Effects of benzophenone-3 on the green alga Chlamydomonas reinhardtii and the cyanobacterium Microcystis aeruginosa

Toxicity of the sunscreen UV filter benzophenone-3 (OBZ) to the microalga Selenastrum capricornutum: An insight into OBZ's damage to photosynthesis and respiration

Oxybenzone (OBZ; benzophenone-3, CAS# 131-57-7), as a new pollutant and ultraviolet absorbent, shows a significant threat to the survival of phytoplankton. This study aims to explore the acute toxic effects of OBZ on the growth of the microalga Selenastrum capricornutum, as well as the mechanisms for its damage to the primary metabolic pathways of photosynthesis and respiration. The results demonstrated that the concentrations for 50 % of maximal effect (EC50) of OBZ for S. capricornutum were 9.07 mg L-1 and 8.54 mg L-1 at 72 h and 96 h, respectively. A dosage of 4.56 mg L-1 OBZ significantly lowered the photosynthetic oxygen evolution rate of S. capricornutum in both light and dark conditions for a duration of 2 h, while it had no effect on the respiratory oxygen consumption rate under darkness. OBZ caused a significant decline in the efficiency of photosynthetic electron transport due to its damage to photosystem II (PSII), thereby decreasing the photosynthetic oxygen evolution rate. Over-accumulated H2O2 was produced under light due to the damage caused by OBZ to the donor and acceptor sides of PSII, resulting in increased peroxidation of cytomembranes and inhibition of algal respiration. OBZ's damage to photosynthesis and respiration will hinder the conversion and reuse of energy in algal cells, which is an important reason that OBZ has toxic effects on S. capricornutum. The present study indicated that OBZ has an acute toxic effect on the microalga S. capricornutum. In the two most important primary metabolic pathways in algae, photosynthesis is more sensitive to the toxicity of OBZ than respiration, especially in the dark.

Zooplankton-based adverse outcome pathways: A tool for assessing endocrine disrupting compounds in aquatic environments

Endocrine disrupting compounds (EDCs) pose a significant ecological risk, particularly in aquatic ecosystems. EDCs have become a focal point in ecotoxicology, and their identification and regulation have become a priority. Zooplankton have gained global recognition as bioindicators, benefiting from rigorous standardization and regulatory validation processes. This review aims to provide a comprehensive summary of zooplankton-based adverse outcome pathways (AOPs) with a focus on EDCs as toxicants and the utilisation of freshwater zooplankton as bioindicators in ecotoxicological assessments. This review presents case studies in which zooplankton have been used in the development of AOPs, emphasizing the identification of molecular initiating events (MIEs) and key events (KEs) specific to zooplankton exposed to EDCs. Zooplankton-based AOPs may become an important resource for understanding the intricate processes by which EDCs impair the endocrine system. Furthermore, the data sources, experimental approaches, advantages, and challenges associated with zooplankton-based AOPs are discussed. Zooplankton-based AOPs framework can provide vital tools for consolidating toxicological knowledge into a structured toxicity pathway of EDCs, offering a transformative platform for facilitating enhanced risk assessment and chemical regulation.

Effects of benzophenone-3 and its metabolites on the marine diatom Chaetoceros neogracilis: Underlying mechanisms and environmental implications

The wide application of benzophenones (BPs), such as benzophenone-3 (BP3), as an ingredient in sunscreens, cosmetics, coatings, and plastics, has led to their global contamination in aquatic environments. Using the marine diatom Chaetoceros neogracilis as a model, this study assessed the toxic effects and mechanisms of BP3 and its two major metabolites (BP8 and BP1). The results showed that BP3 exhibited higher toxicity on C. neogracilis than BP8 and BP1, with their 72-h median effective concentrations being 0.4, 0.8 and 4 mg/L, respectively. Photosynthesis efficiencies were significantly reduced after exposure to environmentally relevant concentrations of the three benzophenones, while cell viability, membrane integrity, membrane potential, and metabolic activities could be further impaired at their higher concentrations. Comparative transcriptomic analysis, followed by gene ontology and KEGG pathway enrichment analyses unraveled that all the three tested benzophenones disrupted photosynthesis and nitrogen metabolism of the diatom through alteration of similar pathways. The toxic effect of BP3 was also attributable to its unique inhibitory effects on eukaryotic ribosome biosynthesis and DNA replication. Taken together, our findings underscore that benzophenones may pose a significant threat to photosynthesis, oxygen production, primary productivity, carbon fixation, and the nitrogen cycle of diatom in coastal waters worldwide.

Effects of the sunscreen ultraviolet filter oxybenzone (benzophenone-3) on the seagrass Posidonia oceanica (L.) Delile and its associated N2 fixers

Oxybenzone/benzophenone-3 (BP-3) is one of the most detrimental organic ultraviolet filters for marine biota, leading to legislative measures banning its presence in commercial sunscreen formulations of several countries. It remains poorly explored how this contaminant is currently threatening the persistence of critical ecosystems for conservation in the Mediterranean, such as Posidonia oceanica meadows, but it is essential for promoting sustainable coastal tourism. Our investigation aimed to determine the effects of BP-3 on P. oceanica under a short-term laboratory setup, recreating summer conditions while testing three environmentally relevant concentrations for Mallorca, Spain (minimum: 53.6 ng L-1, maximum: 557.5 ng L-1 and increased: 1115 ng L-1) and a control (0 ng L-1). Primary productivity was unaffected by the treatments, however, a reduction in leaf chlorophyll content and nitrogen fixation activity associated with rhizomes was evidenced under BP-3 addition. This may be related with oxidative damage, as reactive oxygen species production and catalase activity in P. oceanica leaves were the highest even at minimum BP-3 concentrations. Alkaline phosphatase rates showed inverted trends between old leaves and rhizomes, being enhanced in the former under BP-3 addition and reduced in the latter. These results are of great relevance for the future management of P. oceanica meadows, elucidating that even minimum concentrations of BP-3 reported in coastal waters of Mallorca can induce elevated levels of oxidative stress in the seagrass, that lead to impairments in its photosynthetic pigments production and supply of essential nutrients through belowground tissues.

Unveiling the toxic effects, physiological responses and molecular mechanisms of tobacco (Nicotiana tabacum) in exposure to organic ultraviolet filters

Exposure to organic ultraviolet (UV) filters has raised concerns due to their potential adverse effects on environments. However, their toxic mechanisms on plants remain elusive. In this study, using integrative physiological and transcriptomic approaches we investigated the physiological and molecular responses to three representative UV filters, namely oxybenzone (OBZ), avobenzone (AVB), and octinoxate (OMC), in an agricultural model plant tobacco. The exposure to UV filters disrupts the functionality of photosystem reaction centers and the light-harvesting apparatus. Concurrently, UV filters exert a suppressive effect on the expression of genes encoding Rubisco and Calvin-Benson cycle enzymes, resulting in a decreased efficiency of the Calvin-Benson cycle and consequently hampering the process of photosynthesis. Exposure to UV filters leads to significant generation of reactive oxygen species within tobacco leaves and downregulation of oxidoreductase activities. Moreover, UV filters promote abscisic acid (ABA) accumulation by inducing the expression of ABA biosynthesis genes whereas repress indole-3-acetic acid (IAA) biosynthesis gene expression, which induce leaf yellowing and slow plant growth. In summary, the organic UV filters exert toxic effects on tobacco growth by inhibiting chlorophyll synthesis, photosynthesis, and the Calvin-Benson cycle, while generating excessive reactive oxygen species. This study sheds light on the toxic and tolerance mechanisms of UV filters in agricultural crops.

Fine-scale geographic risk assessment of oxybenzone sunscreen pollution within Hanauma Bay using hydrodynamic characterization and modeling

Hanauma Bay's coral reef system is threatened by sunscreen pollution. Understanding the hydrodynamic nature of the bay is crucial for understanding the transport and fate of pollutants within the bay. This study conducted a comprehensive hydrodynamic analysis, revealing significant aspects of current patterns and their influence on sunscreen pollutant behavior. The analysis demonstrated the formation of flows that drive currents parallel to the shoreline, resulting in increased pollutant retention time over sensitive reef areas. Direct flushing currents were identified as playing a role in reducing pollution buildup. Particle dynamics analysis highlighted the importance of considering temporal dynamics and their implications for pollutant pathways, particularly through the swash zone during high tide phases. The study identified primary current patterns near the reef area and emphasized the circular behavior within the water body, affecting corals' susceptibility to bleaching in the southwestern part of Hanauma bay. To understand where oxybenzone concentrations were a threat to wildlife, we created a geographic model that integrated ecological risk assessment with hydrodynamic behavior in a given system, which we designate the Risk Quotient Plume - the geographic area where the concentration is above the threat level for a chemical. The study found high oxybenzone concentrations throughout the bay, threatening coral, fish, and algae populations. Oxybenzone's distribution indicated a serious threat to the entire back reef habitat and a hinderance to coral restoration efforts. The study also emphasizes the need to consider the hydrodynamic behavior of pollutants and their interaction with microplastics in the bay. Overall, the findings provide insights into hydrodynamics and pollutant dispersion in Hanauma Bay, supporting effective pollution management and conservation strategies.

Physiological impact of personal care product constituents on non-target aquatic organisms

Personal care products (PCPs) are products used in cleaning, beautification, grooming, and personal hygiene. The rise in diversity, usage, and availability of PCPs has resulted in their higher accumulation in the environment. Thus, these constitute an emerging category of environmental contaminants due to the potential of its constituents (chemical and non-chemical) to induce various physiological effects even at lower concentrations (ng/L). For analyzing the impact of the PCPs constituents on the non-target organism about 300 article including research articles, review articles and guidelines were studied from 2000 to 2023. This review aims to firstly discuss the fate and accumulation of PCPs in the aquatic environment and organisms; secondly provides overview of environmental risks that are linked to PCPs; thirdly review the trends, current status of regulations and risks associated with PCPs and finally discuss the knowledge gaps and future perspectives for future research. The article discusses important constituents of PCPs such as antimicrobials, cleansing agents and disinfectants, fragrances, insect repellent, moisturizers, plasticizers, preservatives, surfactants, UV filters, and UV stabilizers. Each of them has been found to display certain toxic impact on the aquatic organisms especially the plasticizers and UV filters. These continuously and persistently release biologically active and inactive components which interferes with the physiological system of the non-target organism such as fish, corals, shrimps, bivalves, algae, etc. With a rise in the number of toxicity reports, concerns are being raised over the potential impacts of these contaminant on aquatic organism and humans. The rate of adoption of nanotechnology in PCPs is greater than the evaluation of the safety risk associated with the nano-additives. Hence, this review article presents the current state of knowledge on PCPs in aquatic ecosystems.

A survey of Irish dermatologists' awareness of the environmental impact of sunscreen

The application of sunscreen is a key pillar of photoprotection; however, there is a growing concern regarding the impact on the environment of ultraviolet filters in sunscreen products. With growing interest in environmental issues, it is important that we are able to discuss these topics with our patients. An online survey was distributed to all members of the Irish Association of Dermatologists regarding knowledge of the impact of sunscreen on the environment. We conclude that although Irish dermatologists routinely recommend the use of sunscreens to patients there is a lack of knowledge regarding the environmental impact of sunscreens.

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

Lymnaea stagnalis and Ophryotrocha diadema as Model Organisms for Studying Genotoxicological and Physiological Effects of Benzophenone-3

Benzophenone-3 (BP-3) is a lipophilic organic compound that occurs naturally in flower pigments. Since it adsorbs ultraviolet (UV) radiation in the UVA and UVB regions, it is one of the most common UV filters found in sunscreen and cosmetic products. We explored by in vivo micronuclei (MNi) assay the genotoxic effects of BP-3 on hemocytes from the freshwater gastropod Lymnaea stagnalis. We also studied its possible toxic effects on life-history traits: body growth in L. stagnalis and egg production of both L. stagnalis and the marine polychaete worm Ophryotrocha diadema. Adult individuals were exposed to increasing concentrations of BP-3 (0.025, 0.050, 0.100, and 0.200 mg/L) once a week for 4 weeks. In L. stagnalis, exposure to BP-3 at concentrations of both 0.2 and 0.1 mg/L produced genotoxic effects on the micronuclei frequencies, but only concentrations of 0.2 mg/L affected the NBUDs frequencies. Similarly, negative effects on body growth were observed at the concentrations of 0.2 and 0.1 mg/L and a significant reduction of egg production at 0.2 mg/L. In O. diadema, a negative correlation between egg production and increasing BP-3 concentrations was observed. Our findings suggest the need for more stringent measures to reduce the presence of BP-3 in the environment.

Proteomics and Lysine Acetylation Modification Reveal the Responses of Pakchoi (Brassica rapa L. ssp. chinensis) to Oxybenzone Stress

The broad-spectrum UV filter oxybenzone is toxic to plants at environmentally relevant concentrations. Lysine acetylation (LysAc) is one of the essential post-translational modifications (PTMs) in plant signaling responses. The goal of this study was to uncover the LysAc regulatory mechanism in response to toxic exposures to oxybenzone as a first step in elucidating xenobiotic acclimatory reactions by using the model Brassica rapa L. ssp. chinensis. A total of 6124 sites on 2497 proteins were acetylated, 63 proteins were differentially abundant, and 162 proteins were differentially acetylated under oxybenzone treatment. Bioinformatics analysis showed that a large number of antioxidant proteins were significantly acetylated under oxybenzone treatment, implying that LysAc alleviated the adverse effects of reactive oxygen species (ROS) by inducing antioxidant systems and stress-related proteins; the significant changes in acetylation modification of enzymes involved in different branches of carbon metabolism in plants under oxybenzone treatment mean that plants can change the direction of carbon flow allocation by regulating the activities of carbon metabolism-related enzymes. Our results profile the protein LysAc under oxybenzone treatment and propose an adaptive mechanism at the post-translational level of vascular plants in response to pollutants, providing a dataset reference for future related research.

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.

Sunscreen exposure interferes with physiological processes while inducing oxidative stress in seagrass Posidonia oceanica (L.) Delile

The effects of a commercial sunscreen mixture on the Mediterranean seagrass Posidonia oceanica were investigated, evaluating its response in physiological processes and biochemical indicators of oxidative stress. Short-term laboratory experiments were conducted recreating summer conditions, and two sunscreen concentrations were tested in whole P. oceanica plants placed inside aquaria. Although primary productivity of leaf segments seemed to benefit from sunscreen addition, probably due to inorganic nutrients released, the rest of the biological parameters reflected possible impairments in the overall functioning of P. oceanica as a result of oxidative damages. Chlorophyll production and nitrogen fixation associated with old leaves were inhibited under high sunscreen concentrations, which concurred with elevated reactive oxygen species production, catalase activity and polyphenols content in the seagrass leaves. These results emphasize the importance of directing future investigations on determining which specific components of sunscreen products are likely threatening the wellbeing of critical species, such as P. oceanica.

Benzophenones in the Environment: Occurrence, Fate and Sample Preparation in the Analysis

The ubiquitous presence of emerging contaminants in the environment is an issue of great concern. Notably, for some of them, no established regulation exists. Benzophenones are listed as emerging contaminants, which have been identified in the environment as well as in human fluids, such as urine, placenta, and breast milk. Their accumulation and stability in the environment, combined with the revealed adverse effects on ecosystems including endocrine, reproductive, and other disorders, have triggered significant interest for research. Benzophenones should be extracted from environmental samples and determined for environmental-monitoring purposes to assess their presence and possible dangers. Numerous sample preparation methods for benzophenones in environmental matrices and industrial effluents have been proposed and their detection in more complex matrices, such as fish and sludges, has also been reported. These methods range from classical to more state-of-the-art methods, such as solid-phase extraction, dispersive SPE, LLE, SBSE, etc., and the analysis is mostly completed with liquid chromatography, using several detection modes. This review critically outlines sample preparation methods that have been proposed to date, for the extraction of benzophenones from simple and complex environmental matrices and for cleaning up sample extracts to eliminate potential interfering components that coexist therein. Moreover, it provides a brief overview of their occurrence, fate, and toxicity.

Toxicological effects of oxybenzone on the growth and bacterial composition of Symbiodiniaceae

Oxybenzone, a common ultraviolet (UV) filter, is a growing environmental concern due to its ecotoxicological effects. However, the responses of Symbiodiniaceae and their bacterial communities to oxybenzone are largely unknown. In this study, the effects of oxybenzone on Effrenium voratum and Cladocopium goreaui were investigated. The results revealed that sensitivity of Symbiodiniaceae to oxybenzone was species-dependent. 50 μg L^-1 of oxybenzone significantly impacted the cell density of C. goreaui, causing a 36.73% decrease. When oxybenzone concentration increased to 500 μg L^-1 and 5000 μg L^-1, cell division was completely suppressed; meanwhile, chl-a content declined to zero. Compared to C. goreaui, E. voratum had higher resistance to oxybenzone. There was no significant difference in cell density between 50 μg L^-1 group and control group. At higher dosage of oxybenzone (500 μg L^-1 and 5000 μg L^-1), the cell density declined 32.02% and 45.45% compared to the control group, respectively. Additionally, we revealed that the diversity and structure of bacterial community were affected by oxybenzone. Briefly, 500 μg L^-1 and 5000 μg L^-1 of oxybenzone altered the diversity of bacterial community in C. goreau. Furthermore, the relative abundances of Costertonia, Roseitalea, Rhodopirellula, and Roseobacter were negatively affected by oxybenzone ranging 50 μg L^-1 to 5000 μg L^-1. Compare to C. goreaui, the bacterial community composition associated with E. voratum was more stable. As revealed by KEGG pathway analysis, oxybenzone affected energy metabolism and inhibited the metabolism of cofactors and vitamins in C. goreaui, while 5000 μg L^-1 of oxybenzone significantly altered the carbohydrate metabolism, membrane transport and amino acid metabolism in E. voratum. The changes of bacterial composition may contribute to the variation in algal growth. These results indicated that oxybenzone pollution could injury Symbiodiniaceae, even threaten coral reef ecosystems.

Environmental impacts due to the use of sunscreen products: a mini-review

Sunscreen use has increased in recent years, as sunscreen products minimize the damaging effects of solar radiation. Active ingredients called ultraviolet (UV) filters or UV agents, either organic or inorganic, responsible for defending skin tissue against harmful UV rays, are incorporated in sunscreen formulations. UV agents have a serious impact on many members of bio communities, and they are transferred to the environment either directly or indirectly. Many organic UV filters are found to be accumulated in marine environments because of high values of the octanol/water partition coefficient. However, due to the fact that UV agents are not stable in water, unwanted by-products may be formed. Experimental studies or field observations have shown that organic UV filters tend to bioaccumulate in various aquatic animals, such as corals, algae, arthropods, mollusks, echinoderms, marine vertebrates. This review was conducted in order to understand the effects of UV agents on both the environment and marine biota. In vivo and in vitro studies of UV filters show a wide range of adverse effects on the environment and exposed organisms. Coral bleaching receives considerable attention, but the scientific data identify potential toxicities of endocrine, neurologic, neoplastic and developmental pathways. However, more controlled environmental studies and long-term human use data are limited. Several jurisdictions have prohibited specific UV filters, but this does not adequately address the dichotomy of the benefits of photoprotection vs lack of eco-friendly, safe, and approved alternatives.

Cytotoxicity of BP-3 and BP-4: Blockage of extrusion pumps, oxidative damage and programmed cell death on Chlamydomonas reinhardtii

The health concern associated with the dangers related to exposure to UV radiation has led to an increase in the use of sunscreens containing UV-filters that can reach aquatic environments and possibly affect ecosystems. Benzophenone-3 (BP-3) and benzophenone-4 (BP-4) are two of the most used UV-filters. In the present work, the microalga Chlamydomonas reinhardtii was exposed to several concentrations of both chemicals. To evaluate their potential cytotoxicity on microalgal cells, different parameters were analysed including fast response biomarkers (increase in intracellular free Ca²⁺) as well as biomarkers related with the presence of oxidative stress (lipid peroxidation), energy metabolism (photosynthetic yield and cytoplasmic lipid accumulations), cell division (proliferation and F-actin content), programmed cell death (PCD) (caspase activation and DNA fragmentation) and possible mechanisms of resistance to xenobiotics (operation of extrusion pumps and presence of autophagic vacuoles). Results showed an increment of the percentage of cells with cytosolic free Ca²⁺ that could act as a secondary messenger in response to the stress. A decrease in photosynthetic yield and an increase in cytoplasmic lipid accumulations and lipid peroxidation levels were also detected. In addition, a decrease in cell proliferation was observed, linked to a decrease in the percentage of cells with F-actin. The increase observed in the microalgal population with caspase activity, together with the DNA fragmentation and the alterations in the cytoskeleton, suggested the induction of processes linked to PCD. Moreover, a blockage of extrusion pumps, which could be related to the toxicity mechanism of these compounds, and an increase in autophagic vacuoles, as an attempt to repair the damage caused by benzophenones, were detected. Overall, these biomarkers indicate that both UV-filters can be a serious threat to non-target photosynthetic microorganisms in aquatic environments, although BP-3 affected C. reinhardtii more markedly.

Beach showers as sources of contamination for sunscreen pollution in marine protected areas and areas of intensive beach tourism in Hawaii, USA

In 2019, sands in nearby runoff streams from public beach showers were sampled on three islands in the State of Hawaii and tested for over 18 different petrochemical UV filters. Beach sands that are directly in the plume discharge of beach showers on three of the islands of Hawaii (Maui, Oahu, Hawai'i) were found to be contaminated with a wide array of petrochemical-based UV-filters that are found in sunscreens. Sands from beach showers across all three islands had a mean concentration of 5619 ng/g of oxybenzone with the highest concentration of 34,518 ng/g of oxybenzone at a beach shower in the Waikiki area of Honolulu. Octocrylene was detected at a majority of the beach shower locations, with a mean concentration of 296.3 ng/g across 13 sampling sites with the highest concentration of 1075 ng/g at the beach shower in Waikiki. Avobenzone, octinoxate, 4-methylbenzylidene camphor and benzophenone-2 were detected, as well as breakdown products of oxybenzone, including benzophenone-1, 2,2'-dihydroxy-4-methoxybenzophenone, and 4-hydroxybenzophenone. Dioxybenzone (DHMB) presented the highest concentration in water (75.4 ng/mL), whereas octocrylene was detected in all water samples. Some of these same target analytes were detected in water samples on coral reefs that are adjacent to the beach showers. Risk assessments for both sand and water samples at a majority of the sampling sites had a Risk Quotient > 1, indicating that these chemicals could pose a serious threat to beach zones and coral reef habitats. There are almost a dozen mitigation options that could be employed to quickly reduce contaminant loads associated with discharges from these beach showers, like those currently being employed (post-study sampling and analysis) in the State of Hawaii, including banning the use of sunscreens using petrochemical-based UV filters or educating tourists before they arrive on the beach.

Development of diffusive gradients in thin film technique for seasonal monitoring of benzophenone-type UV filters in coastal waters

Benzophenone(BP)-type UV filters are continuously released into various aquatic environments via the effluent discharge of wastewater treatment plants (WWTPs) and recreational activities in coastal beaches. In this study, we developed a robust and reliable sampling approach, diffusive gradients in thin-films (DGT), for seasonal monitoring of six BP derivatives in coastal waters to investigate their occurrence and environmental risk. The binding capacities of both XAD-2 and HLB gels for test BPs were over 252 μg with no significant deterioration in marine environment, suggesting that theoretically, DGT is capable of sampling for at least 3 months effectively. The diffusion coefficients of BPs in freshwater and seawater were determined for the first time. The sampling performance showed no dependence on environmental conditions including pH (4.0-8.5), ionic strength (0.0001-0.5 M) and dissolved organic matter (0-20 mg L^-1). The developed DGT samplers were successfully applied in a river estuary linked to a WWTP and a bathing beach at different periods of one year. Results showed that the concentrations of BPs in the coastal waters were dependent on seasonal variation. The highest level in summer and the ecological risk should be considered based on the risk quotient values. These results demonstrated that the present DGT method is suitable for measuring, characterization, and risk assessment of BPs in freshwater and marine environment.

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.

Enhanced removal efficiency of sulfamethoxazole by acclimated microalgae: Tolerant mechanism, and transformation products and pathways

This study utilized sulfamethoxazole (SMX) acclimatization to enhance the tolerance and biodegradation capacity of Chlorella vulgaris. Compared to wild C. vulgaris, the growth inhibition and oxidative damage induced by SMX evidently decreased in acclimated C. vulgaris, and meanwhile photosynthetic and antioxidant activities were significantly promoted. The physiological analyses with the aid of principal component analysis revealed the increase of catalase and glutathione reductase activities was the critical tolerant mechanism of acclimated C. vulgaris. As the consequence, the acclimated C. vulgaris exhibited enhanced efficiency and (pseudo-first-order) kinetic rate for removal of SMX. The distribution analysis of residual SMX demonstrated the biodegradation was the major removal mechanism of SMX by C. vulgaris, while bioadsorption and bioaccumulation made pimping contributions. During the degradation process of SMX, nine transformation products (TPs) were identified. Based on the identified TPs, a possible transformation pathway was proposed.

Oxybenzone contamination from sunscreen pollution and its ecological threat to Hanauma Bay, Oahu, Hawaii, U.S.A

Hanauma Bay is a 101-acre bay created by the partial collapse of a volcanic cone and once supported a vibrant coral reef system. It is the most popular swimming area in the Hawaiian Islands and has been reported to have averaged between 2.8 and 3.5 million visitors a year between the 1980s and the 2010s, with visitors averaging between 3000-4000 a day and peaking around 10,000-13,000 per day. Concentrations of oxybenzone and other common UV filters were measured in subsurface water samples and in sands from the beach-shower areas in Hanauma Bay. Results demonstrate that beach showers also can be a source of sunscreen environmental contamination. Hydrodynamic modeling indicates that oxybenzone contamination within Hanauma Bay's waters could be retained between 14 and 50 h from a single release event period. Focusing on only oxybenzone, two different Hazard and Risk Assessment analyses were conducted to determine the danger of oxybenzone to Hanauma Bay's coral reef system. Results indicate that oxybenzone contamination poses a significant threat to the wildlife of Hanauma Bay. To recover Hanauma Bay's natural resources to a healthy condition and to satisfactorily conserve its coral reef and sea grass habitats, effective tourism management policies need to be implemented that mitigate the threat of sunscreen pollution.

Towards a paradigm shift in environmental health decision-making: a case study of oxybenzone

BACKGROUND

Technological advancements make lives safer and more convenient. Unfortunately, many of these advances come with costs to susceptible individuals and public health, the environment, and other species and ecosystems. Synthetic chemicals in consumer products represent a quintessential example of the complexity of both the benefits and burdens of modern living. How we navigate this complexity is a matter of a society's values and corresponding principles.

OBJECTIVES

We aimed to develop a series of ethical principles to guide decision-making within the landscape of environmental health, and then apply these principles to a specific environmental chemical, oxybenzone. Oxybenzone is a widely used ultraviolet (UV) filter added to personal care products and other consumer goods to prevent UV damage, but potentially poses harm to humans, wildlife, and ecosystems. It provides an excellent example of a chemical that is widely used for the alleged purpose of protecting human health and product safety, but with costs to human health and the environment that are often ignored by stakeholders.

DISCUSSION

We propose six ethical principles to guide environmental health decision-making: principles of sustainability, beneficence, non-maleficence, justice, community, and precautionary substitution. We apply these principles to the case of oxybenzone to demonstrate the complex but imperative decision-making required if we are to address the limits of the biosphere's regenerative rates. We conclude that both ethical and practical considerations should be included in decisions about the commercial, pervasive application of synthetic compounds and that the current flawed practice of cost-benefit analysis be recognized for what it is: a technocratic approach to support corporate interests.

Unraveling the metabolic effects of benzophenone-3 on the endosymbiotic dinoflagellate Cladocopium goreaui

As a well-known pseudo-persistent environmental pollutant, oxybenzone (BP-3) and its related organic ultraviolet (UV) filters have been verified to directly contribute to the increasing mortality rate of coral reefs. Previous studies have revealed the potential role of symbiotic Symbiodiniaceae in protecting corals from the toxic effects of UV filters. However, the detailed protection mechanism(s) have not been explained. Here, the impacts of BP-3 on the symbiotic Symbiodiniaceae Cladocopium goreaui were explored. C. goreaui cells exhibited distinct cell growth at different BP-3 doses, with increasing growth at the lower concentration (2 mg L^-1) and rapid death at a higher concentration (20 mg L^-1). Furthermore, C. goreaui cells showed a significant BP-3 uptake at the lower BP-3 concentration. BP-3 absorbing cells exhibited elevated photosynthetic efficiency, and decreased cellular carbon and nitrogen contents. Besides, the derivatives of BP-3 and aromatic amino acid metabolism highly responded to BP-3 absorption and biodegradation. Our physiological and metabolic results reveal that the symbiotic Symbiodiniaceae could resist the toxicity of a range of BP-3 through promoting cell division, photosynthesis, and reprogramming amino acid metabolism. This study provides novel insights into the influences of organic UV filters to coral reef ecosystems, which urgently needs increasing attention and management.

UV-filter pollution: current concerns and future prospects

UV-filters are widely used in cosmetics and personal care products to protect users' skin from redamage caused by ultraviolet (UV) radiation from the sun. Globally, an estimated 16,000 to 25,000 tonnes of products containing UV-filters were used in 2014 with modern consumption likely to be much higher. Beyond this use in cosmetics and personal care products, UV-filters are also widely used to provide UV-stability in industrial products such as paints and plastics. This review discusses the main routes by which UV-filters enter aquatic environments and summarises the conclusions of studies from the past 10 years that have investigated the effects of UV-filters on environmentally relevant species including corals, microalgae, fish, and marine mammals. Safety data regarding the potential impact of UV-filters on human health are also discussed. Finally, we explore the challenges surrounding UV-filter removal and research on more environmentally friendly alternatives to current UV-filters.

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.

Optimization method for quantification of sunscreen organic ultraviolet filters in coastal sands

Most organic ultraviolet filters are very lipophilic and some of them are difficult to quantify in the environment. This article describes an optimization method for the quantification of these compounds in sand samples with diverse compositions. The standard additions method was used. The search for a unique high-performance liquid chromatography method to analyze all these filters along with the search for optimal detection conditions are presented in detail. The best extraction solvent was methanol, and the best conditions for analysis and detection involved the use of a high-performance liquid chromatography system equipped with a biphenyl column (2.6 μm, 150 × 4.6 mm), and an Orbitrap MS detector. We also demonstrated that sample freeze-drying can induce significant loss of some of the ultraviolet filters.

Exposure to four chemical UV filters through contaminated sediment: impact on survival, hatching success, cardiac frequency, and aerobic metabolic scope in embryo-larval stage of zebrafish

UV filters are widely used in many pharmaceutical and personal care products such as sunscreen and cosmetics to protect from UV irradiation. Due to their hydrophobic properties and relative stability, they have a high capacity to accumulate in sediment. Little information is available on their ecotoxicity on fish. In aquatic ecosystems, fish eggs could be directly affected by UV filters through contact with contaminated sediment. The aim of this study was to investigate the individual toxicity of four UV filters: benzophenone-3 (BP3), butyl methoxydibenzoylmethane (BM), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), and methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), in embryo-larval stages of zebrafish Danio rerio. Fish eggs were exposed to single UV filters by contact with spiked sediment during 96 h at a concentration of 10 μg g^-1. Among the four UV filters tested, BP3 was the more toxic, reducing cardiac frequency and increasing standard metabolic rate of larvae.

Review of aquatic toxicity of pharmaceuticals and personal care products to algae

Pharmaceuticals and Personal Care Products (PPCPs) have been frequently detected in the environment around the world. Algae play a significant role in aquatic ecosystem, thus the influence on algae may affect the life of higher trophic organisms. This review provides a state-of-the-art overview of current research on the toxicity of PPCPs to algae. Nanoparticles, contained in personal care products, also have been considered as the ingredients of PPCPs. PPCPs could cause unexpected effects on algae and their communities. Chlorophyta and diatoms are more accessible and sensitive to PPCPs. Multiple algal endpoints should be considered to provide a complete evaluation on PPCPs toxicity. The toxicity of organic ingredients in PPCPs could be predicted through quantitative structure-activity relationship model, whereas the toxicity of nanoparticles could be predicted with limitations. Light irradiation can change the toxicity through affecting algae and PPCPs. pH and natural organic matter can affect the toxicity through changing the existence of PPCPs. For joint and tertiary toxicity, experiments could be conducted to reveal the toxic mechanism. For multiple compound mixture toxicity, concentration addition and independent addition models are preferred. However, there has no empirical models to study nanoparticle-contained mixture toxicity. Algae-based remediation is an emerging technology to prevent the release of PPCPs from water treatment plants. Although many individual algal species are identified for removing a few compounds from PPCPs, algal-bacterial photobioreactor is a preferable alternative, with higher chances for industrial applications.

A Novel Approach to Derive the Predicted No-Effect Concentration (PNEC) of Benzophenone-3 (BP-3) Using the Species Sensitivity Distribution (SSD) Method: Suggestion of a New PNEC Value for BP-3

The necessity for the aquatic ecological risk assessment for benzophenone-3 (BP-3) is increasing due to its high toxic potential and high detection frequency in freshwater. The initial step in the ecological risk assessment is to determine predicted no-effect concentration (PNEC). This study derived PNEC of BP-3 in freshwater using a species sensitivity distribution (SSD) approach, whilst existing PNECs are derived using assessment factor (AF) approaches. A total of eight chronic toxicity values, obtained by toxicity testing and a literature survey, covering four taxonomic classes (fish, crustaceans, algae, and cyanobacteria) were used for PNEC derivation. Therefore, the quantity and quality of the toxicity data met the minimum requirements for PNEC derivation using an SSD approach. The PNEC derived in this study (73.3 μg/L) was far higher than the environmental concentration detected in freshwater (up to 10.4 μg/L) as well as existing PNECs (0.67~1.8 μg/L), mainly due to the difference in the PNEC derivation methodology (i.e., AF vs. SSD approach). Since the SSD approach is regarded as more reliable than the AF approach, we recommend applying the PNEC value derived in this study for the aquatic ecological risk assessment of BP-3, as the use of the existing PNEC values seems to unnecessarily overestimate the potential ecological risk of BP-3 in freshwater.

Assessment of cytotoxicity biomarkers on the microalga Chlamydomonas reinhardtii exposed to emerging and priority pollutants

Contamination of aquatic ecosystems linked to anthropogenic activity is currently a major concern; therefore, ecotoxicological studies are needed to assess its effect on organisms. The main objective of this study was to investigate the effects of different pollutants on microalgae in search of sensitive biomarkers that can promote a common cytotoxic response regardless of the contaminant. Cultures of the freshwater microalga Chlamydomonas reinhardtii were exposed for 24 h to four chemicals, three emerging pollutants (benzophenone-3, bisphenol A and oxytetracycline) and one priority substance (atrazine). A cytometric panel was carried out to assess toxicity biomarkers including cellular growth, inherent cell properties, viability, vitality, cytoplasmic membrane potential and ROS levels. Lipid peroxidation, photosynthetic efficiency and transcriptional responses of photosynthesis- and oxidative stress-related genes using RT-qPCR were also studied. Some toxicity responses showed a similar pattern; a decrease in growth rate, vitality and photosynthetic efficiency and an increase in autofluorescence and in the number of cells with depolarised cytoplasmic membrane and were found for all chemicals tested. However, ATZ and OTC provoked a decrease in cell size, whereas BP-3 and BPA caused an increase in cell size, intracellular complexity and ROS levels and a decrease in cell viability. Assayed pollutants generally promoted an overexpression of genes related to cellular antioxidant defence system and a subexpression of photosynthesis-related genes. In addition to the traditional growth endpoint, cell vitality, autofluorescence and gene expression of catalase, glutathione peroxidase and Fe-superoxide dismutase were significantly affected for all chemicals tested, showing a common cytotoxic response. Among the tested substances, BP-3 provoked the strongest cytotoxic alterations on this microalga, pointing out that some emerging contaminants could be more harmful to organisms than priority pollutants.

Comparative acute toxicity of benzophenone derivatives and bisphenol analogues in the Asian clam Corbicula fluminea

Among UV-filters, benzophenones are one of the most abundantly used and detected groups in the environment. Bisphenols are also one of the most widely used chemicals in plastics, but their demonstrated deleterious effects on several organisms and humans have led to the production of alternative analogues. However, few comparative studies on the ecotoxicological effects of these derivatives or analogues have been carried out. The present study aimed to investigate the effects of two benzophenones (BP-3 and BP-4) and two bisphenols (BPA and BPS) in a short-term exposure of the freshwater endobenthic bivalve Corbicula fluminea. Clams were exposed for 96 h to several concentrations of the four pollutants: BP-3 (0.63; 1.25; 2.5; 5 mg l^-1), BP-4 (4.75; 9.5; 19; 38 mg l^-1), BPA (3.75; 7.5; 15; 30 mg l^-1), and BPS (2.5; 5; 10; 20 mg l^-1). The comparative acute toxicity of these pollutants was evaluated by the analysis of the post-exposure filtering capacity of clams, lipid peroxidation (LP) levels and the activity of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR). After the exposure period, except for BP-4, the chemicals tested seemed to be detected by clams and provoked valve closure, decreasing filter-feeding in a concentration-dependent manner. Furthermore, C. fluminea exposed to the highest concentrations of BP-3, BP-4 and BPA showed a significant increase in LP, CAT and GR activities with respect to their controls. BP-3 and BPA were the most toxic compounds showing significant differences in all the parameters analysed at the highest concentrations assayed. However, clams exposed to BPS showed only significant alterations in filtration parameters and in GR activity, in the two highest concentrations tested, indicating that this compound was the least toxic to clams. Obtained results highlight the importance of investigating the effects that emerging pollutants have on aquatic organisms.

Distribution, removal efficiencies and environmental risk assessment of benzophenone and salicylate UV filters in WWTPs and surface waters from Romania

This article presents the environmental pollution level with organic UV filters and the effect they pose on aquatic organisms in Romania.

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.

Distinct mechanisms underlying the assembly of microeukaryotic generalists and specialists in an anthropogenically impacted river

Microeukaryotic communities are sensitive to environmental changes; and are considered essential for microbial food webs and biogeochemical cycles. Therefore, understanding the community responses of microeukaryotes to environmental changes is of great ecological significance. Very little is known about the assembly mechanisms underlying the microeukaryotic communities, especially for the key ecological groups (e.g., habitat generalists/specialists) in the riverine ecosystems. Here, we employed 18S rDNA amplicon sequencing to study the assembly processes governing the microeukaryotic communities and their habitat generalists and specialists across three hydrological seasons in a subtropical river in China. The results showed that deterministic and stochastic processes jointly shaped the microeukaryotic communities, where the relative importance of stochastic processes decreased in the following order: wet > normal > dry seasons. However, deterministic processes played more important role in shaping the microeukaryotic communities than those of prokaryotes. Meanwhile, stochastic and deterministic processes were responsible for structuring the microeukaryotic habitat generalists and specialists, respectively. Generally, the pure effects of physicochemical factors on the microeukaryotic communities and their key ecological groups were ~ 1.7 folds than those of the micropollutants. However, several micropollutants (e.g., acetaminophen, benzophenone-3, bisphenol A, sulfadiazine, triclocarban and triclosan) were found to have a strong effect on the habitat specialists. Altogether, we suggested that the ecological responses of the riverine microeukaryotes to micropollutants may vary among species due to the intrinsic differences in their environmental plasticity.

Effect of Benzophenone-3 on performance, structure and microbial metabolism in an EGSB system

Benzophenone-3 is an organic compound widely used as a UV filter, which has been reported as water pollutant and is connected with endocrine disruption in humans and animals. Expanded granular sludge beds (EGSB) are a form of an anaerobic digestion system, which has been successfully evaluated for wastewater treatment, and the removal of different compounds, however little is known about the effect of compounds as Benzophenone-3 in the performance of EGSB systems. In this study, we evaluate the effect of BP-3 on the performance, microbial structure and metabolism of EGSB reactors. For this purpose, biogas production, removal efficiencies of BP-3 and DQO were monitored. Changes in bacteria and archaea microbial structure were investigated using PCR-DGGE, and the effect on anaerobic metabolism was evaluated by measuring the expression of mcrA and ACAs genes through qRT-PCR. The systems remained stable and efficient throughout the operation stages, with CH4 percentages greater than 55% and COD and BP-3 removal percentages greater than 90%. The presence of different concentrations of Benzophenone-3 influenced the organization of microbial communities, especially archaea. However, this did not affect the stability and performance of the EGSB systems.

Antioxidant responses in cyanobacterium Microcystis aeruginosa caused by two commonly used UV filters, benzophenone-1 and benzophenone-3, at environmentally relevant concentrations

Benzophenone-type ultraviolet filters (BPs) have recently been recognized as emerging organic contaminants. In the present study, the cyanobacterium Microcystis aeruginosa was exposed to environmentally relevant levels (0.01-1000 μg L^-1) of benzophenone-1 (BP-1) and benzophenone-3 (BP-3) for seven days. A battery of tested endpoints associated with photosynthetic pigments and oxidative stress was employed for a better understanding of the mode of action. The tested cyanobacterium could uptake the two BPs (27.4-54.9%) from culture media. The two BPs were able to inhibit the production of chlorophyll a (chl-a) and promote the accumulation of carotenoids, leading to unaffected chl-a autofluorescence. Slightly increased malondialdehyde (MDA) contents suggested that BP-1 and BP-3 caused moderate oxidative stress. BP-1 stimulated the activities of superoxide dismutase (SOD), glutathione reductase (GR) and glutathione S-transferase (GST) in M. aeruginosa while BP-3 increased the activities of SOD, GST, and glutathione (GSH), showing a concentration- and time-dependent relationship. The activities of other biomarkers, such as catalase (CAT) and glutathione peroxidase (GPx) fluctuated depending on exposure time and concentration. The overall results suggested that the two BPs can trigger moderate oxidative stress in M. aeruginosa and the tested cyanobacterium was capable of alleviating stress by different mechanisms.

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

Organic UV filters are of emerging concern due to their occurrence and persistence in coastal ecosystems. Because marine bacteria are crucial in the major biogeochemical cycles, there is an urgent need to understand to what extent these microorganisms are affected by those chemicals. This study deciphers the impact of five common sunscreen UV filters on twenty-seven marine bacteria, combining both photobiology and toxicity analysis on environmentally relevant species. Seven bacteria were sensitive to different organic UV filters at 1000 μg L^-1, including octinoxate and oxybenzone. This is the first report demonstrating inhibition of bacterial growth from 100 μg L^-1. None of the UV filters showed any toxicity at 1000 μg L^-1 on stationary phase cells, demonstrating that physiological state was found to be a key parameter in the bacterial response to UV-filters. Indeed, non-growing bacteria were resistant to UV filters whereas growing cells exhibited UV filter dependent sensitivity. Octinoxate was the most toxic chemical at 1000 μg L^-1 on growing cells. Interestingly, photobiology experiments revealed that the toxicity of octinoxate and homosalate decreased after light exposure while the other compounds were not affected. In terms of environmental risk characterization, our results revealed that the increasing use of sun blockers could have detrimental impacts on bacterioplanktonic communities in coastal areas. Our findings contribute to a better understanding of the impact of the most common UV filters on bacterial species and corroborate the importance to consider environmental parameters such as solar radiation in ecotoxicology studies.

Toxicity of benzophenone-3 and its biodegradation in a freshwater microalga Scenedesmus obliquus

Environmental contamination by benzophenone-3 has gained attention because of its frequent occurrence and adverse environmental impact. Studies investigating the toxicity and removal mechanisms, along with its degradation pathway in microalgae are still rare. In this study, the ecotoxicity of benzophenone-3 on Scenedesmus obliquus was assessed through dose-response test, risk quotient evaluation, and changes of microalgal biochemical characteristics and gene expression. The calculated risk quotients of benzophenone-3 were >1, implying its high environmental risk. Expression of the ATPF0C and Tas genes encoding ATP-synthase and oxidoreductase was significantly increased in S. obliquus after exposure to benzophenone-3, while that of Lhcb1 and HydA genes was reduced. When exposed to 0.1-3 mg L^-1 benzophenone-3, 23-29 % removal was achieved by S. obliquus, which was induced by abiotic removal, bioadsorption, bioaccumulation and biodegradation. Metabolic fate analyses showed that biodegradation of benzophenone-3 was induced by hydroxylation, and methylation, forming less toxic intermediates according to the toxicity assessment of the identified products. This study provides a better understanding of the toxicity and metabolic mechanisms of benzophenone-3 in microalgae, demonstrating the potential application of microalgae in the remediation of benzophenone-3 contaminated wastewater.

Comparison of toxicological effects of oxybenzone, avobenzone, octocrylene, and octinoxate sunscreen ingredients on cucumber plants (Cucumis sativus L.)

Oxybenzone (OBZ), avobenzone (AVB), octocrylene (OCR) and octinoxate (OMC) are ultraviolet (UV) filters commonly added to chemical sunscreens. These UV filters are known to widely contaminate the environment through a variety of anthropogenic sources, including sewage discharge. However, systematic studies of the damage caused by these four UV filters and their toxicopathological differences in a variety of plant species are lacking. In this study, we demonstrated that irrigation with water containing these four UV filters could significantly inhibit the aboveground growth of cucumber plant. All of the UV filters decreased photosynthesis through nonstomatal factors but via different inhibitory mechanisms. Only OBZ inhibited photosynthesis by directly inhibiting photosynthetic electron transport, while the other three (AVB, OCR, and OMC) inhibited photosynthesis by inhibiting the Calvin-Benson cycle. Additionally, these four UV filters also decreased plant respiration under long-term treatment. Photosynthesis and respiration inhibition led to the over production of reactive oxygen species (ROS) and the formation of lipid peroxidation damage products, which further damaged the structure and function of plant cells, causing secondary pathologies and potentially leading to reduced crop yields. The study also demonstrated that these four UV filters caused different degrees of phototoxic damage to cucumber plants. On the basis of comprehensive evaluation, we speculated that the order of the four UV filters in terms of plant damage was OBZ > AVB > OMC > OCR. Because of the severe damaging effects of these UV filters on plant growth, the application of contaminated biosolids/reclaimed water in agriculture reduces agricultural production and may damage ecosystems. The results of this study can advance recognition of the hazards associated with environmental and agricultural pollution via UV filters and encourage consumers and the industry to limit or reduce the application of cosmetics and over-the-counter drugs containing these substances.

Effect of 10 UV Filters on the Brine Shrimp Artemia salina and the Marine Microalga Tetraselmis sp

The presence of pharmaceutical and personal care product (PPCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through gray water, and accumulation in the environment that may affect living organisms, ecosystems and public health. The aim of this study is to assess the toxicity of benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), 2-ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS) and octocrylene (OC) on marine organisms from two major trophic levels, including autotrophs (Tetraselmis sp.) and heterotrophs (Artemia salina). In general, results showed that both HS and OC were the most toxic UV filters for our tested species, followed by a significant effect of BM on Artemia salina due to BM—but only at high concentrations (1 mg/L). ES, BP3 and DHHB affected the metabolic activity of the microalgae at 100 µg/L. BEMT, DBT, ET, MBBT had no effect on the tested organisms, even at high concentrations (2 mg/L). OC toxicity represents a risk for those species, since concentrations used in this study are 15–90 times greater than those reported in occurrence studies for aquatic environments. For the first time in the literature, we report HS toxicity on a microalgae species at concentrations complementing those found in aquatic environments. These preliminary results could represent a risk in the future if concentrations of OC and HS continue to increase.

Biodegradation of Chiral Flufiprole in Chlorella pyrenoidosa: Kinetics, Transformation Products, and Toxicity Evaluation

Pesticide pollution of surface water represents a considerable risk for algae and thus affects the structure and stability of aquatic ecosystems. To investigate the risk of flufiprole to phytoplankton, the digestion and uptake of flufiprole as well as the toxic effects of flufiprole enantiomers and the six metabolites to Chlorella pyrenoidosa were investigated. Flufiprole enantiomers were mainly metabolized to flufiprole amide and detrifluoromethylsulfinyl flufiprole in culture medium, while various metabolites were formed in algae, notably the amide derivative and fipronil. Chlorella pyrenoidosa showed a strong absorption capacity for the flufiprole series. The EC₅₀ values (96 h) indicated that fipronil was the most toxic compound, approximately 5 times as toxic as rac-flufiprole. R-flufiprole was more toxic than S-flufiprole. The contents of chlorophylls, malondialdehyde (MDA), reactive oxygen species (ROS), and total antioxidant capacity (T-AOC) were significantly altered by the chemicals in most cases, especially fipronil. Our results supported the potential detrimental effect of the metabolites of flufiprole on algae.

The toxicological effects of oxybenzone, an active ingredient in suncream personal care products, on prokaryotic alga Arthrospira sp. and eukaryotic alga Chlorella sp

Oxybenzone (OBZ; benzophenone-3, CAS# 131-57-7) is a known pollutant of aquatic and marine ecosystems, and is an ingredient in over 3000 personal care products, as well as many types of plastics. The aim of this study is to explore the different toxicities of OBZ on an eukaryotic (Chlorella sp.) and a prokaryotic algae (Arthrospira sp.). OBZ is a photo-toxicant, with all observed toxicities more sever in the light than in the dark. Cell growth and chlorophyll inhibition were positively correlated with increasing OBZ concentrations over time. Twenty days treatment with OBZ, as low as 22.8 ng L^-1, significantly inhibited the growth and chlorophyll synthesis of both algae. Both algae were noticeably photo-bleached after 7 days of exposure to OBZ concentrations higher than 2.28 mg L^-1. Relatively low OBZ concentrations (0.228 mg L^-1) statistically constrained photosynthetic and respiratory rates via directly inhibiting photosynthetic electron transport (PET) and respiration electron transport (RET) mechanisms, resulting in over production of reactive oxygen species (ROS). Transmission and scanning electron microscopy showed that the photosynthetic and respiratory membrane structures were damaged by OBZ exposure in both algae. Additionally, PET inhibition suppressed ATP production for CO₂ assimilation via the Calvin-Benson cycle, further limiting synthesis of other biomacromolecules. RET restriction limited ATP generation, restricting the energy supply used for various life activities in the cell. These processes further impacted on photosynthesis, respiration and algal growth, representing secondary OBZ-induced algal damages. The data contained herein, as well as other studies, supports the argument that global pelagic and aquatic phytoplankton could be negatively influenced by OBZ pollution.

An automated 3D-printed smartphone platform integrated with optoelectrowetting (OEW) microfluidic chip for on-site monitoring of viable algae in water

A sudden increase of algae and their associated toxins in aquatic ecosystems can detrimentally affect the quality of the water, causing serious socio-economic and public health problems. To prevent the spread of harmful algae in aquatic ecosystems, it is essential to track the water's quality through rapid and in-situ monitoring systems. Conventional methods of algae quantification such as microscopy, hemocytometry, and UV-vis spectroscopy, however, are often unsuitable or inconvenient for in-situ assessment as they require skilled labor and expensive equipment. In this study, we developed a three-dimensional (3D)-printed smartphone platform integrated with a light-driven microfluidic chip operated by optoelectrowetting (OEW). This OEW-driven microfluidic chip not only allows multiplexed drop-wise functions such as droplet transportation, merging, mixing, immobilization on a detection zone, for on-chip water sample preparation but also fluorescent detection and counting of target algae cells using a commercially-available smartphone. Two freshwater algae (C. reinhardtii and M. aeruginosa) and two marine water algae (Amphiprora sp and C. closterium) were employed to validate the 3D-printed smartphone platform in this study. The fluorescence images of viable algae and the cell counting from the microfluidic chip were comparable to the results from a hemocytometer (P > 0.05). We have further conducted tests with spiked samples using freshwater and marine water that were directly collected from environmental samples, showing the same order of magnitude of cell numbers in the spiked and control cultures of algae cells (10⁶ cell/mL, P > 0.05). Unlike traditional quantification methods, the 3D-printed smartphone platform integrated with the OEW offers a highly portable, user-friendly, low-cost tool that enables simple on-chip sample preparation and detection of viable algae. Thus, this stand-alone technology has the potential for rapid and in-situ monitoring of water quality, while using the smartphone's wireless communication capabilities to report the quality of the water in real-time.

Differential toxicity of the UV-filters BP-3 and BP-4 in Chlamydomonas reinhardtii: A flow cytometric approach

Due to the concern about the negative effects of exposure to sunlight, UV-filters are being introduced in all kind of cosmetic formulas. Wastewater treatment plants are not able to remove and/or degrade them; consequently they find their way into rivers, lakes and oceans. These chemicals are acquiring a concerning status due to their increasingly common use and the potential risk for the environment. Benzophenone-3 (BP-3) and Benzophenone-4 (BP-4) are broad-spectrum UV-filters used for the same purpose in personal care products, insecticides and plastic bags; however, after 96 h of exposure to several concentrations of these UV-filters, the growth of C. reinhardtii was more affected by BP-3 than by BP-4, being the 96 h-EC₅₀ for growth 5 mg L^-1 and 38 mg L^-1, respectively. Based on these values Chlamydomonas reinhardtii cultures were exposed during 24 h to 2.5, 5 and 10 mg L^-1 of BP-3 and 19, 38 and 76 mg L^-1 of BP-4. A cytometric panel was carried out to evaluate the effect of sublethal concentrations of these UV-filters, thus several cytotoxicity biomarkers were analysed, including chlorophyll a fluorescence, viability, metabolic activity, oxidative stress, cytoplasmic and mitochondrial membrane potentials, and intracellular pH. BP-3 and BP-4 affect C.reinhardtii cells in a different way, showing differences for three of the examined parameters. Chlorophyll a fluorescence and mitochondrial membrane potential showed a significant increase (p < 0.05) in BP-3 and a significant decrease in BP-4, whereas viability only decreased significantly in the highest concentrations of BP-3. Regarding to the other parameters analysed, a similar pattern of cytotoxicity was observed. Growth rate, vital population and metabolic activity (esterase activity) and intracellular pH decreased significantly and cytoplasmic membrane potential and ROS levels increased significantly in cultures exposed to both pollutants.

Effect of elevated benzophenone-4 (BP4) concentration on Chlorella vulgaris growth and cellular metabolisms

Benzophenone-4 (BP4), as the raw material of common sunscreen products, usually shows strong eco-toxicity and endocrine-disrupting activity in aquatic animals. However, the potential adverse effect of BP4 on aquatic vegetation is still unclear. In order to evaluate the inhibitory effect of BP4 on phytoplankton, wild and acclimated Chlorella vulgaris was used as representative aquatic plant cells and experimental studies were conducted on the characteristics of its growth and cellular metabolisms upon exposure to elevated BP4 concentrations (1, 5, 10, 20, 50, and 100 mg L^-1). C. vulgaris basically appeared low sensitivity to BP4 exposure because the 96-h EC₅₀ was measured as 65.16 mg L^-1 for its wild type. The 96-h EC₅₀ of the acclimated type, which was pre-exposed to 10 mg L^-1 of BP4 and transferred twice, was 140.76 mg L^-1. By cellular response tests regarding non-enzymatic antioxidants carotenoid content, malondialdehyde (MDA), enzyme antioxidant superoxide dismutase (SOD) activity, and the photosynthetic efficiency, it was clarified that increasing exposure concentration elevated the hindrance to cellular metabolism. However, the rate of BP4 utilization as substrates for C. vulgaris growth showed a trend of decreasing with increasing BP4 concentration. The higher 96-h EC₅₀ value of the acclimated C. vulgaris to BP4 inhibition than the wild C. vulgaris showed the enhanced tolerance capability; however, the continuous stress response of acclimated type should be taken into account when using microalgae species for toxicity assessment.

Evaluating the Joint Toxicity of Two Benzophenone-Type UV Filters on the Green Alga Chlamydomonas reinhardtii with Response Surface Methodology

The widespread occurrence of benzophenone-type ultraviolet (UV) filter has raised the public concerns over the ecotoxicological effects of these chemicals. The present study assessed the joint toxicity of two representative benzophenones, benzophenone-1 (BP-1) and benzophenone-3 (BP-3), on the green alga Chlamydomonas reinhardtii using response surface methodologies (RSM). Specific growth rate and photosynthetic pigments were used as endpoints to evaluate the toxic effects. Generally, exposure to the combined BP-1 and BP-3 negatively affected cell growth and pigments production, with higher inhibitions at higher exposure concentrations. The simultaneous reduction in growth rate and pigments contents indicated that BP-1 and BP-3 regulated the growth of the tested alga by affecting the photosynthesis process. Results also showed that second order polynomial regression models fitted well with experimental results for all endpoints. The obtained regression models further indicated that the effects of the combination stemmed significantly from the linear concentration of BP-1 and BP-3. The overall results demonstrated that RSM could be a useful tool in ecotoxicological studies.