High Chronic Toxicity Research Articles

Degradation of Chlorothalonil by Catalytic Biomaterials

Chlorothalonil (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile, TPN, CAS: 1897-45-6) is a halogenated fungicide currently widely applied to a large variety of crops. Its carcinogenicity, embryo lethality, and high chronic oral toxicity in mammals, among other effects on a variety of organisms, has made its biodegradation of great interest. Chlorothalonil dehalogenase (Chd) from the bacterium Pseudomonas sp. CTN-3 offers a potential solution by catalyzing the first step in the degradation of chlorothalonil. Reported herein are active biomaterials of Chd when encapsulated in tetramethylorthosilicate (TMOS) gels using the sol–gel method (Chd/sol), alginate beads (Chd/alginate), and chitosan-coated alginate beads (Chd/chitosan). Both Chd/sol and Chd/chitosan increased protection from the endopeptidase trypsin as well as imparted stability over a pH range from 5 to 9. Chd/sol outperformed Chd/alginate and Chd/chitosan in long-term storage and reuse experiments, retaining similar activity to soluble Chd stored under similar conditions. All three materials showed a level of increased thermostability, with Chd/sol retaining >60% activity up to 70 °C. All materials showed activity in 40% methanol, suggesting the possibility for organic solvents to improve TPN solubility. Overall, Chd/sol offers the best potential for bioremediation of TPN using Chd.

The presence of erionite in North American geologies and the estimated mesothelioma potency by region

Objective Erionite is a naturally occurring fibrous mineral found in soils in some geographical regions. Known for its potency for causing mesothelioma in the Cappadocia region of Turkey, the erionite fiber has attracted interest in the United States due to its presence in a band of rock that extends from Mexico to Montana. There are few toxicology studies of erionite, but all show it to have unusually high chronic toxicity. Despite its high potency compared to asbestos fibers, erionite has no occupational or environmental exposure limits. This paper takes what has been learned about the chemical and physical characteristics of the various forms of asbestos (chrysotile, amosite, anthophyllite, and crocidolite) and predicts the potency of North American erionite fibers. Materials and Methods Based on the fiber potency model in Korchevskiy et al. (2019) and the available published information on erionite, the estimated mesothelioma potency factors (the proportion of mesothelioma mortality per unit cumulative exposure (f/cc-year)) for erionites in the western United States were determined. Results and Discussion The model predicted potency factors ranged from 0.19 to 11.25 (average ∼3.5), depending on the region. For reference, crocidolite (the most potent commercial form of asbestos) is assigned a potency factor ∼0.5. Conclusion The model predicted mesothelioma potency of Turkish erionite (4.53) falls in this same range of potencies as erionite found in North America. Although it can vary by region, a reasonable ratio of average mesothelioma potency based on this model is 3,000:500:100:1 comparing North American erionite, crocidolite, amosite, and chrysotile (from most potent to least potent).

Hydrolysis of propyrisulfuron in water: Kinetics, influence of 34 environmental factors, transformation products identification, mechanisms and toxicities

Propyrisulfuron is a novel sulfonylurea herbicide used for controlling annual grass and broad-leaved weeds in fields, but its fates and behaviors in environment are still unknown, which are of utmost importance for environmental protection. To reduce its potential environmental risks in agricultural production, the hydrolysis kinetics, influence of 34 environmental factors including 12 microplastics (MPs), disposable face masks (DFMs) and its different parts, 6 fertilizers, 5 ions, 3 surfactants, a co-existed herbicide of florpyrauxifen-benzy, humic acid and biochar, and the effect of MPs and DFMs on its hydrolysis mechanisms were systematically investigated. The main hydrolysis products (HPs), possible mechanisms, toxicities and potential risks to aquatic organisms were studied. Propyrisulfuron hydrolysis was an acid catalytic pyrolysis, endothermic and spontaneous process driven by the reduction of activation enthalpy, and followed the first-order kinetics. All environmental factors can accelerate propyrisulfuron hydrolysis to varying degrees except humic acid, and different hydrolysis mechanisms occurred in the presence of MPs and DFMs. In addition, 10 possible HPs and 7 possible mechanisms were identified and proposed. ECOSAR prediction and ecotoxicity testing showed that acute toxicity of propyrisulfuron and its HPs for aquatic organisms were low, but may have high chronic toxicity and pose a potential threat to aquatic ecosystems. The investigations are significantly important for elucidating the environmental fates and behaviors of propyrisulfuron, assessing the risks in environmental protection, and further providing guidance for scientific application in agro-ecosystem.

EVALUATION OF THE ACUTE AND CHRONIC TOXICITY OF THE ETHANOLIC EXTRACT OF ABELMOSCHUS ESCULENTUS INSWISS ALBINO MICE

Objectives: This work aimed to evaluate the acute and chronic toxicity of the ethanolic extract of Abelmoschus esculentus, administered orally to Swiss albino mice. Methods: An dosage of 2000 mg/kg was administrated and toxicity studies were conducted following organization for economic cooperation and development guidelines of 425 and 407 respectively in Swiss albino mice. During the study, general signs of toxicity were monitored. The mice which are used in the toxicology study were sacrificed, and histological, hematological, and biochemical analyses were done. Results: No behavioral changes were observed in all mice subjected to the study. The extract did not bring about any deaths after 14 days for the acute toxicity study in all the doses and also 90 days at a very high dosage chronic toxicity study days. Although a significant variation was observed in hematocrit, granulocyte, lymphocyte, Alanine transaminase, total cholesterol levels, and blood glucose levels, the extract did not have any significant effect (p<0.05) on the other biochemical and hematological parameters evaluated during the study. Conclusion: The result indicates that the oral administration of ethanolic extract of A. esculentus did not produce any significant toxic effect in the mice. Hence, the extract can be utilized safely for therapeutic use in pharmaceutical formulations.

Effects of yoga vs placebo on inflammation among cancer survivors: A nationwide multicenter phase III randomized controlled trial (RCT).

12111 Background: Inflammation, both acute and chronic, is universally associated with primary and secondary cancer development and progression, as well as a myriad of toxicities that negatively affect cancer treatment adherence and survival. The effectiveness of targeting inflammation with non-pharmaceutical therapies such as yoga is not known. As part of a nationwide, multicenter, phase III RCT with cancer survivors, we compared the effects of yoga (Yoga for Cancer Survivors; YOCAS) to a behavioral placebo (survivorship health education) on inflammation (i.e. pro-inflammatory, anti-inflammatory, and overall inflammatory status). Methods: Participants were recruited via the URCC NCORP Research Base in partnership with 23 community oncology practices across the United States. Eligible participants were cancer survivors with insomnia 2-60 months post-treatment. They were randomized to receive YOCAS (gentle Hatha and Restorative yoga, 75-min./session, 2x/week, 4 weeks) or placebo (ASCO survivorship recommendation-based health education, 75-min./session, 2x/week, 4 weeks). Serum samples were collected at baseline and post-intervention to assess inflammation (i.e., pro-inflammatory markers IL-1β, IL-6, TNF-α, IFN-γ and anti-inflammatory markers IL-4, IL-8, IL-10, sTNFRI), via Luminex multiplex assays. Analysis of covariance (ANCOVA) and structural equation modeling (SEM) were used to access yoga's effects on inflammation. Results: 502 survivors (94% female, mean age 56±11 years, 74% breast cancer) were enrolled. ANCOVAs revealed significantly lower levels of pro-inflammatory markers in YOCAS participants compared to placebo participants (IL-1β: -0.07±0.03, p = 0.01; TNF-α: -0.04±0.02, p = 0.08; IFN-γ: -0.07±0.03, p = 0.02) where YOCAS participants exhibited stable pro-inflammatory responses (all p > 0.05) and placebo participants exhibited significant increases in pro-inflammatory responses (all p≤0.05) from baseline to post-intervention. ANCOVAs also revealed a statistical trend toward lower levels of anti-inflammatory markers in YOCAS participants compared to placebo participants (IL-4: -0.06±0.04, p = 0.10; IL-10: -0.06±0.04, p = 0.09; sTNFRI: -0.06±0.04, p = 0.09). SEM also demonstrated significantly lower pro-inflammatory status (-0.16±0.03, p < 0.01), significantly lower anti-inflammatory status (-0.14±0.03, p = 0.03), and significantly lower overall inflammatory status (-0.15±0.03, p = 0.01) in YOCAS participants compared to placebo participants. Conclusions: Our data suggest that YOCAS yoga significantly reduces inflammation among cancer survivors. Clinicians should consider prescribing yoga for survivors experiencing inflammation, which may lead to a high chronic toxicity burden and increased risk of progression, recurrence, and second cancers. Funding: NCI UG1CA189961, R01CA181064, T32CA102618. Clinical trial information: NCT02613364 .

Full profile contamination process simulation and risk prediction of synthetic musk from reclaimed water receiving river to groundwater via vadose zone: A case study of Chaobai River

Long-term infiltration from river receiving reclaimed water will pose potential risk to vadose zone and groundwater because of the persistent and highly toxic contaminants. In order to predict the spatio-temporal distribution of ecological and health risk, a coupled model of HYDRUS-GMS combined risk quotient was proposed. The model can accurately predict water flow, solute transport and risk with model due to the acceptable efficiency (E:0.99), mean absolute error (MAE:0.031 m) and root-mean-square error (RMSE:0.039 m). The content of galaxolide (HHCB), a typical pharmaceutical and personal care product with hydrophobicity and refractory in reclaimed water, increased in vadose zone at an accumulative rate of 6.1 ng g−1 year−1 with infiltration time extension. The accumulation will pose ecological risk after 53 years infiltration. The potential risk will extent to groundwater once penetrate through vadose zone, and mainly diffuse along groundwater flow direction. The migration rate along horizontal direction of groundwater flow is 0.03396 m d−1, which is 9.7 and 1.1 times higher than longitudinal and vertical rates due to the variation of driving force in three directions. The migration rate of HHCB was 2.6% of groundwater flow due to hydrophobicity (LogKow = 5.9). The complete biochemical decomposition of HHCB will take approximately 0.38 year through metabolite within 182.65 m distance. The persistence was attributed to the high chronic toxicity and the low bio-availability. The major biochemical metabolism of HHCB was enzymatic hydrolysis, ring opening, decarboxylation, which was decomposed and carbonized within approximately 0.38 year after 182.65 m migration distance. This study provided a new approach to predict the spatio-temporal risk distribution due to reclaimed water reuse.

플루피라디퓨론 장기노출이 꿀벌 생리에 미치는 영향

The Western honey bees, Apis mellifera, play an essential role in pollinating both commercial crops and wild plants. While foraging, honey bees are exposed to diverse kinds of pesticides via oral ingestion or contact. Several neonicotinoids such as imidacloprid, chlothianidin and thiametoxam have posed a severe threat to honey bees with their high chronic toxicity especially when used for seed treatments. Flupyradifurone (FPF), a butanolide insecticide targeting nicotinic acetylcholine receptors of pests, is considered as a good alternative to neonicotinoids as it selectively targets sucking pests without much harming honey bees. In this study, we investigated any negative effects of chronic oral ingestion of FPF on honey bees under an extreme exposure condition. Foragers chronically exposed to 10 ppm of FPF showed difference in neither the flight ability nor the weight of thoraces. However, transcriptome analysis of foragers revealed increased protein translation/modification and lipid metabolism in the thorax and abdomen, respectively. These results, along with the increase in whole bodyweight, suggest that chronic exposure to high doses of FPF can induce obesity and oxidative stress in honey bees. Nevertheless, our finding does not necessarily mean that field-realistic doses of FTP under the actual chronic exposure scenario likely cause adverse impacts on honey bees.

Maternal Effect of Polyethylene Microplastic Fragments Containing Benzophenone-3 in Different Ages and Broods of Daphnia Magna

The maternal effect of microplastics (MPs) toxicity is likely influenced by age and brood of test species. This study investigated the maternal effect of polyethylene MP fragments (18.23 ± 8.02μm) with benzophenone-3 (BP-3; 2.89 ± 0.20% w/w) on chronic toxicity to Daphnia magna over two generations. Neonate (< 24h old) and adult (5 d old) daphnids in the F0 generation were exposed until 21 d old, then first and third brood neonates in the F1 generation were recovered in clean M4 medium for 21 d. Higher chronic toxicity and maternal effect of MP/BP-3 fragments were observed in the adult group compared with the neonate group, reducing growth and reproduction in both F0 and F1 generations. First brood neonates in the F1 generation showed a higher maternal effect of MP/BP-3 fragments than third brood ones, resulting in enhanced growth and reproduction relative to the control. This study provided insights into the ecological risk of MPs containing plastic additives in the natural environment.

Emission behavior and impact assessment of gaseous volatile compounds in two typical rural domestic waste landfills

Landfill sites are sources of gaseous volatile compounds. The dumping area (LDA) and leachate storage pool (LSP) of two typical rural domestic waste landfill sites in north China (NLF) and southwest China (SLF) were investigated. We found that 45, 46, 61 and 68 volatile organic compounds (VOC) were present in the air of NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. And there were 27, 29, 35 and 37 kinds of odorous compounds being detected. Oxygenated compounds (>48.88%), chlorinated compounds (>6.85%), and aromatics (>5.46%), such as organic acid, 1-chlorobutane, and benzene, were the most abundant compounds in both landfills. The SLF-LDA had the highest olfactory effect, with a corresponding total odor activity value of 29,635.39. The ozone-formation potential analysis showed that VOCs emitted from SLF landfills had significantly higher potential for ozone formation than those from NLF landfills, with ozone generation potentials of 166.02, 225.86, 2511.82, and 1615.99 mg/m3 for the NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. Higher chronic toxicity and cancer risk of VOCs were found in the SLF according to method of Risk Assessment Information System. Based on the sensitivity analysis by the Monte Carlo method, concentrations of benzene, propylene oxide, propylene, trichloroethylene, and N-nitrosodiethylamine, along with exposure duration, daily exposure time, and annual exposure frequency, significantly impacted the risk levels. We provide a scientific basis, which reflects the need for controlling and reducing gaseous pollutants from landfills, particularly rural residential landfills, which may improve rural sanitation.

Effects of the nanoherbicide made up of atrazine-chitosan on the primary events of photosynthesis

In this research, chitosan and alginate nanocapsules (NCs) have been synthesized and designed to act as carriers (controlled release systems) of atrazine molecules. Atrazine is an herbicide associated with relatively high chronic toxicity, which can also be accumulated as a recalcitrant substance in surface and groundwater. This effect is enhanced by the presence of adjuvants that are part of the commercial formulation. Therefore, the proposal to transport the herbicide in a nontoxic biocompatible nano-encapsulated system is particularly relevant. The nano-capsulated systems with and without the incorporated herbicide (NH, nanoherbicide and empty NCs, respectively) were characterized by scanning electron microscopy images showing an average nanocapsule size of 350 nm and a particle concentration of 4.5 × 1013/ml. The chemical composition of the NCs and NH systems was studied by Fourier Transform Infrared Spectroscopy. The OJIP transient chlorophyll fluorescence was used to evaluate the effects of the NH, commercial atrazine (At) and empty NCs on maize plants as non-target and on chicory as target plants. For the chicory plants treated with the NH and At, a decrease in the activity of the oxygen-generating complex (Fv/F0) and in the maximum quantum yield of PSII (φP0 = TR0/ABS) was observed. In addition, serious alterations in the electronic transport flux (ET0/RC), in the quantum yield for electron transport (φE0 = ET0/ABS) and in the efficiency or probability that an electron moves between plastoquinones QA and QB (ET0/TR0) were obtained for this these plants. The quantum yield of the transport stream electrons to PSI electron acceptors (φR0 = RE0/ABS) and the efficiency with which an exciton will be transferred from PSII to PSI acceptors (ψRE = RE0/TR0) also fell in the plants sprayed with the NH or commercial atrazine with respect to the control plants and those treated with the empty NCs. The photosynthetic parameters obtained for corn plants, treated with both NH and commercial atrazine, showed an inhibition of electron transport in the photosynthetic process at 24 h. These effects were reversed after seven days of treatment, due to the ability of corn plants to detoxify atrazine. Foliar damage was observed in chicory plants treated with atrazine and with NH but not concerning corn plants. Chicory or corn plants treated with the proposed carrier (NCs) showed no foliar effects, which implies that the carrier is harmless to the health of the plants.

Organophosphate pesticides in South African eutrophic estuaries: Spatial distribution, seasonal variation, and ecological risk assessment

The seasonal variation, spatial distribution, and ecological risks of thirteen organophosphate pesticides (OPPs) were studied in the Sundays and Swartkops estuaries in South Africa. Ten pesticides were detected in surface water samples from both estuaries, while all OPPs were detected in sediments. The highest concentration of OPPs (18.8 μg pyrazophos L−1) was detected in surface water samples from Swartkops Estuary, while 48.7 μg phosalone kg−1 dw was the highest in sediments collected from Sundays Estuary. There was no clear seasonal pattern in OPPs occurrence in surface water from both systems. However, their occurrence in sediments was in the following order: winter > autumn > summer > spring, perhaps indicating major pesticide input in the winter seasons. Results from ecological risk assessment showed that pyraclofos and chlorpyrifos (CHL) in surface water from both systems are respectively likely to cause high acute and chronic toxicity to fish (risk quotient – RQ > 1). For sediments of both estuaries, the highest acute and chronic RQs for fish were calculated for isazophos and CHL respectively. The majority of the detected OPPs in sediments posed potential high risks to Daphnia magna from both systems. These results suggest that these aquatic organisms (fish, and Daphnia), if present in the studied estuaries, can develop certain forms of abnormalities due to OPP exposure. To this end, proper measures should be taken to reduce OPP input into the estuarine systems.

Revealing the toxicity of lopinavir- and ritonavir-containing water and wastewater treated by photo-induced processes to Danio rerio and Allivibrio fischeri

In coronavirus disease 2019 (COVID-19), among many protocols, lopinavir and ritonavir in individual or combined forms with other drugs have been used, causing an increase in the concentration of antiviral drugs in the wastewater and hospital effluents. In conventional wastewater treatment plants, the removal efficiency of various antiviral drugs is estimated to be low (<20%). The high values of predicted no-effect concentration (PNEC) for lopinavir and ritonavir (in ng∙L−1) reveal their high chronic toxicity to aquatic organisms. This indicates that lopinavir and ritonavir are current priority antiviral drugs that need to be thoroughly monitored and effectively removed from any water and wastewater samples. In this study, we attempt to explore the impacts of two photo-induced processes (photolysis and photocatalysis) on the toxicity of treated water and wastewater samples containing lopinavir and ritonavir to zebrafish (Danio rerio) and marine bacteria (Allivibrio fischeri). The obtained results reveal that traces of lopinavir in water under photo-induced processes may cause severe problems for Danio rerio, including pericardial edema and shortening of the tail, affecting its behavior, and for Allivibrio fischeri as a result of the oxygen-depleted environment, inflammation, and oxidative stress. Hence, lopinavir must be removed from water and wastewater before being in contact with light. In contrast, the photo-induced processes of ritonavir-containing water and wastewater reduce the toxicity significantly. This shows that even if the physicochemical parameters of water and wastewater are within the standard requirements/limits, the presence of traces of antiviral drugs and their intermediates can affect the survival and behavior of Danio rerio and Allivibrio fischeri. Therefore, the photo-induced processes and additional treatment of water and wastewater containing ritonavir can minimize its toxic effect.

Adsorption and detoxification of pharmaceutical compounds from wastewater using nanomaterials: A review on mechanism, kinetics, valorization and circular economy

Antibiotics overuse, inappropriate conduct, and discharge have led to adverse effects on various ecosystems. The occurrence of antibiotics in surface and drinking water is a matter of global concern. It is responsible for multiple disorders, including disruption of endocrine hormones and high chronic toxicity. The hospitals, pharmaceutical industries, households, cattle farms, and aquaculture are the primary discharging sources of antibiotics into the environment. This review provides complete detail on applying different nanomaterials or nanoparticles for the efficient removal of antibiotics from the diverse ecosystem with a broader perspective. Efforts have been made to focus on the degradation pathways and mechanism of antibiotic degradation using nanomaterials. More light has been shed on applying nanostructures in photocatalysis, which would be an economical and efficient solution. The nanoscale material or nanoparticles have incredible potential for mineralizing pharmaceutical compounds in aqueous solutions at low cost, easy handling characteristics, and high efficacy. Furthermore, nanoparticles can absorb the pharmaceutical by-products and wastes at a minimum cost as they can be easily recycled. With the increasing number of research in this direction, the valorization of pharmaceutical wastes and by-products will continue to expand as we progress from old conventional approaches towards nanotechnology. The utilization of nanomaterials in pharmaceutical wastewater remediation is discussed with a major focus on valorization, energy generation, and minimization and its role in the circular economy creating sustainable development.

Guadipyr, a new insecticide, induces microbiota dysbiosis and immune disorders in the midgut of silkworms (Bombyx mori)

Guadipyr, which combines neonicotinoid and semicarbazone functional groups in one molecule, exhibits good activity on several pests and high acute and chronic toxicity to silkworms (Bombyx mori). In this report, the effects of low-dose guadipyr on the midgut microbiota and immune system of silkworms were studied. Results showed that the structure and richness of the midgut microbiota of silkworms were altered after being treated with 5.25 mg/L (1/10 of LC50) of guadipyr. The abundance of Pseudomonas was evidently increased, whereas Curvibacter was substantially reduced, which might be related to the growth and immunity of silkworms. The expression of key genes in the Toll, IMD, and JAK/STAT pathways, which ultimately led to the downregulation of antimicrobial peptide genes (AMPs), such as CecA, Defensin1, Leb, and glv2, was reduced upon guadipyr exposure. Simultaneously, the suppression of steroid hormone 20-hydroxyecdysone receptor and response genes, such as BR-C Z4, was detected in the exposed groups. The decreased expression of these immune regulatory pathway-related and 20-hydroxyecdysone signal pathway-related genes indicated that the immune system of silkworms was affected by low-dose guadipyr. Our results revealed the negative effects of guadipyr on silkworms and highlighted the unneglectable toxicity of low-dose guadipyr to this economic insect. Given the risk, it is necessary to control the application of guadipyr in or around the mulberry fields.

Evidence for Specific Receptor-Mediated Toxicity of Pharmaceuticals in Aquatic Organisms Derived from Acute and Chronic Standard Endpoints.

The toxicity of 17 active pharmaceutical ingredients (APIs) was investigated using standardized acute and chronic tests with Daphnia magna and 2 algae species. Chronic toxicity was generally greater for Daphnia than for algae. Compilation of additional data resulted in 100 APIs for which the acute-to-chronic ratio (ACR) was determined for Daphnia. The frequency of high ACRs (~20% with ACRs > 100) indicates that specific receptor-mediated toxicity toward D. magna is rather common among APIs. The 11 APIs with ACRs > 1000 included lipid-modifying agents, immunosuppressants, antibiotics, antineoplastics, antiobesics, antivirals, and antihistamines. There was no consistent association between ACR and chronic toxicity, ionization status, or lipophilicity. High ACRs were not exclusively associated with the presence of orthologs of the pharmacological target in Daphnia. Statins, acetylcholinesterase inhibitors, and antihistamines are discussed in more detail regarding the link between targets and toxic mode of action. For acetylcholinesterase inhibitors, receptor-mediated toxicity was already apparent after acute exposure, whereas the high ACR and chronic toxicity of some antihistamines probably related to interaction with a secondary rather than the primary pharmacological target. Acute or modeled chronic toxicity estimates have often been used for prioritizing pharmaceuticals. This may be seriously misleading because chronic effects are currently not predictable for APIs with specific receptor-mediated toxicity. However, it is exactly these APIs that are the most relevant in terms of environmental risks. Environ Toxicol Chem 2022;41:601-613. © 2021 SETAC.

Chronic Toxicities of Neonicotinoids to Nymphs of the Common New Zealand Mayfly Deleatidium spp.

Neonicotinoid insecticides have been shown to have high chronic toxicity relative to acute toxicity, and therefore short-term toxicity tests ≤96 h in duration may underestimate their environmental risks. Among nontarget aquatic invertebrates, insects of the orders Diptera and Ephemeroptera have been found to be the most sensitive to neonicotinoids. To undertake a more accurate assessment of the risks posed by neonicotinoids to freshwater ecosystems, more data are needed from long-term tests employing the most sensitive taxa. Using nymphs of the common New Zealand mayfly genus Deleatidium spp., we performed 28-d static-renewal exposures with the widely used neonicotinoids imidacloprid, clothianidin, and thiamethoxam. We monitored survival, immobility, impairment, and mayfly moulting propensity at varying time points throughout the experiment. Imidacloprid and clothianidin exerted strong chronic toxicity effects on Deleatidium nymphs, with 28-d median lethal concentrations (LC50s) of 0.28 and 1.36 µg/L, respectively, whereas thiamethoxam was the least toxic, with a 28-d LC50 > 4 µg/L (highest concentration tested). Mayfly moulting propensity was also negatively affected by clothianidin (during 3 of 4 wk), imidacloprid (2 of 4 wk), and thiamethoxam (1 of 4 wk). Comparisons with published neonicotinoid chronic toxicity data for other mayfly taxa and larvae of the midge genus Chironomus showed similar sensitivities for mayflies and midges, suggesting that experiments using these taxa provide reliable assessments of the threats of neonicotinoids to the most vulnerable freshwater species. Environ Toxicol Chem 2019;38:2459-2471. © 2019 SETAC.

Ozonation of the algaecide irgarol: Kinetics, transformation products, and toxicity

The degradation of irgarol, a frequently detected algaecide in the aquatic environment, by ozonation was investigated in this study. The second-order rate constants for the reaction of irgarol with ozone (O3) and hydroxyl radical (OH) were determined to be 505 M−1 s−1 and 4.96 × 109 M−1 s−1, respectively. During ozonation, sixteen transformation products (TPs) of irgarol were proposed using an electrospray ionization quadrupole time-of-flight mass spectrometer. Most of the TPs are ozone-refractory compounds and therefore could only be further transformed by oxidation with OH generated from O3 decomposition during ozonation. Toxicity analysis using the ecological structure activity relationship class program indicates that some of the TPs (e.g., irgarol sulfoxide) still exhibit high acute or chronic toxicity to aquatic organisms (fish, daphnia, and algae) as the parent compound. With a typical ozone dose applied in water treatment (2 mg/L, corresponding to a specific ozone dose of 0.8 mg O3/mg dissolved organic carbon), irgarol could be completely abated in a selected surface water by ozonation. However, most of the TPs persisted in the ozonation effluent because of their low ozone reactivity. The results of this study suggest that ozonation with typical ozone doses applied in water treatment may not be able to sufficiently reduce the ecotoxicological effects of irgarol on aquatic organisms. More effective treatment processes such as ozone-based advanced oxidation processes may be required to enhance the removal of toxic TPs of irgarol in water treatment.

Comparison of the Chronic Anticonvulsant Activity and Safety of IEM-1913, Sodium Valproate, IEM-1676, and Memantine in Experiments on Rats

Chronic oral administration of the selective AMPA receptor blocker IEM-1676 and the combined NMDA and AMPA receptor blocker IEM-1913 decreased the severity of convulsions kindled by corasol (pentylenetetrazole) and also the number of rats with full kindling by 20–40% more than the standard antiepileptic sodium valproate and the selective NMDA receptor blocker memantine. IEM-1913 and IEM-1676 induced anticonvulsant effects over wide dose ranges, of 0.03–1 and 3–40 mg/kg, respectively, while memantine and sodium valproate were effective only in narrow dose ranges, of 12–20 and 100–200 mg/kg, respectively. Sodium valproate, memantine, and IEM-1676 had low therapeutic indexes (TD50/ED50), of 1.7, 2.0, and 8.0, respectively, evidencing the high chronic toxicity and low safety of these agents. IEM-1913 had a therapeutic index of 1600, which is evidence of low toxicity and high safety in the chronic use of IEM-1913. Thus, the selective blockade of AMPA receptors induced by IEM-1676 is sufficient to achieve a maximum anticonvulsant effect in rats with corasol kindling, though only combined blockade of NMDA and AMPA receptors provide both the maximal anticonvulsant activity and the safety of using IEM-1913 over a wide range of effective doses.

TREATMENT OF WASTEWATER FROM BIODIESEL GENERATION AND ITS TOXICITY EVALUATION BY Raphidocelis subcapitata

ABSTRACT Biodiesel was developed to solve vast economic and environmental problems related to the use of petroleum as fuel. However, large quantities of water are necessary for biodiesel production, generating a high volume of effluent waste. Therefore, it is important to treat this wastewater in order to meet the environmental legislations according to the Brazilian Resolution Number 430/2011 (CONAMA). This work aimed to treat this effluent by coagulation/flocculation (CF) and an electrochemical advanced oxidation process. The combination of CF techniques (pH = 6.5) and electrochemical oxidation (boron doped diamond - BDD - electrode with NaCl) led to 78.5% removal of total organic carbon. The evaluation of the toxicity with Raphidocelis subcapitata indicated that the treated samples (IC5072h = 1.66%) had higher chronic toxicity when compared to raw effluent samples (IC5072h = 0.17%). This indicates that the proposed treatment was effective to decrease the organic load and reduce the environmental impact of these effluents in water bodies.

Light-stick: A problem of marine pollution in Brazil

Light-sticks are used as bait in surface long-line fishing, to capture swordfish and other large pelagic predators. When discharged in the ocean, it may reach the beaches. The traditional Brazilian community of Costa dos Coqueiros, Bahia, use light-sticks as a medicine for rheumatism, vitiligo and mycoses. It may affect the marine life when its content leak in the open ocean. This work evaluated and identified the acute and chronic toxicity of the light-stick. A high acute toxicity was observed in the mobility/mortality of Artemia sp.; in the fertilization of sea urchin eggs, and a high chronic toxicity in the development of the pluteus larvae of the same sea urchin. The main compounds that probably caused toxicity were the volatiles such as the fluorescent PAH and oxidants such as the hydrogen peroxide. Its disposal in the open ocean is a potential threat for marine life.