Toxicity of Aged Paint Particles to Soil Ecosystems: Insights from Caenorhabditis elegans.

Despite the extensive global consumption of architectural paint, the toxicological effects of aged exterior paint particles on terrestrial biota remain largely uncharacterized. Herein, we assessed the toxic effect of aged paint particles on soil environments using the nematode Caenorhabditis elegans (C. elegans) as a test organism. Various types of paint particles were generated by fragmentation and sequential sieving (500-1000, 250-500, 100-250, 50-100, 20-50 µm) of paint coatings collected from two old residential areas. The paint particles exerted different levels of toxicity, as indicated by a reduction in the number of C. elegans offspring, depending on their size, color, and layer structure. These physical characteristics were found to be closely associated with the chemical heterogeneity of additives present in the paint particles. Since the paint particle sizes were larger than what C. elegans typically consume, we attributed the toxicity to leachable additives present in the paint particles. To assess the toxicity of these leachable additives, we performed sequential washings of the paint particles with distilled water and ethanol. Ethanol washing of the paint particles significantly reduced the soil toxicity of the hydrophobic additives, indicating their potential environmental risk. Liquid chromatography-mass spectrometry analysis of the ethanol leachate revealed the presence of alkyl amines, which exhibited a high correlation with the toxicity of the paint particles. Further toxicity testing using an alkyl amine standard demonstrated that a paint particle concentration of 1.2% in soil could significantly reduce the number of C. elegans offspring. Our findings provide insights into the potential hazards posed by aged paint particles and their leachable additives in the terrestrial environment.

Combined effects of toxic Microcystis aeruginosa and high pH on antioxidant responses, immune responses, and apoptosis of the edible freshwater bivalve Corbicula fluminea.

Due to increasing anthropogenic perturbation and water eutrophication, cyanobacterial blooms (CYBs) have become a global ecological and environmental problem. Toxic CYBs and elevated pH are considered to be the two key stressors associated with eutrophication in natural waters, particularly in the event of CO2 depletion induced by dense blooms. However, previous research has been focused on investigating the impacts of toxic CYBs or pH changes in isolation, whereas the interactive effects of such stressors on edible bivalves that inhabit CYB waters still lack information. In this study, the combined effects of toxic Microcystis aeruginosa and pH shifts on the antioxidant responses, immune responses, and apoptosis of the edible freshwater bivalve Corbicula fluminea were explored. The results showed that the activity of antioxidant enzymes was significantly impacted by the interactive effects between toxic M. aeruginosa exposure and time course, yet pH shifts showed no significant effects on the activities of these antioxidant enzymes, implying that the antioxidant response in C. fluminea was mainly triggered by toxic M. aeruginosa exposure. Toxic M. aeruginosa also induced an increased production of reactive oxygen species and malondialdehyde in treated clams, particularly under high pH settings. The elevated lysosomal enzyme activity helped C. fluminea defend against toxic M. aeruginosa exposure under high pH conditions. The principal component analysis (PCA) and the integrated biomarker response (IBR) results suggested that the treated clams were subjected to the elevated toxicity of toxic M. aeruginosa in conditions of high pH. The heat shock proteins-related genes might be triggered to resist the oxidative damage in treated clams. Moreover, the upregulation of TNF and casp8 genes indicated the potential activation of the caspase8-mediated apoptotic pathway through TNF receptor interaction, potentially resulting in apoptosis. The TUNEL assay results further confirmed that apoptosis appeared in treated clams. These findings improve our understanding of the combined toxicological effects of harmful algae and pH shifts on bivalves, which will provide insights into a comprehensive ecological risk assessment of toxic CYBs to edible bivalve species.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health.

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

Interaction of Micro- and Nanoplastics with Enzymes: The Case of Carbonic Anhydrase.

Microplastics (MPs) and nanoplastics (NPs) have emerged as significant environmental pollutants with potential detrimental effects on ecosystems and human health. Several studies indicate their interaction with enzymes; this topic represents a multifaceted research field encompassing several areas of interest from the toxicological and ecotoxicological impact of MPs and NPs on humans and wildlife to the biodegradation of plastics by microbial enzymes. This review aims to provide a critical analysis of the state-of-the-art knowledge of the interaction of MPs and NPs on the enzyme carbonic anhydrase (CA), providing recent insights, analyzing the knowledge gaps in the field, and drawing future perspectives of the research and its application. CA is a widespread and crucial enzyme in various organisms; it is critical for various physiological processes in animals, plants, and bacteria. It catalyzes the reversible hydration of CO2, which is essential for respiration, acid-base balance, pH homeostasis, ion transport, calcification, and photosynthesis. Studies demonstrate that MPs and NPs can inhibit CA activity with mechanisms including adsorption to the enzyme surface and subsequent conformational changes. In vitro and in silico studies highlight the role of electrostatic and hydrophobic interactions in these processes. In vivo studies present mixed results, which are influenced by factors like particle type, size, concentration, and organism type. Moreover, the potentiality of the esterase activity of CA for plastic degradation is discussed. The complexity of the interaction between CA and MPs/NPs underscores the need for further research to fully understand the ecological and health impacts of MPs and NPs on CA activity and expression and glimpses of the potentiality and perspectives in this field.

Responses of microRNA in digestive glands of mussel Mytilus galloprovincialis exposed to polystyrene nanoplastics.

Polystyrene nanoplastics (PS-NPs) are typical accumulated nanoplastics in the marine environment and organisms, and have strong potential risks to marine ecological environment and human health. MiRNAs could respond to and participate in the response process of environmental stressors. However, the response of miRNAs to nanoplastics has not been fully explored. In this study, miRNA responses of digestive glands in mussels Mytilus galloprovincialis treated by 200 nm PS-NPs (20, 200, 2000 µg/L) for 7 days were characterized by BGISEQ-500 deep sequencing and bioinformatics analysis, along with histopathological quantification with planimetric parameters on hematoxylin and eosin (H&E) staining. Results showed that one novel miRNA (novel_mir63) and seven known miRNAs (miR-34_2, miR-34_5, miR-281_8, let-7-5p_6, miR-10, miR-124, miR-29b-3p) were significantly (adjusted P-value < 0.05) differentially expressed after PS-NPs treatments, and most of them were down-regulated expect for novel_mir63 and miR-34_2. Function analysis of target genes corresponding to these differentially expressed miRNAs indicated that PS-NPs disturbed the process related to metabolism, aging, cardiac function, neural excitation, and repairment. Among them, acetyl-CoA C-acetyltransferase and purine metabolism pathway played vital connection roles. Meanwhile, significantly morphology changes of digestive tubes obtained from H&E stained sections also implied severely disrupted metabolic capability in digestive glands, reflected by significantly increased mean diverticular radius (MDR) and mean luminal radius (MLR) values and the ratio of MLR to mean epithelial thickness (MET), and significantly decreased MET value and MET/MDR. Overall, these findings have revealed new characterization of miRNAs and their target genes in mussel M. galloprovincialis under PS-NPs stress, and provide important clues to further elucidate the toxicity mechanisms of PS-NPs.

Evaluation of the Toxicity Potential of the Metabolites of Di-Isononyl Phthalate and of Their Interactions with Members of Family 1 of Sulfotransferases-A Computational Study.

Di-isononyl phthalates are chemicals that are widely used as plasticizers. Humans are extensively exposed to these compounds by dietary intake, through inhalation and skin absorption. Sulfotransferases (SULTs) are enzymes responsible for the detoxification and elimination of numerous endogenous and exogenous molecules from the body. Consequently, SULTs are involved in regulating the biological activity of various hormones and neurotransmitters. The present study considers a computational approach to predict the toxicological potential of the metabolites of di-isononyl phthalate. Furthermore, molecular docking was considered to evaluate the inhibitory potential of these metabolites against the members of family 1 of SULTs. The metabolites of di-isononyl phthalate reveal a potency to cause liver damage and to inhibit receptors activated by peroxisome proliferators. These metabolites are also usually able to inhibit the activity of the members of family 1 of SULTs, except for SULT1A3 and SULT1B1. The outcomes of this study are important for an enhanced understanding of the risk of human exposure to di-isononyl phthalates.

Ex Vivo Antiplatelet and Thrombolytic Activity of Bioactive Fractions from the New-Fangled Stem Buds of Ficus religiosa L. with Simultaneous GC-MS Examination.

Different parts of Ficus religiosa are the common components of various traditional formulations for the treatment of several blood disorders. The new-fangled stem buds' powder was extracted with 80% ethanol and successively fractionated by chloroform and methanol. Chloroform and methanol fractions of Ficus religiosa (CFFR and MFFR) were tested for antiplatelet, antithrombotic, thrombolytic, and antioxidant activity in ex vivo mode. The MFFR was particularly investigated for GC-MS and toxicity. The antiplatelet activity of the CFFR, MFFR, and standard drug aspirin at 50 µg/mL was 54.32%, 86.61%, and 87.57%, and a significant delay in clot formation was noted. CFFR at different concentrations did not show a significant effect on the delay of clot formation, antiplatelet, and free radical scavenging activity. The most possible marker compounds for antiplatelet and antioxidant activity identified by GC-MS in the MFFR are salicylate derivatives aromatic compounds such as benzeneacetaldehyde (7), phenylmalonic acid (13), and Salicylic acid (14), as well as Benzamides derivatives such as carbobenzyloxy-dl-norvaline (17), 3-acetoxy-2(1H)-pyridone (16), and 3-benzylhexahydropyrrolo [1,2-a] pyrazine-1,4-dione (35). A toxicity study of MFFR did not show any physical indications of toxicity and mortality up to 1500 mg/kg body weight and nontoxic up to 1000 mg/kg, which is promising for the treatment of atherothrombotic diseases.

Individual and combined effects of cadmium and lead exposure in rats.

The exposure of humans and animals to environmental compounds is rarely restricted to a single chemical. Cadmium (Cd) and lead (Pb) are two heavy metals known to be the most toxic. Deleterious effects of each metal alone are well documented. Unfortunately, very few studies were conducted to determine their combined effect. Four groups of Wistar rats were treated intravenously for 15 days. The control group received physiological saline solution; groups 2 and 3 were treated with Cd chloride and lead acetate, respectively ; and the treatment group 4 received a combined treatment of Cd and Pb . A significant decrease was recorded for hematological parameters , with an increase in white blood cells and an inhibition in δ-ALAD level. Cell injury in the livers and kidneys was clearly shown by the significant elevation of the biochemical markers. Cd and Pb induced oxidative stress and had adverse health effects at lower exposure levels than previously thought.

Toxicological responses of juvenile Chinese shrimp Fenneropenaeus chinensis and swimming crab Portunus trituberculatus exposed to cadmium.

Cadmium (Cd) is one of the typical metal pollutants in the Bohai Sea. To evaluate the acute toxicological effects of Cd on marine crustaceans, juvenile Fenneropenaeus chinensis and Portunus trituberculatus were exposed to Cd at environmentally relevant concentrations (5 and 50 µg/L) for 96 h. Cd accumulation, antioxidants and metabolite profiles were characterized to elucidate the responses of juvenile crustaceans to Cd stress. Significant Cd accumulation was observed in both juvenile crustaceans in 50 µg/L Cd-treated group. Results showed that Cd exposure induced hormesis based on the alterations of GSH, SOD and CAT activities (i.e. increased levels in the low concentration of Cd treatment and recovered levels in the high concentration of Cd treatment) in juvenile P. trituberculatus. Similarly, the responses of GSH contents presented hormesis pattern in Cd-treated juvenile F. chinensis. Na+-K+-ATPase contents were significantly elevated in 50 µg/L Cd-treated group. In addition, untargeted NMR-based metabolomics indicated Cd caused the disturbance in osmotic regulation and energy consumption in both juvenile F. chinensis and P. trituberculatus via different pathways. The immunotoxicity and movement disorder were uniquely demonstrated in juvenile P. trituberculatus after Cd exposure.

Elucidating the negatively influential and potentially toxic mechanism of single and combined micro-sized polyethylene and petroleum to Chlorella vulgaris at the cellular and molecular levels.

Although microplastics (MPs; <5 mm) may interact with co-contaminants (e.g., petroleum) in marine aquatic systems, little is known about their combined toxicity. Therefore, this study explored the toxicities and their mechanisms of micro-sized polyethylene (mPE) and their combination with petroleum to Chlorella vulgaris. The single MPs at various particle sizes, concentrations, and aging degree, single petroleum, and their combinations, were found to pose toxicities to C. vulgaris. This study also found the microcosm's microbial diversity changed. The microbial communities in the C. vulgaris biotopes were altered under exposure to mPE and petroleum, and were disturbed by external factors such as MPs particle size, concentration, aging time, and the combination with petroleum. Furthermore, as compared with the toxicity of petroleum on microalgal transcriptional function, mPE caused less toxic to C. vulgaris, and only impact the posttranslational modification, protein turnover, and signal transduction processes. Most importantly, mPE reduced petroleum toxicity in C. vulgaris via regulating the ABC transporter, eukaryotic ribosome synthesis, and the citrate cycle metabolic pathways. Overall, our findings could fundamentally provide insights into the joint ecotoxicological effects of MPs and petroleum, and highlight the potential risks of co-exsiting pollutants.

Ketamine plus Alcohol: What We Know and What We Can Expect about This.

Drug abuse has become a public health concern. The misuse of ketamine, a psychedelic substance, has increased worldwide. In addition, the co-abuse with alcohol is frequently identified among misusers. Considering that ketamine and alcohol share several pharmacological targets, we hypothesize that the consumption of both psychoactive substances may synergically intensify the toxicological consequences, both under the effect of drugs available in body systems and during withdrawal. The aim of this review is to examine the toxicological mechanisms related to ketamine plus ethanol co-abuse, as well the consequences on cardiorespiratory, digestive, urinary, and central nervous systems. Furthermore, we provide a comprehensive discussion about the probable sites of shared molecular mechanisms that may elicit additional hazardous effects. Finally, we highlight the gaps of knowledge in this area, which deserves further research.

Stress responses in expressions of microRNAs in mussel Mytilus galloprovincialis exposed to cadmium.

MicroRNAs (miRNAs) are known to have complicated functions in aquatic species, but little is known about the role of miRNAs in mollusk species under environmental stress. In this study, we performed small RNA sequencing to characterize the differentially expressed miRNAs in different tissues (whole tissues, digestive glands, gills, and gonads) of blue mussels (Mytilus galloprovincialis) exposed to cadmium (Cd). In summary, 107 known miRNAs and 32 novel miRNAs were significantly (p < 0.01) differentially expressed after Cd exposure. The peak size of miRNAs was 22 nucleotides. Target genes of these differentially expressions of miRNAs related to immune defense, apoptosis, lipid and xenobiotic metabolism showed significant changes under Cd stress. These findings provide the first characterization of miRNAs in mussel M. galloprovincialis and expressions of many target genes in response to Cd stress.

Ethnoveterinary for food-producing animals and related food safety issues: A comprehensive overview about terpenes.

Alternatives to the use of conventional veterinary drugs in food-producing animals have gained attention, such as the use of natural products (NPs), mainly to soften the risks to the animal, the environment, and consumer's health. Although NPs have consistent advantages over conventional drugs, they cannot be considered risk free under food safety matters. In this way, this document presents a comprehensive overview of the importance of considering both the pharmacological and toxicological properties of the constituents of a NP from plants intending the standardization and regulation of its use in food-producing animals. Terpenes are the most diverse class of natural substances present in NP of vegetal origin with a broad range of biological activities that can be explored in veterinary science; however, certain plants and terpenes also have significant toxic effects, a fact that can harm the health of animals and consequently generate economic losses and risks for humans. In this context, this review gathered scientific data of vegetal species of importance to ethnoveterinary for food-producing animals, which produce terpenes, its biological effects, and their implications on food safety issues for consumers. For this, more than 300 documents were selected from different online scientific databases. The present data and discussion may contribute to the rational commercial exploration of this class of NPs in veterinary medicine.

Advances in Research on the Toxicological Effects of Selenium.

Selenium is a trace element necessary for the growth of organisms. Moreover, selenium supplementation can improve the immunity and fertility of the body, as well as its ability to resist oxidation, tumors, heavy metals, and pathogenic microorganisms. However, owing to the duality of selenium, excessive selenium supplementation can cause certain toxic effects on the growth and development of the body and may even result in death in severe cases. At present, increasing attention is being paid to the development and utilization of selenium as a micronutrient, but its potential toxicity tends to be neglected. This study systematically reviews recent research on the toxicological effects of selenium, aiming to provide theoretical references for selenium toxicology-related research and theoretical support for the development of selenium-containing drugs, selenium-enriched dietary supplements, and selenium-enriched foods.

Recent Clinical and Preclinical Studies of Hydroxychloroquine on RNA Viruses and Chronic Diseases: A Systematic Review.

The rapid spread of the new Coronavirus Disease 2019 (COVID-19) has actually become the newest challenge for the healthcare system since, to date, there is not an effective treatment. Among all drugs tested, Hydroxychloroquine (HCQ) has attracted significant attention. This systematic review aims to analyze preclinical and clinical studies on HCQ potential use in viral infection and chronic diseases. A systematic search of Scopus and PubMed databases was performed to identify clinical and preclinical studies on this argument; 2463 papers were identified and 133 studies were included. Regarding HCQ activity against COVID-19, it was noticed that despite the first data were promising, the latest outcomes highlighted the ineffectiveness of HCQ in the treatment of viral infection. Several trials have seen that HCQ administration did not improve severe illness and did not prevent the infection outbreak after virus exposure. By contrast, HCQ arises as a first-line treatment in managing autoimmune diseases such as rheumatoid arthritis, lupus erythematosus, and Sjögren syndrome. It also improves glucose and lipid homeostasis and reveals significant antibacterial activity.

Dose-dependent effects induced by cadmium in polychaete Perinereis aibuhitensis.

Cadmium is a known metal contaminant in the Bohai Sea. In this study, the dose-dependent responses induced by Cd were characterized in marine polychaete Perinereis aibuhitensis using the endpoints, including activities of enzymes, expression levels of stress-responsive genes and metabolic responses. Both enzyme activities and gene expression levels exhibited the hormetic effects induced by Cd in P. aibuhitensis, as shown by the typical U-shaped or inverted U-shaped response profiles. The highest concentration (1280 µg/L) of Cd exposure induced obvious oxidative stresses. NMR-based metabolomics revealed that Cd induced both linear dose-dependent effects (69.13% of the total variation) and a relatively slight hormesis (5.54% of the total variation) in energy metabolism in P. aibuhitensis at metabolite level. In details, Cd exposures linearly reduced the consumption of amino acids and enhanced the consumption of glucose for energy supply, resulting in elevated contents of amino acids and depleted contents of glucose. Additionally, Cd treatments induced hormesis in the conversion of ATP hydrolysis to AMP. This work suggested that the hormetic effects should be considered in the ecological risk assessment for the environmental pollutants.

Occurence and Prioritization of Pharmaceutical Active Compounds in Domestic/Municipal Wastewater Treatment Plants.

In this study, pharmaceutically active compounds (PhACs) were analyzed in the influent and effluent of a domestic wastewater treatment plant in Turkey and a municipal wastewater treatment plant in Germany and the toxicity of these wastewaters were estimated using a toxic unit (TU) approach. A total of 21 and 32 PhACs were detected in the domestic wastewater and the municipal wastewater, respectively. The TUs estimated for PhACs in municipal wastewater were higher than the TUs estimated for PhACs present in domestic wastewater. The levels of the anti-anxiety drug, oxazepam were estimated to be in the high risk category (HQ > 10) in both wastewaters. In bench-scale tests with ozonation, the removals of four PhACs in the municipal wastewater were investigated. At a dose of 2 mg/L ozone, 97%-98% of diclofenac and carbamazepine were removed. The lowest removal rate at 71% was observed for metoprolol.

[Chemical components and pharmacological action of Aconiti Radix].

Aconiti Radix is a commonly used traditional Chinese medicine( TCM) herb in clinic,with the effects in expelling wind and removing damness,warming menstruation and relieving pain. With a long medicinal history and high medicinal value,it was used for anemofrigid-damp arthralgia,arthralgia,cold hernia and anesthesia analgesia. Modern pharmacological studies have shown that Aconiti Radix has a good therapeutic effect on rheumatoid arthritis,neuropathic pain and hypertension. As a well-known toxic TCM herb,its main pharmacodynamic and toxic components are alkaloids,which can lead to neurotoxicity and cardiotoxicity while exerting anti-inflammatory,analgesic,anti-tumor and other pharmacodynamic effects. Therefore,it is often processed to reduce its toxicity or combined with Paeoniae Radix Alba and Stephaniae Tetrandrae Radix to achieve the purpose of reducing toxicity and increasing efficacy in clinic.In recent years,with the deepening of the study on the incompatibility of TCM represented by " eighteen incompatible herbs",there have been new findings about TCM incompatibility. It has been found complementary effect,rather than no obvious toxic and side effects after the combination with incompatible herbs of Aconiti Radix. To provide the basis for further study and clinical application of Aconiti Radix,this paper reviewed chemical components,pharmacological action,toxicity and compatibility of Aconiti Radix by consulting relevant literatures published in recent years at home and abroad. Meanwhile,this paper also described the relationship between chemical constituents,as well as anti-inflammatory,analgesic,anti-tumor and other pharmacological effects and toxicity.

Comparison of triadimefon and its metabolite on acute toxicity and chronic effects during the early development of Rana nigromaculata tadpoles.

Pesticides are one of major causes for amphibian population declines and the behavior of pesticide metabolite products to amphibians has become a rising concern. In this study, the acute toxicity and the chronic effects of triadimefon and triadimenol (the metabolite of triadimefon) on Rana. nigromaculata were investigated. In the acute assay, significant differences were observed in antioxidant enzyme activities and malondialdehyde levels between the triadimefon and triadimenol. The 96 h-acute toxicity of triadimefon (25.97 mg/L) and triadimenol (34.55 mg/L) to tadpoles was low. In 28d-chronic exposure, we studied the relative expression of tadpoles genes related to thyroid hormone-dependent metamorphic development, histological examination of liver and some biological index, including wet weight, snout-to-vent length (SVL) and development stages. The results revealed that the effects of triadimefon and triadimenol on tadpole development are driven by a disruption of the hormonal pathways involved in metamorphosis. Interestingly, triadimefon was more harmful on R. nigromaculata than triadimenol at high dose, whereas the reverse result was observed at low doses. According to the relative expression of thyroid hormone-dependent genes, we also found that the two compounds may have different mechanisms of toxic action on R. nigromaculata. Our study developed a pragmatic approach for use in the risk assessment of pesticide and its metabolite，and increased the information and understanding of the impacts of fungicides and other potential endocrine disrupting environmental contaminants on amphibians.

TiO2 nanoparticles in seawater: Aggregation and interactions with the green alga Dunaliella tertiolecta.

Titanium dioxide nanoparticles (TiO2 NPs) have been widely employed in industrial applications, thus rising concern about their impact in the aquatic environment. In this study we investigated the chemical behaviour of TiO2 NPs in the culture medium and its effect on the green alga Dunaliella tertiolecta, in terms of growth inhibition, oxidative stress, ROS (Reactive Oxygen Species) accumulation and chlorophyll content. In addition, the influence of exopolymeric substances (EPS) excreted by the microalgae on the stability of NPs has been evaluated. The physicochemical characterization showed a high propensity of TiO2 NPs to form micrometric-sized aggregates within 30min, large enough to partially settle to the bottom of the test vessel. Indeed, an increasing amount of TiO2 particles settled out with time, but the presence of EPS seemed to mitigate this behaviour in the first 6h of exposure where the main effects in D. tertiolecta were observed. TiO2 NPs did not inhibit the 72-h growth rate of D. tertiolecta, nor affected the cellular chlorophyll concentration in the range 0.01-10mgL-1. The time-course of ROS production showed an initial transient increase of ROS in TiO2 NP-exposed algae compared to the control, concomitant with an enhancement of catalase activity. Interestingly, intracellular ROS was a small fraction of total ROS, the highest amount being extracellular. The occurrence of cell-mediated chemical transformations of TiO2 NPs in the external medium, related to the presence of EPS, has been evaluated. Our results showed that carbohydrates were the major component of EPS, whereas proteins of medium molecular weight (20-80kDa) were preferentially bound to TiO2 NPs, likely influencing their biological fate.