Pesticide Active Ingredients Research Articles

The Use of Thyme (Thymus vulgaris) Essential Oil for Controlling Cercospora Leaf Spot (Cercospora beticola) on Sugar Beets (Beta vulgaris)

Decreasing efficacy of fungicides and the withdrawal of further hazardous active ingredients in pesticides from use have prompted the search for alternative methods of crop protection. Essential oils (EOs) are secondary metabolites of plants and have been proven to show antibacterial, antifungal, and pest-repellent properties. This study was undertaken to determine the activity of grapefruit, rosemary, pine, sage, and thyme EOs against the fungus Cercospora beticola, which is the most dangerous pathogen of sugar beet and the causal agent of Cercospora leaf spot. According to the determined Minimum Inhibitory Concentration (MIC), thyme EO was found the most effective against C. beticola. For most of the fungal isolates tested, the MIC of this EO was 0.313 mL/L. Thyme EO also inhibited the growth of multi-resistant isolates. Based on the results obtained, thyme EO was subjected to further testing in field conditions, where its efficiency in controlling C. beticola was also proven. The results indicate that the use of thyme EO may be a promising method for the protection of sugar beets, although it requires further optimization in the context of its inclusion in sustainable protection programs assuming a reduced number of synthetic fungicide treatments.

Aquatic hazard and risk posed by four pesticides detected in waterways discharging to the Great Barrier Reef, Australia: Part 2. Hazard and risk assessment

Pesticide active ingredients (PAIs) are regularly detected in the rivers, creeks, wetlands, and inshore waterways that discharge to the Great Barrier Reef (GBR) lagoon. Pesticide active ingredients detected above ecologically protective concentrations may pose a hazard and risk to aquatic species. The ability to assess this hazard and risk is reliant on the availability of water quality guidelines, which are only available for a limited number of PAIs detected in GBR catchment waterways. Unendorsed guideline values, known as ecotoxicity threshold values (ETVs) were developed in part one of this study for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. In the current study, the hazard and risk posed by these PAIs was assessed by comparing the ETVs to environmental monitoring data from the Great Barrier Reef Catchment Loads Monitoring Program. Exceedances of the concentrations that should protect 99 % of aquatic species (i.e., PC99) were observed for all four pesticides. Detected concentrations of 4-hydroxychlorothalonil, carbendazim and methoxyfenozide exceeded the PC95 ETV, however no exceedances of the PC95 were observed for dimethoate. The hazard quotient (HQ) method was used to identify high hazard sites across the GBR catchment area. In total, six sites were identified as having concentrations that exceeded the PC95 ETVs. For 4-hydroxychlorothalonil, the risk to aquatic species based on the 95th percentile concentrations ranged from 3 to 13 %, 1 to 8 % for carbendazim and 2 to 8 % for methoxyfenozide. Detected concentrations of carbendazim were two orders of magnitude higher than concentrations that are reported to induce behavioural effects in some fish species. Considering that detected concentrations of three of the four PAIs individually pose a potential risk to aquatic species, their contributions to pesticide mixture toxicity should be further assessed.

OXIDATION OF 4-METHYLPYRIDINE ON V-Cr-O CATALYST

Isonicotinic acid derivatives are used in the development of new antibacterial agents, active ingredients in pesticides and herbicides. In addition, isonicotinic acid is a precursor for the synthesis of isoniazid, one of the most effective anti-TB drugs. Considering the importance of isoniazid in the treatment of tuberculosis, improving methods of synthesizing isonicotinic acid has a direct impact on the availability and cost of this life-saving drug. The goal of this work was to investigate the efficiency of V-Cr-O catalyst in the oxidation of 4-methylpyridine to produce isonicotinic acid, to study its composition and properties. Research methods. Methods of chemical analysis, scanning electron microscope (SEM), Raman spectroscopy were applied. Results and Discussion. In this work, the processes of isonicotinic acid synthesis by oxidation of 4-methylpyridine on the V-Cr-O catalyst were studied. Analysis of the obtained results showed that with an increase in the water feed, there is a general tendency towards a decrease in the conversion of 4-methylpyridine at all temperatures. For example, at a temperature 300oC, the degree of conversion drops from 91.72% at 1.79 g/h to 84.20% at 6.6 g/h. The yield of isonicotinic acid increases as the amount of water rises, reaching its peak at 47.46% with a temperature of 360°C and a water supply of 6.6 g/h. In contrast, the minimum yield is only 15.27% at 280°C with a water supply of 1.79 g/h. This highlights the positive correlation between water supply and yield, especially at higher temperatures.

Influence of nanopesticide surface chemistry on adsorption to plant cuticle and wax layer: The role of zeta potential and wetting

Nanopesticidal adsorption on plant surfaces is a critical determinant of their application efficacy, persistence, and ecological impact. In this study, we systematically investigate the impact of surface chemistry on the attachment of nanopesticides for seven different nanocarriers: ethyl lauroyl arginate (ELA, cationic), cocamidopropyl betaine (CAPB, zwitterionic), tween 80 (TW80, nonionic), β-cyclodextrin (βCD), sodium dodecyl sulfate (SDS, anionic), whey protein isolate (WPI), and poloxamer 407 (PXL, nonionic). Azadirachtin from neem seed extract was employed as a model pesticide active ingredient. The nanopesticides were characterized using dynamic light scattering, UV–visible spectroscopy, static contact angle (SCA, θ), and zeta (ζ) potential measurements. Pepper leaves (ζ = −11.6 mV) and candelilla wax (ζ = −2.6 mV) films were utilized to analyze the effect of nanocarrier chemical composition on nanopesticide adsorption. Fluorescence microscopy was utilized to quantify the adsorption of nanopesticides (with fluorophore tagging) on the substrates. It was found that the choice of nanocarrier significantly influenced the adsorption behavior. Nanopesticides with ELA corona, which was cationic with a zeta potential of ∼+19 mV and θ of ∼ 61°, exhibited the highest affinity towards the leaf cuticle and wax substrates, attributed to favorable electrostatic interactions forces. Conversely, nanopesticides with SDS (ζ = −48 mV; θ = 45°), WPI (ζ = −24 mV; θ = 54°), and PXL (ζ = −31 mV; θ = 64°) corona demonstrated the least adsorption. These findings indicate a weak correlation between the wetting behavior of nanopesticide suspensions and nanopesticide adsorption on plant and wax surfaces, as well as a strong correlation between nanopesticide zeta potential and nanopesticide adsorption. These findings heuristically recommend that aqueous cationic and zwitterionic nanocarriers for pesticides provide superior adsorption characteristics on pepper leaves and candelilla wax surfaces. Aqueous macromolecular carriers such as PXL and WPI have performed less effectively in adherence compared to shorter chain amphiphiles with similar zeta potential and wetting characteristics, indicating that the steric and osmotic chain effects of hydrophilic macromolecules hinder the adsorption relative to shorter chains.

Microbial Fermentation and Shelf Life of Potential Biotechnological Products Capable of Pesticide Degradation

The pesticide active ingredient azoxystrobin is widely used in agriculture and has negative effects for the environment and contained organisms. Bacterial strains have been reported to degrade azoxystrobin, but precise methodologies for producing and storing these strains as potential biotechnological products are lacking. The study focused on creating and optimising a non-sterile, small-scale microbial fermentation protocol to produce azoxystrobin-degrading products and to test their shelf life. By testing 14 variants and sampling at three production and two storage time points, the trial demonstrated the successful production and storage of microbial products capable of pesticide degradation. Various measurement parameters such as pH value and organic acids were used to monitor the quality of the microbial products during the production and storage. Further, we developed and validated qPCR assays to rapidly and specifically assess the concentration of the two azoxystrobin degrading strains, namely Bacillus subtilis strain MK101 and Rhodococcus fascians strain MK144. To ensure good specificity, the combination of two qPCR assays targeting two different genome regions was implemented for each strain. The study highlights the significant impact of media selection and bacterial inoculum quantity on the microbial product quality.

Inhibition of Botrytis cinerea infection on tomato leaves by submicronization of penthiopyrad particles

If the spray concentration of the pesticide remains constant, submicronization of the active ingredients significantly increase the particle number concentration, thereby substantially enhancing the probability of contact with plant pathogens and is anticipated to result in reduced pesticide usage. In this study, we investigated the effect of submicronization of pesticide active ingredients on the inhibitory effect against plant pathogens. Three types of monodispersed penthiopyrad (pesticide) particles with different median diameters and minimal overlap in the particle size distribution were successfully prepared using a poor solvent dilution method. Using these penthiopyrad particles, we conducted experiments on infection of tomatoes (model plants) with Botrytis cinerea (plant pathogen). The results showed that the submicronization of pesticide particles enhanced the inhibitory effects of the sprayed pesticide on the plant pathogen, while also decreasing the required amount of pesticide sprayed to the plants. Furthermore, confocal microscopy images showed that smaller particles are taken up by B. cinerea hyphae better than larger particles. Additionally, the bacterial flora on the leaf surface was not affected by submicronized pesticide particles larger than 100 nm. These findings imply that submicronization of pesticide active ingredients increases the probability of reaching targeted plant pathogens on the leaf surface, ultimately resulting in an increase in their uptake by the plant pathogens (i.e., significantly improved delivery of pesticides).

Overview of the pesticide contamination provided by the last Brazilian water quality surveillance information system for human consumption (SISÁGUA 2022) report

The Water Quality Surveillance Information System for Human Consumption (SISÁGUA) is designed to manage the risks of water contamination for human consumption. This short communication focuses on data from the 2022 Report regarding pesticide analysis. The data centers on 27 active pesticide ingredients found in drinking water samples exceeding the maximum residual limits (MRLs) established by Brazilian legislation. Results indicate that 1609 municipalities (60 %) found at least one pesticide in their water. Two hundred ten municipalities detected all 27 pesticides tested, with 11 of these pesticides reported to have some carcinogenic potential. Nearly one and a half million people were exposed to levels above the Brazilian MRL, with the sum of maximum detected residues exceeding 80,000 ppb. Additionally, the report highlights that 53 % of Brazilian municipalities did not submit water monitoring data for human consumption. Thus, improving and expanding the scope of water analysis within the SISÁGUA framework is essential.

Ornamental plants as vectors of pesticide exposure and potential threat to biodiversity and human health

The production of conventional ornamental plants is pesticide-intensive. We investigated whether pesticide active ingredients (AIs) are still present in ornamentals at the time of purchase and assessed their potential ecotoxicity to non-target organisms. We purchased 1000 pot plants and 237 cut flowers of different species from garden centers in Austria and Germany between 2011 and 2021 and analyzed them for up to 646 AIs. Ecotoxicological risks of AIs were assessed by calculating toxic loads for honeybees (Apis mellifera), earthworms (Eisenia fetida), birds (Passer domesticus), and mammals (Rattus norvegicus) based on the LD50 values of the detected AIs. Human health risks of AIs were assessed on the basis of the hazard statements of the Globally Harmonized System. Over the years, a total of 202 AIs were detected in pot plants and 128 AIs in cut flowers. Pesticide residues were found in 94% of pot plants and 97% of cut flowers, with cut flowers containing about twice as many AIs (11.0 ± 6.2 AIs) as pot plants (5.8 ± 4.0 AIs). Fungicides and insecticides were found most frequently. The ecotoxicity assessment showed that 47% of the AIs in pot plants and 63% of the AIs in cut flowers were moderately toxic to the considered non-target organisms. AIs found were mainly toxic to honeybees; their toxicity to earthworms, birds, and mammals was about 105 times lower. Remarkably, 39% of the plants labeled as “bee-friendly” contained AIs that were toxic to bees. More than 40% of pot plants and 72% of cut flowers contained AIs classified as harmful to human health. These results suggest that ornamental plants are vectors for potential pesticide exposure of consumers and non-target organisms in home gardens.

Pesticide contamination pattern of surface water in an urban–agricultural mediterranean watershed (Wadi Guenniche, Bizerte Lagoon, Northern Tunisia)

Two years of monthly sampling and hydrological monitoring were performed at the outlet of a Mediterranean watershed in northern Tunisia to determine the contents of 469 pesticide active ingredients and metabolites in water and evaluate their behavior. Wadi Guenniche is a tributary of the Bizerte coastal lagoon, with a watershed area of 86 km2, which exhibits pluvial cereal, legume, and orchid cultivation and irrigated market gardening. Twenty-nine pesticide active ingredients and 2 metabolites were detected in water. Twenty-four pesticide active ingredients were authorized for use in Tunisia. Among them, 14 had never been mentioned in previous farmer surveys. Five herbicides and their metabolites were the most frequently detected: aminomethylphosphonic acid (AMPA) (100%), glyphosate (94%), simazine (94%), 2,4-D (70%), and deisopropylatrazine (DIA) (47%). The detection frequency and concentration range suggested that the phytosanitary pressure and resulting water contamination are close to those on the northern Mediterranean shore. These results, in addition to characterizing the pollution state, emphasized the need for additional studies on the use and fate of pesticides on the southern shore of the Mediterranean Sea, particularly in Tunisia.

Ecotoxicity threshold values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide in fresh and marine waters: Part 1. Derivation of threshold values

Pesticide active ingredients are frequently detected in the rivers, creeks, wetlands, estuaries, and marine waters of the Great Barrier Reef (GBR) region and are one of the main contributors to poor water quality. Pesticide concentrations detected in the environment through water quality monitoring programs can be compared against estimates of ecologically “safe” concentrations (i.e., water quality guidelines) to assess the potential hazard and risk posed to aquatic ecosystems. Water quality guidelines are also required to estimate the aquatic risk posed by pesticide mixtures, which is used for the Reef 2050 Water Quality Improvement Plan pesticide target. Seventy-four pesticide active ingredients and their degradates are frequently detected in GBR catchment waterways, however many do not have water quality guidelines in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The current study derives ecotoxicity threshold values (ETVs) as unendorsed guideline values for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. The proposed ETVs have been derived using species sensitivity distributions, as recommended in the Australian and New Zealand nationally endorsed method for deriving water quality guidelines for aquatic ecosystem protection. Four ETVs were derived for each chemical with values that should theoretically protect 99, 95, 90 and 80 % of species (i.e., PC99, PC95, PC90, PC80, respectively). The PC99 and PC95 values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide were 0.49 μg/L and 4 μg/L, 0.029 μg/L and 0.45 μg/L, 0.11 μg/L and 5.8 μg/L and 0.19 μg/L and 2 μg/L, respectively. The ETVs will be used in an ecological hazard and risk assessment across GBR waterways in part two of this study. The ETVs can also be used to assess potential risk across Australia and internationally where monitoring data are available.

Forever Pesticides: A Growing Source of PFAS Contamination in the Environment.

Environmental contamination by fluorinated chemicals, in particular chemicals from the per- and polyfluoroalkyl substances (PFAS) class, has raised concerns around the globe because of documented adverse impacts on human health, wildlife, and ecosystem quality. Recent studies have indicated that pesticide products may contain a variety of chemicals that meet the PFAS definition, including the active pesticide ingredients themselves. Given that pesticides are some of the most widely distributed pollutants across the world, the legacy impacts of PFAS addition into pesticide products could be widespread and have wide-ranging implications on agriculture and food and water contamination, as well as the presence of PFAS in rural environments. The purpose of this commentary is to explore different ways that PFAS can be introduced into pesticide products, the extent of PFAS contamination of pesticide products, and the implications this could have for human and environmental health. We submitted multiple public records requests to state and federal agencies in the United States and Canada and extracted relevant data from those records. We also compiled data from publicly accessible databases for our analyses. We found that the biggest contributor to PFAS in pesticide products was active ingredients and their degradates. Nearly a quarter of all US conventional pesticide active ingredients were organofluorines and 14% were PFAS, and for active ingredients approved in the last 10 y, this had increased to 61% organofluorines and 30% PFAS. Another major contributing source was through PFAS leaching from fluorinated containers into pesticide products. Fluorination of adjuvant products and "inert" ingredients appeared to be limited, although this represents a major knowledge gap. We explored aspects of immunotoxicity, persistence, water contamination, and total fluorine load in the environment and conclude that the recent trend of using fluorinated active ingredients in pesticides may be having effects on chemical toxicity and persistence that are not given adequate oversight in the United States. We recommend a more stringent risk assessment approach for fluorinated pesticides, transparent disclosure of "inert" ingredients on pesticide labels, a complete phase-out of post-mold fluorination of plastic containers, and greater monitoring in the United States. https://doi.org/10.1289/EHP13954.

Droplet size, velocity, and spray coverage from a magnetic-assisted sprayer

The increase in pesticide regulations, diminished pesticide options due to resistance concerns, and narrowing grower profit margins require each application to be optimised to reduce spray drift and enhance coverage. However, alternative strategies outside of increasing droplet size are needed as reductions in pest control have been observed. This research explored the potential of a magnetic-assisted sprayer (MAS) to aid in spray coverage and determine its impact on spray droplet size and velocity. The MAS minimally impacted spray droplet size characteristics across the four nozzle types tested (only five of twenty F-tests were statistically significant) and did not impact average or maximum droplet velocities when measured 51-cm from the nozzle compared to the conventional sprayer. Although statistically, the MAS increased droplet size by only 4.6 and 12.5% in two of 12 parameter instances compared to the conventional sprayer, there were indications it may reduce spray drift potential as the driftable fines (% of individual droplets measured with diameters less than 200 μm) were numerically less across all nozzle types tested. Across the five experiments, an improvement in spray coverage and deposition by the MAS compared to the conventional sprayer was only observed in one treatment from one experiment. Overall, the MAS minimally to negatively impacted the measured coverage and calculated deposition from water-sensitive paper. Future research is needed to measure actual spray drift from a MAS as well as to evaluate other potentially influential variables such as water quality, pesticide active ingredient, and plant species.

Quantitative determination of residue amounts of pesticide active ingredients used in grapes by LC-MS/MS and GC-MS/MS devices and evaluation of these pesticides in terms of public health.

The aim of this study was to quantitatively determine pesticide residues in grapes, one of the most produced and consumed fruits in Turkey and in the world. A total of 226 active ingredients were analyzed in 21 samples collected from Southeastern and Eastern Anatolia regions using QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method and multiple residue analysis technique and LC-MS/MS and GC-MS/MS devices. In 11 out of 21 samples (52.4%), no active ingredient was detected, while at least one active ingredient was detected in 10 samples (47.6%). Thirteen different active substances (Ametoctradin, Azoxystrobin, Boscalid, Diphenoconazole, Dimethomorph, Fenhexamid, Fluopyram, Flutriafol, Metalaxyl- Metalaxyl-M, Metrafenone, Tebuconazole, Trifloxystrobin) were detected in the samples. The top 3 most detected active substances were Boscalid-Azoxystrobin and Fluopyram, respectively. The active ingredients were found between 0.015 and 0.499 mg kğ-1 values.

Transport of polyethylene and polypropylene microplastics under the action of agricultural chemicals: Role of pesticide adjuvants and neonicotinoid active ingredients

Understanding the impact of various agricultural chemical components on the fate and transport of microplastics (MPs) in the subsurface is essential. In this study, column experiments on saturated porous media were conducted to explore the influence of the coexistence environment of pesticide adjuvants (surfactants) and active ingredients (neonicotinoids) on the transport of polyethylene (PE) and polypropylene (PP) MPs. An anionic surfactant (sodium dodecyl sulfate (SDS)), a nonionic surfactant (nonylphenol ethoxylate (NP-40)), and three neonicotinoid insecticides (acetamiprid, dinotefuran, and nitenpyram) could independently increase MP migration by 9.31%–61.01% by improving the hydrophilicity. Acetamiprid or dinotefuran reduced the adhesion work of the binary system by competing with SDS for adsorption sites, thereby inhibiting PE mobility. However, nitenpyram in the mixture was not easily adsorbed on the surface of PE MPs together with SDS because of nitenpyram's high hydrophilicity. Neonicotinoid molecules could not reduce the hydrophilic modification of SDS on PP MPs by competing for adsorption sites. Owing to their weak charge and adhesion work of nonionic surfactants (−4.80 mV and 28.45 kT for PE and −8.21 mV and 17.64 kT for PP), neonicotinoids tended to occupy the adsorption sites originally belonging to NP-40. The long molecular chain of NP-40 made it difficult for high-concentration neonicotinoids to affect the adhesion on MPs. In addition, NP-40 was harder to peel off from the MP surface than SDS, leading to a larger MP transport ability in the sand column.

Pesticide loaded nanohydrogel based on attapulgite and gelatin with improved foliar adhesion.

Pesticides have been widely applied to promote plant growth due to their high insecticidal efficiency. However, most pesticides easily slip from the leaf surface due to the low foliar adhesion, leading to significant damage to the environment and human health. Increasing foliar adhesion of pesticides has been a major challenge. Nanomaterial technology, which can deliver pesticide active ingredients, offers a new opportunity to increase pesticides efficacy with higher foliar adhesion. In this study, we prepared the pesticide loaded nanohydrogel ALP@Ge-g-P(AA-co-AM)/ATP by grafting attapulgite and gelatin onto P(AA-co-AM), and loading the pesticide alphacypermethrin synchronously via the emulsion solvent evaporation method. The size of the new nanohydrogel was 20.5 nm and the pesticide loading capacity was 21.5%. Compared to P(AA-co-AM), the water absorbency of Ge-g-P(AA-co-AM)/ATP increased by 54.3% in 120 min, while the water retention increased from 4.27% to 38.7% after 48 h. Washout experiments and contact angle results suggested that the nanohydrogel, with a contact angle of 44.8° indicating good wettability, can resist rain flush and increase foliar adhesion naturally. Overall, the preparation of pesticide loaded nanohydrogel is simple. Experiments demonstrated the pesticide loaded nanohydrogel has high efficiency and strong foliar adhesion. This makes it a promising candidate for spraying application and reducing pollution levels. © 2024 Society of Chemical Industry.

Evaluating the use of unmanned aerial vehicles for spray applications in mountain Nanguo pear orchards.

Nanguo pear is a distinctive pear variety in northeast China, grown mainly in mountainous areas. Due to terrain limitations, ground-based pesticide application equipment is difficult to use. This limitation could be overcome by using unmanned aerial vehicles (UAVs) for pesticide application in Nanguo pear orchards. This study evaluated the spraying performance of two UAVs in the Nanguo pear orchards and compared them with a manually used backpack electric sprayer (BES). The study also analyzed the effect of canopy size on droplet deposition and ground loss, and evaluated two sampling methods, leaf sampling and telescopic rod sampling. Compared to BESs, droplet deposition is lower for UAVs, but the actual pesticide active ingredient deposition is not necessarily lower given the solution concentration. The droplet deposition varies among different UAVs due to structural differences. Under the same UAV operating parameters, droplet deposition on trees with smaller canopy sizes is typically greater than that on trees with larger canopy sizes, and the ground loss was also more severe. Although telescopic rod sampling is a quick and convenient method, it can only reflect the trend of droplet deposition, and the data error is greater compared with leaf sampling. UAVs can achieve better droplet deposition in mountainous Nanguo pear orchards and does almost no harm to the operators compared with the BES. However, canopy size needs to be considered to adjust the application volume rate. Telescopic rods can be used for qualitative analyses, but are not recommended for quantitative analyses. © 2024 Society of Chemical Industry.

Dietary Exposure of Filipinos to Pesticide Residues in Rice (Oryza sativa) Using National Theoretical Maximum Daily Intake (NTMDI) Approach

Exposure to pesticides, at levels above the regulatory limits, is detrimental to health. Rice, being a staple food of Filipinos, is a significant vector of pesticide residues in the diet. The current study aimed to determine the exposure of Filipinos to different pesticide residues in well-milled rice using the National Theoretical Maximum Daily Intake (NTMDI) approach. The NTMDI of 71 permitted pesticide active ingredients (PAIs) was estimated using the 2013 national food consumption data, established maximum residue limits (MRL), and the estimated average weight of the population groups. Estimates were then compared with the acceptable daily intake (ADI) for each PAI. The top six PAIs were then subjected to probabilistic analysis of exceeding the ADI. Results showed that all Filipino population groups were at risk of exposure to thiram, isoprocarb, and carbofuran with a 100% probability of exceeding the ADI. Exposures of Filipinos to these PAIs across all population groups were up to 870, 435, and 348% ADI, respectively. Infants and children were the most at-risk populations due to their low body weight. The NTMDI estimates, therefore, recognize the need to conduct a more refined dietary exposure assessment on the identified PAIs.

In Silico Prediction of Chemical Acute Dermal Toxicity Using Explainable Machine Learning Methods.

The research on acute dermal toxicity has consistently been a crucial component in assessing the potential risks of human exposure to active ingredients in pesticides and related plant protection products. However, it is difficult to directly identify the acute dermal toxicity of potential compounds through animal experiments alone. In our study, we separately integrated 1735 experimental data based on rabbits and 1679 experimental data based on rats to construct acute dermal toxicity prediction models using machine learning and deep learning algorithms. The best models for the two animal species achieved AUC values of 78.0 and 82.0%, respectively, on 10-fold cross-validation. Additionally, we employed SARpy to extract structural alerts, and in conjunction with Shapley additive explanation and attentive FP heatmap, we identified important features and structural fragments associated with acute dermal toxicity. This approach offers valuable insights for the detection of positive compounds. Moreover, a standalone software tool was developed to make acute dermal toxicity prediction easier. In summary, our research would provide an effective tool for acute dermal toxicity evaluation of pesticides, cosmetics, and drug safety assessment.

Pesticides in the Great Barrier Reef catchment area: Plausible risks to fish populations.

Waterways that drain the Great Barrier Reef catchment area (GBRCA) transport pollutants to marine habitats, provide a critical corridor between freshwater and marine habitats for migratory fish species, and are of high socioecological value. Some of these waterways contain concentrations of pesticide active ingredients (PAIs) that exceed Australian ecotoxicity threshold values (ETVs) for ecosystem protection. In this article, we use a "pathway to harm" model with five key criteria to assess whether the available information supports the hypothesis that PAIs are or could have harmful effects on fish and arthropod populations. Strong evidence of the first three criteria and circumstantial weaker evidence of the fourth and fifth criteria are presented. Specifically, we demonstrate that exceedances of Australian and New Zealand ETVs for ecosystem protection are widespread in the GBRCA, that the PAI contaminated water occurs (spatially and temporally) in important habitats for fisheries, and that there are clear direct and indirect mechanisms by which PAIs could cause harmful effects. The evidence of individuals and populations of fish and arthropods being adversely affected species is more circumstantial but consistent with PAIs causing harmful effects in the freshwater ecosystems of Great Barrier Reef waterways. We advocate strengthening the links between PAI concentrations and fish health because of the cultural values placed on the freshwater ecosystems by relevant stakeholders and Traditional Owners, with the aim that stronger links between elevated PAI concentrations and changes in recreationally and culturally important fish species will inspire improvements in water quality. Integr Environ Assess Manag 2024;20:1256-1279. © 2023 Commonwealth of Australia and The Commonwealth Scientific and Industrial Research Organisation. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Occurrence and distribution of trisiloxane ethoxylates in citrus orchard soils in China: Analytical challenges

Trisiloxane ethoxylates (TSEOn) are widely used as agricultural surfactants due to their significant synergism with the active ingredients of pesticides, generally, including three typical end groups which are hydroxyl (TSEOn-H), methoxy (TSEOn-CH3), and acetoxy (TSEOn-COCH3), respectively. However, the potential ecotoxicological and endocrine-disrupting risks of TSEOn congeners have recently attracted ever-growing concern. Above all, there is limited research on the concentration levels of TSEOn in agroecosystems. This study, simultaneous analysis of 39 TSEOn oligomers in citrus orchard soils in China was implemented by the modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method detection limits (MDLs) and the method quantification limits (MQLs) for TSEOn were 0.003–0.07 μg/kg and 0.01–0.20 μg/kg, respectively. The recoveries for TSEOn oligomers in soils ranged from 81 % ∼ 106 % with related standard deviations (RSDs) < 7 %. This newly developed UPLC-MS/MS method with high sensitivity and stability allows us to successfully trace the occurrence of TSEOn congeners in the citrus orchard soils from 3 provinces and 1 municipality in China. The detected concentrations of TSEOn-H oligomers in the sampled soils ranged from 0.02 to 0.288 μg/kg (dry weight). The congener profiles of TSEOn-H were dominated by TSEOn-H (n = 6– 8) in the soils. Additionally, the total concentrations of TSEOn-H congeners (ΣTSEOn-H) in the soils were in the range of 0.03 to 1.49 μg/kg. A comparison of ΣTSEOn-H distribution among the different citrus orchard soils indicated a higher level of ΣTSEOn-H in the soil samples collected from Zhejiang Province. Notably, TSEOn-CH3 or TSEOn-COCH3 oligomers were not detected in the tested soils. To the best of our knowledge, this is the first report on the occurrence and distribution of TSEOn congeners in agricultural soils.