Organisms in aquatic environments are exposed to a number of pollutants such as pharmaceutical residues. As such, the aim of the present study is to achieve the Lethal Concentration (LC50) of Povidone-iodine (Betadine) for Cyprinus carpio. To do so, the study employs samples, weighing 4±1 [mean±SD] gr, and carries out an experiment in static condition. Based on OECD instructions, after a period of 4 days under controlled water, the physicochemical factors give the following results: pH= 8-8.3, BOD= 690 mg/l, total hardness= 210 mg, and CaCo3 and temperature= 17±0.1 °C. All fish are acclimatized for 10 days in an aquarium, 60×55×30 cm in size, which included the control group (no toxic concentration) as well as the treated aquariums, with Betadine concentration of 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 400, and 600 mg/l. LC10, LC20, LC30, LC40, LC50, LC60, LC70, LC80, LC90, and LC95 have been measured for 6, 12, 18, and 24 hours. LC50 24h Betadine for C. carpio has been 158.273 ml/l, showing no mortality after 24 hours (i.e. 48h, 72h, and 96h). Results of the present study suggest that Betadine is practically nontoxic and not irritant at low concentrations for this species and it has a short half-life in aquatic environments.

A broad-spectrum fungicide, dichlofluanid is widely used in antifouling paints and agricultural pesticides. In this study, the acute and chronic effects of sublethal concentrations, namely, no observable effect concentration (NOEC) and 50% lethal concentration (LC₅₀) of dichlofluanid (1/10 NOEC, NOEC, 1/10 LC₅₀, and LC₅₀) were evaluated on the marine mysid, Neomysis awatschensis. Acute toxicity test (96 h) showed higher sensitivity to dichlofluanid in juvenile mysids (LC₅₀ 3.1 μg L⁻¹) than adults (LC₅₀ 24.5 μg L⁻¹), with lower survival rate and reduction in food consumption. Exposure with dichlofluanid considerably induced oxidative imbalance, as NOEC (0.006 μg L⁻¹ for juveniles and 0.074 μg L⁻¹ for adults) and 1/10 LC₅₀ values increased intracellular concentrations of malondialdehyde and glutathione, and the enzymatic activities of catalase and superoxide dismutase, whereas exposure to LC₅₀ value decreased the values of oxidative parameters. Enzymatic activity of acetylcholinesterase decreased considerably when exposed to LC₅₀ value. In the case of chronic effects, exposure to NOEC for 4 weeks markedly decreased the juvenile survival rate, while adults showed tolerance. Multigenerational monitoring in response to NOEC showed a significant growth retardation with an increase in intermolt duration as well as a decrease in the number of newborn mysids from females of the third generation. Consistent exposure to environmentally relevant sublethal concentrations of dichlofluanid would be detrimental to mysid individuals and the survival of the mysid population.

Plant-based products such as essential oils and other extracts have been used for centuries due to their beneficial properties. Currently, their use is widely disseminated through a variety of industries and new applications are continuously emerging. For these reasons, they are produced industrially in large quantities and consequently they have the potential to reach the environment. However, the potential effects that these products have on the ecosystems’ health are mostly unknown. In recent years, the scientific community started to focus on the possible toxic effects of essential oils and plant extracts towards non-target organisms. As a result, an increasing body of knowledge has emerged. This review describes the current state of the art on the toxic effects that essential oils and plant extracts have towards organisms from different trophic levels, including producers, primary consumers, and secondary consumers. The majority of the studies (76.5%) focuses on the aquatic environment, particularly in aquatic invertebrates (45.1%) with only 23.5% of the studies focusing on the potential toxicity of plant-derived products on terrestrial ecosystems.While some essential oils and extracts have been described to have no toxic effects to the selected organisms or the toxic effects were only observable at high concentrations, others were reported to be toxic at concentrations below the limit set by international regulations, some of them at very low concentrations. In fact, L(E)C₅₀ values as low as 0.0336 mg.L⁻¹, 0.0005 mg.L⁻¹ and 0.0053 mg.L⁻¹ were described for microalgae, crustaceans and fish, respectively. Generally, essential oils exhibit higher toxicity than extracts. However, when the extracts are obtained from plants that are known to produce toxic metabolites, the extracts can be more toxic than essential oils.Overall, and despite being generally considered “eco-friendly” products and safer than they synthetic counterparts, some essential oils and plant extracts are toxic towards non-target organisms. Given the increasing interest from industry on these plant-based products further research using international standardized protocols is mandatory.

Ecological risk assessment of contaminated sediment has become a fundamental component of water quality management programs, supporting decision-making for management actions or prompting additional investigations. In this study, we proposed a machine learning (ML)-based approach to assess the ecological risk of contaminated sediment as an alternative to existing index-based methods and costly toxicity testing. The performance of three widely used index-based methods (the pollution load index, potential ecological risk index, and mean probable effect concentration) and three ML algorithms (random forest, support vector machine, and extreme gradient boosting [XGB]) were compared in their prediction of sediment toxicity using 327 nationwide data sets from Korea consisting of 14 sediment quality parameters and sediment toxicity testing data. We also compared the performances of classifiers and regressors in predicting the toxicity for each of RF, SVM, and XGB algorithms. For all algorithms, the classifiers poorly classified toxic and non-toxic samples due to limited information on the sediment composition and the small training dataset. The regressors with a given classification threshold provided better classification, with the XGB regressor outperforming the other models in the classification. A permutation feature importance analysis revealed that Cr, Cu, Pb, and Zn were major contributors to toxicity prediction. The ML-based approach has the potential to be even more useful in the future with the expected increase in available sediment data.

It is difficult to achieve simultaneous and efficient removal of heterocyclic drugs (HCDs) and total nitrogen (TN) in conventional denitrification biofilter (DNBF). Inspired by the effective degradation of refractory organic matter by cobalt-based advanced oxidation process and the need for in-situ upgrading of DNBF, peracetic acid (PAA)/cobalt-loaded ceramsite-based DNBF system was constructed for the first time to treat biochemical tailwater containing HCDs. Results showed that PAA/Co-DNBF had relatively high removal rates for the four HCDs with the order of CBZ > TMP > SDZ > SMX, and the optimal DNBF was H2 with 150 μg L⁻¹of PAA. Overall, TN and HCDs removal increased by 178%–455% and 2.50%–40.99% respectively. When the influent concentration of NO₃⁻-N, COD and each HCDs of 20 mg/L, 60 mg/L and 20 μg/L, below 15 mg/L of effluent TN and the highest average removal rate of SMX (67.77%) could be achieved, under HRT of 4 h in H2. More even distribution of microbial species and low acute toxicity of effluent were also achieved. More even distribution of microbial species and low acute toxicity of effluent were also achieved. In addition, high extracellular polymeric substance (EPS) content and Gordonia after the addition of PAA contributed to the degradation of HCDs. This study supplied a potentially effective strategy for the treatment of biochemical tailwater containing HCDs and provided new insight into the advance of denitrification technology.

The well-known toxicity of conventional chemical oil spill dispersants demands the development of alternative and environmentally friendly dispersant formulations. Therefore, in the present study we have developed a pair of less toxic and green dispersants by combining lactonic sophorolipid (LS) biosurfactant individually with choline myristate and choline oleate ionic liquid surfactants. The aggregation behavior of resulted surfactant blends and their dispersion effectiveness was investigated using the baffled flask test. The introduction of long hydrophobic alkyl chain with unsaturation (attached to choline cation) provided synergistic interactions between the binary surfactant mixtures. The maximum dispersion effectiveness was found to be 78.23% for 80:20 (w/w) lactonic sophorolipid-choline myristate blends, and 81.15% for 70:30 (w/w) lactonic sophorolipid-choline oleate blends at the dispersant-to-oil ratio of 1:25 (v/v). The high dispersion effectiveness of lactonic sophorolipid-choline oleate between two developed blends is attributed to the stronger synergistic interactions between surfactants and slower desorption rate of blend from oil-water interface. The distribution of dispersed oil droplets at several DOR were evaluated and it was observed that oil droplets become smaller with increasing DOR. In addition, the acute toxicity analysis of developed formulations against zebra fish (Danio rerio) confirmed their non-toxic behavior with LC₅₀ values higher than 400 ppm after 96 h. Overall, the proposed new blends/formulations could effectively substitute the toxic and unsafe chemical dispersants.

The use of chemotherapy agents has been growing worldwide, due to the increase number of cancer cases. In several countries, mainly in Europe countries, these drugs have been detected in hospitals and municipal wastewaters. In Brazil this issue is poorly explored. The main goal of this study was to assess the presence of three anti-cancer drugs, 5-fluorouracil (5-FU), gemcitabine (GEM) and cyclophosphamide (CP), and two metabolites, alpha-fluoro-beta-alanine (3-NH₂-F) and 2′-deoxy-2′,2′-difluorouridine (2-DOH-DiF), in effluents from a large cancer hospital, in the municipal wastewater treatment plant (WWTP) influent and effluent, and also to evaluate toxicity of the mixtures of these compounds by ecotoxicological testing in zebrafish. The sample collections were performed in Barretos Cancer Hospital of the large cancer center in Brazil. After each collection, the samples were filtered for subsequent Liquid Chromatography Mass Spectrometry analysis. The presence of CP, GEM, and both metabolites (3-NH₂-F and 2-DOH-DiF) were detected in the hospital wastewater and the WWTP influent. Three drugs, GEM, 2-DOH-DiF and CP, were detected in the WWTP effluent. Two drugs were detected below the limit of quantification, 2-DOH-DiF: <LOQ (above 1400 ng L⁻¹) and CP: <LOQ (above 300 ng L⁻¹), and GEM was quantified at 420 ng L⁻¹. Furthermore, 2-DOH-DiF (116,000 ng L⁻¹) was detected at the highest level in the hospital wastewater. There were no zebrafish deaths at any of the concentrations of the compounds used. However, we observed histological changes, including aneurysms and edema in the gills and areas of necrosis of the liver. In summary, we found higher concentrations of CP, GEM and both metabolites (3-NH₂-F and 2-DOH-DiF) were detected for the first time. There is currently no legislation regarding the discharge of anti-cancer drugs in effluents in Brazil. This study is first to focus on effluents from specific treatments from a large cancer hospital located in small city in Brazil.

There is limited information regarding the toxicity of the trace element thallium (Tl) to aquatic biota, most of which assesses acute toxicity and bioaccumulation. The relative lack of chronic Tl toxicity data compromises the establishment of water quality criteria for this trace metal. In the presented work, chronic toxicity endpoints (final body weight (a proxy measure of growth), survival, and reproduction) and Tl body burden were measured in the freshwater crustacean Daphnia magna during a 21-day exposure to dissolved Tl. Thallium caused complete mortality in daphnids between exposure concentrations of 424 and 702 μg L⁻¹. In contrast with previously published work examining acute Tl toxicity, exposure to Tl for 21 days was not associated with changes in whole-body potassium concentration. This was despite a 710-fold increase in Tl body burden in animals exposed to 424 μg L⁻¹ relative to the control. Median effect concentrations (EC₅₀’s) for growth and reproduction (total neonates produced), were 1.6 (95% confidence interval: 1.0–3.1) and 11.1 (95% confidence interval: 5.5–21.8) μg Tl L⁻¹, respectively. A no observable effect concentration (NOEC) of 0.9 μg Tl L⁻¹ for growth, and a NOEC range of 0.9–83 μg Tl L⁻¹ for a variety of reproductive metrics, was measured. A lowest observable effect concentration (LOEC) of 8.8 μg Tl L⁻¹ was determined for the effects of Tl on growth and most of the reproductive endpoints examined. These data indicate that under controlled laboratory conditions D. magna is significantly less sensitive to Tl than the species on which the current Canadian Council of Ministers of the Environment regulatory guideline value of 0.8 μg L⁻¹ is based.

Moxidectin is an antiparasitic drug belonging to the class of the macrocyclic lactones, subgroup mylbemicins. It is used worldwide in veterinary practice, but little is known about its potential environmental risks. Thus, we used the zebrafish embryo as a model system to study the potential effects of moxidectin on aquatic non-target organisms. The analyses were performed in two experimental sets: (1) acute toxicity and apical endpoints were characterized, with biomarker assays providing information on the activity levels of catalase (CAT), glutathione S-transferase (GST), lactate dehydrogenase (LDH), and acetylcholinesterase (AChE); and (2) internal concentration and spatial distribution of moxidectin were determined using ultraperformance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-QToF-MS) and matrix-assisted laser desorption/ionization-MS imaging (MALDI-MSi). The acute toxicity to zebrafish embryos (96 hpf) appeared mainly as a decrease in hatching rates (EC₅₀ = 20.75 μg/L). It also altered the enzymatic activity of biomarker enzymes related to xenobiotic processing, anaerobic metabolism, and oxidative stress (GST, LDH, and CAT, respectively) and strongly accumulated in the embryos, as internal concentrations were 4 orders of magnitude higher than those detected in exposure solutions. MALDI-MSi revealed accumulations of the drug mainly in the head and eyes of the embryos (72 and 96 hpf). Thus, our results show that exposure to moxidectin decreases hatching success by 96 h and alters biochemical parameters in the early life stages of zebrafish while accumulating in the head and eye regions of the animals, demonstrating the need to prioritize this compound for environmental studies.

Drilled seeds are an important food resource for many farmland birds but may pose a serious risk when treated with pesticides. Most compounds currently used as seed treatment in the EU have low acute toxicity but may still affect birds in a sub-chronic or chronic way, especially considering that the sowing season lasts several weeks or months, resulting in a long exposure period for birds. Tebuconazole is a triazole fungicide widely used in agriculture but its toxicity to birds remains largely unknown. Our aim was to test if a realistic scenario of exposure to tebuconazole treated seeds affected the survival and subsequent reproduction of the red-legged partridge (Alectoris rufa). We fed captive partridges with wheat seeds treated with 0%, 20% or 100% of tebuconazole application rate during 25 days in late winter (i.e. tebuconazole dietary doses were approximately 0.2 and 1.1 mg/kg bw/day). We studied treatment effects on the physiology (i.e. body weight, biochemistry, immunology, oxidative stress, coloration) and reproduction of partridges. Exposed birds did not reduce food consumption but presented reduced plasmatic concentrations of lipids (triglycerides at both exposure doses, cholesterol at high dose) and proteins (high dose). The coloration of the eye ring was also reduced in the low dose group. Exposure ended 60 days before the first egg was laid, but still affected reproductive output: hatching rate was reduced by 23% and brood size was 1.5 times smaller in the high dose group compared with controls. No significant reproductive effects were found in the low dose group. Our results point to the need to study the potential endocrine disruption mechanism of this fungicide with lagged effects on reproduction. Risk assessments for tebuconazole use as seed treatment should be revised in light of these reported effects on bird reproduction.