Acute toxicity of the UV filter oxybenzone to the coral Galaxea fascicularis

Assessing the interaction between 4-methylbenzylidene camphor and microplastic fibers in aquatic environments: Adsorption kinetics and mechanisms

Wastewater treatment plants play a crucial role in managing environmental pollutants, but they often release persistent contaminants like synthetic microplastic fibers (MPFs) into ecosystems. These microplastics, mainly from the textile industry and domestic washing of synthetic fabrics, are a major type of microplastic found in aquatic environments. Some harmful chemicals have an affinity for these microplastics, making them vectors for contaminants. This study investigates the adsorption of 4-methylbenzylidene camphor (4-MBC), an organic UV filter, onto microplastic fibers from two different sources. Batch experiments conducted at room temperature (25 °C) under laboratory conditions assessed the adsorption kinetics and mechanisms. Morphological and visual characterization of the microplastic fibers was done using optical microscopy and scanning electron microscopy (SEM), revealing diverse shapes, types, and colors. Physico-chemical properties were confirmed through thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR). The data matched well with the PSO kinetic model and Langmuir isotherm, indicating monolayer chemisorption with equilibrium achieved within 24 h. The adsorption mechanisms involved electrostatic attraction, hydrogen bonding, and π-π interactions. Both types of microplastic fibers exhibited a tendency to adsorb 4-MBC, indicating the significance of this research in understanding the interactions between this compound and various fiber types emphasizing the need for further research under the different environmental conditions.

Long-term exposure to climbazole may affect the health of stress-tolerant coral Galaxea fascicularis

The persistence of coral reefs globally is threatened by various forms of chemical pollution. Climbazole, an azole antibacterial agent extensively utilized in pharmaceuticals and personal care products (PPCPs) in everyday life, has been detected in various environment media and proved to have significant adverse effects on aquatic organism. However, the effects of climbazole on coral remain largely unknown. Therefore, in this study, we conducted a 42-day investigation to examine the effects of varying concentrations of climbazole on Galaxea fascicularis (G. fascicularis), a stress-tolerant coral species. Our investigations included coral color observations, physiological experiments, and assessments of microbial diversity. The results showed that, after 42 days of exposure, the coral color in the treatment group exposed to 100 μg/L climbazole significantly decreased by one color category on the reference chart (D6 shifted to D5), while there was no change in the control group. This was accompanied by an increase in oxidative stress and a decrease in photosynthetic capacity in coral specimens. Additionally, there was a notable alteration in microbial diversity, resulting in reduced community stability. Elevated levels of climbazole (100 μg/L) stress led to an increased abundance of potentially pathogenic bacteria such as unclassified Erysipelotrichaceae. However, at an environmentally relevant concentration of 1 μg/L, climbazole decreased the photosynthetic efficiency and induced oxidative stress in the stress-tolerant coral G. fascicularis, while not significantly impacting the microbial community diversity of the coral. The findings of our study have important implications for the protection and management of nearshore coral reefs and offer essential data for ecological risk assessment of climbazole.

Deciphering mechanisms of UV filter (benzophenone-3)- and high temperature-induced adverse effects in the coral Acropora tenuis, using ecotoxicogenomics

Coral reefs are at risk of bleaching due to various environmental and anthropogenic stressors such as global warming and chemical pollutants. However, there is little understanding of stressor-specific mechanisms that cause coral bleaching. Therefore, conducting accurate ecotoxicological risk assessments and deciphering modes of action of potentially deleterious ultraviolet (UV) filters (sunscreen compounds) are crucial issues. In this study, we evaluated the toxicity and bleaching effect of benzophenone-3 (BP-3), which is widely used in sunscreen products, on the reef-building coral Acropora tenuis. Furthermore, to understand differences in UV filter- and temperature-induced adverse effects, a comparative ecotoxicogenomic approach using RNA-seq was integrated into a toxicity test to clarify differences in gene expression changes induced by BP-3 and heat stress (31 °C). The lethal concentration 50 % (LC50) was calculated as 3.9 mg/L, indicating that the aquatic environmental risk on corals posed by BP-3 was low based on the risk assessment in this study. Differentially expressed genes related to oxidative stress and extracellular matrix organization were involved in coral responses to both BP-3 and heat stress, but their patterns differed. Whereas immune and heat-shock responses were activated in response to heat stress, activation of a drug metabolism pathway and several signal transduction pathways were identified in BP-3 treatment groups. Our study enhances understanding of stress responses in corals induced by UV filters and thermal stress. Using potential gene markers identified in this study for eco-epidemiological surveys of stressed corals, we urgently need to develop effective countermeasures.

Prevalence of selected UV filter compounds in Biscayne National Park

This research was carried out in order to assess a baseline occurrence in Biscayne National Park, Florida, of four organic contaminants: the UV filters oxybenzone, dioxybenzone, and benzophenone, as well as the topical pain reliever benzocaine. A total of 35 samples were taken from five locations within the park, four near barrier islands, and one at a coral reef. Analyses were carried out using liquid chromatography coupled to high-resolution mass spectrometry. Oxybenzone was detected in 26% of samples from the park at concentrations up to 31 ng/L. Benzophenone was detected in 49% of samples from the park at concentrations up to 131 ng/L. Benzocaine and dioxybenzone were not detected in any of the samples.

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

Coral reefs are globally declining due to various anthropogenic stressors. Amongst those, chemical pollutants, such as pesticides from agricultural runoff, sewage or an overabundance of personal care products in coastal waters due to intense tourism, may be considered as a local stressor for reef-building corals. The extent to which such chemicals exhibit toxic effects towards corals at environmentally relevant concentrations is currently controversially discussed and existing studies are often based on varying and sometimes deficient test methods. To address this uncertainty, we adapted available methods into a reliable and comprehensive acute coral toxicity test method for the reef-building coral Montipora digitata. The toxicities of the four substances benzophenone-3 (BP-3), Diuron (DCMU), copper (Cu2+ as CuCl2, positive control) and dimethylformamide (DMF, solvent) were assessed in a 96 h semi-static test design. Endpoints such as maximum quantum yield, bleaching, tissue loss and mortality were evaluated with respect to their suitability for regulatory purposes. Overall, the endpoints bleaching and mortality yielded sensitive and robust results for the four tested substances. As the test method follows the principles of internationally standardized testing methods (ISO, OECD), it can be considered suitable for further validation and standardization. Once validated, a standardized test method will help to obtain reproducible toxicity results useful for marine hazard and risk assessment and regulatory decision making.

Acute toxicity assessment of nine organic UV filters using a set of biotests

UV filters in environmental compartments are a source of concern related to their ecotoxicological effects. However, little is known about UV filters' toxicity, particularly those released into the environment as mixtures. Acute toxicity of nine organic UV filters benzophenone-1, benzophenone-2, benzophenone-3, 4-methoxy benzylidene camphor, octocrylene, ethylhexyl methoxycinnamate, 2-ethylhexyl salicylate, homosalate, and butyl methoxydibenzoylmethane was determined. UV filter solutions were tested as single, binary, and ternary mixtures of various compositions. Single solutions were tested using a set of bio tests, including tests on saline crustaceans (Artemia franciscana), freshwater crustaceans (Daphnia magna), marine bacteria (Aliivibrio fischeri), and freshwater plants (Lemna minor). The tests represent different stages of the trophic chain, and hence their overall results could be used to risk assessment concerning various water reservoirs. The toxicity of binary and ternary mixtures was analyzed using the standardized Microtox® method. Generally, organic UV filters were classified as acutely toxic. Octocrylene was the most toxic for Arthemia franciscana (LC50 = 0.55 mg L-1) and Daphnia magna (EC50 = 2.66-3.67 mg L-1). The most toxic against freshwater plants were homosalate (IC50 = 1.46 mg L-1) and octocrylene (IC50 = 1.95 mg L-1). Ethylhexyl methoxycinnamate (EC50 = 1.38-2.16 mg L-1) was the most toxic for marine bacteria. The least toxic for crustaceans and plants were benzophenone-1 (EC50 = 6.15-46.78 mg L-1) and benzophenone-2 (EC50 = 14.15-54.30 mg L-1), while 4-methoxy benzylidene camphor was the least toxic for marine bacteria (EC50 = 12.97-15.44 mg L-1). Individual species differ in their sensitivity to the tested organic UV filters. An assessment of the toxicity of mixtures indicates high and acute toxicity to marine bacteria after exposition to a binary mixture of benzophenone-2 with octocrylene, 2-ethylhexyl salicylate, or homosalate. The toxicity of mixtures was lower than single solutions predicting antagonistic interaction between chemicals.

Graphical abstract

The effects of UV filters on health and the environment

Sunscreens are an important means of protection against sunburns, dyspigmentation, photoaging, and photocarcinogenesis. Sunscreens come in a variety of formulations that can protect against ultraviolet B (UVB) radiation, both UVB and ultraviolet A (UVA) radiation (broad-spectrum sunscreens), and UVB, UVA, and visible light (tinted broad-spectrum sunscreens). In the USA, there is currently a paucity of FDA-approved broad-spectrum filters on the market. Studies have identified the presence of multiple UV filters in water sources globally. Many laboratory studies have implicated the potential impact of UV filters on coral reef bleaching, the food chain, and human health. However, many of these studies are performed at concentrations that are much higher than those present in the natural environment. With increasing discussion surrounding the role of organic and inorganic UV filters as potential environmental pollutants over the past decade, approval of additional broad-spectrum filters would be an important means of alleviating the use of more controversial filters. The aim of this article is to review the effects of UV filters on health and the environment and explore potential adjunctive agents for photoprotection.

Cosmetic UV filters in the environment-state of the art in EU regulations, science and possible knowledge gaps

OBJECTIVE

The aim of this work was to review the principals of environmental hazard and risk assessment (ERA) of cosmetic UV filters registered under EU REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). Furthermore, effects as obtained from non-standardized testing methods and organisms from scientific literature were compared against the predicted no effect concentrations (PNECs) as derived based on standardized test methods for the various environmental compartments under REACH.

METHODS

The REACH dossiers at the ECHA webpage were screened for available information related to basic physico-chemical data (i.e. water solubility, octanol-water partitioning coefficient), PNECs and associated data (data basis, assessment factors (AFs)). Scientific literature was screened for available ecotoxicity data and the adverse effect levels were compared against the derived PNECs under REACH. Current approaches for environmental risk assessments of UV filters were evaluated for its applicability for a direct release scenario.

RESULTS

Under REACH, PNECs were derived for all hazardous UV filters. Although, PNECs were often derived for various environmental compartments (i.e. freshwater, marine water, sediment, soil), results from literature focused on aquatic data. Effects as observed within scientific literature matches in principle with the hazardous profile of the UV filters. Effects levels both on the acute and the chronic toxicity as retrieved from the non-standardized test organisms (literature) were above the derived PNECs under REACH. Currently, ERAs performed for cosmetic UV filters under REACH are solely tonnage driven and thus do not fully capture the use in sunscreens and associated leisure activities.

CONCLUSION

Existing EU REACH regulation is considered as sufficient to evaluate the environmental safety of UV filters used in sunscreens. To cover the direct release of UV filters due to various leisure activities into the aquatic freshwater and marine environment, an additional application-based ERA is considered necessary.

UV filter occurrence in beach water of the Mediterranean coast - A field survey over 2 years in Palavas-les-Flots, France

OBJECTIVE

A 2-year sampling campaign was realized on French Mediterranean beach (Palavas-les-Flots Hérault) in order to measure the concentration of UV filters released from the sunscreen used by bathers. Multiple factors suspected of playing determining roles in the UV filter pattern in water were explored, such as the seasonal and daily time evolutions, or the vertical and horizontal distributions, and they were regarded through the UV filter characteristics.

METHODS

The beach was monitored during periods of high and low tourist attendance, typically before, during and after the summer peak. The beachgoers attendance was counted. Bathing water was sampled distinctly from the bulk column and from the top surface layer, testing different sampling tools. Sediments and mussels were also sampled and analysed as potential UV filter sinks. Three organic UV filters (octocrylene OCR, avobenzone BMDBM and octyl methoxycinnamate OMC) and one mineral (titanium dioxide TiO2 ) were studied here as representatives of the current cosmetic market.

RESULTS

Summer peak attendance on the beach was confirmed associated with peak levels of UV filter concentration in the bathing water, even more pronounced during a heat wave period. This relation was also observed at day scale with an afternoon peak, suggesting a rapid evolution of the UV filter pattern in water. Contrasted fates were measured between the four studied UV filters, that could be mainly explained by their respective characteristics, i.e. particulate or dissolved, hydrophilic or lipophilic, lifetime. Generally, this resulted in a concentration ranking TiO2  > OCR > OMC > BMDBM, ranging from 0.5 to 500 μg/L. The most lipophilic and recalcitrant OCR was found most vertically differentiated and over concentrated in the top surface layer of water. Finally, a large horizontal heterogeneity was also observed in the UV filter concentration pattern, raising the need for sample replicates that cover a significant area.

CONCLUSION

This work fulfils some knowledge gaps on the issue of UV filter release in coastal environments, not only by providing original field data and methodological recommendations but also importantly in the comparison made of organic and mineral UV filters, which are often considered separately and rarely evaluated at the same time.

Microplastics enhance the toxicity and phototoxicity of UV filter avobenzone on Daphnia magna

Microplastics (MPs) and ultraviolet (UV) filters cause pollution in aquatic ecosystems. Moreover, regulations on the use and discharge of UV filters in personal care products are lacking. Therefore, the combined toxicity of MPs (virgin polystyrene (PS) spheres; size: 200 nm) and avobenzone (AVO; a UV filter) on Daphnia magna were assessed. The exposure groups were AVO, AVO + UV irradiation for 6 h [AVO (UV)], AVO with MPs (Mix), and AVO with MPs + UV irradiation for 6 h [Mix (UV)]. The daphnids were exposed to these treatments for 48 h and observed for an additional 6 h. Energy reserves of all treated groups increased compared to that of the control group. Growth in the Mix group was inhibited despite a high food uptake, and food uptake and growth inhibition were validated in the Mix (UV) group. Additionally, the food uptake of the AVO (UV) and Mix (UV) groups decreased during the recovery period, possibly owing to a decrease in the normal feeding ability resulting from an increase in abnormality. These results indicate that the combined toxicity of MPs+AVO can be exacerbated under natural conditions; the complex toxicity should be considered when assessing aquatic environment pollution.

First report on per- and polyfluoroalkyl substances (PFASs) in coral communities from the Northern South China sea: Occurrence, seasonal variation, and interspecies differences

In this study, the contamination levels and seasonal variation of 22 PFASs were investigated in coastal reef-building corals (n = 68) from the northern South China Sea (SCS) during wet and dry seasons. Perfluorohexane sulfonate (PFHxS) was the predominant PFASs in all coral samples, representing 43% of the total PFAS. Long-chain PFASs, as well as PFAS alternatives, were frequently detected above the MQL (>88%) but showed relatively low concentrations compared to short-chain PFASs in most species and seasons. Seasonal variation of PFAS concentrations were observed in branching corals, indicating that the accumulation of PFASs may be associated with coral morphological structures. Interspecies differences in PFAS levels agree well with different bioaccumulation potentials among coral species. Redundancy analysis (RDA) showed that seasonal factor and coral genus could partly influence PFAS concentrations in coral tissues. In summary, our study firstly reported the occurrence of PFASs in coral communities from the SCS and highlights the necessity for future investigations on more toxicity data for coral communities.

Ecotoxicological effects of the UV-filter 4-MBC on sperms and adults of the mussel Mytilus galloprovincialis

Present in an increasing number of products, UV-filters are continuously discharged into aquatic environments. Despite potential risks for inhabiting organisms are recognized, the effects of UV-filter 4-methylbenzylidenecamphor (4-MBC) on marine invertebrates are poorly investigated. By combining in vitro/in vivo exposures through a multi-biomarker approach on sperms and adults, the present study evaluated how 4-MBC affect the mussel species Mytilus galloprovincialis, providing ecologically relevant information on organisms' responses. From the obtained results, considering mortality as endpoint, sperms revealed a greater sensitivity (EC₅₀:347 μg/L) than adults (EC₅₀: not calculable). From an ecotoxicological perspective, this resulted in a derived threshold concentration (LOEC) of 100 μg/L and 72 μg/L, respectively. Effects at the cell/molecular level were provided by general redox-status imbalance and oxidative stress. Sperms showed functional and structural impairments, hyperactivation and DNA damage, while adults showed physiological, metabolic/energetic dysfunctions, DNA damage and activation of oxidative and biotransformation enzymes. High 4-MBC bioaccumulation was also observed in exposed mussels (BCFs:14.0-32.0 L/kg). These findings suggest that 4-MBC may impair fitness and survival of the broadcast spawning mussel M. galloprovincialis, affecting reproduction success and population growth.

Towards the Development of Standardized Bioassays for Corals: Acute Toxicity of the UV Filter Benzophenone-3 to Scleractinian Coral Larvae

Coral reefs have been declining globally at a historically unprecedented rate. Ultraviolet (UV) filters used in sunscreens may contribute to this decline at local scales, which has already led to bans on various organic UV filters in some regions. However, the underlying studies for these bans demonstrated significant flaws in the experimental design due to a lack of validated and standardized testing methods for corals. This study aimed to investigate options for the development of a standard acute toxicity test for the larval stage of scleractinian corals. Planula larvae of two brooding (Leptastrea purpurea and Tubastraea faulkneri) and two spawning (Acropora digitifera and A. millepora) species were exposed to the organic UV filter benzophenone-3 (BP3) for 48 h under static conditions. We observed interspecific variations in toxicity, with A. digitifera being the most sensitive (LC₅₀ = 0.75 µg L⁻¹) and T. faulkneri the least sensitive (LC₅₀ = 2951.24 µg L⁻¹) species. Inhibition of settlement was found to be a useful endpoint leading to an EC₅₀ of 1.84 µg L⁻¹ in L. purpurea larvae. Although the analytical challenges of measuring lipophilic substances in small volume test setups remain, the here applied test design and selected endpoints are suitable for further validation and subsequent standardization.