Risk Quotient Values Research Articles

A comparative study of surfactant distribution and fate (western and eastern) Egyptian Mediterranean coasts focusing on its environmental toxicity

One of the most difficult-to-manage new contaminants constantly released into the environment is linear alkylbenzene sulphonate (LAS), an anionic surfactant. Significant volumes of LAS are received by the Mediterranean coast of Egypt. The current study is a comprehensive assessment of the environmental fate of the LAS 1505 km off the Mediterranean coast of Egypt in the fall of 2023 in order to track its geographic spread and eventual demise in the water column. Critical analysis of LAS revealed that it is vertically distributed in various ways according to sources, uses, production amounts, and salinity levels. The vertical variation of LAS can be explained by its amphiphilic structure. A significant increase in surfactant concentration (>300 μg/L) was recorded in 66% and 43% of the total samples, ranging from 301.128 to 455.36 and from 304.556 to 486.135 for the western and eastern sides along the Egyptian Mediterranean coast, respectively. Evaluation of the average acute and chronic risk quotient (RQ) along the investigated locations revealed that fish were the most susceptible to LAS in both long and short exposure periods. The presented results also indicated significant LAS toxicity to three trophic levels (RQ values > 1). LAS toxicity to marine organisms was greater in the western than in eastern coastal regions according to acute and chronic mixture risk characterization ratios (RCRmix). The three trophic levels in the study area had the following order of acute relative contribution (RC) to LAS toxicity: fish > invertebrates > algae. The ANOVA test results showed that in both the western and eastern regions, LAS varied significantly (p < 0.05) with salinity (1.04E-60 and 5.44E-42) and depth (6.02E-65 and 1.59E-47), respectively. In addition, a significant difference was observed using the ANOVA test between the eastern and western regions of the Egyptian Mediterranean coast.

Influence of the use of remediated soil and agricultural drainage water on the safety of tomato fruits

The objective of this study is to assess the effectiveness of different techniques employed in remediating contaminated soil and wastewater ecosystems to ensure the safety of tomato fruits (Solanum lycopersicum L. var. cerasiforme) cultivated in these environments. Three biochemical techniques T1–T3, besides two controls CCU and CCT, were used to remediate contaminated soil ecosystems using rock phosphate, elemental sulfur, bentonite, phosphate-dissolving bacteria, and Thiobacillus sp. The contaminated agricultural drainage water was remediated by a down-flow hanging sponge (DHS) system. Two experiments were conducted: a pot experiment took place in the greenhouse at the National Research Center of Cairo (Egypt) and a field experiment was carried out at the basin site in the village of El-Rahawy, applying the optimal treatment(s) identified from the greenhouse experiment. The health risk assessment for potentially toxic elements (PTEs) in the harvested tomato fruits was conducted by calculating estimated daily intake (EDI) and target risk quotient (THQ) values. Results from the greenhouse experiment indicated the high effectiveness of the DHS technique in remediating El-Rahawy agricultural drainage water. The content of PTEs after remediation was significantly reduced by 100%, 93.3%, 97.8, and 77.8% for cadmium, copper, manganese, and zinc, respectively. The application of treated drainage water in employed reclaimed soil ecosystems led to a remarkable decrease in PTE levels, especially under T3 treatment; the reduction reached 89.4%, 89.5%, and 78.4% for nickel, copper, and zinc, respectively. The bioremediation technique also reduced the content of PTEs in tomato fruits harvested from both greenhouse and field experiments; the cadmium content, for example, was below detection limits in all treatments. The T3 treatment applied in the greenhouse experiment caused the highest percentage decrease among the employed PTEs in tomato fruits grown in the greenhouse. The same trend was also reached in the field experiment. Microbiological analyses of tomato fruits revealed that E. coli, Salmonella, or S. aureus bacteria were identified on tomato fruits harvested from either greenhouses or field experiments, showing that the counted total bacteria were higher under the field experiment compared to the greenhouse experiment. The health risk assessment parameter THQ was below 1.0 for all tested metals under all treatments. This means that no potential health risk is expected from consuming tomato products produced under the different employed remediation treatments. In conclusion, the employed bioremediation techniques successfully reduced the PTE content and microbial load in both soil and drainage water ecosystems and in harvested tomato fruits. Henceforth, no health risks are expected from the consumption of this product.

Shells That Have Been Polluted by Lead Around Youtefa Bay in Jayapura City Have Potential Risk of Non-Carcinogenic

Objective: This study aims to analyze how much of a health risk caused by lead exposure in shellfish can affect the health of humans or communities living around this location. Method: This study is an observational study with risk analysis or Hazard Quotient. Samples have been collected through purposive sampling methods, using a cross-sectional study design. Results and conclusions: The results showed that the concentration of lead in shellfish concentrations from 12 stations had an average value of 0.57 mg/kg and was classified as polluted because it was above the limit of the number of Indonesian National Standard 7387 of 2009 because the polluted standard was more than 0.3 mg/kg. Of the 75 respondents, the study found 33 respondents (44%) who had an RQ (risk quotient) of more than 1 indicating that they were vulnerable to lead contamination. It showed that the average RQ value of clams among the 75 respondents was 2.42. An average RQ of more than one suggests that people living near Youtefa Bay are at risk for developing the effects of lead exposure from polluted shellfish. Implications of the study: This study in addition to measuring the concentration of Lead in shellfish also calculated the Risk Quotient of people who consumed shellfish with Hazard Quotient analysis. Originality/value: Based on the calculation of the formula, the average value of RQ (2.42) is very high because RQ is above 1; therefore, this number (RQ) must be controlled. Researchers recommend that residents living near Youtefa Bay should be cautious of lead exposure by reducing total shellfish intake and reducing prolonged lead exposure.

Presence and Distribution of Sun-Blocking Agents in the Danube River: Implications for Aquatic Ecosystem Health

Organic sun-blocking agents are recognized as emerging pollutants of the aquatic environment. The consequences and effects of these harmful substances on aquatic organisms are not fully understood, particularly in the context of Romania. This study examines the presence and environmental hazards posed by ten UV filters found in the Danube River. Six of the ten targeted contaminants were detected in surface water samples: 2-hydroxy-4-methoxy-benzophenone (BP-3), 2,4-dihydroxy benzophenone (BP-1), 2,3,4-trihydroxy benzophenone (234HBP), 2,2′-dihydroxy-4-methoxy-benzophenone (BP-8), 2-hydroxy-4-methoxy-4′-methyl-benzophenone (BP-10), and benzyl salicylate (BS). In sediment samples, seven of the ten compounds were identified: BS, BP-3, 4-hydroxybenzophenone (4HBP), BP-1, 234HBP, 2,2′,4,4′-tetrahydroxybenzophenone (BP-2), and BP-10, with different frequencies. The correlation coefficients showed strong relationships between benzophenone derivatives in surface water samples and a common contamination source for BP-3 and BS in sediment samples. In the assessment, the risk quotient (RQ) for BP-1 in fish was determined to be 1.81. Similarly, RQ values for BP-3 were calculated as 1.24 for Daphnia magna and 57 for fish, suggesting that these UV filters could potentially present substantial hazards to the aquatic ecosystem. The study findings indicate that additional research is needed to investigate the presence and potential risks of organic sun-blocking agents in surface waters, with a particular emphasis on densely populated areas in Romania.

Dissipation and Risk Assessment of Propaquizafop in Ginseng under Field Conditions.

Propaquizafop is a highly efficient aryloxy phenoxy propionate chiral herbicide. However, the use of propaquizafop, including its safe use methods, residue patterns, dietary risk assessment, and maximum residue limits, for ginseng, a traditional Chinese medicinal plant, has not been studied. An analytical method was established for the simultaneous determination of propaquizafop and its four metabolites in ginseng soil, fresh ginseng, ginseng plant, and dried ginseng using HPLC-MS/MS. This approach showed good linearity (R2 ranging from 0.9827 to 0.9999) and limit of quantification ranging from 0.01 to 0.05 mg/kg. The intra- and interday recovery rates of this method ranged from 71.6 to 107.1% with relative standard deviation ranging from 1.3 to 23.2%. The method was applied to detect residual samples in the field, and it was found that the degradation of propaquizafop in ginseng plants and soil followed a first-order kinetic equation. R2 was between 0.8913 and 0.9666, and the half-life (t1/2) ranged from 5.04 to 8.05 days, indicating that it was an easily degradable pesticide (T1/2 < 30 days). The final propaquizafop residues in ginseng soil, plants, fresh ginseng, and dried ginseng ranged from 0.017 to 0.691 mg/kg. A dietary risk assessment was conducted on the final propaquizafop residue in fresh and dried ginseng. The results showed that the chronic exposure risk quotient values were less than 100% for fresh and dried ginseng (1.15% for fresh ginseng and 1.13% for dried ginseng). This illustrates that the dietary risk associated with the use of 10% propaquizafop emulsifiable concentrate in ginseng is very low. Thus, applying 750 mL/ha of propaquizafop on ginseng could not pose an unacceptable risk to public health. The results of the present study support the registration of propaquizafop in ginseng.

Dissipation behaviours, residues, and health risk of six herbicides in sugar beets under field conditions

This study established a residue detection method based on the QuEChERS pre-treatment method and combined it with high-performance liquid chromatography–tandem mass spectrometry to test six herbicides (metamitron, clopyralid, desmedipham, phenmedipham, ethofumesate, and haloxyfop-p-methyl) in sugar beet plants, soil, and roots. The degradation dynamics and terminal residues of each herbicide in sugar beets were analysed. Finally, the dietary risks of various herbicides in sugar beets were evaluated based on the dietary structure of Chinese people, and the risk quotient values were below 100%. Using this detection method, all reagents exhibited good linearity (0.9724 ≤ R2 ≤ 0.9998), The limit of quantification (LOQ) ranged from 0.01 to 0.05 mg/L, the matrix effect ranged from −1.2% to −50%, the addition recovery rate ranged from 77.00% to 103.48%, and the relative standard deviation ranged from 1.61% to 16.17%; therefore, all indicators of this method met the residue detection standards. Under field conditions, the half-lives (t1/2) ranged about 0.65 ∼ 2.96 d and 0.38 ∼ 27.59 d in sugar beet plants and soil, respectively. All herbicides were easily degraded in sugar beet plants and soil (t1/2 < 30 d). The terminal residue amounts in the beet plants, soil, and roots ranged from < LOQ to 0.243 mg/kg. The dietary risk assessment of each pesticide was conducted based on the residual median of the terminal residues and the highest residual values on the edible part of the beetroot. The chronic exposure risk quotient (RQc) and acute exposure risk quotient (RQa) values were < 100%, indicating that the residue of each pesticide in beetroot posed low risks to consumers in China at the recommended dosage.

Pesticides in surface water of the Ondas river watershed, western Bahia, Brazil: Spatial-seasonal distribution and risk assessment

This study investigated the occurrence and seasonal distribution of different classes of pesticides in surface waters of the Ondas River Watershed, as well as potential risks to the aquatic health and human water consumption in the western region of Bahia state, Brazil. Two gas chromatography-mass spectrometry analytical methods were applied to monitor 34 pesticides in water samples collected during both the dry and rainy seasons at 17 sites. Upon individual analysis, only γ-HCH, methoxychlor, demeton-S, methyl parathion, fenitrothion, chlorpyrifos, and azoxystrobin exhibited statistically significant differences between seasons. During rainy season, concentration medians of residues were higher for γ-HCH (74.7 ng L−1), methoxychlor (25.1 ng L−1), and azoxystrobin (47.2 ng L−1), potentially linked to historical contamination or illegal use. Conversely, pesticides like methyl parathion, fenitrothion, and chlorpyrifos, belonging to the organophosphate class, showed higher concentration medians in the dry period, measuring 75.1, 5.50, and 10.8 ng L−1, respectively, probably due to region crop activities. The risk quotient (RQ) assessment for aquatic life indicated that 59.0% of the samples in the dry season and 76.0% in the rainy season had RQ values greater than one, signifying a critical scenario for species conservation. Regarding human consumption, elevated risks were observed for heptachlor in both sampling periods and for azoxystrobin during the rainy season, surpassing RQ levels above 1, indicating danger in untreated water ingestion. Additionally, 24.0% and 53.0% of the samples in the dry and rainy seasons, respectively, contained at least one pesticide exceeding the EU resolution limit (100 ng L−1). Therefore, considering this information, implementing mitigation measures to avoid the river's contamination becomes imperative.

Simultaneous degradation of chlorpyrifos and profenofos in soils at sublethal concentrations in presence of Eisenia foetida and a native bacterial consortium

The use of organophosphates (OPPs) in agriculture is an environmental problem due to their persistence in the environment, affecting non-target species, including human beings. For this reason, this study evaluated the degradation of chlorpyrifos (CPF) and profenofos (PFF) simultaneously in soils at sublethal concentrations in the presence of Eisenia foetida (EF) and a native bacterial consortium (NBC). For this, we first studied the avoidance behavior of EF to soils contaminated with CPF and PFF by calculating the percentage avoidance response (AR%), finding that EF presents an avoidance behavior to soils contaminated with CPF (6.45 to 65.5 mg/kg) and PFF (2.26 to 112.95 mg/kg) and their mixture, giving values of AR% (+). EF did not show avoidance behavior with AR% (-) values when melon rinds were added as substrate making it feasible to study the degradation of CPF and PFF at concentrations of 65.5 mg/kg and 112.95 mg/kg. EF and NBC showed synergism in degradation, reducing the half-life time from 70 days (CPF) and 50 days (PFF) to 15 days in both cases, with degradation percentages at 28 days of 73.75% for CPF and 71.73% for PFF, with pH being the determining factor in degradation, favoring degradation at pH higher than 7. The study was scaled to real agricultural soils with concentrations of 0.801 and 0.592 mg/kg CPF and PFF, respectively. These concentrations represented an ecological risk with risk quotient values of RQ>1. After the application of EF and NBC, both OPPs were eliminated to non-detectable concentrations. It has been demonstrated that the application of EF and NBC is an effective alternative to be applied in agricultural soils contaminated with OPPs, which would reduce the negative impacts of these toxics on the environment and human beings.

High pesticide exposure and risk to bees in pollinator plantings adjacent to conventionally managed blueberry fields

Wildflower plantings adjacent to agricultural fields provide diverse floral resources and nesting sites for wild bees. However, their proximity to pest control activities in the crop may result in pesticide exposure if pesticides drift into pollinator plantings. To quantify pesticide residues in pollinator plantings, we sampled flowers and soil from pollinator plantings and compared them to samples from unenhanced field margins and crop row middles. At conventionally managed farms, flowers from pollinator plantings had similar exposure profiles to those from unenhanced field margins or crop row middles, with multiple pesticides and high and similar risk quotient (RQ) values (with pollinator planting RQ: 3.9; without pollinator planting RQ: 4.0). Whereas samples from unsprayed sites had significantly lower risk (RQ: 0.005). Soil samples had overall low risk to bees. Additionally, we placed bumble bee colonies (Bombus impatiens) in field margins of crop fields with and without pollinator plantings and measured residues in bee-collected pollen. Pesticide exposure was similar in pollen from sites with or without pollinator plantings, and risk was generally high (with pollinator planting RQ: 0.5; without pollinator planting RQ: 1.1) and not significant between the two field types. Risk was lower at sites where there was no pesticide activity (RQ: 0.3), but again there was no significant difference between management types. The insecticide phosmet, which is used on blueberry farms for control of Drosophila suzukii, accounted for the majority of elevated risk. Additionally, analysis of pollen collected by bumble bees found no significant difference in floral species richness between sites with or without pollinator plantings. Our results suggest that pollinator plantings do not reduce pesticide risk and do not increase pollen diversity collected by B. impatiens, further highlighting the need to reduce exposure through enhanced IPM adoption, drift mitigation, and removal of attractive flowering weeds prior to insecticide applications.

Distribution and risk assessment of pesticide pollution in small streams adjoining paddy fields

The present investigation was planned to bridge the knowledge gap on spatiotemporal variations of pesticide pollution in small streams adjacent to paddy fields, and to visualize the associated risks in the aquatic ecosystems. We screened 106 pesticides using GCMSMS and LCMSMS from 10 small streams (n = 212, surface water samples) adjacent to paddy fields over seven months. Fifty-five pesticides were detected across different streams and months. The highest mean concentration was detected for fenobucarb (272 ng L−1), followed by thiamethoxam (199 ng L−1). The highest maximum concentration was detected for thiamethoxam ( 13,264 ng L−1), followed by triflumezopyrim ( 11,505 ng L−1). The highest detection frequency was recorded for fenobucarb (80.00%), followed by pretilachlor (79.00%). Out of the ten streams, Attabira stream had the highest mean number of pesticides detected in each sample. Maximum number of pesticides were detected in October followed by September. Pesticides namely, hexaconazole, pretilachlor, tricyclazole, fenobucarb and thiamethoxam were consistently detected across all streams. The risk assessment against the fishes, micro-invertebrates and algae were measured by risk quotient index (RQ). Twenty-five pesticides out of the detected pesticides (n = 55) had risk quotient values greater than 1. The highest RQmax values were observed in case of fenpropathrin followed by cyfluthrin-3. The highest RQmean value was observed in case of cyfluthrin, indicating its higher toxicity to fishes. The present study reveals that small streams are polluted with pesticides and there is a need to develop strategies and policy interventions in regularizing the pesticide uses for reducing the pesticide pollution in aquatic systems.

Risk assessment of veterinary treatments in bee brood and adult honey bees

Amitraz and tau-fluvalinate are veterinary treatments administered for the control of Varroa destructor in honey bee colonies. These treatments can generate harmful residues for bees. This field study addresses the issue under two scenarios: 1) administration according to the posology and 2) placing contaminated wax containing the treatments. Tau-fluvalinate (Apistan®) residues were detected in larval stages from 25.34 to 84.72 ng g−1 in scenario 1 and from 29.63 to 173.97 ng g−1 in scenario 2. In addition, it was detected in bee bread in scenario 2 from 55.72 to 573.79 ng g−1. In scenario 1, DMPF + DMF (amitraz metabolites) were found from 37.09 to 171.58 ng g−1 (Amicel®) and from 36.74 to 42.64 ng g−1 (Apivar®) in bee bread. In honey, DMPF + DMF ranged from 19.96 to 145.30 ng g−1 (Amicel®) and from 32.20 to 78.43 ng g−1 from (Apivar®). With these treatments, a significant reduction in the population of Varroa mites (mean ± s.d.) was observed between 95.15 ± 2.56% and 98.29 ± 1.97%. There were significant positive correlations between Amicel®, the population of adult bees and the population of brood during evaluation 2 showing a higher effectiveness. According to both RQ (Risk Quotient) and SRA (Standard Risk Approach) values for adult bees and larvae, there is no risk when considering exposure by contact or by ingestion of bee bread or honey. In scenario 2, there is no risk for most of the larval stages, except in two bee hives treated with tau-fluvalinate, where the SRA values were 1.73 and 1.29%, indicating a moderate risk due to acute oral exposure.

Final Residues, Dissipation Dynamics and Dietary Risk Assessment of Cupric Nonyl Phenolsulfonate in Citrus and Soil

ABSTRACT Field trials were conducted in two consecutive years to evaluate the terminal residue levels, dissipation trend of cupric nonyl phenolsulfonate in citrus and soil. Analyses were carried out using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine the concentration of cupric nonyl phenolsulfonate in citrus and soil. The results showed a good linear relationship within the range of 0.01 to 5.0 mg·L−1 (R2 = 0.9999). Average recoveries were 77.70%-105.25% for cupric nonyl phenolsulfonate at the spiked levels of 0.01, 0.1,1, and 5 mg·kg−1, the relative standard deviations (RSDs) were 2.23–7.22%. Half-lives (t1/2) of cupric nonyl phenolsulfonate were 2.76–5.87 and 1.27–3.22 days in citrus and soil, respectively. The results showed that the final contents of cupric nonyl phenolsulfonate in citrus peel were the highest while that of citrus pulp were the lowest. As for soil, the final contents range from < 0.010 to 4.081 mg·kg−1. The dietary risk assessment of citrus was evaluated with risk quotients. The risk quotient values were found to be significantly < 100%, indicating that using recommended doses of cupric nonyl phenolsulfonate in citrus fruits poses risks to human health within acceptable risk levels. The results of this study contribute to the guidance of safe and reasonable use of cupric nonyl phenolsulfonate.

Distribution, sources, partition behavior and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the waters and sediments of Lake Ulansuhai, China

This study represents the first comprehensive investigation of 16 polycyclic aromatic hydrocarbons (PAHs) in the waters and sediments of Lake Ulansuhai. It explores their occurrence, sources, transport behavior, and associated risks to human health and ecosystems. The results revealed that concentrations of ∑PAHs in dissolved phase and sediment with no significant seasonal differences. In contrast, ∑PAHs concentrations in suspended particulate matter were significantly higher during the ice-free period compared to the ice period. Spatially, the northern part of Lake Ulansuhai displayed higher PAHs content. Diagnostic isomeric ratios and PMF models indicated that the PAHs were primarily derived from combustion sources. The distribution of PAHs within water-sediment demonstrated that non-equilibrium status. Fugacity calculations indicated that 2–4 rings PAHs acted as secondary sources of sediment emissions. Toxicity assessment, indicated that PAHs posed no significant carcinogenic risk to humans. Risk quotient values showed that PAHs as low to high ecological risk.

Dissipation Kinetics, Leaching, and Ecological Risk Assessment of S-Metolachlor and Benfluralin Residues in Soil

The use of selective herbicides is one of the best methods for weed management. However, the extensive use of herbicides can have adverse impacts on non-target organisms. The goals of this study were to assess the dissipation kinetics, leaching, and ecological risk assessment of S-metolachlor and benfluralin residues in silty loam soil planted with chickpea (Cicer arietinum L.). The experimental setup included four different layers with four replications corresponding to an experimental randomized complete block design consisting of 16 plots. The application doses of S-metolachlor and benfluralin were 1350 and 1920 g a.i./ha, respectively, according to manufacturer recommendations. Soil samples were split into four depths, 0 to 20 cm (Layer A), 20 to 40 cm (Layer B), 40 to 60 cm (Layer C), and 60 to 80 cm (Layer D), to determine the dissipation kinetics and the leaching behavior of the herbicides. Gas chromatography coupled with the electron capture detector (GC-ECD) method was developed and validated for the determination of S-metolachlor and benfluralin residues in soil. The analytes were extracted from the soil with distilled water and ethyl acetate followed by solid-phase extraction (SPE). The limit of quantification (LOQ) of the method was 0.1 μg/g, and the recoveries of S-metolachlor and benfluralin were in the ranges 81% to 97% and 88% to 101%, respectively, with relative standard deviations (RSD) of less than 9.7%. The dissipation kinetics of S-metolachlor and benfluralin in soil (0–20 cm) followed first-order kinetics with half-lives of 21.66 and 30.13 days, respectively. The results for samples obtained from the 20–80 cm soil profile showed that both benfluralin and S-metolachlor presented high leaching, following preferential flow. Also, a soil ecological risk assessment was conducted in the top 0–20 cm soil profile, estimating the toxicity–exposure ratio (TER) for four soil organisms and the risk quotient (RQ). The mean herbicide levels found at the studied soil profile at 0 days (2 h) and 60 days of the experiment were used for risk assessment. In the first case, the mean pesticide concentration (MPC) gives a worst-case scenario (ws); in the second case, a dissipation scenario (ds) is given using the respective MPC. In all cases, both TER and RQ values showed that benfluralin corresponds to a higher risk than S-metolachlor for soil organisms.

Exposure Level and Risk Impact Assessment of Pesticides and Veterinary Drugs in Aquaculture Environment

To explore the exposure level of pesticides and veterinary drugs in an aquaculture environment and its impact on the ecological environment, this study took the aquaculture environment in Shanghai as an example, and samples of water, sediment, and inputs from 40 major aquaculture farms were collected from July to September 2022. The types and contents of pesticides and veterinary drugs were screened using high-performance liquid chromatography-electrostatic field orbital ion trap mass spectrometry, and the risk quotient (RQ) method was used to assess the ecological risk of pesticide contamination in water and sediment. The results showed that 13 drugs were screened out from 204 samples (72 samples of water, 72 samples of mud, and 60 samples of input), namely, chlorpromazine, carbendazim, thiophanate, diazepam, florfenicol, simazine, amantidine, diazepam, trimethoprim, ciprofloxacin, ofloxacin, mebendazole, and enrofloxacin. Among them, 12 species were found in water samples with concentrations ranging from 0.016 μg·L-1 to 2.084 μg·L-1. The concentrations of seven species in the mud samples ranged from 0.018 μg·kg-1 to 23.101 μg·kg-1. The results showed that there were four types of inputs, ranging from 1.979 μg·kg-1 to 101.940 μg·kg-1. Seven drugs were found in both water and sediment. The risk quotient (RQ) results showed that there were some high and middle risks in both water and sediment samples of aquaculture farms, and the ecological risks of carbendazim were the highest in both water and sediment samples of aquaculture farms; the RQ values were 3.848 and 1.580, respectively, indicating high risk. It is suggested to strengthen the control and management of exogenous pesticides and veterinary drugs in aquaculture environments to protect the ecosystem health of the aquaculture environment.

Spatiotemporal Occurrence of Organophosphate Esters in the Surface Water and Sediment of Taihu Lake and Relevant Risk Assessment

Aiming to explore the spatiotemporal occurrence of organophosphate esters (OPEs) in the aquatic environment of Taihu Lake and to assess the relevant ecological risk, monomeric and oligomeric OPEs in the surface water and sediment of Taihu Lake were determined using solid phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry. The target monomeric OPEs included chlorinated OPEs, alkyl OPEs, and aryl OPEs. There was no significant difference in the spatial distribution of OPEs in water and sediment between the pollutant-impacted and less-impacted zones. The average concentrations of OPEs in summer and winter were, respectively, 752.7 and 498.5 ng·L-1 in water and 124.0 and 54.5 ng·g-1 in sediment, indicating an obvious seasonal difference, especially for the monomeric OPEs. The OPEs levels in both the water and sediment were ranked in the order of chlorinated OPEs &gt; alkyl OPEs &gt; aryl OPEs≈oligomeric OPEs. The pseudo-partitioning coefficients (Kd) of OPEs between the sediment and surface water of Taihu Lake were much higher in summer (0.05-4.17 L·g-1) compared to those in winter (0.02-3.47 L·g-1) and were significantly positively correlated with the lg Kow values of OPEs. Based on the median concentrations of OPEs in the water of Taihu Lake, the ecological risk of OPEs was assessed by risk quotient (RQ) values, which indicated a medium risk at an RQ level of 0.34 during winter and 0.35 during summer. The assessment results showed that the risk ranking of OPEs was consistent with that of their concentrations, and the monomeric OPEs posed a higher ecological risk in summer compared to that in winter. Although the ecological risk of oligomeric OPEs in this study was not serious and was lower than that of monomeric OPEs, it is an urgent requirement to conduct ecotoxicology studies on oligomeric OPEs in the future since available data is highly limited at present.

Effects of low concentration of gallic acid on the growth and microcystin production of Microcystis aeruginosa

Gallic acid (GA) is an allelochemical that has been utilized in high concentrations for the management of harmful algal blooms (HABs). However, there is limited knowledge regarding its impact on the growth of M. aeruginosa as the GA concentration transitions from high to low during the HABs control process. This study has revealed that as the GA concentration decreases (from 10 mg/L to 0.001 μg/L), a dose-response relationship becomes apparent in the growth of M. aeruginosa and microcystin production, characterized by high-dose inhibition and low-dose stimulation. Notably, at the concentration of 0.1 μg/L GA, the most significant growth-promoting effect on both growth and MCs synthesis was observed. The growth rate and maximum cell density were increased by 1.09 and 1.16 times, respectively, compared to those of the control group. Additionally, the contents of MCs synthesis saw a remarkable increase, up by 1.85 times. Furthermore, lower GA concentrations stimulated the viability of cyanobacterial cells, resulting in substantially higher levels of reactive oxygen species (ROS) and chlorophyll-a (Chl a) compared to other concentrations. Most importantly, the expression of genes governing MCs synthesis was significantly upregulated, which appears to be the primary driver behind the significantly higher MCs levels compared to other conditions. The ecological risk quotient (RQ) value of 0.1 μg/L GA was the highest of all experimental groups, which was approximately 30 times higher than that of the control, indicating moderate risk. Therefore, it is essential to pay attention to the effect of M. aeruginosa growth, metabolism and water ecological risk under the process of reducing GA concentration after dosing during the HABs control process.

Residue degradation and metabolism of dinotefuran and cyromazine in Agrocybe aegerita: A risk assessment from cultivation to dietary exposure

Sensitive, simple and quick methods for determination of dinotefuran, cyromazine, and the metabolites 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine (DN), 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF), and melamine in Agrocybe aegerita were established and validated by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The dissipation and residues of these compounds in A. aegerita were investigated. The field results showed that dinotefuran and cyromazine dissipated rapidly with half-lives ranging from 24.9 h to 38.5 h. The terminal residues of total dinotefuran (the sum of dinotefuran and its metabolites), cyromazine, and melamine in fresh mushroom samples collected with sampling intervals of 3 d to 6 d ranged from 0.089 to 0.652 mg/kg, 0.593 to 2.054 mg/kg, and 0.002 to 0.005 mg/kg, respectively. During the drying processes of A. aegerita, the processing factors of dinotefuran, cyromazine, DN, UF, and melamine were 0.028, 0.012, 0.301, 0.002, and 0.001, respectively. Given that cyromazine and dinotefuran are not registered for use on A. aegerita, dietary risk was assessed. Based on a consumption survey, risk quotient (RQ) values significantly below 1 implied that the risk of A. aegerita consumption was acceptable, although the risk for children was relatively higher. The findings could provide valuable guidance for the appropriate use of these insecticides in A. aegerita cultivation and serve as a scientific reference for setting corresponding maximum residue limits (MRL) in China.

Safe Application of 75% Trifloxystrobin-Tebuconazole as Water-Dispersible Granules in Paddy Based on Residue and Dietary Risk Assessment.

The present study describes the development of a highly effective approach for determining the residue distribution and dissipation of trifloxystrobin and tebuconazole, and their risk assessment in brown rice, husk, straw, and grain using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The current study provides considerable novel information regarding the safe utilization of a mixture of trifloxystrobin and tebuconazole in paddy production. The samples demonstrated a range of mean recoveries between 72% and 86%, with a 1.1-9.2% relative standard deviation (RSD). The limits of quantification (LOQ) and half-lives (t1/2) for brown rice, husk, straw, and grain were, respectively, established to be 0.001-0.01 mg/kg and 4.1-7.7 days. The concentrations of terminal residues in the brown rice, husk, straw, and grain were, respectively, found to be 0.02-0.05, 0.03-0.11, 0.02-0.07, and 0.02-0.05 mg/kg after being treated twice at 168.75 g a.i./ha with 21 and 28 days of pre-harvest intervals (PHIs). Trifloxystrobin and tebuconazole presented a non-negligible chronic risk to human subjects, as evidenced by a risk quotient (RQ) value of less than 1.

Pesticide screening of surface water and soil along the Mekong River in Cambodia

Widespread use of pesticides globally has led to serious concerns about environmental contamination, particularly with regard to aquatic and soil ecosystems. This work involved investigating concentrations of 64 pesticides in surface-water and soil samples collected in four provinces along the Mekong River in Cambodia during the dry and rainy seasons (276 samples in total), and conducting semi-structured interviews with local farmers about pesticide use. Furthermore, an ecological risk assessment of the detected pesticides was performed. In total, 56 pesticides were detected in surface water and 43 in soil, with individual pesticides reaching maximum concentrations of 1300 ng/L in the surface-water samples (tebufenozide) and 1100 ng/g dry weight in the soil samples (bromophos-ethyl). The semi-structured interviews made it quite evident that the instructions that farmers are provided regarding the use of pesticides are rudimentary, and that overuse is common. The perceived effect of pesticides was seen as an end-point, and there was a limited process of optimally matching pesticides to pests and crops. Several pesticides were used regularly on the same crop, and the period between application and harvest varied. Risk analysis showed that bromophos-ethyl, dichlorvos, and iprobenfos presented a very high risk to aquatic organisms in both the dry and rainy seasons, with risk quotient values of 850 for both seasons, and of 67 in the dry season and 78 in the rainy season for bromophos-ethyl, and 49 in the dry season and 16 in the rainy season for dichlorvos. Overall, this work highlights the occurrence of pesticide residues in surface water and soil along the Mekong River in Cambodia, and emphasizes the urgent need for monitoring and improving pesticide practices and regulations in the region.