Toxicity of UV filters on marine bacteria: Combined effects with damaging solar radiation

The temperate seagrass species Cymodocea nodosa and the associated bacteria co-response to sunscreen pollution

Sunscreens are included among the contaminants of emerging concern (CECs) as their production and use have spread over years while damaging aquatic biota. Sunscreens can damage the photosynthetic systems and change the microbiome of seagrasses, triggering alterations in carbon metabolism -including primary production and dissolved organic carbon (DOC) fluxes- and ecological functions. Here, we conducted a 31-day mesocosm experiment exposing Cymodocea nodosa plants to a mixture of commercial sunscreens. Sunscreens produced a significant reduction on net production rates, switching the system from autotrophic to heterotrophic, which was ascribable to an increase in heterotrophic bacteria families (some known to degrade complex substrates) and, more importantly, to a significant reduction of photosynthetic pigments in plants. Moreover, a significant release of DOC at night attributed to exudation from disrupted roots was recorded, which accounted for the observed increase in bacteria abundance and family richness recorded in the phyllosphere. A higher accumulation of starch in rhizomes suggests a certain degree of resistance of this species. However, we observed a trend to reduce some protective bacteria taxa, whereas promoted the growth of other pathogenic ones for seagrasses, along with other taxa related with the consumption of plant-derived polysaccharides and lignin compounds. Therefore, our results indicated that this CEC may reduce the contribution of seagrasses to the blue carbon pool, among others ecosystem services, and suggest a possible prompt of seagrass diseases if stressing conditions are maintained over time.

Ecotoxicological effects of sunscreen derived organic and inorganic UV filters on marine organisms: A critical review

Sunscreens are topical personal care products that provide protection against the sun's ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Ultraviolet (UV) filters are compounds added to sunscreens to block, absorb, or reflect the sun's UV rays, but are of major emerging concern due to their widespread use and global distribution. They pose a significant risk to marine organisms owing to their chemical properties, including high lipophilicity which increases their bioavailability. The present review identifies and summarises the factors that contribute to UV filter pollution, their sources, pathways, and effects on marine organisms. We identify and evaluate the current knowledge base and gaps pertaining to their effects. Here, we retrieved 111 peer-reviewed articles from four academic search engines between January and October 2024 with the topic search relating to UV filters, sunscreen and ecotoxicology. Most publications (60 %) focused on the biological effects of organic UV filters, with oxybenzone (benzophenone-3) being the most studied (57 %). Fewer publications assessed the biological effects of inorganic UV filters (40 %). Throughout all search results, the most commonly tested species were in the class of bivalvia (24 %) and oxidative stress based assays were the most popular (organic studies 40 %, inorganic studies, 39 %). To enhance understanding, future research should explore a broader range of organisms and life stages, considering dietary uptake and realistic environmental conditions, including the use of UV lighting in laboratory settings.

2-Ethylhexyl-4-methoxycinnamate on marine and coastal environments: A comprehensive review of its environmental significance and biological impact

Marine and coastal environments are constantly subjected to increasing pressures associated with population growth, industrialization development, pollution and higher demand feeding society's consumerism. Among these pressures, there has been an increasing concern towards UV filters occurrence in aquatic ecosystems due to a greater use of personal care products (PCPs). 2-ethylhexyl-4-methoxycinnamate (EHMC) is one of the most used UV filters in sunscreen formulations, yet few reports address its effects in biota. This literature review intends to collect the available information concerning the environmental presence of EHMC in marine and coastal ecosystems and their effects in biota. The EHMC effects have been reported for the taxonomic groups: Actinomycetes, Alphaproteobacteria, Bacilli, Cytophagia, Flavobacteriia, Gammaproteobacteria, Actinopterygii, Anthozoa, Bacillariophyceae, Bivalvia, Branchiopoda, Coccolithophyceae, Echinoidea, Gastropoda, Malacostraca, Annelida and Thecostraca. The reported literature evaluated endpoints mainly related to development, viability, mortality, estrogenicity, gene transcription disruptions, biochemical alterations and morphophysiological changes. Based on the available information, there is still a clear need for further investigations related to EHMC and its toxicological effects on marine and coastal organisms.

The Potential of Natural Compounds in UV Protection Products

Overexposure to ultraviolet radiation mainly leads to skin disorders (erythema, burns, immunosuppression), skin aging, and skin cancer as the most serious side effect. It has been widely accepted that using sunscreen products is an important way to protect against the harmful effects of UV rays. Although commercial sunscreens have constantly changed and improved over time, there are emerging concerns about the safety of conventional, organic, UV filters due to adverse effects on humans (such as photoallergic dermatitis, contact sensitivity, endocrine-disrupting effects, etc.) as well as accumulation in the environment and aquatic organisms. This is why natural compounds are increasingly being investigated and used in cosmetic and pharmaceutical sunscreens. Some of these compounds are widely available, non-toxic, safer for use, and have considerable UV protective properties and less side effects. Plant-based compounds such as flavonoids can absorb UVA and UVB rays and possess antioxidant, anticarcinogenic, and anti-inflammatory effects that contribute to photoprotection. Apart from flavonoids, other natural products such as certain vegetable oils, carotenoids, stilbenes, and ferulic acid also have UV-absorbing properties. Some vitamins might also be beneficial for skin protection due to their antioxidant activity. Therefore, the aim of this research was to gain insight into the potential of natural compounds to replace or reduce the amount of conventional UV filters, based on recent research.

Environmental implications and nanotechnological advances in octocrylene-enriched sunscreen formulations: A comprehensive review

Ultraviolet (UV) radiation is a major contributor to skin aging, cancer, and other detrimental health effects. Sunscreens containing FDA-approved UV filters, like avobenzone, offer protection but suffer from photodegradation and potential phototoxicity. Encapsulation, antioxidants, and photostabilizers are strategies employed to combat these drawbacks. Octocrylene, an organic UV filter, utilizes nanotechnology to enhance sun protection factor (SPF). This review examines recent literature on octocrylene-enriched sunscreens, exploring the interplay between environmental impact, nanotechnological advancements, and clinical trial insights. A critical focus is placed on the environmental consequences of sunscreen use, particularly the potential hazards UV filters pose to marine ecosystems. Research in the Mediterranean Sea suggests bacterial sensitivity to these filters, raising concerns about their integration into the food chain. This review aims to guide researchers in developing effective strategies for photostabilization of UV filters. By combining encapsulation, photostabilizers, and antioxidants, researchers can potentially reduce phototoxic effects and contribute to developing more environmentally friendly sunscreens.

In vitro safety evaluation of (6-methoxy-9-oxo-9H-xanthen-2-yl)methyl (E)-3-(2,4-dimethoxyphenyl)acrylate (K-116) - the novel potential UV filter designed by means of a double chromophore strategy

The use of topical photoprotection is necessary to reduce adverse effects caused by excessive exposure to ultraviolet radiation. Despite the high standards set for UV filters, many of them may contribute to the occurrence of adverse effects. The newly synthesised compound K-116, the (E)-cinnamoyl xanthone derivative, could be an alternative. We conducted extended in vitro safety evaluation of compound K-116. The research included assessment of irritation potential on skin tissue, evaluation of penetration through the epidermis, and assessment of phototoxicity, and mutagenicity. Additionally, the eco-safety of compound K-116 was evaluated, including an examination of its degradation pathway in the Cunninghamella echinulata model, as well as in silico simulation of the toxicity of both the parent compound and its degradation products. The research showed that compound K-116 tested in future application conditions is deprived of skin irritant potential additionally it does not penetrate through the epidermis. Results showed that K-116 concentrate is not phototoxic and not mutagenic. The eco-safety studies showed that it undergoes biodegradation in 27% in Cunninghamella echinulata model. The parent compound and formed metabolite are less toxic than reference UV filters (octinoxate and octocrylene).

Effects associated with exposure to the emerging contaminant octyl-methoxycinnamate (a UV-B filter) in the aquatic environment: a review

Given the increasing concern surrounding ultraviolet (UV) radiation-induced skin damage, there has been a rise in demand for UV filters. Currently, UV-filters are considered emerging contaminants. The extensive production and use of UV filters have led to their widespread release into the aquatic environment. Thus, there is growing concern that UV filters may bioaccumulate and exhibit persistent properties within the environment, raising several safety health concerns. Octyl-methoxycinnamate (OMC) is extensively employed as a UV-B filter in the cosmetic industry. While initially designed to mitigate the adverse photobiological effects attributed to UV radiation, the safety of OMC has been questioned with some studies reporting toxic effects on environment. The aim of this review to provide an overview of the scientific information regarding the most widely used organic UV-filter (OMC), and its effects on biodiversity and aquatic environment.

A narrative review of the impact of ultraviolet radiation and sunscreen on the skin microbiome

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.

Fish gut and skin microbiota dysbiosis induced by exposure to commercial sunscreen formulations

UV filters (organic or mineral) present in sunscreen products are emerging contaminants of coastal aquatic environments. There is an urgent need to understand marine organisms responses to these compounds. In this study, we investigated the effect of exposure to dilutions of commercial sunscreen formulations on bacterial communities of mullet (Chelon sp.). The gut and skin mucus microbial communities were characterized using a metabarcoding approach targeting the 16S rRNA gene. Our results revealed that mullets had its own bacterial communities that differ from their surrounding habitats and specific to tissue. The dilutions of commercial sunscreens modified the relative abundance of Actinobacteroita, Bacteriodota and Proteobacteria for both gut and skin microbiota. They also allowed to bacteria affiliated to Mycobacterium, Nocardia and Tenacibaculum genera, known to house pathogenic species, to colonize the epithelium which may have implications for fish host health.

Microbial consortia degrade several widely used organic UV filters, but a number of hydrophobic filters remain recalcitrant to biodegradation

Organic UV filters are important ingredients in many personal care products, including sunscreens. Evaluating the biodegradability of organic UV filters is key to estimate their recalcitrance and environmental fate and thus central to their overall environmental risk assessment. In order to further understand the degradation process, the aim was to investigate whether specific consortia could degrade certain UV filters. Several bacterial strains were isolated from enrichment cultures actively degrading octocrylene (OC), butyl methoxydibenzoylmethane (BM), homosalate (HS), and 2-ethylhexyl salicylate (ES) and were utilized to construct an in-house consortium. This synthetic consortium contained 27 bacterial strains and degraded OC, BM, HS, and ES 60-80% after 12 days, but not benzophenone-3 (BP3), methoxyphenyl triazine (BEMT), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (EHT), or diethylamino hydroxybenzoyl hexyl benzoate (DHHB). Furthermore, several commercial microbial mixtures from Greencell were tested to assess their degradation activity toward the same organic UV filters. ES and HS were degraded by some of the commercial consortia, but to a lesser extent. The rest of the tested UV filters were not degraded by any of the commercial bacterial mixes. These results confirm that some organic UV filters are recalcitrant to biodegradation, while others are degraded by a specific set of microorganisms.

Multi-biomarker approach for the (eco)toxicity of UV-filter environmental pollution on the Mediterranean mussel Mytilus galloprovincialis in a multiple stressor context. The case of 4-MBC under salinity shifts

Marine-coastal ecosystems are rapidly transforming because of climate change (CC). At the same time, the impacts of emerging organic contaminants (i.e., organic UV-filters) on these ecosystems are intensifying. In the Mediterranean, the consequences of these disturbances are occurring at a fast pace making this area a potential sentinel site to be investigated. While singular effects of organic UV-filters or CC-related factors on marine biota have been relatively described, their combined impact is still largely unknown. Thus, the objective of this study was to assess the long-term responses of the Mediterranean mussel Mytilus galloprovincialis towards anticipated salinity changes (decreases-S20 or increases-S40) when exposed to environmentally relevant concentrations of the UV-filter 4-methylbenzylidene camphor (4-MBC). An integrated multi-biomarker approach was applied, featuring general and oxidative stress, antioxidant and biotransformation enzyme capacity, energy metabolism, genotoxicity, and neurotoxicity biomarkers. Results showed that both projected salinities, considered separately, exerted non-negligible impacts on mussels' health status, with greater biological impairments found at S 40. Combining both stressors resulted in an evident increase in mussels' susceptibility to the UV-filter, which exacerbated the toxicity of 4-MBC. The dominant influence of salinity in the climate change-contaminant interaction played a crucial role in this outcome. The most severe scenario occurred when S 20 was combined with 4-MBC. In this situation, mussels exhibited a decrease in filtration rate, metabolic capacity and deployment of energy reserves increased, with an upregulation of biotransformation and inhibition of antioxidant enzyme activities. This exposure also led to the observation of cellular and DNA damage, as well as an increase in AChE activity. Furthermore, salinity-dependent bioaccumulation patterns were evaluated revealing that the lowest values in contaminated mussels are found at S 20. Overall, the present findings provide evidence that projected CC/pollutant scenarios may represent high risks for mussels' populations, with global relevant implications for the ecosystem level.

Transformation and toxicity studies of UV filter diethylamino hydroxybenzoyl hexyl benzoate in the swimming pools

Diethylamino hydroxybenzoyl hexyl benzoate (DHHB), an ultraviolet (UV) filter, can be found in sunscreens and other personal care products and thus can be introduced into swimming pools through the swimmers. In outdoor pools, DHHB will inevitably interact with free chlorine and sunlight. Therefore, the mechanism of solar‑chlorine chemical transformation of DHHB, as well as the environmental risk, were investigated in this work. In chlorinated with solar (Cl + solar) process, free chlorine was the dominant contributor to 85% of the DHHB degradation, while hydroxyl radicals and reactive chlorine species contributed only 15% because of low free radical generation and fast DHHB and free chlorine reaction rates. Scavenging matrices, such as Cl^-, NH₄⁺, and dissolved organic matter (DOM), inhibited the degradation of DHHB in the Cl + solar process, while Br^-, HCO₃^-, NO₃^-, and urea promoted DHHB degradation. DHHB degradation was inhibited in tap water swimming pool samples, while it was enhanced in seawater pool samples by the Cl + solar process. Seven transformation by-products (TBPs) including mono-, dichlorinated, dealkylate, and monochloro-hydroxylated TBPs were identified. Three degradation pathways, chlorine substitution, chlorine and hydroxyl substitution, and dealkylation were proposed for DHHB transformation in the Cl + solar process. Both Quantitative structure-activity relationship and Aliivibrio fischeri toxicity tests demonstrated increased toxicity for the chlorinated TBPs. A risk assessment of the DHHB and its TBPs suggested that both DHHB and its chlorinated TBPs pose a significant health risk.

The response of aquatic ecosystems to the interactive effects of stratospheric ozone depletion, UV radiation, and climate change

Variations in stratospheric ozone and changes in the aquatic environment by climate change and human activity are modifying the exposure of aquatic ecosystems to UV radiation. These shifts in exposure have consequences for the distributions of species, biogeochemical cycles, and services provided by aquatic ecosystems. This Quadrennial Assessment presents the latest knowledge on the multi-faceted interactions between the effects of UV irradiation and climate change, and other anthropogenic activities, and how these conditions are changing aquatic ecosystems. Climate change results in variations in the depth of mixing, the thickness of ice cover, the duration of ice-free conditions and inputs of dissolved organic matter, all of which can either increase or decrease exposure to UV radiation. Anthropogenic activities release oil, UV filters in sunscreens, and microplastics into the aquatic environment that are then modified by UV radiation, frequently amplifying adverse effects on aquatic organisms and their environments. The impacts of these changes in combination with factors such as warming and ocean acidification are considered for aquatic micro-organisms, macroalgae, plants, and animals (floating, swimming, and attached). Minimising the disruptive consequences of these effects on critical services provided by the world's rivers, lakes and oceans (freshwater supply, recreation, transport, and food security) will not only require continued adherence to the Montreal Protocol but also a wider inclusion of solar UV radiation and its effects in studies and/or models of aquatic ecosystems under conditions of the future global climate.

Environmental impacts of the ultraviolet filter oxybenzone

Organic UV filters are emerging contaminants with increasing evidence of their negative impact on environmental health and water quality. One of the most common and environmentally relevant organic UV filters is oxybenzone (OBZ). While much of the initial focus has been on investigating the interaction of OBZ with coral reefs, there have been several recent studies that indicate that organic UV filters are affecting other environmental endpoints, including marine animals, algae, and plants. OBZ has been found to bioaccumulate in marine animals such as fish and mussels and then potentially acting as an endocrine disruptor. In plants, exposure to OBZ has been associated with decreased photosynthesis, inhibited seed germination, and impaired plant growth. In this review, we summarize the current state of knowledge regarding the environmental impacts of OBZ and suggest potential future directions.

Occurrence, effects, and ecological risks of chemicals in sanitizers and disinfectants: A review

In response to the novel coronavirus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – a virus that causes COVID-19 disease has led to wide use of sanitizers and disinfectants. This, in turn, triggered concerns on their potential deleterious effects to human health and the environment due to numerous chemicals incorporated in both product categories. Here, the current state of science regarding the occurrence and ecological effects of different classes of chemicals in these products (e.g., ultraviolent filters, fragrances, etc.) are summarized in different natural (e.g., rivers) and engineered (e.g., wastewater treatment plants) systems. Data collected in the literature suggests chemicals incorporated in sanitizers and disinfectants are present in the environment, and a large portion are toxic to fish, algae, and daphnia. Using the risk quotient approach based on occurrence data, we found eight chemicals that posed the highest risk to aquatic organisms in freshwater systems were benzalkonium chloride, 4-chloro-m-cresol, sodium ortho phenyl phenate, hydrogen peroxide, 1, 2-propanediol, 4-Methyl-benzilidine-camphor, ethylhexyl methoxy cinnamate, and octocrylene. Considering limited occurrence and effects information for most chemicals, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystems are recommended.

Assessing the eco-compatibility of new generation sunscreen products through a combined microscopic-molecular approach

There is now unequivocal evidence that sunscreen can severely affect marine ecosystems. However, so far, most studies have focused on the impact of single sunscreen ingredients rather than on the whole sunscreen products, which are released into the marine environment. In the present work, we investigated the ecological impact of six formulations, which represent the "new generation" organic UV filters such as diethylamino hydroxybenzoyl hexyl benzoate (DHHB), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), ethylhexyl triazone (EHT), and bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), which are progressively replacing the "old generation" organic UV filters (e.g., oxybenzone, octinoxate) banned in several countries of the world. The six formulations tested were characterized by a different combination of ingredients, on a model species particularly sensitive to environmental alterations: the sea urchin, Paracentrotus lividus. We investigated the sea urchin responses both in terms of gene expression and anomalies in embryonic development. We found that all sunscreen products containing only MBBT, DHHB, BEMT, and EHT as UV filters, are more eco-compatible than those also containing also ES, or other ingredients such as emollients and texturizing compounds, which may act synergistically causing molecular stress, morphological anomalies, and ultimately possible death. Overall, the results presented here provide new insights on the effects of sunscreen products based on "new generation" UV filters, and highlights the urgency of testing complete formulations, rather than just specific UV filters to ascertain the eco-compatibility of sunscreen products, to effectively minimize their impact on marine ecosystems.

Synthesis of cross-linked magnetic chitosan beads immobilised with bacteria for aerobic biodegrading benzophenone-type UV filter

Bacterial immobilisation is a technique by which bacteria are embedded into or adsorbed onto a carrier material thereby increasing bacterial tolerance to harsh environments. This technique can be used to enhance bacterial activity and to degrade pollutants. Immobilised bacterial beads that contain nanomagnetic particles allow bead recycling and reuse. In this study, our objective was to produce cross-linked nanomagnetic chitosan beads (MCBs) for the biodegradation of benzophenone-type UV filter chemicals such as 2,4-dihydroxybenzophenone (BP-1) and oxybenzone (BP-3). We found that the optimal concentration for creating these MCBs to be 1.2% by weight chitosan and 10% by weight nano-magnetite. We selected and isolated six benzophenone-n (BPs)-biodegrading bacteria identified to be various Pseudomonas spp., a Gordonia sp., and Rhodococcus zopfii; these were used to create MCBs that were able to effectively biodegrade BP-1 or BP-3 as a sole carbon source. Both BPs were effectively biodegraded and mineralised over 8 days in the presence of the selected MCB-immobilised bacterial strains. The highest pseudo-first-order constant rates for BP biodegradation were 8.7 × 10^-3 h^-1 for BP-1 (strain BP1-D) and 1.02 × 10^-3 h^-1 for BP-3 (strain BP3-1). The mechanical strength of the MCBs was measured to be above 90% based on recovered weight. The MCBs released their bacteria at rates in the range of 10⁴-10⁵ CFU/day. We also determined the pathway through which the BPs were being aerobically biodegraded based on the GC/MS profiles of the intermediates. Our findings provide a novel strategy for treating BPs via the use of reusable and recyclable MCBs that are cheap, easy and fast to synthesise.

Plastic pollution fosters more microbial growth in lakes than natural organic matter

Plastic debris widely pollutes freshwaters. Abiotic and biotic degradation of plastics releases carbon-based substrates that are available for heterotrophic growth, but little is known about how these novel organic compounds influence microbial metabolism. Here we found leachate from plastic shopping bags was chemically distinct and more bioavailable than natural organic matter from 29 Scandinavian lakes. Consequently, plastic leachate increased bacterial biomass acquisition by 2.29-times when added at an environmentally-relevant concentration to lake surface waters. These results were not solely attributable to the amount of dissolved organic carbon provided by the leachate. Bacterial growth was 1.72-times more efficient with plastic leachate because the added carbon was more accessible than natural organic matter. These effects varied with both the availability of alternate, especially labile, carbon sources and bacterial diversity. Together, our results suggest that plastic pollution may stimulate aquatic food webs and highlight where pollution mitigation strategies could be most effective.

Ultra-high resolution mass spectrometry revealed that plastic bags leach labile compounds. Bioassays performed in Scandinavian lakes indicated that these compounds are incorporated into biomass faster and more efficiently than natural organic matter.

UV-filter octyl methoxycinnamate causes reproductive toxicity associated with germline apoptosis and vitellogenin decrease in Caenorhabditis elegans

Octyl methoxycinnamate (OMC) is a common UV filter found in personal care products such as sunscreen and cosmetics. However, OMC's presence in wastewater has raised concerns that it could potentially pollute aquatic ecosystems because of its limited biodegradability and its estrogenic disrupting properties. In this study, we investigated the environmental toxicity of OMC and its potential biomarkers using the nematode Caenorhabditis elegans. Our results showed that body length, eggs in utero, and total brood size decreased with increasing dose (experimental concentrations = 0, 1, 5, 10, 100, 500 μM for body length and eggs in utero, and 0, 5, 10 μM for total brood size) in C. elegans after L1 larval stage (the first larval stage for 0 - 12 hours post-hatching) larval stage exposure to OMC. The minimum effective concentrations were 1, 5, and 10 μM, respectively. Modeling results demonstrated that the threshold concentration of OMC inducing 10% inhibited eggs in utero was 0.33 μM (95.11 μg/L). Furthermore, germline apoptosis was induced in 10 μM OMC-treated worms (experimental concentrations = 0, 5, 10 μM). Decreased mRNA levels of vitellogenin-related genes (vit-2 and vit-6) and increased mRNA levels of apoptosis-related genes (egl-1 and ced-3) were observed in 10 μM OMC-treated C. elegans (experimental concentrations = 0, 10 μM), suggesting that reproductive toxicity was associated with decreased vitellogenin levels and germline apoptosis. In summary, our study shows that OMC is reproductively toxic and leads to reduced egg formation and decreased brood size in C. elegans by reducing vitellogenin levels and promoting germline apoptosis.

UV Filters: Challenges and Prospects

The use of sunscreens is an established and recommended practice to protect skin from solar-induced damage. Around 30 UV filters can be used in sunscreen products in the European Union, which ought to follow the requirements of the regulation 1223/2009 to ensure their efficacy and safety for humans. Nevertheless, low photostability and putative toxicity for humans and environment have been reported for some UV filters. Particularly, the negative impact in marine organisms has recently raised concern on the scientific community. Therefore, it is important to develop new UV filters with improved safety profile and photostability. Over the last two decades, nearly 200 new compounds have revealed promising photoprotection properties. The explored compounds were obtained through different approaches, including exploration of natural sources, synthetic pathways, and nanotechnology. Almost 50 natural products and around 140 synthetic derivatives, such as benzimidazoles, benzotriazoles, hydroxycinnamic acids, xanthones, triazines, among others, have been studied aiming the discovery of novel, effective, and safer future photoprotective agents. Herein, we provide the reader with an overview about UV filters’ challenges and prospects, offering a forward-looking to the next-generation of UV filters.

Effect of sunlight and salinity on the survival of pathogenic and non-pathogenic strains of Vibrio parahaemolyticus in water microcosms

The effect of sunlight and salinities (10, 20, 39, and 60 psu) on the survival of Vibrio parahaemolyticus strains carrying either (thermostable direct hemolysin) tdh, the (thermostable related hemolysin) trh, and both or none of them were studied in water microcosms stabilized at 20°C using plate count agar and acridine orange direct viable count. All V. parahaemolyticus strains exposed to sunlight rapidly lose their culturability and evolve into a viable but non-culturable state (VBNC). However, the tdh positive strains remain more culturable than the non-virulent or trh positive strain but statically insignificant. At tested salinities, the survival time was higher at 10, 20, and 60 psu compared with that observed in seawater (39 psu). In seawater under dark condition, Vibrio strains remain culturable for up to 200 days with a significant difference between strains (p < 0.05). Furthermore, the non-pathogenic strain survives longer than the virulent ones. At different salinities, a better adaptation is observed at 10 and 20 psu compared with 39 and 60 psu. Resuscitations essays performed on VBNC bacteria in a nutrient broth at 20°C and 37°C does not show any revivification. PRACTITIONER POINTS: Effect of sunlight and salinities on the survival of V. parahaemolyticus in the marine environment. Resuscitation essay performed on viable but no cultivable bacteria. Microscope motility examines show that all strains exposed to sunlight remain motile after the loss of cultivability.

Ecotoxicological screening of UV-filters using a battery of marine bioassays

The present study aimed to assess the toxicity of seven UV-filters: zinc oxide nanoparticles (nZnO, particle size <100 nm), titanium dioxide nanoparticles (nTiO₂, primary particle size 21 nm), 2-ethylhexyl-4-methoxycinnamate (EHMC), 4-methylbenzylidene camphor (4-MBC), avobenzone (AVO), octocrylene (OCTO) and benzophenone-3 (BP-3) on three species: Aliivibrio fischeri (inhibition of bioluminescence), Phaeodactylum tricornutum (growth inhibition) and Ficopomatus enigmaticus (larval development success). Results showed nTiO₂ to be the most toxic for P. tricornutum (EC₅₀ 0.043 mg L^-1), while no effect was observed in A. fischeri and F. enigmaticus. EHMC was the most toxic to A. fischeri (EC₅₀ 0.868 mg L^-1 (15 min) and 1.06 mg L^-1 (30 min)) and the second most toxic to P. tricornutum. For F. enigmaticus, the lowest percentages of correct development resulted from 4-MBC exposure, with EC₅₀ of 0.836 mg L^-1. Overall, AVO induced low toxicity to every assessed species and OCTO was the least toxic for F. enigmaticus larvae. Considering the results obtained for F. enigmaticus, further larval development assays were performed with nZnO and EHMC under different light (light vs darkness) and temperature (20 and 25 °C) conditions, showing higher percentages of correct development at 25 °C, independently on light/darkness conditions. Under different temperature and photoperiod conditions, nZnO was more toxic than EHMC. Overall, nZnO and EHMC were among the most toxic UV filters tested and, when testing the effects of these UV-filters with temperature the results highlight that the impacts are liable to be lessened at higher temperatures (25 °C compared with 20 °C), in the case of this estuarine polychaete species. Nevertheless, further experiments are necessary to describe the effects of these two UV-filters at different organization levels, to study the toxicity of eventual degradation by-products and to provide more information on the combination of different stressors.

Shedding light on the bacterial resistance to toxic UV filters: a comparative genomic study

UV filters are toxic to marine bacteria that dominate the marine biomass. Ecotoxicology often studies the organism response but rarely integrates the toxicity mechanisms at the molecular level. In this study, in silico comparative genomics between UV filters sensitive and resistant bacteria were conducted in order to unravel the genes responsible for a resistance phenotype. The genomes of two environmentally relevant Bacteroidetes and three Firmicutes species were compared through pairwise comparison. Larger genomes were carried by bacteria exhibiting a resistant phenotype, favoring their ability to adapt to environmental stresses. While the antitoxin and CRISPR systems were the only distinctive features in resistant Bacteroidetes, Firmicutes displayed multiple unique genes that could support the difference between sensitive and resistant phenotypes. Several genes involved in ROS response, vitamin biosynthesis, xenobiotic degradation, multidrug resistance, and lipophilic compound permeability were shown to be exclusive to resistant species. Our investigation contributes to a better understanding of UV filters resistance phenotypes, by identifying pivotal genes involved in key pathways.

Unraveling the molecular effects of oxybenzone on the proteome of an environmentally relevant marine bacterium

The use of Benzophenone-3 (BP3), also known as oxybenzone, a common UV filter, is a growing environmental concern in regard to its toxicity on aquatic organisms. Our previous work stressed that BP3 is toxic to Epibacterium mobile, an environmentally relevant marine α-proteobacterium. In this study, we implemented a label-free quantitative proteomics workflow to decipher the effects of BP3 on the E. mobile proteome. Furthermore, the effect of DMSO, one of the most common solvents used to vehicle low concentrations of lipophilic chemicals, was assessed to emphasize the importance of limiting solvent concentration in ecotoxicological studies. Data-independent analysis proteomics highlighted that BP3 induced changes in the regulation of 56 proteins involved in xenobiotic export, detoxification, oxidative stress response, motility, and fatty acid, iron and amino acid metabolisms. Our results also outlined that the use of DMSO at 0.046% caused regulation changes in proteins related to transport, iron uptake and metabolism, and housekeeping functions, underlining the need to reduce the concentration of solvents in ecotoxicological studies.

UV filters and UV stabilisers adsorbed in microplastic debris from beach sand

Microplastics (MPs) in oceans adsorb different types of pollutants, which can negatively impact the food chain. The extensive use of personal care products (PCPs) has led to their ubiquitous environmental presence, and their partition between plastic matrices and surroundings is determined by their physico-chemical characteristics and environmental conditions. This work develops and applies a methodology to determine 12 UV filters (UVFs) and UV stabilisers (UVSs) in MPs collected in beach sand. The analyses were carried out by ultrasound-assisted extraction and ultrahigh-performance liquid chromatography with tandem mass spectrometry detection. The validated procedure was applied to MPs samples taken in sand samples from 13 beaches on the Canary Islands (Spain). The results showed the presence of 10 UV filters and UV stabilisers at concentrations between 1 and 4031 ng·g^-1, where octocrylene was the most frequently found. The target analytes were present in all the sampling beaches.

Ethylhexyl methoxycinnamate and butyl methoxydibenzoylmethane: Toxicological effects on marine biota and human concerns

Ethylhexyl methoxycinnamate (EHMC) (CAS number: 5466-77-3) and butyl methoxydibenzoylmethane (BMDM) (CAS number: 70356-09-1) are important sunscreens. However, frequent application of large amounts of these compounds may reflect serious environmental impact, once it enters the environment through indirect release via wastewater treatment or immediate release during water activities. In this article, we reviewed the toxicological effects of EHMC and BMDM on aquatic ecosystems and the human consequences. According to the literature, EHMC and BMDM have been detected in water samples and sediments worldwide. Consequently, these compounds are also present in several marine organisms like fish, invertebrates, coral reefs, marine mammals, and other species, due to its bioaccumulation potential. Studies show that these chemicals are capable of damaging the aquatic beings in different ways. Further, bioaccumulation studies have shown that EHMC biomagnifies through trophic levels, which makes human seafood consumption a concern because the higher position in the trophic chain, the more elevate levels of ultraviolet (UV) filters are detected, and it is established that EHMC present adverse effects on the human organism. In contrast, there are no studies on the BMDM bioaccumulation and biomagnification potential. Different strategies can be adopted to avoid the damage caused by sunscreens in the environment and human organism. Two of them include the use of natural photoprotectors, such as polyphenols, in association with UV filters in sunscreens and the development of new and safer UV filters. Overall, this review shows the importance of studying the impacts of sunscreens in nature and developing safer sunscreens and formulations to safeguard marine fauna, ecosystems, and humans.

Risks of organic UV filters: a review of environmental and human health concern studies

Organic UV filters are compounds that absorb UV irradiation by their highly conjugated structure. With the developing consciousness over the last century of the skin damage UV radiation can cause, the demand for organic UV filters has risen, for use not only in sunscreens, but also in other personal care products. The massive production and usage of these organic UV filters has resulted in extensive release into the aquatic environment, and thereby making an important group of emerging contaminants. Considering the widespread occurrence of organic UV filters in not only ambient water, but also sediment, soil and even indoor dust, their threats towards the health of living organisms have been a subject of active investigation. In this review article, we present an overall review of existing knowledge on the risks of organic UV filters from the aspects of both environmental and human health impacts. As for the environment, some organic UV filters are proven to bioaccumulate in various kinds of aquatic organisms, and further to have adverse effects on different kinds of animal models. Toxicological studies including in vivo and in vitro studies are important and effective means to ascertain the effects and mechanisms of organic UV filters on both the ecosystem and humans. Subsequent concerns arise that these compounds will affect human health in the long term. This review concludes by suggesting future lines of research based on the remaining knowledge gaps.

A systematic review and ecological risk assessment for organic ultraviolet filters in aquatic environments

Organic ultraviolet filters (OUVFs) are used in a wide range of manufactured products including personal care (e.g. sunscreens) and plastic items. This review summarizes the available data regarding the toxic effects of OUVFs on marine and freshwater organisms and generates the predicted no-effect concentration (PNEC) values necessary for assessing ecological risk. Through a systematic search of the literature, 89 studies were identified and ecotoxicological data extracted. Collectively, these studies described toxicity testing with 39 OUVF from 10 structural classes, with derivatives of benzophenones (49%) and camphors (16%) most studied. There was a bias towards selecting freshwater species (61%), and evaluating single OUVF effects (87%) rather than OUVF mixtures. Short-term (acute) experimentation (58%) was marginally more common than long-term (chronic) testing (42%). Reproductive, developmental, genetic, and neurological toxicity were the most commonly identified effects in aquatic organism, and were associated with molecular interactions with steroid receptors, DNA, or the production of reactive oxygen species. Species sensitivity distribution and/or assessment factors were used to calculate PNECs for 22 OUVFs and the risk quotients for 12 OUVFs. When using maximum concentrations, high risk was observed for six OUVFs in marine environments (4-methylbenzylidene-camphor, octocrylene, padimate-O, benzophenone-1, and oxybenzone, ethylhexyl-4-methoxycinnamate), and for four OUVFs in freshwater environments (ethylhexyl-4-methoxycinnamate, octocrylene, avobenzone and oxybenzone). When using median concentrations, a risk to marine environments was observed for oxybenzone. The results of this review underline that there is limited knowledge of the pathological effects of OUVFs and their metabolites in aquatic environments, and this inhibits the development of informed water-quality guidelines.