Over the past few years, the ecotoxicological hazard potential of agrochemicals has received much attention in the industries and regulatory agencies. In the current work, we have developed ...quantitative structure-activity relationship (QSAR) models for Daphnia magna toxicities of different classes of agrochemicals (fungicides, herbicides, insecticides and microbiocides) individually as well as for the combined set with the application of Organization for Economic Co-operation and Development (OECD) recommended guidelines. The models for the individual data sets as well as for the combined set were generated employing only simple and interpretable two-dimensional descriptors, and subsequently strictly validated using test set compounds. The validated individual models were used to generate consensus models, with the objective to improve the prediction quality and reduced prediction errors. All the individual models of different classes of agrochemicals as well as the global set of agrochemicals showed encouraging statistical quality and prediction ability. The general observations from the derived models suggest that the toxicity increases with lipophilicity and decreases with polarity. The generated models of different classes of agrochemicals and also for the combined set should be applicable for data gap filling for new or untested agrochemical compounds falling within the applicability domain of the developed models.
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•We propose simple QSAR models for toxicity prediction of agrochemicals against D. magna.•2D descriptors with definite physicochemical meaning were employed for model development.•The models were validated by considering various internal as well as external parameters.•All the models suggest the impact of lipophilicity and polarity in governing agrochemical toxicity.•The models can be utilized in data gap filling, regulatory screening and for prediction of new or untested agrochemicals.
Microplastics (MPs) are gradually spreading around the world and becoming a ubiquitous environmental contamination in aquatic environments. Due to its unique physicochemical properties, MPs are ...considered to be strong adsorbents for environmental pollutants and may affect their fate and toxicity in the environment. In this study, the adsorption behaviors of four typical heavy metal ions (Pb2+, Cu2+, Cd2+, and Ni2+) on two sizes of polystyrene MPs (10 μm and 50 μm) were investigated based on batch experiments, and the combined effects of heavy metals and MPs were assessed using Daphnia magna as model. The results showed that smaller MPs (SMPs) exhibited higher adsorption capacities for metal ions (0.261–0.579 mg/g) than that of the larger MPs (LMPs) (0.243–0.525 mg/g), and the affinity sequence of heavy metals on MPs is Pb2+ > Cu2+ > Cd2+ > Ni2+. There are better admirable agreements for pseudo-second-order model and Langmuir model to fit the adsorption kinetics and adsorption isotherms, respectively. Additionally, the combined toxicity of MPs and heavy metals was negatively correlated with the adsorption capacity between them. The combined effects of mixtures toward D. magna changed from antagonism to additive effect with increasing MPs concentrations, and SMPs exhibited higher toxicological risk than LMPs. Our findings compared the accumulative effects of various heavy metals on MPs and can contribute to understanding the combined effects of plastics and heavy metals on biota.
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•Affinity sequence of heavy metals on microplastics was Pb2+ > Cu2+ > Cd2+ > Ni2+.•Combined effects of mixtures varied with increasing microplastics concentrations.•Combined toxicity of microplastics and metals was related to adsorption behaviors.•Smaller microplastics exhibited higher environmental risks.
The objective of this study was to investigate the impact of two pharmaceuticals, diclofenac and sulfamethoxazole, and their binary mixture on aquatic organisms, marine bacteria Aliivibrio fischeri, ...crustacean Daphnia magna, and vascular plant Lemna minor. The binary mixture of the drugs showed the highest toxicity towards the model organisms. Diclofenac had an average toxicity which posed a high environmental risk to aquatic organisms, while sulfamethoxazole was characterized by a low toxicity with low environmental risk. The organism most sensitive to diclofenac was A. fischeri (IC50 = 8.72 ± 1.14 mg L−1) and for sulfamethoxazole and the binary mixture, it was L. minor (IC50 = 12.56 ± 4.48 and 4.83 ± 0.43 mg L−1, respectively). The toxicity of the mixture was predicted using the Concentration Addition and Independent Action models, and the results were compared with the experimental data. None of the models suitably predicted the real toxicity of the pharmaceutical mixture. Interactions between the mixture components were confirmed by calculating the mixture toxicity index values which showed that the pharmaceuticals displayed synergistic or partial additive effects which depended on the selected test organism and test duration. When added as a complex matrix to wastewater (at a concentration of 2 mg L−1 each), the pharmaceuticals did not display increased toxicity. This observation confirms that the presence of micro-contaminants in aquatic environments may cause interactions between different compounds, the results of which are difficult to predict and model.
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•Synergistic or partial additive effects of DCF and SMX mixture were observed.•DCF posed an average toxicity and high environmental risk.•SMX is a low-toxicity compound with a low environmental risk.•The CA and IA models did not suitably predict the toxicity of the mixture.
Among the most used non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen (KTF) assumes an important position. Nevertheless, its ecotoxicological effects in non-target organisms are poorly ...characterized, despite its use and frequency of occurrence in aquatic matrices. Thus, the aim of this study was to evaluate the possible toxicological effects of KTF contamination, in two freshwater species, Lemna minor and Daphnia magna, by measuring biochemical, physiological and population parameters. To attain this objective, both species were exposed to KTF at the same concentrations (0, 0.24, 1.2, 6 and 30 μg/L). L. minor plants were exposed during 4 d to these levels of KTF, and the enzymatic activity (catalase (CAT), glutathione S-transferases (GSTs) and carbonic anhydrase (CA)), and pigments content (chlorophylls a, b and total and carotenoids) were analyzed to evaluate the toxicity of this drug. D. magna was acutely and chronically exposed to KTF, and enzymatic activities (CAT, GSTs and cyclooxygenase (COX)), the feeding rates, and reproduction traits were assessed. In L.minor, KTF provoked alterations in all enzyme activities, however, it was not capable of causing any alteration in any pigment levels. On the other hand, KTF also provoked alterations in all enzymatic activities in D. magna, but did not affect feeding rates and life-history parameters. In conclusion, exposure to KTF, provoked biochemical alterations in both species. However, these alterations were not reflected into deleterious effects on physiological and populational traits of L. minor and D. magna.
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•Ketoprofen (KTF) acts different on Lemna minor and on Daphnia magna.•Effects of KTF were limited only to biochemical effects on both species.•L. minor effects of low KTF concentrations suggest resilience and hormetic effects.•D. magna, in general, presented a dose response pattern to KTF exposure.
KTF demonstrates species-specific toxicity to different aquatic organisms affecting biochemical levels but not impairing physiological and population levels.
Cysteine (Cys) and homocysteine (Hcy) are essential for maintaining the cellular redox homeostasis and play critical roles in pathological and physiological processes. The development of ...Cys/Hcy-specific responsive fluorescent probes that are independent of the surrounding environment, equipment, and abundant endogenous GSH is critical to accurately investigate the roles of Cys/Hcy in living biological systems. In this work, a novel ratiometric and mitochondria-anchored fluorescence chemosensor, PYR, was constructed on the basis of 4-methylphenol-substituted pyronin fluorophore. The probe exhibited ratiometric fluorescence emission (F 540 nm/F 620 nm) for the detection of Cys/Hcy with high selectivity, sensitivity (Cys, 22 nM; Hcy, 23 nM), rapid response (Cys, 5 min), and a merit enhancement of ratio fluorescent signal (Cys, 163-fold; Hcy, 125-fold). The probe showed excellent membrane permeability and was applied to visualize mitochondrial biothiols in living cells under H2O2-induced redox imbalance, kidney tissues with a penetration depth of 100 μm, and Daphnia magna model for the first time. The results demonstrate that PYR will provide a promising platform for the diagnosis of thiol-related diseases.
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•High degradation of antibiotic isoniazid used for tuberculosis treatment Fenton-based processes.•Photo-Fenton by artificial and solar radiation achieves high mineralization of ...isoniazid.•Fenton and photo-Fenton processes generate isonicotinic acid, isonicotinamide,N'-(pyridyl-4-carbonyl)-hydrazide and four new by-products in the first 10 minutes of treatment.•Fenton reaction reduces acute toxicity in D. magna yet inhibits seeds growth in L. sativa, and photo-Fenton performed by artificial radiation reduces toxicity in both test organisms.•Solar photo-Fenton needs prolonged time to generate non-toxic results.
This paper presents the degradation of the most widely used antibiotics for the treatment of tuberculosis, isoniazid (INH), by Fenton, photo-Fenton on bench-scale, and solar photo–Fenton on a pilot scale. The INH dosage in tuberculosis treatment varies according to disease stage, between 300 and 400 mg d−1patient−1, and its excretion range via urine is 50–70% within 24 h. The photodegradation processes were performed with 25 mg L−1 of INH, 10 mg of Fe2+, and 125 mgL−1 of H2O2 for 120 min. The degradation of INH was monitored by HPLC–DAD and dissolved organic carbon (DOC). The degradation by-products were analyzed by UPLC QToF-MS and the toxicity was evaluated by Daphnia magna (acute toxicity) and Lactuca sativa (phytotoxicity). INH removal was higher than 99% at 60 min for Fenton, 10 min for photo-Fenton, and 15 min for solar photo–Fenton. The DOC results indicated that under light irradiation (photo–Fenton and solar photo–Fenton), the mineralization rate was >70%. The nitrite ion analysis indicated the complete oxidation of nitrogen. Besides the main INH degradation by-products, isonicotinic acid, isonicotinamide, and N'-(pyridyl-4-carbonyl)-hydrazide, we detected four unknown by-products by mass spectrometry. The Fenton treatment decreased the toxicity of D. magna by 75% in 15 min, achieving 87% in 60 min of treatment, while the photo–Fenton process conducted with artificial radiation reduced 87% of the toxicity of D. magna and resulted in no significant effect in L. sativa seeds in 15 min (QUV-A 1.29 kJ L−1). However, solar photo-Fenton (QUV-A 3.38 kJ L−1) did not reduce toxicity.
Nanoplastics (NPs; <0.1 μm) are speculated to be a bigger ecological threat due to their predicted wider distribution, higher concentrations, and bioavailability. Primary NPs are manufactured to be ...that size, while secondary NPs originate from fragmentation of bigger debris. To date, the long-term impact of NPs in freshwater systems, particularly secondary NPs, is not well-understood. Thus, we employed a freshwater invertebrate,
, to investigate the chronic effects of model primary NPs, fluorescent polystyrene nanospheres (PS-NPs; 20 nm), and water leachate of weathered single-use plastics that contained micro- and nanosized particles. In experiment 1, parent
(F0) were exposed to 1 and 50 mg/L PS-NPs until the production of the neonates (F1) followed by a two-generation recovery. PS-NPs were mainly detected in the intestine and brood chamber in F0 and transferred to F1 and F2. PS-NPs significantly decreased the appendage curling and heartbeat rate in F0 and reduced reproduction in F2. In experiment 2, the plastic leachate also reduced the appendage curling rate but increased growth and reproduction. The results suggest that the acute toxicity of primary and secondary plastic particles is low even at high concentrations, but their chronic and sublethal effects should not be overlooked.
In many ecosystems, the zooplankton community has been pressured simultaneously by microplastic pollution and alterations resulting from global climate changes. The potential influence of light ...intensity rise (from 10,830 lx to 26,000 lx) and water temperature rise (from 20 °C to 25 °C) on the long term-toxicity of microplastics (MPs) to Daphnia magna were investigated. Three 21-day laboratory bioassays with model MPs (1–5 μm diameter) were carried out at (i) 20 °C/10830 lx, (ii) 20 °C/26000 lx, and (iii) 25 °C/10830 lx. In each bioassay, one control (no MPs) and three MP concentrations (0.04, 0.09, 0.19 mg/L) were tested. In all the bioassays, MPs caused parental and juvenile mortality, and reduced the somatic growth, reproduction and population growth rate. The MP EC50s on living offspring (95% confidence interval within brackets) were 0.146 mg/L (0.142–0.151 mg/L) at 20 °C/10830 lx, 0.102 mg/L (0.099–0.105 mg/L) at 20 °C/26000 lx, and 0.101 mg/L (0.098–0.104 mg/L) at 25 °C/10830 lx. Relatively to the respective control group, 0.19 mg/L of MPs decreased the mean of the population growth rate by 27% at 20 °C/10830 lx, 38% at 20 °C/26000 lx and 59% at 25 °C/10830 lx. Based on the population growth rate and in relation to 20 °C/10830 lx (control, no MPs), the interaction between increased light intensity (26,000 lx) and MPs was synergism (at all the MP concentrations tested). The interaction between water temperature rise (25 °C) and MPs was antagonism at 0.04 mg/L of MPs and synergism at 0.09 and 0.19 mg/L of MPs. In the present scenario of climate changes and global MP pollution such findings raise high concern because zooplankton communities are crucial for aquatic biodiversity conservation, ecosystem functioning and services provided to humans. Further studies on the combined effects of MPs, other common pollutants, and alterations due to climate changes are needed.
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•21-D exposure to microplastics (MP) ≥0.09 mg/L reduced D. magna population fitness.•At 20 °C, MP reduced the population fitness up to 27% (10,830 lx) or 38% (26,000 lx).•At 25 °C/10830 lx, MP decreased the population fitness up to 59%.•MP effects increased with light intensity (1.4 x) and temperature (2.2 x) rise.
Mycotoxins are low molecular weight compounds present in food and feed. Although their effects on human health have been widely described, their mechanisms of action are still undefined. Gliotoxin ...(GTX) and ochratoxin A (OTA) are among the most dangerous mycotoxins produced by Aspergillus spp. Therefore, their toxicity was studied in the Daphnia magna model, which has high capacity to predict cytotoxicity and assess ecotoxicity, comparable to mammalian models. The study consisted of a series of tests to evaluate the effects of mycotoxins GTX, OTA and their combinations at different dilutions on Daphnia magna that were conducted according to standardized OECD 202 and 211 guidelines. The following assays were carried out: acute toxicity test, heartbeat, delayed toxicity test, reproduction, growth rate test. Reproducibility was determined by observing the offspring after 21 days of GTX exposure. In acute and delayed toxicity transcript levels of genes involved in xenobiotic metabolism (mox, gst, abcb1, and abcc5), and oxidative stress (vtg-SOD) were analyzed by qPCR. GTX showed acute toxicity and decreased heart rate in D. magna compared to OTA. On the other hand, OTA showed a delayed effect as evidenced by the immobility test. Both mycotoxins showed to increase genes involved in xenobiotic metabolism, while only the mycotoxin mixture increased oxidative stress. These results suggest that the mycotoxins tested could have negative impact on the environment and human health.
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