Paraquat Concentration Research Articles

Enhanced bioremediation of pesticides contaminated soil using organic (compost) and inorganic (NPK) fertilizers

This research examined the bioremediation of pesticides (Carbofuran and Paraquat) contaminated farmyard soil using compost and Nitrogen, Phosphorus, and Potassium (NPK) fertilizer. Microcosms representing each treatment were set-up in triplicates. Biostimulation was done using two concentrations (0.5 % and 1.0 % w/w) of NPK fertilizer and compost, following pesticides application at recommended rates [Carbofuran (1 g/kg) and Paraquat (5 ml/kg)] and four times the recommended rates. Two control soils were set-up; Abiotic control (sterile farmyard soil + pesticide) and Control (farmyard soil without treatment). Monitoring of the dynamics in microbial community abundance, and pesticide residues during the biostimulation period was done weekly for 28 days, using standard enumeration method, and High Performance Liquid Chromatography (HPLC), respectively. At the end of the monitoring period, considerable reduction in pesticide residues across the treatment set-ups was recorded. In Carbofuran-treated soils, there were no complete, but considerable losses in residual pesticide, however, in most of the Paraquat-treated soils, there were complete losses within 21 days. Lower pesticide residues were recorded in set-ups amended with compost than NPK, across both Carbofuran and Paraquat-treated soils. After pesticides application, decreases in microbial counts were recorded at Day 7 across all the treatments, followed by increases from Day 14–21, then decreases at Day 28. Microbial counts were lower in Carbofuran than in Paraquat-treated soils irrespective of nutrient (compost and NPK) amendments. Bacterial and fungal counts were in the magnitude of 106 and 105 CFU/g soil, respectively. Also, increased counts were recorded for Actinomycetes, Nitrifiers, Phosphate solubilizers across all treatments, and were in magnitude of 103–104 CFU/g soil. Soil microorganisms could breakdown and eliminate large concentrations of Carbofuran and Paraquat in compost-amended soils than in NPK-amended soils. This study suggests that bioremediation of pesticides contaminated soils can be achieved and enhanced by stimulating the indigenous microbial community with requisite nutrients (compost).

Direct determination of paraquat herbicide by square-wave voltammetry by two-step transfer mechanism at heterogeneous boron-doped carbon nanowall electrodes

Boron-doped carbon nanowalls (B:CNW) versus boron-doped diamond (BDD) materials were investigated for the effective electrochemical detection of highly toxic herbicide paraquat (PQ). Depending on the surface morphology and functional groups of BDD and B:CNWs, the electrochemical absorption and detection of the target analyte PQ revealed different detection mechanisms. The surface absorption mechanism was mainly observed for BDD, while for B:CNWs, both surficial and edge absorption were observed due to the sharp edges of carbon nanowalls. This effectually drives the high heterogenous electron transfer kinetics at absorption sites. Detection of PQ was carried out in phosphate buffer solution with an optimized pH of 10 and parameters of the square-wave voltammetry. Comparative studies show higher voltammetric current peak heights for B:CNWs (∼90.5 μA) than BDD (∼7.5 μA) at a much lower PQ concentration of 4 μM. B:CNWs show a higher sensitivity of 11 μA/μM/cm2 than BDD of 2.23 μA/μM/cm2, hence BDD shows a LOD of 1.8 μM, whereas B:CNWs have a much lower LOD of 0.47 μM. Density functional theory calculations (DFT) show a higher propensity of the B:CNW models toward electrocatalytic reduction of the PQ. Moreover, the proposed two-step detection mechanism is strongly supported by the distribution of the PQ electrostatic potential in different oxidation states in conjunction with the slab surfaces. The higher the sensitivity, the lower the LOD, and the excellent performance of B:CNWs in the detection of PQ in real water samples also suggests its potential for use in the environmental monitoring and assessment of emerging pollutants.

A novel 2D g-C3N4 material applied for Paraquat adsorbing and detoxifying in vitro and in vivo

In the environmental safety area, the widespread use of the herbicide Paraquat (PQ) poses a great threat to hydrobionts and mammals. Due to the lack of specific antidote, it may lead to irreversible pulmonary fibrosis with a mortality rate of 60%. Therefore, it is necessary to develop an effective and specific PQ antidote. The g-C3N4 (HPCN) with excellent surface physicochemical properties was prepared by a two-step calcination method using urea and dicyandiamide as raw materials, showing a significant photocatalyst against environmental PQ pollution. The SEM results showed that HPCN possesses a porous layered structure. X-ray diffraction and infrared spectroscopy indicated that the conjugated aromatic rings were orderly stacked, forming a 2D layered structure of g-C3N4. The HPCN had a larger specific surface area (56.84 m2 g−1) and pore volume (0.2718 cm3 g−1), which enhanced its adsorption capacity and photocatalytic activity. HPCN exhibited an effective adsorption rate of 38.25% for PQ in water under light. Compared with the PQ group (54.8%), the cell viability of the HPCN group (91.4%) significantly increased by 36.6%, and the SEM observation revealed the restoration of normal cell morphology. The HPCN effectively reduced PQ content in zebrafish and mice in vivo, resulting in an approximately 70% increase in survival rate. The UV-Vis results indicated that the adsorption rate of HPCN for PQ in zebrafish was 43.5%. The enhanced catalytic performance of HPCN provides a promising solution for the detoxification of PQ and of other environmental pollutants.

Biodegradation Capabilities of Paraquat-Degrading Bacteria Immobilized on Nanoceramics.

The biodegradation of paraquat was investigated using immobilized microbial cells on nanoceramics fabricated from nanoscale kaolinite. Pseudomonas putida and Bacillus subtilis, which degrade paraquat, were immobilized separately on nanoceramics (respectively called ICnc-P and ICnc-B). The attachment of bacteria to nanoceramics resulted from electrostatic force interactions, hydrogen bonding, and covalent bonding (between the cells and the support materials). The initial 10 mg L-1 concentration of paraquat in water was removed by the adsorption process using nanoceramics at 68% and ceramics at 52%, respectively. The immobilized cells on the nanoceramics were able to remove approximately 92% of the paraquat within 10 h, whereas the free cells could only remove 4%. When the paraquat was removed, the cell-immobilized nanoceramics exhibited a significant decrease in dissolved organic nitrogen (DON). ICnc-B was responsible for 34% of DON biodegradation, while ICnc-P was responsible for 22%. Ammonia was identified as the end product of ammonification resulting from paraquat mineralization.

Effects of specimen preservation and transportation on blood paraquat concentration in rats

Objective: To investigate the effects of duration, temperature and shake on paraquat (PQ) concentration in the blood of PQ-exposed rats during the specinen preservation and transportation. Methods: In March 2021, 60 SD male rats of Specific Pathogen Free class were randomly divided into low-dose group (10 mg/kg PQ) and high-dose group (80 mg/kg PQ). Each group was divided into 5 subgroups (normal temperature group, cold storage group, 37 ℃ storage group, shaking on normal temperature group and shaking on 37 ℃ group), six rats in each subgroup. The rats were given intraperitoneal injection of PQ, 1 h after exposure, the blood samples were obtained by cardiac extraction. After different interventions, the concentrations of PQ were detected and compared before and after the intervention in each subgroup. Results: In the shaking on 37 ℃ group, the results of PQ concentrations in PQ-exposed rats were significantly lower than those before the intervention (P<0.05). In the other subgroups, the results were not significantly different compared with before intervention (P>0.05) . Conclusion: The concentration of PQ in the blood of rats exposed to PQ was decreased by shaking for 4 hours at 37 ℃.

Toxicity of Paraquat and Dicamba on Caenorhabditis Elegans LC50 Value

Paraquat and dicamba are chemicals commonly used in agriculture for plant control. The US Environmental Protection Agency (EPA) has classified paraquat into a restricted use class for use only by practitioners, as it is highly toxic. In this study, the effects of different concentrations of paraquat and dicamba toxic substances on C. elegans were studied. In tests, C. elegans were directly exposed to different concentrations of paraquat and dicamba for 6h, 12h, 18h, 24h. In particular, it was determined at which paraquat and dicamba doses that half of the C. elegans individuals (LC50) died. In the analysis results, paraquat LC50 values were found as LC50 6h= LC50 6h= 7412 µM, LC50 12h= 459 µM, LC50 18h= 123 µM, LC50 24h= 61 µM. Similarly, dicamba LC50 values were found as LC50 6h= 14610 µM, LC50 12h= 1404 µM, LC50 18h= 906 µM, LC50 24h= 463 µM.

Effect of pirfenidone on paraquat-induced pulmonary fibrosis in rats

Objective: To construct paraquat (PQ) poisoning rat model and to explore the effect of pirfenidone (PFD) on PQ-induced pulmonary fibrosis. Methods: In April 2017, male 6-8 week-old Wistar rats were selected, and PQ was administered intraperitoneally at one time. PFD was administered by gavage 2 hours after poisoning. The daily gavage doses were 100, 200 and 300 mg/kg, and the rats were divided into physiological saline group, PQ group, PQ+PFD 100 group, PQ+PFD 200 group, PQ+PFD 300 group, with 10 rats in each group at each observation time point. The pathological changes of lung tissue at different time points (the 1st, 3rd, 7th, 14th, 28th, 42nd and 56th days) after poisoning and the effect of PFD intervention with different dose on PQ-induced pulmonary fibrosis were observed. Pathological evaluation of lung tissue was performed by Ashcroft scale method. The PQ+PFD 200 group was selected to further explore the pathological changes of lung tissue, the contents of hydroxyproline and malondialdehyde in lung tissue were determined.And the tumor necrosis factor (TNF) -α, interleukin (IL) -6, transforming growth factor (TGF) -β1, fibroblast growth factor (FGF) -B, platelet-derived growth factor (PDGF) -AB, insulin-like growth factor (IGF) -1 and PQ concentrations in serum and lung tissue were determined. Results: On the 1st to 7th day after PQ exposure, rats developed lung inflammation, which was aggravated on the 7th to 14th day, and pulmonary fibrosis appeared on the 14th to 56th day. Compared with PQ group, the Ashcroft scores of lung fibrosis in PQ+PFD 200 group and PQ+PDF 300 group decreased significantly in 7th and 28th day (P<0.05), while the Ashcroft score of lung fibrosis in PQ+PFD 100 group had no significant difference (P>0.05). After PQ exposure, the content of hydroxyproline in lung tissue increased gradually and reached the peak value on the 28th day. Compared with the PQ group, the contents of hydroxyproline in the PQ+PFD 200 group decreased at the 7th, 14th and 28th day, and the contents of malondialdehyde decreased at the 3rd and 7th day, the differences were statistically significant (P<0.05). The levels of TNF-α, IL-6 in rat serum and lung tissue reached the peak value on the 7th day after PQ exposure, and the levels of TGF-β1, FGF-B and IGF-1 in rat serum and lung tissue reached the peak value on the 14th day after PQ exposure, and the level of PDGF-AB in rat serum and lung tissue reached the peak value on the 28th day after PQ exposure. Compared with PQ group, the level of serum IL-6 in PQ+PFD 200 group decreased significantly on the 7th day, and serum TGF-β1, FGF-B, PDGF-AB and IGF-1 on the 14th and 28th day were decreased significantly (P<0.05). The levels of TNF-α, IL-6 in lung tissue of rats in PQ+PFD 200 group on the 7th day decreased significantly, and the levels of TGF-β1, FGF-B and IGF-1 in lung tissue of rats on the 14th day were significantly decreased, and the level of PDGF-AB in lung tissue of rats on the 28th day were significantly decreased (P<0.05) . Conclusion: PFD partially alleviates the PQ-induced lung inflammation and fibrosis by inhibiting oxidative stress, reducing the levels of pro-inflammatory and pro-fibrotic cytokines in serum and lung tissue, but does not affect the concentrations of PQ in serum and lung tissue.

Rapid and highly sensitive determination of unexpected diquat and paraquat in biological fluids by electro-enhanced SPME-SERS

Poisoning with diquat (DQ) and paraquat (PQ) herbicides has been a public health problem. Unfortunately, rapid detection in biofluids remains challenging. Herein, a hyphenated approach of electro-enhanced adsorption, solid-phase microextraction, and surface-enhanced Raman spectroscopy (EE−SPME−SERS) was exploited for rapid and sensitive in situ analysis of DQ and PQ in human urine and plasma. A porous Ag fiber with an Au layer (p-Ag/Au fiber) was fabricated with multi-functions (SERS substrate, SPME sorbent, and working electrode). Clear trends could be observed between signal intensity and concentration of DQ or PQ with high reproducibility. The method detection limits (MDLs) calculated from the characteristic peak of DQ were 0.064 ppb and 0.65 ppb in urine and plasma, respectively. Corresponding MDLs for DQ and PQ in urine and plasma were 0.036 ppb and 0.35 ppb, respectively. The whole process of “extracting and detecting” was completed within 4 min with satisfactory recoveries. Notably, the EE−SPME−SERS technique could easily realize in situ analysis of DQ and PQ in biofluids with good selectivity, which is practical in clinical diagnosis. This EE−SPME−SERS method provides a potential avenue for efficient pretreatment and in situ poison detection in biological samples.

Impact of Paraquat on Acid and Alkaline Phosphatase Activity in Indian Major Carp &lt;i&gt;Cirrhinus mrigala&lt;/i&gt; Hamilton

Paraquat is a non-selective aquatic herbicide used to control nuisance vegetation in aquatic bodies. It potentially causes fish toxicity. The present investigation was undertaken to evaluate alterations in Acid Phosphatase (ACP) and Alkaline Phosphatase (ALP) activity in fingerlings of commercially important Indian Major Carp Cirrhinus mrigala. Both ACP and ALP are popular biomarkers of pesticide toxicity- induced aquatic pollution. 96 hours of acute exposure to LC&lt;sub&gt;0&lt;/sub&gt; and LC&lt;sub&gt;50&lt;/sub&gt; concentrations and 30 days of chronic exposure to LC&lt;sub&gt;1/20th&lt;/sub&gt; and LC&lt;sub&gt;1/10th&lt;/sub&gt; concentration of paraquat were studied during the present experiment in selected four tissues viz. gill, liver, muscle and brain to interpret its comparative impact at different effective concentrations on selected target tissues of fish. 30 days of chronic exposure to LC&lt;sub&gt;1/10th&lt;/sub&gt; dose of paraquat showed exceptionally highly significant (p&lt;0.001) decline in ACP activity of all four tissues among all other treatment groups when compared with the control. The liver tissue of fishes exposed to both the acute concentrations of paraquat shows an exceptionally highly significant (p&lt;0.001) decrease in ALP activity among all other treatment groups and tissues when compared with control. From the present study, it can be concluded that paraquat-induced decline in ACP and ALP activity in Cirrhinus mrigala can be utilized as a prominent biomarker of aquatic toxicity induced due to pesticides in non-targeted organisms like fish. Paraquat can be potentially considered an aquatic ecosystem hazard leading to severe environmental pollution and eco-toxicity.

Paraquat and Diquat: Recent Updates on Their Pretreatment and Analysis Methods since 2010 in Biological Samples.

Paraquat (PQ) and diquat (DQ) are quaternary ammonium herbicides which have been used worldwide for controlling the growth of weeds on land and in water. However, PQ and DQ are well known to be toxic. PQ is especially toxic to humans. Moreover, there is no specific antidote for PQ poisoning. The main treatment for PQ poisoning is hemoperfusion to reduce the PQ concentration in blood. Therefore, it is essential to be able to detect PQ and DQ concentrations in biological samples. This critical review summarizes the articles published from 2010 to 2022 and can help researchers to understand the development of the sample treatment and analytical methods for the determination of PQ and DQ in various types of biological samples. The sample preparation includes liquid-liquid extraction, solid-phase extraction based on different novel materials, microextration methods, and other methods. Analytical methods for quantifying PQ and DQ, such as different chromatography and spectroscopy methods, electrochemical methods, and immunological methods, are illustrated and compared. We focus on the latest advances in PQ and DQ treatment and the application of new technologies for these analyses. In our opinion, tandem mass spectrometry is a good choice for the determination of PQ and DQ, due to its high sensitivity, high selectivity, and high accuracy. As far as we are concerned, the best LOD of 4 pg/mL for PQ in serum can be obtained.

Dose ingested, vomiting, and outcome in patients ingesting a standard paraquat 20SL formulation

Background FAO specifications for liquid paraquat dichloride SL formulations require the use of an emetic agent to stimulate vomiting within 30 min of ingestion. To date, there is no high-quality evidence of efficacy, despite use of the PP796 emetic since 1979. We first examined the validity of patients’ self-reported dose of paraquat ingested by examining the relationship with blood paraquat concentration and time to death for patients ingesting the standard paraquat SL formulation in a Sri Lankan cohort. As a secondary outcome, we assessed whether ingestion resulted in vomiting within 30 min and whether vomiting was associated with good outcome. Methods Patients presenting with paraquat SL self-poisoning were prospectively studied in ten Sri Lankan hospitals in 2003–08. Data on reported dose ingested, incidence and timing of vomiting after ingestion, treatment received, plasma paraquat concentration, and outcome were collected prospectively on presentation to hospital. Time between ingestion and blood sampling was incorporated by covariate adjustment. Results 441 patients were recruited to the case series, presenting a median (IQR) of 3.0 (1.5–8.1] h post ingestion. Outcome was known for 435 patients of whom 322 (74.0%) died within 42 days, a median of 1.3 (0.6–4.4) days post ingestion. Median reported dose ingested was 15 to <30 mL. There was a highly significant linear trend between log plasma paraquat and reported dose ingested (p < .001); adjustment for the log of the time from ingestion to sampling further improved the model fit. Case fatality and median time to death also showed good agreement with estimated ingestion amount. 347/438 patients (79.2%) were stated to have vomited before reaching the study hospital with 300 (68.5%) vomiting within 30 min of ingestion; time to vomiting was unknown for a further 12 (2.7%). The proportion vomiting was strongly associated with reported dose ingested (p < .001); of note the proportion vomiting within 30 min only increased to 83.3% for the highest ingestion group. Patients vomiting within 30 min had higher plasma paraquat concentrations (p = .008), and higher hazard ratio in the adjusted Cox regression model of 2.01 (95% CI 1.45–2.77) compared to those who did not. Vomiting within 30 min was associated with a higher case fatality (241/295 [81.7%] vs 68/125 [54.4%], p < .001). Forty-three (47.3%) of the 91 patients who did not vomit before reaching hospital died (one had unknown outcome). Conclusion Importantly, we found good agreement between reported dose ingested and plasma paraquat concentration, case fatality, and time to death, suggesting that the reported dose is a valid marker for the dose ingested. Vomiting occurred within 30 min for 68.5% of patients, exceeding the characteristics for a purported effective emetic in the FAO specifications. However, vomiting within 30 min was associated with approximately double the risk of death compared to those who did not vomit, larger paraquat ingestions, and higher blood paraquat concentrations. In addition, death occurred in many patients who did not vomit, and the proportion vomiting within 30 min only reached 82.1% for the highest ingested dose group. Overall, we found no evidence of benefit resulting from incorporation of the emetic, suggesting that the current FAO specification is not effective at preventing deaths after ingestion of the paraquat SL formulation.

Electrochemical Sensors Based on Flexible Laser-Induced Graphene for the Detection of Paraquat in Water

Paraquat (PQ) is known to be highly toxic among herbicides and harmful to human health upon exposure because it causes various kinds of organ failure and affects the nervous system. Nowadays, increasing concentration of PQ in water bodies is a growing concern among many countries. On-site-based detection is very needed along with selectivity and sensitivity, which can be achieved through an electrochemical-based sensor. In this paper, a flexible laser-induced graphene (LIG)-based electrode was developed for the effective detection of PQ by the electrochemical square-wave-voltammetry (SWV) method. LIG is a 3D porous material fabricated by patterning with the help of CO2 laser irradiation on polyimide (PI) films and has extensive properties such as high conductivity, biocompatibility, and high porosity. LIG was further treated in a phosphate buffer solution to obtain treated LIG (t-LIG). The surface morphology and carbon fingerprint of both LIG and t-LIG were then characterized using scanning electron microscopy (SEM) and Raman spectroscopy, where SEM images have shown a more exposed porous structure in t-LIG. Electrochemical characterization was carried out using cyclic voltammetry and revealed a good current response and more surface activation of t-LIG over LIG. The detection of PQ carried out using t-LIG by the SWV method showed a high linear range of 0.5–35 μM with a sensitivity of 46.6 μA μM–1 cm–2 and a limit of detection of 0.54 μM. t-LIG has shown a very good average recovery rate of PQ when spiked in real water samples of 96.6%.

Study of paraquat-induced pulmonary fibrosis using biomimetic micro-lung chips

Paraquat (PQ) poisoning induces pulmonary fibrosis in vivo. The pathogenesis of pulmonary fibrosis is complex, which has prevented the development of specific treatments. Pulmonary fibrosis shows several characteristics including epithelial-mesenchymal transition (EMT), fibroblast activation, and extracellular matrix (ECM) deposition. To investigate pulmonary fibrosis, we designed a biomimetic multichannel micro-lung chip to imitate the in vivo interface between the lung epithelium and the lung interstitium. In our model, A549 (lung epithelial cells) and MRC-5 (fetal lung fibroblasts) cells were used to test the efficacy of our chip-based model. Rat tail type I collagen and hyaluronic acid were used to simulate ECM and to provide a 3D microenvironment. The micro-lung chips were cultured with PQ (0, 75, 150, 300, and 400 µM). The viability of A549 and MRC-5 cells significantly decreased with increasing PQ concentrations. There were significant changes in surfactant proteins C (SP-C), alpha smooth muscle actin protein (α-SMA), and vimentin protein levels during PQ-induced pulmonary fibrosis. SP-C levels were decreased in A549 cells, while those of α-SMA and vimentin were increased in A549 cells and MRC-5 cells treated with PQ in the micro-lung chip. We also designed a reference model without interaction between the lung epithelial cells and fibroblasts. Compared to the non-contact model, co-culturing A549 and MRC-5 cells in chips induced more severe EMT in A549 cells after treatment with 75 µM PQ and together defended against PQ-induced damage. Thus, our novel co-culture micro-lung chip that models the lung epithelium and interstitium may provide a new approach for studying lung fibrosis and will facilitate drug development.

Pathophysiological Changes in Rhesus Monkeys with Paraquat-Induced Pulmonary Fibrosis.

PurposePulmonary fibrosis is a life-threatening lung disorder. A comprehensive understanding of the pathophysiological changes in the development of pulmonary fibrosis will lead to new insights into its treatment.MethodsWe used a paraquat (PQ)-induced rhesus monkey model of pulmonary fibrosis to comprehensively investigate the process of pulmonary fibrosis development. Rhesus monkeys were orally administered PQ at concentrations of 25 mg/kg, 40 mg/kg, and 80 mg/kg. The dose was given once. Behavior and clinical data, such as PQ concentration, arterial oxygen saturation, biochemical evaluation, lung histopathology, and medical imaging, were continuously observed.ResultsParaquat-exposed monkeys developed pulmonary fibrosis following an expected time course, especially at 25 mg/kg. CT images showed ground-glass lesions in the lung after 4 weeks, and pulmonary fibrosis persisted until the end of follow-up. Using pathological examination, the lung sustained collagen deposition and slight inflammatory cell infiltration. All rhesus monkeys had obvious inflammatory infiltration within 1 week according to the immunohistochemical results and the number of leukocytes in the blood. The CT results showed that pulmonary fibrosis had not formed, indicating that drugs with powerful anti-inflammatory ability are potential candidates for early pulmonary fibrosis treatment.ConclusionOur study describes the dynamic process of paraquat-induced pulmonary fibrosis in rhesus monkeys and provided a pathophysiological basis for the treatment of pulmonary fibrosis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00408-022-00572-9.

The toxicokinetics of acute paraquat poisoning in specific patients: a case series

Paraquat is a non-selective contact herbicide that is absorbed through the digestive tract and skin and can cause multiple organ damage. The toxicokinetics of paraquat poisoning in specific patients are rarely reported. Case 1 was a 76-year-old man who intermittently immersed his perineum in diluted paraquat solution for 3 consecutive days because of eczema of the perineal skin. On admission, the patient’s scrotal skin was severely corroded and his blood paraquat concentration was 0.5 μg/mL. He developed severe kidney and lung damage after admission and died on Day 6 of admission. Case 2 was a 23-year-old woman who ingested paraquat during gestational week 36. Her initial blood paraquat concentration was 0.81 μg/mL. The patient refused hemoperfusion and a cesarean section. She birthed a baby girl 83 hours after ingesting paraquat. Paraquat concentrations in postnatal maternal blood, fetal blood, umbilical cord blood, and amniotic fluid were 0.19 μg/mL, 0.23 μg/mL, 0.20 μg/mL, and 0.47 μg/mL, respectively. The baby died within hours of birth and the mother died of refractory respiratory failure 2 days after delivery. This paper provides clues about paraquat toxicokinetics in specific patient types and indicates that paraquat can be absorbed through the scrotal skin and the placental barrier.

PARAQUAT-INDUCED HISTOPATHOLOGICAL CHANGES ON THE GILLS, KIDNEY AND LIVER TISSUES OF ANABAS TESTUDINEUS (BLOCH 1792)

Paraquat is the most widely used herbicide in agricultural activities for land preparation and weed control. Uncontrolled usage and poor waste management will introduce the chemical into the aquatic ecosystem due to agricultural runoff, causing harm to non-targeted aquatic species, especially fish. Therefore, this study was performed to evaluate the histological alterations of the gill, liver and kidney of the freshwater fish Anabas testudineus. Fish were exposed to four paraquat concentrations (2.0, 5.0, 12.0 and 15.0 mg/L) for 96 hours in controlled water parameters and without feeding. Following treatment, all fish were pithed and their gills, livers and kidneys were collected. Histopathological analysis with semi-quantitative scoring lesions were performed to determine the severity of the tissue changes in each fish organ. Histopathological changes in the gills after 96 hours of paraquat exposure showed lamella curvature, hyperplasia, edema, blood vessel congestion and necrosis compared with the control group. Histological changes, like degeneration in hepatocytes and necrosis were observed in the livers and kidneys exposed to 2.0-12.0 mg/L of paraquat. Prominent histopathological changes were observed in 15.0 mg/L of paraquat exposure, including nuclear pyknosis and necrosis. Overall, this study demonstrated deleterious effects of paraquat on the tissues of A. testudineus. The histopathological changes were proportional to the paraquat concentration and may impair organs’ vital functions which in turn affects the fish’s health.

Nanoporous Carbon from Oil Palm Leaves via Hydrothermal Carbonization-Combined KOH Activation for Paraquat Removal.

In this study, nano-porous carbon was completely obtained from oil palm leaves (OPL) by hydrothermal pretreatment with chemical activation, using potassium hydroxide (KOH) as an activating agent. Potassium hydroxide was varied, with different ratios of 1:0.25, 1:1, and 1:4 (C: KOH; w/w) during activation. The physical morphology of nano-porous carbon has a spongy, sponge-like structure indicating an increase in specific surface area and porosity with the increasing amount of KOH activating agent. The highest specific surface area of OPL nano-porous carbon is approximately 1685 m2·g−1, with a total pore volume of 0.907 cm3·g−1. Moreover, the OPL nano-porous carbon significantly showed a mesoporous structure designed specifically to remove water pollutants. The adsorptive behavior of OPL nano-porous carbon was quantified by using paraquat as the target pollutant. The equilibrium analyzes were explained by the Langmuir model isotherm and pseudo-second-order kinetics. The maximum efficiency of paraquat removal in wastewater was 79%, at a paraquat concentration of 400 mg·L−1, for 10 min in the adsorption experiment. The results of this work demonstrated the practical application of nano-porous carbon derived from oil palm leaves as an alternative adsorbent for removing paraquat and other organic matter in wastewater.

Magnetically recoverable steel slag/TiO2 visible‐light‐driven photocatalyst for paraquat degradation

AbstractParaquat is a bipyridylium herbicide with high solubility in water, which is widely used for aquatic weed control. The purposes of the present study were to introduce a navel TiO2‐based photocatalyst (SCS@Fe‐TiO2) and investigate its performance in paraquat degradation from aqueous solution under visible light. The response surface methodology (RSM) method was used to optimize pH, catalyst dose, initial concentration of paraquat, and irradiation intensity in the photocatalytic process. The characterization results of the photocatalyst revealed that coating Fe‐TiO2 onto the SCS has improved its photo‐degradation properties. Diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) results showed that not only doping TiO2 by Fe but also coating Fe‐TiO2 onto the SCS makes a reduction in the bandgap and electron–hole recombination. Totally, the performance of the photocatalytic process was high (90%–99%) and the effect of the parameters studied on the process was significant (p‐value &lt;0.05). The concentration of paraquat and irradiation intensity variables had linear relationships, so increasing the concentration of paraquat reduced the efficiency but the light intensity had the opposite effect. On the other hand, pH and photocatalyst mass had optimum values of 7 and 0.7 g, respectively, so they were the most important variables. and h+ played a crucial role in the photo‐degradation of paraquat by SCS@Fe‐TiO2. SCS@Fe‐TiO2 exhibited excellent photocatalytic reactivity for paraquat over 10 cycles. Finally, the SCS@Fe‐TiO2 would be a promising photocatalyst for the photo‐degradation of paraquat from aqueous solutions under visible light.

Anthrahydroquinone-2,6-disulfonate alleviates paraquat-induced kidney injury via the apelin-APJ pathway in rats

Objective: To explore the protective effects of anthrahydroquinone- 2,6-disulfonate (AH2QDS) on the kidneys of paraquat (PQ) poisoned rats via the apelin-APJ pathway. Methods: Male Sprague Dawley rats were divided into four experimental groups: control, PQ, PQ+sivelestat, and PQ+AH2QDS. The PQ+sivelestat group served as the positive control group. The model of poisoning was established via intragastric treatment with a 20% PQ pesticide solution at 200 mg/kg. Two hours after poisoning, the PQ+sivelestat group was treated with sivelestat, while the PQ+AH2QDS group was given AH2QDS. Six rats were selected from each group on the first, third, and seventh days after poisoning and dissected after anesthesia. The PQ content of the kidneys was measured using the sodium disulfite method. Hematoxylin-eosin staining of renal tissues was performed to detect pathological changes. Apelin expression in the renal tissues was detected using immunofluorescence. Western blotting was used to detect the expression levels of the following proteins in the kidney tissues: IL- 6, TNF-α, apelin-APJ (the apelin-angiotensin receptor), NF-κB p65, caspase-1, caspase-8, glucose-regulated protein 78 (GRP78), and the C/EBP homologous protein (CHOP). In in vitro study, a PQ toxicity model was established using human tubular epithelial cells treated with standard PQ. Twenty-four hours after poisoning, sivelestat and AH2QDS were administered. The levels of oxidative stress in human renal tubular epithelial cells were assessed using a reactive oxygen species fluorescence probe. Results: The PQ content in the kidney tissues of the PQ group was higher than that of the PQ+AH2QDS group. Hematoxylin-eosin staining showed extensive hemorrhage and congestion in the renal parenchyma of the PQ group. Vacuolar degeneration of the renal tubule epithelial cells, deposition of crescent-like red staining material in renal follicles, infiltration by a few inflammatory cells, and a small number of cast formation were also observed. However, these pathological changes were less severe in the PQ+sivelestat group and the PQ+AH2QDS group (P&lt;0.05). On the third day after poisoning, immunofluorescence assay showed that the level of apelin in the renal tissues was significantly higher in the PQ+AH2QDS group than in the PQ group. Western blotting analysis results showed that IL-6, TNF-α, NF-κB p65, caspase-1, caspase-8, GRP78, and CHOP protein levels in the PQ group were higher than in the PQ+AH2QDS group (P&lt;0.05). The expression of apelin-APJ proteins in the PQ+AH2QDS group was higher than in the PQ+sivelestat and PQ groups (P&lt;0.05); this difference was significant on Day 3 and Day 7. The level of oxidative stress in the renal tubular epithelial cells of the PQ+AH2QDS group and the PQ+sivelestat group was significantly lower than in the PQ group (P&lt;0.05). Conclusions: This study confirms that AH2QDS has a protective effect on PQ-poisoned kidneys and its positive effect is superior to that of sivelestat. The mechanism of the protective effects of AH2QDS may be linked to reduction in cellular oxidative stress, PQ content of renal tissue, inflammatory injury, endoplasmic reticulum stress, and apoptosis. AH2QDS may play a role in the treatment of PQ poisoning by upregulating the expression of the apelin-APJ.

Health Risk Assessment of Paraquat Contaminated in &lt;i&gt;Spirogyra spp.&lt;/i&gt; (tao) in Chiang Mai, Thailand

Spirogyra spp. (tao) is freshwater green algae which are consumed as an uncooked food especially in the north of Thailand. Aquatic plants especially algae are easily contaminated by pesticide residues from soil and water. Paraquat (1,1β-dimethyl, 4,4β-bipyridinium dichloride; PQ), a widely used herbicide among Thai farmers, is toxic, mutagenic, and carcinogenic to mammals through ingestion, inhalation and skin contact. This study aims to determine the concentrations of paraquat contaminated in Spirogyra spp. (tao) and health risk assessment on the consumption of Spirogyra spp. (tao) in Chiang Mai province, Thailand. The levels of paraquat were analyzed by using a simple, sensitive, and reliable method which was high performance liquid chromatography (HPLC). Seven samples were collected from the different districts. The levels of paraquat contamination were 5.07±0.00 to 12.69±0.10 mg/kg. The results showed that the concentrations of paraquat in all samples were lower than the standard level of the European Commission Regulation. Risk assessment of paraquat found that the hazard quotient was in the range of 0.18-0.46. It indicated that the consumption of Spirogyra spp. (tao) was expected to have no adverse health effects. However, the consumption of Spirogyra spp. (tao) should be a concern in terms of chronic exposure to toxic herbicide contaminated in the environment.