Concentrations Of Chlorothalonil Research Articles

Exposure to a fungicide for a field-realistic duration does not alter bumble bee fecal microbiota structure.

Social bees are frequently exposed to pesticides when foraging on nectar and pollen. Recent research has shown that pesticide exposure not only impacts social bee host health but can also alter the community structure of social bee gut microbiotas. However, most research on pesticide-bee gut microbiota interactions has been conducted in honey bees; bumble bees, native North American pollinators, have received less attention and, due to differences in their ecology, may be exposed to certain pesticides for shorter durations than honey bees. Here, we examine how exposure to the fungicide chlorothalonil for a short, field-realistic duration alters bumble bee fecal microbiotas (used as a proxy for gut microbiotas) and host performance. We expose small groups of Bombus impatiens workers (microcolonies) to field-realistic chlorothalonil concentrations for 5 days, track changes in fecal microbiotas during the exposure period and a recovery period, and compare microcolony offspring production between treatments at the end of the experiment. We also assess the use of fecal microbiotas as a gut microbiota proxy by comparing community structures of fecal and gut microbiotas. We find that chlorothalonil exposure for a short duration does not alter bumble bee fecal microbiota structure or affect microcolony production at any concentration but that fecal and gut microbiotas differ significantly in community structure. Our results show that, at least when exposure durations are brief and unaccompanied by other stressors, bumble bee microbiotas are resilient to fungicide exposure. Additionally, our work highlights the importance of sampling gut microbiotas directly, when possible.IMPORTANCEWith global pesticide use expected to increase in the coming decades, studies on how pesticides affect the health and performance of animals, including and perhaps especially pollinators, will be crucial to minimize negative environmental impacts of pesticides in agriculture. Here, we find no effect of exposure to chlorothalonil for a short, field-realistic period on bumble bee fecal microbiota community structure or microcolony production regardless of pesticide concentration. Our results can help inform pesticide use practices to minimize negative environmental impacts on the health and fitness of bumble bees, which are key native, commercial pollinators in North America. We also find that concurrently sampled bumble bee fecal and gut microbiotas contain similar microbes but differ from one another in community structure and consequently suggest that using fecal microbiotas as a proxy for gut microbiotas be done cautiously; this result contributes to our understanding of proxy use in gut microbiota research.

Unsaturated Vertical Flow Constructed Wetland for Chlorothalonil Remediation with Target Application in Ethiopian Floriculture Industry

The Ethiopian floriculture industry produces large amounts of wastewater, which requires treatment systems with lower retention times, higher hydraulic flow, and higher hydraulic loading rates (HLRs). Unsaturated vertical flow constructed wetlands (UVF-CWs), which represent these characteristics, have not been studied in depth for chlorothalonil remediation from wastewater. In this study, six UVF-CWs and nine pumping stations were organized into three experimental groups as three independent two-stage CW systems. The influent was pumped into the first vertical-flow stage, after which the effluent was collected and pumped into the second vertical-flow stage. The stage A and stage B effluents were tested for chlorothalonil removal at three different HLR of 50, 200, and 400 L d−1 m−2 and two influent chlorothalonil concentrations of 100 and 500 µg L−1. The chlorothalonil levels for the stage A effluent at an HLR of 50 L d−1 m−2 for both influent chlorothalonil concentrations were below the detection limit of 0.08 µg L−1. A maximum chlorothalonil concentration of 7.9 and 196 µg L−1 was observed in the stage A effluent for influent concentrations of 100 and 500 µg L−1, respectively. The chlorothalonil levels for the stage B effluent were all below the detection limit of 0.08 µg L−1. A final chlorothalonil removal efficiency of at least 99.9% was observed for both influent chlorothalonil concentrations at the three HLRs used. These results demonstrated that UVF-CWs represent a viable solution for chlorothalonil remediation in the Ethiopian floriculture industry.

Acute chlorothalonil exposure had the potential to influence the intestinal barrier function and micro-environment in mice

The intestinal barrier maintains intestinal homeostasis and metabolism and protects against harmful pollutants. Some environmental pollutants seriously affect intestinal barrier function. However, it remains unclear whether or how chlorothalonil (CTL) impacts the intestinal barrier function in animals. Herein, 6-week-old male mice were acutely exposed to different CTL concentrations (100 and 300 mg/kg BW) via intragastric administration once a day for 7 days. Histopathological examination revealed obvious inflammation in the mice’ colon and ileum. Most notably, CTL exposure increased the intestinal permeability, particularly in the CTL-300 group. CTL exposure reduced the secretion of colonic epithelial mucus and changed the transcription levels of genes bound up with ion transport and ileal antimicrobial peptide (AMP) secretion, indicating intestinal chemical barrier damage. The results of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay and Ki67 staining revealed abnormal apoptosis and increased intestinal epithelial cell proliferation, suggesting that CTL exposure led to cytotoxicity and inflammation. The results of 16S rRNA sequencing revealed that CTL exposure altered the intestinal microbiota composition and reduced its diversity and richness in the colon contents. Thus, acute CTL exposure affected the different intestinal barrier- and gut microenvironment-related endpoints in mice.

Pesticides exposure in pregnant Argentinian women: Potential relations with the residence areas and the anthropometric neonate parameters

Intrauterine environment is the first chemical exposure scenario in life, through transplacental transfer. In this study, the aim was to determine concentrations of organochlorine pesticides (OCPs) and selected current use pesticides in the placentas of pregnant women from Argentina. Socio-demographic information, the mother's lifestyle and neonatal characteristics were also analysed and related to pesticides residue concentrations. Thus, 85 placentas were collected at birth, from an area of intensive fruit production for the international market, in Patagonia Argentina. Concentrations of 23 pesticides including, trifluralin (herbicide), the fungicides chlorothalonil and HCB, and the insecticides chlorpyrifos, HCHs, endosulfans, DDTs, chlordanes, heptachlors, drins and metoxichlor, were determined by GC-ECD and GC-MS. Results were first analysed all together and then grouped by their residential settings, in urban and rural groups. Total mean pesticide concentration was 582.6 ± 1034.4 ng/g lw, where DDTs (325.9 ± 950.3 ng/g lw) and chlorpyrifos (188.4 ± 365.4 ng/g lw) showed a high contribution. Pesticide levels found exceeded those reported in low, middle and high income countries from Europe, Asia and Africa. In general, pesticides concentrations were not associated with neonatal anthropometric parameters. When the results were analysed by residence place, significantly higher concentrations of total pesticides and chlorpyrifos (Mann Whitney test p = 0.0003 and p = 0.032, respectively) were observed in placentas collected from mothers living in rural settings compared to urban areas. Rural pregnant women presented the highest pesticide burden (5.9 μg), where DDTs and chlorpyrifos were the major constituents. These results suggested that all pregnant women are highly exposed to complex pesticide mixtures, including banned OCPs and the widely used chlorpyrifos. Based on the pesticide concentrations found, our results warn of possible health impacts from prenatal exposure through transplacental transfer. This is one of the first reports of both chlorpyrifos and chlorothalonil concentrations in placental tissue, and contributes to the knowledge of current pesticide exposure in Argentina.

Effects of fungicide chlorothalonil on freshwater plankton communities: a microcosm study.

Direct and indirect effects of the fungicide chlorothalonil on aquatic plankton community structure were investigated by exposing plankton to chlorothalonil concentrations of 0.010, 0.025, 0.100, 0.250 and 1.000mg/L over 20days in 18 microcosms (glass tanks having 8 L of pond water). Each treatment was executed in three replicates. Total phytoplankton and zooplankton abundance and chlorophyll-a concentrations in microcosms were measured 5, 10 and 20days after pesticide exposure. Plankton community and taxa response to pesticide concentrations were analyzed using the similarity of percentages procedure (SIMPER) and one-way ANOVA test. The results of the study indicated that highest concentration levels of chlorothalonil exposure had a significant impact on phytoplankton and zooplankton taxa. Phytoplankton taxa Amphora sp. and Staurastrum sp. and zooplankton taxa Moina sp. and copepod Nauplius were highly sensitive to chlorothalonil exposure. Phytoplankton taxa Mougeotia sp. increased with increased chlorothalonil (0.1-1.0mg/L) concentrations, and zooplankton taxa of Aeolosoma sp. showed no significant reduction of individuals in response to pesticide exposure. Results showed that pesticide residues have a direct and rapid impact on phytoplankton and zooplankton community structure. Changes in diversity and species composition induced by pesticides indicate the importance of considering indirect effects of pesticides on the ecological food chain in the aquatic environment.

Fungicide exposure accelerated horizontal transfer of antibiotic resistance genes via plasmid-mediated conjugation

Co-pollution of soil with pesticide residues and antibiotic resistance genes (ARGs) is increasing due to the substantial usage of pesticides and organic fertilizers in greenhouse-based agricultural production. Non-antibiotic stresses, including those from agricultural fungicides, are potential co-selectors for the horizontal transfer of ARGs, but the underlying mechanism remains unclear. Intragenus and intergenus conjugative transfer systems of the antibiotic resistant plasmid RP4 were established to examine conjugative transfer frequency under stress from four widely used fungicides: triadimefon, chlorothalonil, azoxystrobin, and carbendazim. The mechanisms were elucidated at the cellular and molecular levels using transmission electron microscopy, flow cytometry, RT-qPCR, and RNA-seq techniques. The conjugative transfer frequency of plasmid RP4 between Escherichia coli strains increased with the rising exposure concentrations of chlorothalonil, azoxystrobin, and carbendazim, but was suppressed between E. coli and Pseudomonas putida by a high fungicide concentration (10 µg/mL). Triadimefon did not significantly affect conjugative transfer frequency. Exploration of the underlying mechanisms revealed that: (i) chlorothalonil exposure mainly promoted generation of intracellular reactive oxygen species, stimulated the SOS response, and increased cell membrane permeability, while (ii) azoxystrobin and carbendazim primarily enhanced expression of conjugation-related genes on the plasmid. These findings reveal the fungicide-triggered mechanisms associated with plasmid conjugation and highlight the potential role of non-bactericidal pesticides on the dissemination of ARGs.

Multilevel assessment of chlorothalonil sediment toxicity to Latin American estuarine biota: Effects on biomarkers, reproduction and survival in different benthic organisms

Chlorothalonil is an organochlorine compound that has long been used in agriculture. In recent years, this compound has been used as an antifouling booster biocide and its presence has been reported in marine coastal environments, especially in navigational areas. Although sediment can be a sink for chlorothalonil due to high affinity to fine particulate matter, toxicity studies with non-target marine and/or estuarine organisms is focused on waterborne exposure only. This study aimed to determine sediment-borne ecotoxicological effects of chlorothalonil on different benthic organisms of the Latin American biota using a integrative multilevel approach. Marine/estuarine organisms were exposed to sediments spiked with chlorothalonil (from 0 to 10.0 μg g−1) and effects at sub-individual (biochemical biomarkers in Anomalocardia flexuosa), individual (lethal effects to Tiburonella viscana and Artemia salina) and subpopulation levels (Nitokra sp. reproduction) were assessed. Increasing chlorothalonil concentrations in sediment caused increasing ecotoxicological effects in different levels of biological organisation, from biochemical to subpopulation levels. The highest exposure concentrations showed increased biomarkers of effects (lipid peroxidation and DNA damage in gills and/or digestive gland of A. flexuosa), lower fecundity and lower survival of the test organisms. GPx activity associated with LPO levels in the digestive gland suggested a response to the oxidant challenge provided by the biocide. At the lowest concentration (0.001 μg g−1), chlorothalonil detoxification mechanisms and defense against its oxidising action, involving GSH and glutathione-dependent enzymes (GST and GPx) were induced. At intermediate concentrations, there was a tendency of decreasing GSH levels, probably due to conjugation with chlorothalonil, which also affected the activities of the glutathione-dependent enzymes. At the highest tested concentration (10.0 μg g−1), chlorothalonil may have restimulated GSH synthesis in the gills of A. flexuosa, although the prooxidant activity has induced effects. This study contributes to assessing the environmental risk of chlorothalonil in sediment for non-target marine and estuarine organisms.

Human health risk assessment of pesticides in lettuce and spinach grown in urban backyard garden soils

Pesticide residues in lettuce and spinach could be a serious human health concern since the average per capita consumption per day of leafy salad vegetables is ∼60 g. Here, we determined the leftover residues (LoR) of dimethoate, 2,4-D, glyphosate, and chlorothalonil in lettuce and spinach grown in three urban backyard soils to assess their potential human health hazards. Pesticide residues were extracted by QuEChERS method and quantified through LC-MS and LC-DAD. In most cases, residue levels in the vegetable samples were above the EU-MRLs. Soil organic carbon, silt, oxides of iron and aluminium negatively correlated (P < 0.05) with LoR of the pesticides while LoR positively correlated (P < 0.05) with contents of sand and clay, and pH. The estimated short-term intake (ESTI) values (mg kg1 day1) for dimethoate, 2,4-D, glyphosate and chlorothalonil even at recommended doses in case of lettuce and spinach were 0.003–9.90 × 103 and 0.005–37.10 × 103 for adults and children, respectively, whereas the corresponding estimated daily intake (EDI) values were 0.007–9.58 × 103 and 0.03–35.90 × 103. Accordingly, the calculated values of non-cancer acute health hazard (aHI <100%) and hazard quotient (HQ <1) indicated that consumption of salad vegetables grown in soils spiked with pesticides at doses recommended in agriculture does not pose human health risks. On the other hand, both lettuce and spinach grown in soils at ten-fold higher concentrations of dimethoate or chlorothalonil exceeded the threshold limit of aHI (>100%) for children and HQ > 1 for both children and adults, suggesting their potential acute and chronic health hazards. The present study, for the first time, provides health awareness about the consumption of pesticide-contaminated leafy vegetables grown in urban backyard garden soils.

Effects of Chlorothalonil Application on the Physio-Biochemical Properties and Microbial Community of a Yellow–Brown Loam Soil

To gain better knowledge of the effects of residual chlorothalonil on soil characteristics and soil microbial communities, we evaluated the dissipation of chlorothalonil and the effects of different chlorothalonil concentrations on soil respiration, enzyme activities, and microbial community structure in yellow–brown loam soils. Bacterial and fungal soil communities were examined using traditional plate counting and polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) methods. Soil properties and the results of DGGE band analysis were both used to estimate the status of the soil microbial ecosystem. The results show that residual chlorothalonil has considerable effects on soil respiration, enzymatic activities, and microbial community structure. In particular, soil respiration and phosphatase activities were increased, while saccharase activity, microbial biomass, and microbial community diversity were decreased by increasing levels of chlorothalonil treatment. Correlation analyses revealed that the application of chlorothalonil was significantly correlated with the change of the soil respiration, urease activity, sucrase activity, soil culturable bacteria, and culturable fungi biomass. We conclude that residual chlorothalonil is directly related to soil respiration, enzyme activities, and microbial community structure.

Long-term exposure to antifouling biocide chlorothalonil modulates immunity and biochemical and antioxidant parameters in the blood of olive flounder

In this study, the potential effects of 30-day exposure to environmentally relevant concentrations of chlorothalonil (0, 5, 10, and 20 μg L-l) were tested in the blood of the economically important olive flounder, Paralichthys olivaceus, using biochemical endpoints. Significant decreases in the enzymatic activities of immunity markers, alternative complements, and lysozymes were detected in the fish exposed to 10 or 20 μg L-l of chlorothalonil at day 20 or 30. The total immunoglobulin content was lowered in response to 20 μg L-l chlorothalonil at day 10 and 20, even when later exposed to 5 μg L-l at day 30. Among the essential blood components, the cortisol level was increased in response to chlorothalonil throughout the study with a decrease in white blood cells, while no changes were observed in hemoglobin, red blood cells, total protein concentration, and glucose in all exposures. The enzymatic activities of the three hepatic toxicity markers, alanine transferases, aspartate transaminase, and alkaline phosphatase, increased by 10 and/or 20 μg L-l of chlorothalonil. Significant oxidative stress was induced by chlorothalonil in the fish exposed to 10 or 20 μg L-l of chlorothalonil, as revealed by increased malondialdehyde and fluctuating glutathione levels with increase in the enzymatic activities of antioxidant defense system, including catalase and superoxide dismutase, during exposure. Taken together, these results suggest that long-term exposure to environmentally relevant concentrations of chlorothalonil can affect susceptibility to pathogens through immunosuppression, hepatic toxicity, and oxidative stress in olive flounder. These results can contribute to the monitoring of aquatic environments and ecotoxicological research through the measurement of blood components against waterborne chlorothalonil.

The effect of chlorothalonil on Saccharomyces cerevisiae under alcoholic fermentation

Chlorothalonil is a broad-spectrum fungicide largely used for the control of several diseases of grapevines. With a moderate persistence in plants, soil and, water, it can be carried to grape musts, particularly when applied to control grape rot diseases. This work aimed to determine the effect of chlorothalonil on Saccharomyces cerevisiae under fermentative conditions using a flow cytometry approach. Yeasts were cultivated in synthetic must with different concentrations of chlorothalonil (0 to 60 μM) and evaluated for culture-ability, membrane integrity, reactive oxygen species (ROS) accumulation, mitochondrial membrane potential, metacaspase activity, ATP, nonprotein SH and, SH-proteins. The results confirmed the oxidation of nonprotein SH, including glutathione, and the binding of the fungicide with sulfhydryl proteins, which led to changes in the cell and mitochondrial membranes that result in the necrotic death of part of the yeast population, and a reduction in metabolic activity. Moreover, the reduction in glutathione-SH concentration was responsible for the increase in ROS which in turn triggers metacaspase-dependent apoptotic cell death. Cells that escape death adapt and began to grow and ferment after a dose-dependent lag-phase period, exhibiting an almost normal fermentative behavior thereafter. Moreover, was observed unexpected protection of chlorothalonil sub-dosages on yeast cell membrane integrity during alcoholic fermentation. This study contributed insights into how chlorothalonil leads the non-target organism S. cerevisiae to cell death and explores the effect of the fungicide during alcoholic fermentation.

Role of Yeasts in the Cranberry Fruit Rot Disease Complex.

Cranberry fruit rot (CFR) is an economically important disease caused by at least 10 species of filamentous fungi. Despite the application of fungicides, incidence of CFR is sometimes high, raising the possibility of a role for microbes other than fungi in the CFR complex. Isolation of microbes from rotten berries on culture media that favor either bacteria or yeasts resulted in mucoid colonies from <15% of dry-harvested rotten berries but up to 60% of wet-harvested berries. The mucoid colonies were identified as yeasts, primarily in the family Saccharomycetaceae. Inoculation of sound berries with three yeasts, Hanseniaspora uvarum, Pichia fermentans, and Pichia terricola, resulted in significantly higher incidence and severity of rot symptoms compared with mock-inoculated controls; these yeasts were recovered from inoculated berries, providing evidence of their pathogenicity. The minimum concentrations of azoxystrobin, chlorothalonil, and prothioconazole that resulted in 80% inhibition of growth compared with untreated controls (MIC80) were determined for a subset of yeasts. In general, MIC80s were higher for azoxystrobin and prothioconazole (usually >64 µg/ml) than for chlorothalonil (usually ≤1 µg/ml). To complement culture-dependent studies, DNA was isolated from wet- and dry-harvested rotten berries, and fungi were identified to the level of family by high-throughput sequencing of the fungal internal transcribed spacer region. There were no fungal families consistently detected among samples by one method (culturing or high-throughput sequencing) and missed by the other that have not previously been reported in cranberry; however, some fungal families were found to be more abundant by one method versus the other. Harvest method (wet or dry) had a significant effect on the composition of fungal communities of rotten berries (P < 0.001), and operational taxonomic units representing the Saccharomycetaceae were more abundant in wet- than dry-harvested berries. Taken together, the results suggest that some yeasts are pathogenic to cranberry and may be especially relevant in wet-harvested berries.

In situ monitoring of chlorothalonil and lambda-cyhalothrin by polyethylene passive samplers under fields and greenhouse conditions.

Sampling is a critical step in pesticide atmospheric analysis. Passive sampling offers advantages of inexpensive and convenient air monitoring. Polyethylene films (PE) were used as a passive sampler at multiple heights in greenhouse and agricultural field for 15 days to trap atmospheric chlorothalonil and lambda-cyhalothrin in the months of May and July. Among the two PE film thicknesses (20 and 80 μm), 20 μm PE was the most effective at absorbing target pesticides from air and attains equilibrium stage earlier than 80 μm PE film. After approximately 240 h of PE exposure in greenhouse and fields, chlorothalonil and lambda-cyhalothrin reached an equilibrium stage of partitioning between air and PE. Atmospheric concentrations of chlorothalonil (p < 0.01) and lambda-cyhalothrin (p < 0.001) at 1.5 m height were higher with the concentrations of 1855.59 ± 243.85 ng/m3 and 3682.11 ± 316.71 ng/m3, respectively, in the month of May as compared to the other three respective heights. The concentrations of chlorothalonil in air at 2 m height (1587.27 ± 284.19 ng/m3) were slightly higher than 0.5 m (1392.28 ± 205.09 ng/m3). Atmospheric concentrations of lambda-cyhalothrin at 2 m (3178.26 ± 299.29 ng/m3) were significantly lower than the other heights (p < 0.05). The greenhouse air concentrations of chlorothalonil and lambda-cyhalothrin in the months of May (1855.59 ± 243.85 and 3682.11 ± 316.71 ng/m3, respectively) and July (1749.33 ± 378.61 and 3445.08 ± 390.32 ng/m3, respectively) were higher than fields. The results indicate the usability of PE films to monitor chlorothalonil and lambda-cyhalothrin and potential other semi-volatile pesticides in agricultural fields.

Health risks of chlorothalonil, carbendazim, prochloraz, their binary and ternary mixtures on embryonic and larval zebrafish based on metabolomics analysis

Chlorothalonil (CTL), carbendazim (CBZ), and prochloraz (PCZ) are fungicides widely used in many countries. The use of these fungicides raises concerns because they are often applied together or used in the same agricultural area. However, the toxicity of these fungicides or mixtures, especially to aquatic organisms, has received limited attention. Here, embryonic and larval zebrafish were exposed to indicated concentrations of CTL, CBZ, and PCZ and their binary (CTL+CBZ, CTL+PCZ and CBZ+PCZ) and ternary (CTL+CBZ+PCZ) mixtures for 24 h. Based on metabolomics analysis, we observed that hundreds of metabolites were altered, and glycolysis metabolism and amino acid metabolism were the two most affected pathways. Interestingly, a total of 9 and 26 metabolites changed significantly in embryos and larvae treated with all fungicides, respectively. Among these altered metabolites, 2-aminoadipic acid (2-AAA) levels increased significantly in all groups, indicating that 2-AAA potentially represents a useful biomarker for evaluating the toxicity of fungicides. Furthermore, the joint effects of CTL+PCZ on embryos and larvae, especially on amino acid metabolism, were weaker than those in other groups, but combined treatment did not influence individual fungicidal activity. Data acquired from metabolomics provided important insight for understanding the mechanism by which fungicides or their mixtures affect zebrafish.

Chlorothalonil causes redox state change leading to oxidative stress generation in Danio rerio

A diverse range of chemicals are used in agriculture to increase food production on a large scale, and among them is the use of pesticides such as chlorothalonil, a broad-spectrum fungicide used in the control of foliar fungal diseases. This study aimed to elucidate the effects of chlorothalonil on biochemical biomarkers of oxidative stress in tissues of the fish Danio rerio. To achieve this, animals were exposed for 4 and 7 days, to nominal concentrations of chlorothalonil at 0 μg/L (DMSO, 0.001%), 0.1 μg/L and 10 μg/L, and after the exposure period, the tissues (gills and liver) were removed for biochemical analysis. Antioxidant capacity against peroxyl radicals (ACAP) and enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutamate cysteine ligase (GCL), were evaluated in both tissues. In addition, the concentration of reactive oxygen species (ROS), reduced glutathione (GSH) and lipid peroxidation (LPO) levels were also analysed. A significant increase in ROS concentration, ACAP levels, GST and GCL activities and a significant reduction of LPO levels in gills exposed to the highest concentration were observed after 4 days. However, there was a significant reduction of ACAP and CAT activity, as well as a significant increase of GST activity and LPO levels in gills exposed to the lower concentration after 7 days. The liver was less affected, presenting a significant reduction in CAT activity and LPO levels after 4 days. However, a significant increase in SOD activity and LPO levels occurred after 7 days. These results indicate that chlorothalonil, after 4 days, caused activation of the antioxidant defence system in gills of animals exposed to the highest concentration. However, after 7 days, the lowest concentration of this compound caused oxidative stress in this same organ. Also, the results show that gills were more affected than the liver, probably because gills can be involved in chlorothalonil metabolisation. Therefore, it is possible that the liver could be exposed to lower chlorothalonil concentrations or less toxic metabolites due to the metabolism taking place in the gills.

Pesticide residues in soils planted with Panax notoginseng in south China, and their relationships in Panax notoginseng and soil.

In this study, 73 samples from soils planted with Panax notoginseng and six P. notoginseng samples were collected in Yunnan Province to investigate the residual levels of six pesticides and their relationships with P. notoginseng and soil. All six pesticides were detected in the soils planted with P. notoginseng located in three regions of Shilin, Kaiyuan, and Yanshan. The detection frequencies of the pesticides in the soils followed the order: quintozene (100%)>iprodione (96%)>procymidone (69%)>chlorothalonil (51%)>pyrimethanil (49%)>pyraclostrobin (29%). The median concentrations of iprodione, pyraclostrobin, pyrimethanil, quintozene, procymidone, and chlorothalonil were 46.40, 6.4, 3.1, 2.86, 2.69, and 0.24μg/kg, respectively. The mean concentrations of pesticides in the three regions followed the order: Kaiyuan>Shilin>Yanshan, except for iprodione. Furthermore, the concentrations of pesticide residues in soils in each region followed the order: soils never planted with P. notoginseng<soils previously planted with P. notoginseng<soils currently planted with P. notoginseng. The concentration of chlorothalonil in P. notoginseng followed the order: root>stem>leaf, whereas those of the other five pesticides followed the opposite order: root<stem<leaf. There were significant positive correlations between the mean concentrations of pesticides in P. notoginseng and those in the corresponding soils. These results indicate that the rational application of pesticides in P. notoginseng cultivation would be effective for reducing the accumulation of pesticides in P. notoginseng to protect people from the harmful effects of residual pesticides.

A pulsed-dose study evaluating chronic toxicity of chlorothalonil to fish: A case study for environmental risk assessment.

Chlorothalonil is a fungicide which is highly toxic to aquatic organisms. However, in natural aquatic environments, it is very rapidly degraded, with a half‐life typically in hours, reducing exposure of aquatic organisms and the potential for effects. In standard regulatory studies looking at the chronic toxicity of chlorothalonil to fathead minnow, the most sensitive endpoint was fecundity. A standard fish full–life cycle study, where chlorothalonil concentrations were maintained constant throughout, resulted in a no‐observed‐effect concentration (NOEC) of 1.4 µg/L. Comparing peak modeled exposure concentrations to this NOEC can result in the chronic risk to fish being considered unacceptable. The present study investigated the effect on fecundity in fathead minnow using a fish short‐term reproduction assay. Five different exposure profiles were employed with time‐varying concentrations based on realistic worst‐case modeled environmental exposure profiles, multiplied by an assessment factor of 10, which resulted in maximum measured concentrations up to 15.5 µg/L. There were no effects on fecundity from any of the exposure profiles tested. Therefore, based on these more realistic exposure profiles, the chronic risk to fish could be considered acceptable if these exposures were deemed to be representative of the worst case. Environ Toxicol Chem 2019;38:1549–1559. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Application of microbial fuel cells in the degradation of 2,4,5,6-tetrachloroisophthalonitrile (chlorothalonil)

Pesticide’s persistence in the environment due to the relatively slow degradation mechanism leads to their bio-accumulation which in turn has adverse impacts on human health. Bio-remediation involves utilization of microbes from nature to the breakdown of organic molecules. The purpose of this study is to investigate the potential of microbes in degrading chlorothalonil. Aerobic-anaerobic combined conditions in an H-shaped double chamber microbial fuel cell (MFC) were employed for the breakdown of chlorothalonil. Decomposing tomatoes were used as the major substrate with their proximate properties being analyzed using standard method. Glucose loaded with different concentrations of chlorothalonil was introduced to the cells on day 10 when voltage production had stabilized. The voltage and current generated were monitored using a digital multi-meter while pesticide concentrations were obtained using a UV-Vis spectrophotometer. The highest voltage readings were obtained on day 9 of degradation, with values ranging from 0.463 to 0.537 V. The current ranged from 0.002 to 0.076 mA. Higher voltage and current values were recorded in solutions with lower pesticide concentration. The obtained degradation level was highest in 10 g glucose at 95.95 and 98.75% for day 10 and 20 respectively. The lowest breakdown was observed in the cells without glucose at 10.54 and 31.04% on day 10 and 20 respectively. The results demonstrate that MFC technology can be employed in mineralization of chlorinated pesticides as an alternative for incineration and photo-degradation

Chlorothalonil induces oxidative stress and reduces enzymatic activities of Na+/K+-ATPase and acetylcholinesterase in gill tissues of marine bivalves.

Chlorothalonil is a thiol-reactive antifoulant that disperses widely and has been found in the marine environment. However, there is limited information on the deleterious effects of chlorothalonil in marine mollusks. In this study, we evaluated the effects of chlorothalonil on the gill tissues of the Pacific oyster, Crassostrea gigas and the blue mussel, Mytilus edulis after exposure to different concentrations of chlorothalonil (0.1, 1, and 10 μg L−1) for 96 h. Following exposure to 1 and/or 10 μg L−1 of chlorothalonil, malondialdehyde (MDA) levels significantly increased in the gill tissues of C. gigas and M. edulis compared to that in the control group at 96 h. Similarly, glutathione (GSH) levels were significantly affected in both bivalves after chlorothalonil exposure. The chlorothalonil treatment caused a significant time- and concentration-dependent increase in the activity of enzymes, such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR), in the antioxidant defense system. Furthermore, 10 μg L−1 of chlorothalonil resulted in significant inhibitions in the enzymatic activity of Na+/K+-ATPase and acetylcholinesterase (AChE). These results suggest that chlorothalonil induces potential oxidative stress and changes in osmoregulation and the cholinergic system in bivalve gill tissues. This information will be a useful reference for the potential toxicity of chlorothalonil in marine bivalves.

An investigation of environmental concentrations of atrazine, chlorothalonil, and fipronil in a Mississippi River-influenced marsh in southern Louisiana

The pesticides atrazine, chlorothalonil, and fipronil are common surface water contaminants due to their high rates of application and their chemical properties. This study investigates the introduction of contaminants into coastal wetlands via the Bayou Lamoque Mississippi River control structure in Plaquemines Parish, Louisiana; results serve as a model for future studies regarding contaminant introduction from freshwater diversions aimed at Gulf Coast restoration. A protocol for environmental sampling using Continuous Low-level Aquatic Monitoring (C.L.A.M.) C-18 disks is described, along with effective solid phase extraction (SPE) and gas chromatography mass spectrometry (GC/MS) methodology for the determination of atrazine, chlorothalonil, and fipronil in surface water. Average concentrations of atrazine and chlorothalonil inside the Bayou Lamoque freshwater diversion structure for the months of June – October 2016, were 33.3 ng l−1 and 3.5 ng l−1, respectively. Fipronil was not detected in concentrations exceeding its method detection limit of 1.26 ng l−1. The detected concentrations are innocuous to non-target organisms based on current ecotoxicity data, and are likely a result of runoff from nearby upstream agricultural and residential land.