Biomarker-based assessment of sublethal toxicity of organic UV filters (ensulizole and octocrylene) in a sentinel marine bivalve Mytilus edulis

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.

Effects of the UV Filter Octocrylene and Its Degradation Product Benzophenone on Pacific Oyster (Magallana gigas) Larvae: A Call for Reassessment of Environmental Hazards

Early life stages are pivotal to the functioning and resilience of ecological systems, displaying heightened vulnerability to environmental changes and exposure to contaminants. Octocrylene (OC), an organic ultraviolet (UV) filter, and its breakdown product benzophenone (BP) are commonly found in aquatic environments, but their impact on keystone processes determining the success or failure of the early life stages of marine organisms remains underexplored. This study aims to assess the impacts of OC and BP at environmentally realistic concentrations (1, 10, and 100 µg.L-1), over a 24 h exposure period, on larvae of the Pacific oyster (Magallana gigas). A multiparametric approach was employed, examining DNA integrity, embryo-larval development and swimming velocity. The results showed that DNA integrity and swimming velocity were not affected by OC or BP; however, both compounds increased developmental abnormalities in D-shaped larvae in all concentrations tested. Considering the robustness of morphological parameters, often assumed as irreversible, and their critical influence on larvae survival, these findings suggest that environmentally relevant concentrations of OC and BP may threaten the success of oyster larvae, potentially impacting the population's long-term stability and, ultimately, raising ecological health issues.

Short-term and long-term effects of microplastics and organic UV-filters on the invertebrate model species Daphnia magna

There is an ongoing debate regarding the role of microplastics (MPs) in enhancing the effects of various chemical compounds, highlighting the need for more detailed analyses. In this study, neonates of the water flea (Daphnia magna) were exposed to polystyrene MPs (PS-MPs; 3 µm; exposure concentration, 1.25 mg/L), a mixture of seven organic UV-filters (avobenzone, ethylhexyl triazone, homosalate, iscotrizinol, octinoxate, octisalate, and octocrylene; each at a low environmental concentration of 200 ng/L), or the combination of both pollutants for 3, 7, or 21 days. Results showed that PS-MPs alone decreased the body size of daphnids, while all treatments increased heart rate by the end of the 21-day exposure. On days 3 and 21, both PS-MPs and PS-MPs + UV-filters reduced swimming speed and total distance travelled. Additionally, PS-MPs increased the time of the first egg production, but decreased the egg number in the first production, total egg number, maximum egg number, and total neonate number during the 21-day treatment. Similarly, UV-filters or the combined pollutants increased the time of the first egg production and decreased the total neonate number. All treatments increased multixenobiotic resistance activity on days 3 and 7, while only UV-filters elevated CYP450 activity on day 3. PS-MPs or combined pollutants increased GST activity during early exposure but showed no effect on day 21. CAT activity was also affected by treatments in a time-dependent manner. These findings demonstrate that chronic exposure to PS-MPs and UV-filters, applied individually or in combination at a low environmental concentration, moderately impacts development, heart rate, and swimming activity in D. magna, while significantly altering reproduction and key cellular functions such as membrane transport activity, metabolism, and antioxidant defense. Co-exposure did not reveal a clear pattern of synergism or antagonism, suggesting that joint toxicity risks of these xenobiotics typically emerge at concentrations higher than low environmental levels. Future studies should explore potential interactions more thoroughly and assess transgenerational effects on reproduction and cellular defense pathways.

Developmental, behavioral, and biochemical effects of chronic exposure to sublethal concentrations of organic UV-filter compounds on a freshwater model species

The prevalence of organic/chemical UV-filter compounds in aquatic ecosystems represents a growing environmental issue. The long-term toxicity risks of many UV-filters at environmentally relevant concentrations to aquatic biota are still less studied, especially in the case of invertebrates. This study was designed to evaluate the chronic toxicity of avobenzone (AVO), octocrylene (OCTO), and octinoxate (OCTI), three UV-filters which frequently occur in the aquatic environment, to the water flea (Daphnia magna) at an environmentally relevant concentration of 200 ng l-1 in a 21-day exposure. Potential alterations in the growth, reproduction, and heart rate were continuously monitored during the treatments. Filtration rate, swimming, and the state of the antioxidant- and metabolic functions were evaluated at the end of exposures. Avobenzone significantly increased the reproductive output, heart rate, and filtration rate, while evoked a significant decrease of swimming behavior, and inhibited the activity of catalase (CAT) and glutathione S-transferase (GST) enzymes. The body size, reproduction, heart rate, and superoxide dismutase (SOD) activity were significantly increased whereas the activity of GST and CAT was significantly reduced by OCTO. OCTI significantly increased reproduction, heart rate, CAT and SOD activity but significantly decreased the swimming behavior. Our results confirmed that chronic exposure to organic UV-filters even at environmentally relevant concentrations affect basic physiological traits and cellular defense pathways in D. magna. Highlighting, our observations revealed previously unknown physiological changes (e.g., altered heart rate, filtration rate, SOD activity) caused by the investigated UV-filter compounds. Future research is to be aimed at investigating the mixture effects of these compounds and at the understanding of the potential cellular and molecular mechanisms underlying the changes induced.

Personal care products: an emerging threat to the marine bivalve Ruditapes philippinarum

In the last few decades, there has been a growing interest in understanding the behavior of personal care products (PCPs) in the aquatic environment. In this regard, the aim of this study is to estimate the accumulation and effects of four PCPs within the clam Ruditapes philippinarum. The PCPs selected were triclosan, OTNE, benzophenone-3, and octocrylene. A progressive uptake was observed and maximum concentrations in tissues were reached at the end of the exposure phase, up to levels of 0.68 µg g-1, 24 µg g-1, 0.81 µg g-1, and 1.52 µg g-1 for OTNE, BP-3, OC, and TCS, respectively. After the PCP post-exposure period, the removal percentages were higher than 65%. The estimated logarithm bioconcentration factor ranged from 3.34 to 2.93, in concordance with the lipophobicity of each substance. No lethal effects were found although significant changes were observed for ethoxyresorufin O-demethylase activity, glutathione S-transferase activity, lipid peroxidation, and DNA damage.

Avoidance behaviour and toxicological impact of sunscreens in the teleost Chelon auratus

There is increasing evidence that sunscreen, more specifically the organic ultra-violet filters (O-UVFs), are toxic for aquatic organisms. In the present study, we simulated an environmental sunscreen exposure on the teleost fish, Chelon auratus. The first objective was to assess their spatial avoidance of environmental concentrations of sunscreen products (i.e. a few μg.L-1 of O-UVFs). Our results showed that the fish did not avoid the contaminated area. Therefore, the second objective was to evaluate the toxicological impacts of such pollutants after 35 days exposure to concentrations of a few μg.L-1 of O-UVFs. At the individual level, O-UVFs increased the hepatosomatic index which could suggest pathological alterations of the liver or the initiation of the detoxification processes. At the cellular level, a significant increase of malondialdehyde was measured in the muscle of fish exposed to O-UVFs which suggests a failure of antioxidant defences and/or an excess of reactive oxygen species.

Bioconcentration and cellular effects of emerging contaminants in sponges from Maldivian coral reefs: A managing tool for sustainable tourism

Tourism is the main income source for the Maldives, but concurrently, it represents a growing threat to its marine ecosystem. Here, we monitored the bioaccumulation of 15 emerging contaminants (ECs) in the Maldivian reef sponges Spheciospongia vagabunda collected in two resort islands (Athuruga and Thudufushi, Ari Atoll) and an inhabited island (Magoodhoo, Faafu Atoll), and we analysed their impact on different sponge cellular stress biomarkers. Caffeine and the insect repellent DEET were detected in sponges of all the islands, whereas the antibiotic erythromycin and the UV filter 4-methylbenzylidene camphor were found in resort islands only. Although concentrations were approximately a few ng/g d.w., we quantified various induced cellular effects, in particular an increase of the levels of the enzyme glutathione S-transferase involved in cell detoxification. Our results highlight the importance to increase awareness on ECs pollution, promoting the use of more environmental friendly products to achieving the sustainable development goals.

Will warmer summers increase the impact of UV filters on marine bivalves?

Marine organisms are constantly exposed to multiple stressors including pollutants released into the environment, such as personal care products (PCPs), and climate change-derived factors, namely warming, which are aggravated by anthropogenic drivers and pose increasing pressure on coastal ecosystems. Avobenzone (AVO) is one of the most used ultraviolet (UV) filters in PCPs which have been increasingly used and, thereby, identified in aquatic environments. However, data regarding the influence of warming on the impacts caused by AVO in bivalves is lacking. Mussels are considered good bioindicators thus being often employed in ecotoxicology studies. Hence, the present study aimed to evaluate the toxic effects of an environmentally relevant concentration of AVO (0.5 μg/L) and warming (21 °C), acting alone or in combination, on sperm and adults of the Mediterranean mussel species Mytilus galloprovincialis, through in vitro and in vivo tests, respectively. AVO and warming effects were evaluated by assessing oxidative status, viability, genotoxicity, motility, and kinetics in sperm, together with the quantification of energy content, metabolic capacity, biological defence mechanisms, cellular damage, and neurotoxicity in adults. AVO induced genotoxicity and increased respiration rate in sperm while enhancing the biotransformation enzymes' activity in adults. Exposure to warming led to an increase in respiration rate, ROS overproduction, cellular damage, and viability decrease in sperm whereas metabolic capacity increased in adults. AVO combined with warming caused oxidative stress, cellular damage, genotoxicity, and decreased motility in sperm, while only antioxidant enzymes' activity was enhanced in adults. Overall, the present study demonstrated that when acting in combination the effects of both stressors were more prominent. Furthermore, considering the multiple-stressor scenario tested, major toxic effects occurred in male gametes in comparison to adults.

Identification of disinfection by-products (DBP) in thermal water swimming pools applying non-target screening by LC-/GC-HRMS

The discovery of new disinfection by-products (DBPs) is still a rarely investigated research area in past studies. In particular, compared to freshwater pools, therapeutic pools with their unique chemical composition have rarely been investigated for novel DBPs. Here we have developed a semi-automated workflow that combines data from target and non-target screening, calculated and measured toxicities into a heat map using hierarchical clustering to assess the pool's overall potential chemical risk. In addition, we used complementary analytical techniques such as positive and negative chemical ionization to demonstrate how novel DBPs can be better identified in future studies. We identified two representatives of the haloketones (pentachloroacetone, and pentabromoacetone) and tribromo furoic acid detected for the first time in swimming pools. Non-target screening combined with target analysis and toxicity assessment may help to define risk-based monitoring strategies in the future, as required by regulatory frameworks for swimming pool operations worldwide.

Biomarkers activity in Oreochromis niloticus under sub-chronic exposure to a UV filters ternary mixture

The behavior of organic UV filters in aquatic ecosystems and living organisms raises concern. For the first time, biochemical biomarkers were evaluated in the liver and brain of juvenile Oreochromis niloticus exposed to 0.001 and 0.5 mg L^-1 of a benzophenone-3 (BP-3), octyl methoxycinnamate (EHMC), and octocrylene (OC) mixture for 29 days. Before the exposure, the stability of these UV filters was investigated using liquid chromatography. The experiment with aeration in the aquarium showed a high percentage of concentration reduction (%) after 24 h: 62 ± 2 for BP-3, 96 ± 6 for EHMC, and 88 ± 2 for OC versus 5 ± 4 for BP-3, 8 ± 7 for EHMC, and 2 ± 3 for OC when without aeration. These results defined the bioassay protocol. The stability of the filters concentrations after being stored in PET flasks and subjected to freezing and thawing cycles was also verified. In PET bottles, the BP-3, EHMC, and OC presented concentration reductions of 8 ± 1, 28 ± 7 and 25 ± 5 respectively, after 96 h storage and four freezing cycles. In falcon tubes the concentration reductions observed were 47 ± 2 for BP-3, >95 ± 1 for EHMC and 86 ± 2 for OC after 48 h and two cycles. The 29 days of sub-chronic exposure indicated the occurrence of oxidative stress through the enhanced lipid peroxidation (LPO) levels for the groups exposed to both bioassay concentrations. The catalase (CAT), glutathione-S-transferase (GST), and acetylcholinesterase (AChE) activities did not show significant alterations. The genetic adverse effects were analyzed in erythrocytes of fish exposed to 0.001 mg L^-1 of the mixture by comet and micronucleus biomarkers and no significant damage was observed.

Prospecting toxicity of octocrylene in Allium cepa L. and Eisenia fetida Sav

Octocrylene sunscreen is found in different environmental compartments. Unlike aquatic organisms, there are few studies evaluating the adverse effects caused by this pollutant on terrestrial plants, and no studies on soil fauna. In this study, octocrylene was evaluated at concentrations of 10, 100, and 1000 µg/L for phytotoxicity, cytogenotoxicity, and oxidative stress in Allium cepa L., and acute toxicity and oxidative stress in Eisenia fetida Sav. In A. cepa, at concentrations of 100 and 1000 µg/L, octocrylene reduced the germination potential in seeds, inhibited root elongation, and caused disturbance in cell division in roots. In E. fetida, the concentration of 1000 µg/L promoted an avoidance rate of 80%, while 10 µg/L caused a hormesis effect. The concentrations 100 and 1000 µg/L caused lipid peroxidation in A. cepa and E. fetida. Based on the results, the recurrent use of biosolids in soil fertilization, as well as the irrigation of plants with wastewater, with the presence of octocrylene can negatively impact the survival of different species that depend directly or indirectly on the soil.

Gone with sunscreens: Responses of blue mussels (Mytilus edulis) to a wide concentration range of a UV filter ensulizole

Organic UV filters have emerged as a new threat to marine organisms, but ecotoxicological studies have so far focused on only a few substances despite the chemical diversity of these synthetic sunscreen agents. Here we examined the responses of blue mussels Mytilus edulis to ensulizole, a non-lipophilic UV filter commonly found in the Baltic Sea. Mussels were exposed for three weeks to five ensulizole concentrations of 10, 10², 10³, 10⁴, and 10⁵ ng/L. Stress on stress response was evaluated by subjecting mussels to air exposure. A battery of biomarkers related to detoxification and antioxidant defense, oxidative stress damage, energy reserves and metabolism, autophagy, apoptosis, inflammation, and DNA damage was measured in the gills and the digestive gland. In general, ensulizole affected the antioxidant response, energy storage, and cell death-related processes in mussel tissues. Mussels exposed to low, environmentally relevant concentrations of ensulizole had a shorter air survival time than the control. Ensulizole often showed the non-monotonic concentration-response curves, suggesting the complex effects of this UV filter at molecular, biochemical, and organismal levels.

A Comparative Metabolomics Approach Demonstrates That Octocrylene Accumulates in Stylophora pistillata Tissues as Derivatives and That Octocrylene Exposure Induces Mitochondrial Dysfunction and Cell Senescence

The objective of this work was to study the effect of octocrylene on Stylophora pistillata and to compare the metabolomic response of this coral species to that obtained with Pocillopora damicornis. When S. pistillata coral was exposed to octocrylene, it accumulated octocrylene derivatives similar to P. damicornis. Octocrylene-fatty acid conjugates were found, as well as octocrylene heterosides. Furthermore, the tissue concentrations of various acylcarnitines and three sphingoid bases increased significantly. This phenomenon was indicative of mitochondrial dysfunction and the induction of cellular senescence processes in exposed corals. Overall, the responses of the two corals to octocrylene pollution were consistent. The proven impact of octocrylene on a second coral species suggests that potential environmental octocrylene pollution could impact many reef-building species. Furthermore, this work demonstrates that octocrylene may be modified in vivo by many organisms and that levels of octocrylene contamination in the food chain have probably been underestimated until now.

Acute toxicity characterization of organic UV-filters and chronic exposure revealing multigenerational effects in DAPHNIA MAGNA

Organic ultraviolet (UV) filters have often been detected in aquatic ecosystems in concentrations ranging from ng/L to μg/L. However, both their acute and chronic effects on aquatic organisms have been insufficiently explored. This study aimed to evaluate acute toxicity of some of the main UV filters used worldwide (2-ethylhexyl,4-methoxycinnamate/EHMC, avobenzone/AVO, benzophenone-3/BP-3, and octocrylene/OC), in three aquatic organisms (Artemia salina, Desmodesmus subspicatus, and Daphnia magna), and to further investigate multigenerational effects in D. magna. After acute toxicity was confirmed, daphnids were chronically exposed to environmentally relevant concentrations of UV filters for two consecutive generations (F0 and F1), and reproductive endpoints, as well as catalase (CAT) and glutathione-S-transferase (GST) activities, were assessed. EHMC showed the most toxic potential, with the lowest EC₅₀ values for the three organisms. On the other hand, reproductive delays and a decrease in the reproduction rate were observed in the F1 generation exposed to AVO (4.4 µg/L), BP-3 (0.17 µg/L), EHMC (0.2 µg/L), and MIX. An increase of the CAT activity in organisms exposed to BP-3 and EHMC suggested induction of the antioxidant system. Although no reproductive effect was observed in the first generation, toxic effects obtained in the F1 revealed the importance of multigenerational studies and the potential harm of UV filters to the life cycle of D. magna, even at environmentally relevant concentrations. This emphasizes the need for further studies considering these levels of exposure and more realistic experimental designs to better understand their potential risks. Environmentally relevant concentrations of Organic UV filters are not lethal to aquatic organisms, however may affect reproductive parameters in Daphnia magna though multigenerational exposures.

Sunscreen filter octocrylene is a potential obesogen by acting as a PPARγ partial agonist

Octocrylene (OC) is an extensively prescribed organic ultraviolet B filter used in sunscreen products. Due to its extensive use, a significant level of OC is detected in marine and freshwater environments. Notably, the bioaccumulation of OC in aquatic biota may affect human health. In this study, the effect of OC on metabolism was investigated using the adipogenesis model of human bone marrow mesenchymal stem cells (hBM-MSCs). OC promoted adiponectin production during adipogenesis in hBM-MSCs compared to the vehicle-treated control (EC₅₀, 29.6 μM). In target identification, OC directly bound to peroxisome proliferator-activated receptor (PPAR) γ (Ki, 37.8 μM). OC-bound PPARγ also significantly recruited nuclear receptor coactivator proteins SRC-1 (EC₅₀, 54.1 μM) and SRC-2 (EC₅₀, 58.6 μM). In the molecular docking simulation study, the optimal ligand-binding mode of OC suggested that OC is a PPARγ partial agonist. A competitive analysis with a PPARγ full agonist pioglitazone revealed that OC acted as a PPARγ partial agonist. OC altered the gene transcription profile of lipid-metabolism associated enzymes in normal human keratinocytes, primarily exposed human cells after the application of sunscreens. In conclusion, OC is a potential metabolic disrupting obesogen.