High Acute Toxicity Research Articles

Biodegradation of profenofos, an acetylcholine esterase inhibitor by a psychrotolerant strain Rahnella sp. PFF2 and degradation pathway analysis

Profenofos (PFF) is an organophosphate insecticide and used worldwide to control harmful pests and insect populations. Removal of PFF from the environment is important because of its high mammalian acute toxicity due to acetylcholinesterase enzyme inhibition. Biodegradation in this context is beneficial as it is a cost-effective and sustainable process. In the present study, microbial degradation of PFF was investigated by using a psychrotolerant bacterium Rahnella sp. PFF2. The bacterial strain was isolated from the soil samples of apple orchards situated in Kufri, Himachal Pradesh, India. Quantitative analysis through High-performance liquid chromatography revealed that the bacterium PFF2 was able to degrade 100% PFF (50 μg/ml) within 14 days at 20 °C, within 16 days at 28 °C, and within 20 days at 15 °C. GC/MS and HPLC studies showed the presence of pathway metabolites 4-Bromo-2-chlorophenol, phosphoric acid, and 3, 4 – dimethyl benzoic acid. Based on these data a probable PFF degradation pathway has been proposed. An inducible and intracellular organophosphorus hydrolase enzyme might responsible for the initial degradation process. To the best of our knowledge, the current finding is the first report of PFF degradation at both the psychrophilic and mesophilic temperature conditions by any psychrotolerant Rahnella sp. isolated from Western Himalayan regions.

Toxicity of hydraulic fracturing wastewater from black shale natural-gas wells influenced by well maturity and chemical additives.

Hydraulic fracturing of deep shale formations generates large volumes of wastewater that must be managed through treatment, reuse, or disposal. Produced wastewater liberates formation-derived radionuclides and contains previously uncharacterized organohalides thought to be generated within the shale well, both posing unknown toxicity to human and ecological health. Here, we assess the toxicity of 42 input media and produced fluid samples collected from four wells in the Utica formation and Marcellus Shale using two distinct endpoint screening assays. Broad spectrum acute toxicity was assessed using a bioluminescence inhibition assay employing the halotolerant bacterium Aliivibrio fischeri, while predictive mammalian cytotoxicity was evaluated using a N-acetylcysteine (NAC) thiol reactivity assay. The acute toxicity and thiol reactivity of early-stage flowback was higher than later produced fluids, with levels diminishing through time as the natural gas wells matured. Acute toxicity of early stage flowback and drilling muds were on par with the positive control, 3,5-dichlorophenol (6.8 mg L-1). Differences in both acute toxicity and thiol reactivity between paired natural gas well samples were associated with specific chemical additives. Samples from wells containing a larger diversity and concentration of organic additives resulted in higher acute toxicity, while samples from a well applying a higher composition of ammonium persulfate, a strong oxidizer, showed greater thiol reactivity, predictive of higher mammalian toxicity. Both acute toxicity and thiol reactivity are consistently detected in produced waters, in some cases present up to nine months after hydraulic fracturing. These results support that specific chemical additives, the reactions generated by the additives, or the constituents liberated from the formation by the additives contribute to the toxicity of hydraulic fracturing produced waters and reinforces the need for careful consideration of early produced fluid management.

Reactive Oxygen Species-Triggered Dissociation of a Polyrotaxane-Based Nanochelator for Enhanced Clearance of Systemic and Hepatic Iron.

Chronic blood transfusions are used to alleviate anemic symptoms in thalassemia and sickle cell anemia patients but can eventually result in iron overload (IO) and subsequently lead to severe oxidative stress in cells and tissues. Deferoxamine (DFO) is clinically approved to treat transfusional IO, but the use of the iron chelator is hindered by nonspecific toxicity and poor pharmacokinetic (PK) properties in humans, resulting in the need to administer the drug via long-term infusion regimens that can often lead to poor patient compliance. Herein, a nanochelator system that uses the characteristic IO physiological environment to dissociate was prepared through the incorporation of DFO and reactive oxygen species (ROS)-sensitive thioketal groups into an α-cyclodextrin-based polyrotaxane platform (rPR-DFO). ROS-induced dissociation of this nanochelator (ca. 10 nm) into constructs averaging 2 nm in diameter significantly increased urine and fecal elimination of excess iron in vivo. In addition to significantly improved PK properties, rPR-DFO was well-tolerated in mice and no adverse side effects were noted in single high dose or multiple dose acute toxicity studies. The overall features of rPR-DFO as a promising system for iron chelation therapy can be attributed to a combination of the nanochelator's improved PK, favorable distribution to the liver, and ROS-induced dissociation properties into constructs <6 nm for faster renal elimination. This ROS-responsive nanochelator design may serve as a promising alternative for safely prolonging the circulation of DFO and more rapidly eliminating iron chelates from the body in iron chelation therapy regimens requiring repeated dosing of nanochelators.

Results of definitive radiotherapy with concurrent chemotherapy for maxillary sinus carcinomas with neck lymph node metastasis

The purpose of this study was to describe the results of definitive radiotherapy (RT) with concurrent chemotherapy for maxillary sinus carcinomas (MSCs) with neck lymph node metastasis to clarify its limitation. Local control (LC), progression-free survival (PFS) and overall survival (OS) rates were calculated using the Kaplan–Meier method and were compared between subgroups using the log rank test. Toxicity was classified using common terminology criteria of adverse events version 5.0. Eighteen patients with inoperable MSC with neck lymph node metastasis including 12 men and 6 women with a median age of 67 years were analyzed. The histologic diagnoses were as follows: 16 patients had squamous cell carcinomas and 2 had other histology. Four patients had stage T3 MSC, 6 had T4a and 8 had T4b. Among 18 patients, 7 received concurrent systemic chemotherapy and 11 received selective arterial chemo-infusion. The median follow-up period was 17 months. The 2-year LC, PFS and OS rates for the entire cohort were 34, 31 and 46%, respectively. No significant differences were observed for LC, PFS and OS rates between systemic chemotherapy and selective arterial chemo-infusion cohorts. Grade 3 or higher acute toxicity, including both non-hematological and hematological, was observed in nine patients (50%), while no grade 3 or higher late toxicity was observed. In conclusion, we described the results of definitive RT for MSCs with neck lymph node metastasis. Local recurrence of primary tumor was a frequent pattern of failure and it should be addressed in future study.

The role of postoperative radiotherapy for thymomas: a multicentric retrospective evaluation from three Italian centers and review of the literature.

BackgroundThymoma is a rare mediastinal neoplasia. Surgery is the backbone of the treatment, but the role of postoperative radiotherapy (PORT) remains controversial. We aimed to obtain data on survival and safety in patients treated with PORT in three different Italian institutions.MethodsWe retrospectively analyzed 183 consecutive patients who underwent surgery from 1981 to 2015. According to the Masaoka-Koga staging system, 39.3%, 32.7%, 18.6% and 9.8% patients were in stage I, II, III and IV of disease, respectively. PORT was indicated in 114 patients (62.3%), while 69 subjects underwent surgery alone. Complete resection was obtained in 68 patients who underwent PORT. Adverse events (AEs) were graded according to CTCAE v4.0. We analyzed the recent literature to describe the current reports on PORT for resected thymoma.ResultsMean follow-up was 130 months (range, 3–417 months). Overall survival (OS) at 1-, 5- and 10-year from surgery was 98.3%, 90.2% and 69.7% respectively. One-, 5- and 10-year disease specific survival (DSS) was 98.9%, 92.3% and 89.8% respectively. Disease free survival (DFS) at 1, 5 and 10 years from surgery was 96.7%, 88.3% and 82.8% respectively. Univariate analysis showed that complete resection, cell histology A-AB-B1 and stages I–II were significant predictors of better DSS and DFS. Multivariate analysis showed that sex, R0 margins and WHO histology was independent prognostic factors. Among patients treated with PORT, a trend towards better OS was evident with Masaoka stage I–II (P=0.09). Patients with R0 margins treated with PORT showed better OS and DSS (P=0.05). No differences in DSS for performance status (P=0.70), WHO histology (P=0.19), paraneoplastic syndrome (P=0.23) and surgical procedure (P=0.53) were evident. Patients treated with PORT had a higher level of acute AEs compared to surgery alone, but none of these was graded ≥3.ConclusionsOur results confirmed that patients with incompletely resected thymoma had the worst OS and DSS. High grade acute toxicity was not different between PORT and surgery alone. Other trials reported a significant benefit in OS, DSS and DFS in stage IIb–IV thymoma treated with PORT.

A Phase Ⅱ Trial of Stereotactic Body Radiotherapy Using 4 Fractions for Patients With Localized Prostate Cancer

To report the results from our phase Ⅱ study of stereotactic body radiotherapy (SBRT) delivering 36 Gy in 4 fractions for patients with localized prostate cancer. From 2015 to 2018, 55 patients were enrolled and treated with SBRT delivering 36 Gy in 4 fractions. Most patients were categorized as intermediate-risk (n = 31) or high-risk (n = 20). The median age was 73 years (range, 54–86). Two-thirds of the patients (n = 37) received androgen deprivation therapy. The median follow-up duration was 30 months. The Radiation Therapy Oncology Group and National Cancer Institute - Common Toxicity Criteria version 4 was used for toxicity assessment. Quality of life (QOL) outcomes were also evaluated using the Expanded Prostate Cancer Index Composite (EPIC). Protocol treatments were completed for all patients. Four patients had biochemical failures. Three patients had clinical failures. One patient died of gastric cancer. The 3-year biochemical control rate was 90.8%. Acute grade 2 genitourinary (GU) and gastrointestinal (GI) toxicities were observed in 5 (9%) and 6 (11%) patients, respectively. No grade 3 or higher acute toxicities were observed. Late grade 2 GU and GI toxicities were observed in 6 (11%) and 5 (9%) patients, respectively. One patient (1.8%) had late grade 3 GU toxicity (radiation cystitis) 2.5 years after treatment. EPIC scores slightly decreased during the acute phase and recovered 3 months after treatment. Our phase II study showed that SBRT delivering 36 Gy in 4 fractions was safe and effective with favorable QOL outcomesTabled 1Abstract 2614; Table; Patient-reported outcomes assessed by Expanded Prostate Cancer Index Compositepre2w1m3m6m9m12m18m24mUrinary83.69 (12.20)66.57 (25.52)85.79 (15.21)90.44 (18.34)92.00 (11.68)88.62 (17.06)87.39 (17.01)87.39 (17.07)82.79 (22.50)Bowel89.93 (11.00)89.93 (11.00)80.18 (20.17)88.04 (12.02)89.63 (12.58)88.44 (11.89)88.45 (10.19)89.76(8.68)88.02 (10.34)Sexual33.57 (12.61)31.39 (12.64)31.84 (5.64)32.34 (10.31)31.37 (7.85)30.08 (7.07)32.45 (13.22)33.00 (9.28)32.06 (8.34)Hormone84.37 (17.20)80.16 (19.19)87.06 (12.82)88.04 (12.55)89.46 (11.96)89.86 (9.33)90.63 (12.41)88.92 (11.74)93.54 (9.78)mean (SD) Open table in a new tab

Hydrazine exposure: A near-infrared ICT-based fluorescent probe and its application in bioimaging and sewage analysis

Hydrazine (N2H4) is an environment pollutant with high acute toxicity and potential carcinogenicity, and detection of N2H4 has attracted increasing attention. In the present study, a low toxicity near-infrared fluorescent probe (DCDB) based on the intramolecular charge transfer (ICT) principle was developed. The probe DCDB exhibits excellent selectivity and high sensitivity (LOD = 1.27 ppb) for N2H4, fast reaction rate (5 min), extremely large Stokes shift (160 nm). The color transformation of the DCDB-N2H4 system from purple to pink can be observed with the naked eye. The success of N2H4 test strips to detect trace N2H4 in actual sewage strongly illustrates the practical application potential of DCDB. Importantly, DCDB can be utilized to monitor the distribution of exogenous N2H4 in vivo and in vitro.

Evaluation of a centralized toxicity view in the electronic health record (EHR) for physician-recorded Common Terminology Criteria for Adverse Events (CTCAE).

296 Background: Patients’ treatment-related acute and late toxicities are essential clinical data, yet this information is widely dispersed among notes in the EHR. This lack of structure impedes clinician ability to efficiently and comprehensively integrate toxicity information into clinical management. We aimed to consolidate toxicity data to improve clinician efficiency in accessing this information, and to evaluate the utility of this tool in radiation oncology. Methods: We developed an auto-updating flowsheet view (“Synopsis”) in the Epic EHR that longitudinally integrates physician-graded CTCAE toxicity selected using a SmartForm embedded in EHR notes. Physicians timed themselves performing 4 tasks to assess acute and post-treatment toxicity information for patients seen in follow-up, alternating with vs. without use of Synopsis. Wilcoxon Rank-Sum testing compared recorded task times with and without Synopsis. A survey was sent to physicians regarding qualitative utility of Synopsis. Results: Six physicians reviewed 98 patients seen in follow-up (49 with Synopsis, 49 without Synopsis) at median 8.1 months (Synopsis) and 6.5 months (no Synopsis) since completion of radiation (p = 0.88). Use of Synopsis was associated with significantly faster assessment of: overall toxicity history (median 50 vs. 93 seconds, p = 0.0007), highest acute toxicity during treatment (median 19 vs. 40 seconds, p = 0.0002), highest post-treatment toxicity (11 vs. 65 seconds, p &lt; 0.0001), and longitudinal review of a single symptom (8 vs. 61 seconds, p &lt; 0.0001). Among 10 physician survey respondents, 100% reported that Synopsis improved efficiency and 30% reported it led to a change in management. All physicians felt it was important to understand a patient’s toxicity history, but 80% reported that time required with the note-based EHR structure was prohibitive; with use of Synopsis, 90% reported that this task was now feasible. Specific domains most improved included ability to: identify high-grade toxicities (100%), contextualize new symptoms (80%), summarize treatment-related toxicity (80%), navigate in the EHR to a time of high-grade toxicity (60%), evaluate the success of an intervention (30%), and decide whether to discuss a reported new symptom (30%). Conclusions: A centralized toxicity view in the EHR improves clinician efficiency in evaluating longitudinal toxicity data and enhances clinician ability to comprehensively integrate toxicity information into patient care.

Insilico study of thymohydroquinone interaction with blood-brain barrier disrupting proteins.

Aim:To evaluate the inhibitory interaction of thymohydroquinone against blood–brain barrier (BBB)-associated neuropsychiatric and neurodegenerative disorders.Materials & methods:An elaborated in silico study was designed to evaluate the interaction of thymohydroquinone with BBB-disrupting proteins and to highlight its pharmacokinetic and safety attributes.Results:Thymohydroquinone demonstrated stable interaction with BBB-disrupting protein active site with Ki (inhibition constant) ranges of (2.71 mM–736.15 μM), binding energy (-4.3 to 5.6 Kcal/mol), ligand efficiency (-0.36 to 0.42 Kcal/mol) and root mean square deviation value of (0.80–2.59 Å).Conclusion:Further pharmacokinetic analysis revealed that thymohydroquinone is BBB and central nervous system (CNS) permeant with high acute toxicity and could be a candidate drug for the treatment of these neurological conditions.

The influence of acetamiprid and deltamethrin on the mortality and behaviour of honeybees (Apis mellifera carnica Pollman) in oilseed rape cultivations

The aim of the research was to determine the influence of acetamiprid and deltamethrin on the mortality and behaviour of honeybees of the same variety, coming from the same source and estimated to be in good condition by a professional beekeeper, but in different years and under different weather conditions. Results of research conducted in field isolators in oilseed rape fields in the years 2012–2018 showed no acetamiprid influence either on the mortality or on the behaviour of honeybees. Deltamethrin activity differed from a lack of influence through causing mortality and a weaker condition of honeybee colonies to the destruction of the colony. This demonstrates the relative safety of acetamiprid to honeybees and the high risk of deltamethrin use. The differences in the bee colonies’ reaction to deltamethrin are probably caused by the high acute toxicity of this active ingredient, genetically dependent, variable metabolic capabilities of particular bee colonies, or coexistence of a variety of different stressors—mainly pathogens.

Acute toxicity of dihydroanatoxin-a from Microcoleus autumnalis in comparison to anatoxin-a

The cyanobacterium Microcoleus autumnalis grows as thick benthic mats in rivers and is becoming increasingly prevalent around the world. M. autumnalis can produce high concentrations of anatoxins and ingestion of benthic mats has led to multiple dog deaths over the past two decades. M. autumnalis produces a suite of different anatoxin congeners including anatoxin-a (ATX), dihydroanatoxin-a, (dhATX), homoanatoxin-a and dihydrohomoanatoxin-a. Benthic mat samples often contain high levels of dhATX, but there is little toxicology information on this congener. In the present study, natural versions of dhATX and ATX were purified from cyanobacteria to determine the acute toxicity by different routes of administration using mice. Nuclear magnetic resonance spectroscopy was used to confirm the putative structure of dhATX. By intraperitoneal (ip) injection, the median lethal dose (LD50) for dhATX was 0.73 mg/kg, indicating a reduced toxicity compared to ATX (LD50 of 0.23 mg/kg). However, by oral administration (both gavage and feeding), dhATX was more toxic than ATX (gavage LD50 of 2.5 mg/kg for dhATX and 10.6 mg/kg for ATX; feeding LD50 of 8 mg/kg for dhATX and 25 mg/kg for ATX). The relative nicotinic acetylcholine receptor-binding affinities of ATX and dhATX were determined using the Torpedo electroplaque assay which showed consistency with the relative toxicity determined by ip injection. This work highlights that toxicity studies based solely on ip injection may not yield LD50 values that are relevant to those derived via oral administration, and hence, do not provide a good estimate of the risk posed to human and animal health in situations where oral ingestion is the likely route of exposure. The high acute oral toxicity of dhATX, and its abundance in M. autumnalis proliferations, demonstrates that it is an important environmental contaminant that warrants further investigation.

Evaluation of hypopigmentation in embryonic zebrafish induced by emerging disinfection byproduct, 3, 5-di-I-tyrosylalanine

Halogenated dipeptides, 3, 5-di-I-tyrosylalanine (DIYA), have been identified as novel disinfection byproducts (DBPs), following chloramination of authentic water. However, little is known about their toxicity. Zebrafish embryos were used to assess the toxicity of novel iodinated DBPs (I-DBPs). Although DIYA did not exhibit high acute toxicity to embryonic zebrafish (LC50 > 2 mM), it significantly inhibited pigmentation of melanophores and xanthophores on head, trunk and tail at 500 μM as determined by photographic analysis. Whereas N-phenylthiourea (PTU) as a pigment inhibitor did not inhibit development of yellow pigments. Colorimetric detection of melanin further confirmed these results. Quantitative real time polymerase chain reaction (qRT-PCR) measurements indicated that genes (dct, slc24a5, tyr, tyrp1a, tyrp1b, silva) associated with the melanogenesis pathway were dramatically down-regulated following exposure to 500 μM DIYA. In addition, enzymatic activity of tyrosinase (TYR) decreased, also demonstrating that the underlying mechanism of hypopigmentation was attributed to the disruption of melanogenesis pathway. Transcription levels of xanthophore genes (gch2, bnc2, csf1a, csf1b, pax7a and pax7b) were also monitored by qRT-PCR assay. DIYA exposure up-regulated expression of gch2 and bnc2, but not csf1 and pax7. Tested DIYA analogues, brominated tyrosine was unlikely to inhibit pigmentation, indicating that the iodine substitution and dipeptides structure are of important structural feature for the inhibition of pigmentation. In this study, we observed that DIYA inhibited melanogenesis related genes, which might contribute to pigmentation defects. Moreover, as an emerging I-DBPs, the developmental toxicity of aromatic dipeptides should be further studied.

Molecular mechanism of action of new 1,4-naphthoquinones tethered to 1,2,3-1H-triazoles with cytotoxic and selective effect against oral squamous cell carcinoma

The oral squamous cell carcinoma (OSCC) stands out as a public health problem due to its high incidence and low survival rate, despite advances in diagnosis and treatment. Moreover, the most commonly chemotherapeutic agents for OSCC, such as carboplatin and cisplatin, generate important side effects, evidencing the urgency in developing new drugs. Naphthoquinones are an important class of natural products or synthetic compounds with cytotoxic effect demonstrated on different cancer types. In the present study, thirty-five 1,4-naphthoquinones tethered to 1,2,3-1H-triazoles were synthesized and the antitumor activity and molecular mechanisms were evaluated in several assays including in vitro and in vivo models of OSCC and normal oral human cells. Compounds 16a, 16b and 16 g were able to induce cytotoxicity in three different tumor cell lines of human OSCC (SCC4, SCC9 and SCC25) and were more toxic and selective to tumor cells (Selective Index, SI > 2) than classical and chemically similar controls (Carboplatin and Lapachol). Compound 16 g showed the higher SI value. Besides, compounds 16a, 16b and 16 g significantly reduced colony formation of SCC9 cells in the tested concentrations. Hemolytic assay using compounds 16a, 16b and 16 g at high concentrations showed no compound exhibited hemolysis higher than 5%, similar to controls. In vivo acute toxicity study showed that 16 g was the only one, among the three compounds, with no apparent limiting toxic effects on mice in the tested concentrations. Thus, the investigation of cell death mechanisms was conducted with this compound. 16 g does not trigger ROS production nor binds to DNA. On the other hand, compound 16 g induced microtubule disorganization, and molecular modeling studies suggests a potential mechanism of action related to inhibition of topoisomerases and/or hPKM2 activities. Cell morphology, pyknotic nuclei presence, cleaved caspase-3 staining and viability assays using caspase-3 inhibitors demonstrate compound 16 g induced cell death through apoptosis. Among the 35 synthesized triazole naphthoquinones, compound 16 g was the most effective compound against OSCC cells, presenting high cytotoxicity (~35 µM), selectivity (SI ~ 6) and low acute toxicity on animals, and therefore might be considered for future cancer therapy.

Evaluation of Toxicity on Ctenopharyngodon idella Due to Tannery Effluent Remediated by Constructed Wetland Technology

Aquatic pollution caused by industrial effluents is an environmental issue, imposing deleterious impacts on the overall environment, specifically, on humans, by disrupting the balance of the ecosystem. Among all the industries, tanneries are considered some of the most polluting due to heavy use of toxic organic and inorganic compounds during leather processing, most of which find their way into rivers, lakes, and streams, thus exerting adverse effects on aquatic life, particularly on fish. Considering the huge concentrations of pollutants present in tannery effluents, toxicity evaluation is of prime importance. Therefore, bioassays are usually employed to assess the acute toxicity of industrial effluents and efficiency of effluent clean-up technologies as they provide a thorough response of test species to the substances present in the tested media. In the present study, the toxic effects of tannery effluent on common grass carp (Ctenopharyngodon idella) were studied for 96 h in laboratory conditions. The effluent was added at different concentrations, before and after treatment by constructed wetlands (CWs). During this period, mortality data was collected to calculate the 96 h-LC50 (lethal concentration inducing 50% mortality) and acute toxicity of C. idella. In addition to this, observations on change in morphological, physiological, and behavioural patterns were also made every 24 h. The present toxicity assay revealed that the raw tannery effluent changed the morphology, physiology, and behavioural response of fish. Moreover, fish exposure to raw/untreated effluent caused high acute toxicity and 100% mortality, due to the presence of high concentrations of salts and chromium (Cr) metal. While treatment of tannery effluent by CWs vegetated with different plants (B. mutica, L. fusca, and T. domingensis) significantly reduced its toxicity and fish mortality as well, and inoculation of salt and Cr-tolerant endophytic bacteria (Enterobacter sp. HU38, Microbacterium arborescens HU33, and Pantoea stewartii ASI11) further reduced (up to 90%) its toxicity level. Hence, the use of CWs for tannery effluent treatment can be recommended to favour public health and promote the overall safety of the environment.

Exposure to sublethal concentrations of zinc pyrithione inhibits growth and survival of marine polychaete through induction of oxidative stress and DNA damage

Effects of zinc pyrithione (ZnPT) and inorganic Zn (ZnCl2) were evaluated on a marine polychaete at sublethal concentrations for 14 days. ZnPT decreased the burrowing activity and AChE activity with higher acute toxicities, implying its cholinergic effect. Both ZnPT and ZnCl2 increased MDA levels at higher concentrations, suggesting lipid peroxidation and oxidative stress. In the ZnPT-treated polychaete, enzymatic activities of CAT and SOD were elevated with an increase in DNA damage, whereas the levels of GSH, GPx, GR, and GST were decreased. However, in the ZnCl2-treated polychaete, the level of GSH and enzymatic activities of CAT, SOD, GPx, GR, and GST were significantly elevated to resist cellular damage. During 97 days depuration experiment, significant mortality and growth retardation were observed in the ZnPT-exposed polychaete. Overall, ZnPT was found to be more toxic than ZnCl2 with the harmful impact on antioxidant defense system and DNA stability in marine polychaete.

Ecological risk assessment (ERA) based on contaminated groundwater to predict potential impacts to a wetland ecosystem.

To assess the ecological risk resulting from an accidental gasoline spill upstream from a wetland, groundwater and sediment sampling was carried out during two campaigns at the 48th and 52nd months after the spill had occurred. In total, 21 groundwater monitoring wells in the affected area were sampled plus an additional reference well located upstream from the accident location. Seven sediment sampling points were selected inside the wetland, plus a reference point upstream from the accident. Physicochemical parameters, BTEX (benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene) and metal concentrations were analysed to estimate the chemical risk. Acute (Allivibrio fischeri, Daphnia similis, Hyalella azteca) and chronic (Artemia salina and Desmodesmus subspicatus) toxicity assays were performed with groundwater and sediments elutriate to determine the ecotoxicological risk. Results from groundwater indicated an extreme chemical level of risk in14 out of 21 monitoring wells. These 14 wells also exhibited free-phase gasoline and lead (Pb) concentrations above the threshold values adopted by this study. The presence of Pb, however, could not be associated with the gasoline accident. High acute and chronic toxicities were reported for the majority of wells. Conversely, the risks associated with the sediments were considered low in most sampling points, and the ecotoxicity found could not be related to the presence of gasoline. Groundwater flow modelling results have evidenced the migration of the contamination plume towards the wetland. Thus, to prevent contamination from reaching the protected area, more effective groundwater clean-up techniques are still required.

Acute toxicity of four heavy metal ions to Oncomelania hupensis

To assess the acute toxicity of Cu2+, Cd2+, Hg2+ and Pb2+ to Oncomelania hupensis. Cu2+, Cd2+, Hg2+ and Pb2+ solutions were prepared at five concentrations, and 10 snails were exposed to each concentration for 24, 48, 72 h and 96 h. Then, the inhibition of snail activity and snail death was observed, and the half maximal effective concentration (EC50) and median lethal concentrations (LC50) were estimated. The 24, 48, 72 h and 96 h EC50 values of Cu2+, Cd2+, Hg2+ and Pb2+ were 0.74, 0.56, 0.46, 0.37 mg/L, 4.79, 3.52, 1.70, 1.26 mg/L, 1.90, 1.49, 0.83, 0.76 mg/L and 21.40, 9.98, 7.90, 5.42 mg/L for snails, respectively. The 96 h LC50 values of Cu2+, Cd2+, Hg2+ and Pb2+ were 0.43, 2.96, 1.12 mg/L and 12.22 mg/L for snails, the safe concentrations were 0.004 3, 0.029 6, 0.011 2, 0.122 2 mg/L, respectively. Cu2+ shows a high acute toxicity to snails, and Cd2+ and Hg2+ exhibit a moderate acute toxicity to snails, while Pb2+ is lowly toxic to snails.

Oxymatrine-based bioacaricide as a management tool against Oligonychus ilicis (McGregor) (Acari: Tetranychidae) in coffee

The acaricidal bioactivity of an oxymatrine-based commercial formulation was assessed against Oligonychus ilicis (McGregor) (Acari: Tetranychidae), a pest in coffee cropping systems. For this purpose, a series of assays were carried out under laboratory and greenhouse conditions using different concentrations (from 0.25 to 1.0 mL c.p. L−1) of the oxymatrine formulation. In the laboratory, a significant reduction in egg hatchability was observed in treatment using 1.00 mL c. p. L−1 of the oxymatrine formulation. Egg hatchability rates ranging from 69.9 to 91.7% were observed in eggs treated with 0.25–0.75 mL c. p. L−1 of the bioacaricide. Although the ovicidal activity was low, all tested bioacaricide concentrations caused significant larval mortality for newly hatched larvae in relation to the negative control. For adult females, the highest concentrations (0.75–1.00 mL c. p. L−1) of the bioacaricide caused high acute toxicity and residual (≥86.7% mortality) at 10 days after exposure, which were similar to the synthetic acaricide spirodiclofen. In the greenhouse, the bioacaricide caused ~74% reduction in population levels of O. ilicis, while spirodiclofen provided a population reduction of ~96%. In this study, no phytotoxic effect was observed on the coffee nursery trees treated with the bioacaricide. The oxymatrine-based commercial formulation has potential to be used for O. ilicis management in coffee, though field trials are needed to validate findings of our study.

Occurrence of Toxigenic Microcystis spp in Major Water Bodies of North East India

Toxigenic cyanobacterial blooms in the water bodies represent a major ecological problem around the world. Some species produces a diverse range of toxins that have hepatotoxic, neurotoxic, cytotoxic and dermatoxic activity and hence have deleterious effect on humans, animals and fishes leading to death as well. Cultural eutrophication of water bodies leads to increased incidence of these harmful cyanobacterial blooms worldwide. North-East India being a biodiversity hotspot harbor many species of cyanobacteria. Few reports suggested presence of few toxigenic cyanobacteria in the water bodies of Assam, but no systematic studies have been undertaken to evaluate their toxicity. This work is being conducted to gather information on major toxigenic cyanobacteria, with special emphasis to microcystin (a cyclic heptapeptides with high acute and chronic toxicities to humans and animals) producing strains. Water samples have been collected from few water bodies of North-East and enriched in specific media. The toxin Microcystin was detected using specific ELISA kit and positive results have been obtained. Further, 16s rDNA sequencing was employed for molecular identification of the strains.

Fluoxastrobin-induced effects on acute toxicity, development toxicity, oxidative stress, and DNA damage in Danio rerio embryos.

Strobilurin fungicides (SFs), the most commonly used fungicides, pose threats for controlling fungal diseases. The fungicides were monitored in aquatic ecosystems and may have negative effects on nontarget organisms. This project was undertaken to monitor the toxic effects of fluoxastrobin (FLUO) on Danio rerio embryos and to evaluate the SF risks in aquatic ecosystems. The 96-hour median lethal concentration (96h LC50), hatching rates, and morphological abnormalities were used to analyze acute toxicity and teratogenicity of FLUO to Danio rerio embryos at an FLUO dose of 0.549mg/L (95% confidence limits: 0.423 to 0.698mg/L); the results showed that FLUO has high toxicity in embryos that is analogous to the toxicity observed in adult Danio rerio. Fluoxastrobin may lead embryos to delayed hatching at concentrations >0.6mg/L, and it may lead to teratogenicity (i.e., pericardial edema and spinal curvature). Based on the 96h LC50 results, the following parameters were evaluated in Danio rerio: development-related indicators (body length and heart rates), reactive oxygen species (ROS) levels, lipid peroxidation (LPO) levels, the levels of three antioxidants, 8-hydroxy-2-deoxyguanosine (8-OHdG), and apoptosis. The results elucidated that FLUO inhibition of spinal and heart development may be induced by oxidative stress. In addition, FLUO induced a notable climb in ROS content, LPO, the activated activity of superoxide dismutase (SOD) and catalase (CAT), and it inhibited glutathione peroxidase (GSH-PX) activity. Fluoxastrobin led to DNA damage (i.e., a notable climb of 8-OHdG contents and apoptotic cells). Collectively, FLUO posed threats to Danio rerio embryos at multiple levels, and this investigation could be a reminder for people to be more judicious in SF-use to avoid or relieve SF toxicity to nontarget organisms.