

RESULTS

Sunscreen-discouraging posts addressed natural remedies, sunscreen recipes, and vitamin D. Sunscreen-encouraging posts focused on skin cancer and protective clothing. Sunscreen-ambivalent posts were associated with scientific studies. Sunscreen-discouraging posts received more comments (mean 124) than encouraging (31) or ambivalent posts (8). Discouraging (65%) and ambivalent posts (75%) cited scientific literature more often than encouraging posts (14%). Comments were twice as likely to discourage photoprotection as to encourage it (1340 vs 447 comments).

CONCLUSIONS

Parenting blogs are a substantial resource of both information and misinformation on pediatric photoprotection. However, misinformation receives substantially more engagement. The themes revealed in this study may help physicians and public health officials in developing interventions to target misinformation around pediatric photoprotection.

The banned sunscreen ingredients and their impact on human health: a systematic review

Recent evidence of high systemic absorption of sunscreen ingredients has raised concerns regarding the safety of sunscreen products. Oxybenzone (BP-3) and octinoxate (OMC), two common sunscreen ingredients, were recently banned in Key West and Hawaii owing to their toxic effects on marine ecosystems. Their impact on human health requires a careful assessment. To summarize the current evidence on the association between the systemic level of BP-3 or OMC and its health impact, a primary literature search was conducted using PubMed database in February 2019. There are 29 studies that address the impact of these ingredients on human health. Studies show that elevated systemic level of BP-3 has no adverse effect on male and female fertility, female reproductive hormone level, adiposity, fetal growth, child's neurodevelopment, and sexual maturation. However, the association of BP-3 level on thyroid hormone, testosterone level, kidney function, and pubertal timing has been reported and prompts further investigations to validate a true association. The systemic absorption of OMC has no reported effect on thyroid and reproductive hormone levels. In conclusion, current evidence is not sufficient to support the causal relationship between the elevated systemic level of BP-3 or OMC and adverse health outcomes. There are either contradictory findings among different studies or an insufficient number of studies to corroborate the observed association. To accurately evaluate the long-term risk of exposure to BP-3 and OMC from sunscreen, a well-designed longitudinal randomized controlled trial needs to be conducted.

Dermal exposure to the UV filter benzophenone-3 during early pregnancy affects fetal growth and sex ratio of the progeny in mice

The aim of this study was to analyze whether dermal exposure to benzophenone 3 (BP-3) during pregnancy affects critical parameters of pregnancy, and whether this exposure may affect the outcome of a second pregnancy in mice. Pregnant mice were exposed to 50-mg BP-3/kg body weight/day or olive oil (vehicle) from gestation day (gd) 0 to gd6 by dermal exposure. High-frequency ultrasound imaging was used to follow up fetal and placental growth in vivo. Blood flow parameters in uterine and umbilical arteries were analyzed by Doppler measurements. Mice were killed at gd5, gd10, and gd14 on the first pregnancy, and at gd10 and 14 on the second pregnancy. The weight of the first and second progenies was recorded, and sex ratio was analyzed. BP-3 levels were analyzed in serum and amniotic fluid. BP-3 reduced the fetal weight at gd14 and feto-placenta index of first pregnancy, with 16.13% of fetuses under the 5th percentile; arteria uterina parameters showed altered pattern at gd10. BP-3 was detected in serum 4 h after the exposure at gd6, and in amniotic fluid at gd14. Offspring weight of first progeny was lower in BP-3 group. Placenta weights of BP-3 group were decreased in second pregnancy. First and second progenies of mothers exposed to BP-3 showed a higher percentage of females (female sex ratio). Dermal exposure to low dose of BP-3 during early pregnancy resulted in an intrauterine growth restriction (IUGR) phenotype, disturbed sex ratio and alterations in the growth curve of the offspring in mouse model.

A Versatile Sunscreen with Minimal ROS Damage and Low Permeability

Organic and inorganic ultraviolet (UV) filters possess themselves advantages, while they suffer from different limitations including photostability, penetration, and cytotoxicity. Integrating organic and inorganic UV filters in a single unit holds great potential for enhanced UV protection. Herein, the dendritic silicon dioxide microspheres (DSMs) are encapsulated with Bi₂Ti₂O₇ nanocomposites (BTO-DSMs), an inorganic filter, and decorated with organic filters including sinapoyl malate (SM) and baicalin (BS/BTO-DSM) to enhance UV protection while significantly reducing ROS and skin permeability under UV exposure. The inorganic BTO-DSM component presents an expanded UV shield range and suppressed photocatalytic properties while preventing the organic filter SM direct contact with the epidermis and penetration behaviors. The baicalin efficiently scavenges the generated ROS from SM and reduces the transmittance of blue light. Notably, the results show that the proposed combined system significantly broadens the UV absorption region. Thus, the BS/BTO-DSM presents advanced in vitro anti-UV performance and in vivo UV protection against keratinocyte apoptosis and epidermal hyperplasia without long-term toxicity. The excellent anti-UV properties coupling with the suppressed photocatalytic capability and minimal epidermal penetration of BS/BTO-DSM make it promising for skin protection.