Herbicide micropollutants in surface, ground and drinking waters within and near the area of Zagreb, Croatia

Hesperidin alleviates terbuthylazine-induced ferroptosis via maintenance of mitochondria-associated endoplasmic reticulum membrane integrity in chicken hepatocytes

Terbuthylazine (TBA) is a common triazine herbicide used in agricultural production, which causes toxic damage in multiple tissues. Hesperidin (HSP) is a flavonoid derivative that has anti-inflammatory, antioxidant and cytoprotective effects, but its role in reducing toxic damage caused by pesticides is still unclear. In this study, we aimed to investigate the toxic effect of TBA exposure on chicken hepatocytes and the therapeutic effect of HSP on the TBA-induced hepatotoxicity. Our results demonstrated that HSP could alleviate TBA exposure-induced endoplasmic reticulum (ER) stress. Interestingly, TBA significantly disrupted the integrity of mitochondria-associated endoplasmic reticulum membrane (MAM), while HSP treatment showed the opposite tendency. In addition, TBA could significantly trigger ferroptosis in liver, and HSP treatment reversed ferroptosis under TBA exposure. These results suggested that HSP could inhibit ER stress and alleviate ferroptosis under TBA exposure via maintaining MAM integrity, which provided a novel strategy to take precautions against TBA toxicity.

Comprehensive Assessment of Herbicide Toxicity on Navicula sp. Algae: Effects on Growth, Chlorophyll Content, Antioxidant System, and Lipid Metabolism

This study investigated the effects of herbicide exposure on Navicula sp. (MASCC-0035) algae, focusing on growth density, chlorophyll content, antioxidant system, and lipid metabolism. Navicula cultures were exposed to different concentrations of atrazine (ATZ), glyphosate (Gly), and acetochlor (ACT) for 96 h. Results showed a significant decrease in cell numbers, with higher herbicide concentrations having the most noticeable impacts. For instance, Gly-G2 had reduced cell populations by 21.00% at 96 h. Chlorophyll content varied, with Gly having a greater impact on chlorophyll a compared to ATZ and ACT. Herbicide exposure also affected the antioxidant system, altering levels of soluble sugar, soluble protein, and reactive oxygen species (ROS). Higher herbicide rates increased soluble sugar content (e.g., ATZ, Gly, and ACT-G2 had increased by 14.03%, 19.88%, and 19.83%, respectively, at 72 h) but decreased soluble protein content, notably in Gly-G2 by 11.40%, indicating cellular stress. Lipid metabolism analysis revealed complex responses, with changes in free proline, fatty acids, and lipase content, each herbicide exerting distinct effects. These findings highlight the multifaceted impacts of herbicide exposure on Navicula algae, emphasizing the need for further research to understand ecological implications and develop mitigation strategies for aquatic ecosystems.

CYP3A4-Mediated Metabolic Activation and Cytotoxicity of Chlortoluron

Chlortoluron (CTU) is an herbicide extensively used in agricultural settings for crop cultivation. Its presence in water has been identified as a pollutant detrimental to aquatic species. The objective of the present study was to explore the metabolic activation and hepatotoxicity of CTU. Through human and rat liver microsomal incubations supplemented with CTU, nicotinamide adenine dinucleotide phosphate (NADPH), and either glutathione or N-acetyl cysteine, a benzylic alcohol metabolite (M1) was discerned, alongside a phenol metabolite (M2), a glutathione conjugate (M3), and an N-acetyl cysteine conjugate (M4). In rats exposed to CTU, biliary M3 and urinary M4 were detected in their bile and urine, respectively. The generation of M1 was detected in the presence of NADPH. The observation of M3 and M4 suggests the formation of an iminoquinone methide intermediate arising from the oxidation of M1. CYP3A4 was found to be the principal enzyme catalyzing the metabolic activation of CTU. Furthermore, CTU exhibited cytotoxic properties in cultured rat primary hepatocytes in a concentration-dependent pattern. Concomitant treatment of hepatocytes with ketoconazole mitigated their susceptibility to the cytotoxic effects of CTU.

Gut microbiota disorders aggravate terbuthylazine-induced mitochondrial quality control disturbance and PANoptosis in chicken hepatocyte through gut-liver axis

Terbuthylazine (TBA) is a widely prevalent pesticide pollutant, which is a global concern due to its environmental residual. However, the toxic mechanism of TBA have not been fully solved. Here, we explored that TBA exposure disrupts the intestinal flora and aggravated disturbance of mitochondrial quality control and PANapoptosis in hepatocytes via gut-liver axis. Our findings demonstrated that TBA exposure induced significant damage to the jejunum barrier, evidenced by a marked decrease in the expression of Occludin and ZO-1. Moreover. TBA led to intestinal microflora disorder, manifested as the decreased abundance of Firmicutes, and increased abundance of the Nitrospirota, Chloroflexi, Desulfobacterota, Crenarchaeota, Myxococcota, and Planctomycetota. Meanwhile, intestinal microflora disorder affected the biological processes of lipid metabolism and cell growth and death of hepatocytes by RNA-Seq analysis. Furthermore, TBA could induced mitochondrial quality control imbalance, including mitochondrial redox disorders, lower activity of mitochondrial fusion and biogenesis decrease, and increasing level of mitophagy. Subsequently, TBA significantly increased expression levels of pyroptosis, apoptosis and necroptosis-related proteins. In general, these results demonstrated the underlying mechanisms of TBA-induced hepatotoxicity induced via the gut-liver axis, which provides a theoretical basis for further research of ecotoxicology of TBA.

Human health risk assessment based on direct and indirect exposure to endocrine disrupting herbicides in drinking, ground, and surface water in Croatia

The recognition of certain herbicides as endocrine disrupting compounds has raised concerns due to their ability to interfere with the normal functioning of the endocrine system, which regulates various physiological processes in organisms. The objective of this study was to assess the possible human health risks associated with terbuthylazine and endocrine-disrupting herbicides atrazine, acetochlor, and metolachlor in the drinking, surface, and groundwater of the Zagreb city region, Croatia. We relied on advanced statistical methods and principal component analysis (PCA), which revealed higher levels of atrazine and acetochlor in drinking and groundwater samples and higher presence of metolachlor and terbuthylazine in surface waters. To evaluate the danger to human health, various exposure scenarios have been assessed. The risk of direct human exposure to analyzed herbicides through drinking or bathing with drinking (tap) or groundwater, as well as from recreational activities like swimming in rivers, streams, and lakes, has been quantified. In addition to these direct exposure scenarios, indirect ones based on consumer goods, fruits, and vegetables, treated with surface and groundwater for irrigation, were assessed to investigate the danger to human health. Judging by the reported herbicide levels there was no significant risk of carcinogenic (CR ≤ 1 × 10-6) or non-carcinogenic (HI < 1) diseases, not even when we assessed the so-called "cocktail effect" of combined the herbicide exposure in different waters.

Occurrence, fate, seasonal variability, and risk assessment of twelve triazine herbicides and eight related derivatives in source, treated, and tap water of Wuhan, Central China

Triazine herbicides have been widely used, are frequently detected in aqueous environments and soils, and can cause acute or chronic toxicity to living organisms. We collected source water samples (n = 20) originating from the Hanshui River and the Yangtze River of Wuhan section, treated water samples (n = 20), and tap water samples (n = 169) in Wuhan, Central China during 2019 for determination of twelve triazine herbicides and their eight derivatives (collectively defined as TZs) and characterizing their fate during water treatment. Eighteen of the twenty TZs were detected in the source water. Atrazine (ATZ) had the highest concentrations (median: 22.4 ng/L) in the source water samples while DACT had the highest concentrations (median: 31.4 ng/L) in the treated water. "Tryns" (ametryn, prometryn, simetryn, terbutryn) were efficiently removed by conventional water treatment, while other target analytes were not; interestingly, hydroxypropazine and prometon increased significantly accompanied by prometryn disappearance, which implicated potential transformation pathways. In addition, "tryns" might be transformed into "tons" (atraton, prometon, secbumeton, terbumeton) by ozonation. In the tap water samples, diaminochlorotriazine had the highest concentrations (median: 34.9 ng/L) among the target analytes, followed by ATZ (18.3 ng/L), hydroxyatrazine (5.17 ng/L), deethylatrazine (5.00 ng/L), hydroxypropazine (3.20 ng/L), deisopropylatrazine (2.05 ng/L), hydroxydesethylatrazine (1.68 ng/L), and others. The TZs had the highest cumulative concentration in July in the tap water samples (median: 89.7 ng/L). This study found that ozonation in combination with activated carbon was more efficient in removing triazine herbicides, although "tryns" could also be transformed during conventional treatment. Ecological risk assessment showed moderate risks posed by hydroxyterbuthylazine, prometryn, and simetryn; the Hanshui River had higher risks than the Yangtze River, and July had higher risks than February. Human exposure to the TZs via water ingestion was low compared to the reference doses. This study characterized the occurrence of some new emerging TZs in the source water, their fate during drinking water treatment, and their seasonal variability in the tap water.

Bioaccumulation and toxicity of terbuthylazine in earthworms (Eisenia fetida)

Terbuthylazine is an effective and widely used s-triazine herbicide. However, limited data exists on its toxicity and bioaccumulation in earthworms (Eisenia fetida). In this study, we investigated the bioaccumulation, antioxidant enzyme activity, detoxification enzyme activity, and DNA damage in earthworms when exposed to terbuthylazine. The results indicated that terbuthylazine in soil had low bioaccumulation in earthworms and the biota-soil accumulation factors of terbuthylazine declined with an increasing soil terbuthylazine concentration. In the enzyme activity assays, the superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities showed upward trends when compared with the control. The carboxylesterase (CarE) activity increased on day 21. The 8-hydroxy-2-deoxyguanosine (8-OHdG) content, a DNA damage bioindicator, was higher than that of the control on day 21. Combined with the integrated biological response index version 2 analysis, these results can provide a comprehensive evaluation of the toxicological effects that terbuthylazine has on earthworms and soil ecosystems.

Toxicological effects, environmental behaviors and remediation technologies of herbicide atrazine in soil and sediment: A comprehensive review

Atrazine has become one of the most popular applied triazine herbicides in the world due to its high herbicidal efficiency and low price. With its large-dosage and long-term use on a global scale, atrazine can cause widespread and persistent contamination of soil and sediment. This review systematically evaluates the toxicological effects, environmental risks, environmental behaviors (adsorption, transport and transformation, and bioaccumulation) of atrazine, and the remediation technologies of atrazine-contaminated soil and sediment. For the adsorption behavior of atrazine on soil and sediment, the organic matter content plays an extremely important role in the adsorption process. Various models and equations such as the multi-media fugacity model and solute transport model are used to analyze the migration and transformation process of atrazine in soil and sediment. It is worth noting that certain transformation products of atrazine in the environment even have stronger toxicity and mobility than its parent. Among various remediation technologies, the combination of microbial remediation and phytoremediation for atrazine-contaminated soil and sediment has wide application prospects. Although other remediation technologies such as advanced oxidation processes (AOPs) can also efficiently remove atrazine from soil, some potential problems still need to be further clarified. Finally, some related challenges and prospects are proposed.

The state-of-the-art development of photocatalysts for the degradation of persistent herbicides in wastewater

Herbicides are one of the most recurring pollutants in the aquatic system due to their widespread usage in the agriculture sector for weed control. Semiconductor-based photocatalysts have gained recognition due to their ability to degrade and mineralize pollutants into harmless by-products completely. Lately, many studies have been done to design photocatalysts with efficient separation of photogenerated charge carriers and enhanced light absorption. Photocatalyst engineering through doping with metal and non-metal elements and the formation of heterojunction are proven effective for minimizing the recombination of electron-hole pairs and enlarging the absorption in the visible light region. This review focuses on discussing and evaluating the recent progress in the types of photocatalysts and their performance in the remediation of herbicides in wastewater. The development of innovative hybrid technologies is also highlighted. The limitations and challenges of photocatalysis technology in the present literature have been identified, and future studies are recommended.

Assessing the colonization by Daphnia magna of pesticide-disturbed habitats (chlorpyrifos, terbuthylazine and their mixtures) and the behavioral and neurotoxic effects

The spread of pesticides in water bodies integrated into agricultural landscapes may prevent some areas from being colonized. In this study, the effects on the colonization responses of D. magna exerted by gradients of realistic environmental concentrations of the pesticides chlorpyrifos, terbuthylazine and their mixtures were tested in a novel multicompartment non-forced exposure system. Furthermore, the effects of both pesticides and their mixtures on the swimming behavior and the neurotransmission activity of D. magna were analyzed using a traditional forced exposure system. The synthesis and concentration of the main environmental metabolites of terbuthylazine were also analyzed. Results confirmed that D. magna exposed to mixture gradients were able to detect the pollutants and their colonization dynamics were drastically inhibited. The swimming behavior increased in D. magna exposed to the highest concentration of the mixture treatment. AChE activity was only significantly inhibited in the D. magna exposed to the highest concentration of chlorpyrifos. Changes in swimming behavior could not be directly related to the effects on AChE. Furthermore, the synthesis of the metabolite terbuthylazine 2-hydroxy during the course of the experiments was confirmed. These results demonstrate the importance of integrating pesticide mixtures in both non-forced and forced exposure systems during ecotoxicological assays.

Effects of the presence of triclocarban on the degradation and migration of co-occurring pesticides in soil

Triclocarban (TCC), a bactericide widely used in personal care products, is frequently detected in soil and surface water, which may affect the environmental behavior of other environmental pollutants by changing the community structure of environmental microorganisms. This work evaluated the effects of TCC on the degradation and migration of seven herbicides and five fungicides in soil under co-occurrence conditions. TCC significantly increased the persistence of the pesticides in soil, and this effect increased with TCC concentration. For example, the half-life of metolachlor, atrazine, metribuzin, and metamitron increased 44%, 38%, 153%, and 33%, respectively, with 10 mg/kg TCC and increased 60%-640% with 100 mg/kg TCC. After 90 days, the residue of the pesticides in soil treated with TCC was significantly elevated relative to the control. TCC treatment could also increase the potential leaching risk of the herbicides in the soil, as indicated by an increased Groundwater Ubiquity Score (GUS) index. The reduced abundance of soil bacteria by TCC might be an essential reason for the impacts on the environmental behavior of the pesticides. This study confirmed that TCC could slow down the degradation of pesticides in soil, increase their persistence and even affect the leaching behavior, thus influencing the risks of the pesticides to the environment.

Pesticide occurrence in an agriculturally intensive and ecologically important coastal aquatic system in Australia

Coastal agricultural practices are often located in catchments upstream of ecologically important aquatic systems. Here, we investigate the occurrence of pesticides in a coastal creek flowing into a habitat-protected area within the Solitary Islands Marine Park, Australia. Water samples were collected from six sites along a creek transect during three sampling periods. Samples were analysed for 171 pesticide analytes, including organochlorines, organophosphates, herbicides, and fungicides. Five insecticides, two herbicides, and two fungicides were detected. The neonicotinoid imidacloprid was detected at 5 out of 6 sites, with concentrations reaching 294 μg L^-1, the highest yet detected in Australian waterways. The organophosphate insecticide dimethoate was detected at 4 sites, which occurred at the 2nd highest detected concentration in the study (12.8 μg L^-1). The presence of these pesticides in the aquatic environment downstream of horticulture in this and other regions may have serious implications for stream biota and ecologically important marine ecosystems.

Analytical method for sequential determination of persistent herbicides and their metabolites in fish tissues by UPLC-MS/MS

A novel and accurate liquid chromatography-tandem mass spectrometry method was developed to sequentially determine three persistent herbicides (atrazine (ATZ), acetochlor (ACE), and metolachlor (MET)) and seven characteristic metabolites (desethylatrazine (DEA), deisopropylatrazine (DIA), diaminochlorotriazine (DACT), MET-oxanilic acid (MET-OA), MET-ethanesulfonic acid (MET-ESA), ACE-ESA, and ACE-OA) in fresh fish tissues from six fish species. A modified QuEChERS method was conducted to extract the target compounds from fish tissues. Matrix-matched calibrations of the target analytes were carried out at spiking levels of 1, 10, 100, and 1000 ng g^-1. The method was validated in accordance with Codex guidelines (CAC/GL 71-2009). Recoveries for the target analytes were 67-120% with relative standard deviations below 20%, and the matrix effects ranged from -58.7% to 59.3%. The limits of detection and quantitation were 0.01-1.90 and 0.02-6.35 ng g^-1, respectively. Moreover, the method was successfully applied to analyze the concentrations of the target chemicals in fresh tissue samples of six fish species (n = 67) collected from four markets in Nanning City, Guangxi Province, China. The concentrations in all samples were 1.1-140.5 ng g^-1. Interestingly, this study was the first to measure DEA and DIA in fish liver, and their highest concentrations were 10.7 and 14.2 ng g^-1, respectively. This method provides a basis for studying the pathways of biotransformation, bioaccumulation, detoxification, and exposure patterns of ACE, ATZ, MET, and their metabolites in aquatic environments.

Multiple detection of 15 triazine herbicides by gold nanoparticle based-paper sensor

Triazine herbicides have been widely used in agriculture, but their residues can harm the environment and human health. To help monitor these, we have developed an effective immunochromatographic strip test that can simultaneously detect 15 different triazines in grain samples (including ametryn, cyprazine, atraton, prometon, prometryn, atrazine, propazine, terbuthylazine, simetryn, trietazine, secbumeton, simazine, desmetryn, terbumeton and simetone). Based on our optimization procedure, the visual limit of detection (vLOD) for these triazines was found to be 2-10 ng/mL in assay buffer, and 0.02-0.1 mg/kg in grain samples. Four different grain matrices including corn, brown rice, wheat, and sorghum were studied and the test results showed no significant differences between the 15 triazines analyzed using this method. This test is simple, convenient, rapid, and low-cost, and could be an effective tool for primary screening of triazine residues in grain samples.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (UV-vis spectra of 15 nm-GNP; K₂CO₃ usage; cross reactivity; strip images for spiked rice, wheat and sorghum samples, UPLC-MS/MS parameters; gray values for strip optimization) is available in the online version of this article at 10.1007/s12274-022-4164-2.

Seasonal distribution of multiclass pesticide residues in the surface waters of northwest Croatia

As part of our OPENTOX project, we evaluated the incidence and mass concentrations of multiclass pesticide residues in 23 river/stream water samples collected in urban and agricultural areas of northwest Croatia at various points of the pesticide application season in 2015. The study included 16 compounds of five herbicide classes and seven compounds of three insecticide classes. Pesticide residues were accumulated from water by solid-phase extraction and analysed using high performance liquid chromatography with UV-diode array detection and/or gas chromatography-mass spectrometry. Herbicide residues were more common than the insecticide ones, and, as expected, they peaked in the middle of the application season. Metolachlor showed the highest concentrations and was found in 91 % of all samples, followed by terbuthylazine, found in 70 % of the samples. The highest total mass concentration of detected pesticides was measured in the water samples of the Krapina (3992 ng/L) and Sutla (3455 ng/L) collected in rural areas with intensive agriculture. Our findings strongly speak in favour of continued monitoring of surface waters and possibly extending the list of priority water pollutants.

Assessment of pesticide residues in waters and soils of a vineyard region and its temporal evolution

Sustainable agriculture practices and integrated pest management for avoiding environmental pollution are necessary to maintain a high yield in vineyard areas. Pesticide residues in groundwater in a vineyard area of La Rioja (Spain) have been evaluated in previous years, and they could now have varied after farmers have adopted the different measures recommended. Accordingly, this research's objectives were (i) to evaluate the occurrence and seasonal distribution (spring, summer, and autumn samplings) of pesticides (36) plus their degradation products (DP) (11) in water and soil samples (23 + 15) in La Rioja (Northern Spain), and (ii) to compare the current water quality (2019) with that determined previously (2011). A multi-residue method based on solid phase extraction (for water samples) or solid liquid extraction (for soil samples) and high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) was used to determine and quantify pesticides. The results reveal the presence in waters of 30 compounds from those selected (15 fungicides + 2 DP, 7 insecticides + 1 DP, and 3 herbicides +2 DP), with 14 of them at concentrations > 0.1 μg L^-1 (water quality threshold for human consumption). The highest number of compounds was detected in summer (waters) and spring (soils). The pesticides most frequently detected in water samples were the fungicides metalaxyl, tebuconazole, and boscalid, with the last one being the compound found in the highest number of soil samples. The comparison of water pollution in 2011 and 2019 indicates a significant decrease in the total concentration of herbicides, fungicides and insecticides in 95-100%, 76-90%, and 42-85% of samples in the three campaigns, respectively. The results indicate that an optimized and sustainable use of pesticides in intensive and high-yield agricultural areas could reduce environmental pollution.

Accumulation, distribution and removal of triazine pesticides by Eichhornia crassipes in water-sediment microcosm

After application, pesticides remained in the field may contaminate water resources through surface runoff and leaching, posing a threat to aquatic ecosystem. In the current study, the accumulation, translocation, distribution and removal of four triazine pesticides (simazine, atrazine, terbuthylazine and metribuzin) by free floating aquatic plant Eichhornia crassipes (E. crassipes) in water-sediment microcosm were investigated and the removal mechanisms were explored. E. crassipes was exposed to an initial concentration of 50 μg·L^-1 and the pesticide levels in water, sediment, roots and shoots of E. crassipes were monitored during 30 days. The results demonstrated that E. crassipes was capable of accumulating triazine pesticides with the bio-concentration factor (BCF) ranging from 0.8 to 18.4. Triazine pesticides were mainly stored in roots, and root accumulation and translocation amount depend on the hydrophobicity of the pesticides. The removal of the pesticides in water were significantly accelerated by the presence of E. crassipes, with the removal efficiency ranging from 66% to 79% after 30 days of treatment. Though phytoaccumulation only constituted 2-18% of the total spiked pesticides in the microcosm, E. crassipes played a vital role in removing simazine, atrazine and metribuzin. However, microbial degradation in sediment was the main pathway for the removal of terbuthylazine in the microcosm. This study demonstrated the potential application of E. crassipes to accelerate removal of contaminants from aquatic environment.

Sorption Properties of Specific Polymeric Microspheres towards Desethyl-Terbuthylazine and 2-Hydroxy-Terbuthylazine: Batch and Column Studies

This work investigates the sorption properties of poly(divinylbenzene) modified in the Diels-Alder reaction towards persistent and mobile metabolites of terbuthylazine. The batch experiments were carried out to examine the efficiency of desethyl-terbuthylazine and 2-hydroxy-terbuthylazine adsorption on the specific adsorbent and the impact of different factors on the adsorption process. Results fit well to a pseudo-second order kinetic model. It was confirmed that hydrogen bonds play an important role in the studied systems. Five times greater sorption of 2-hydroxy-terbuthylazine than desethyl-terbuthylazine was observed. The molecular structures of both metabolites exhibit complementarity to the arrangement of functional groups in the polymer but the differences in the physicochemical properties of the desethyl derivative make it a highly mobile compound with higher affinity to the aqueous phase. The equilibrium data in the batch study fit the Freundlich isotherm for 2-hydroxy-terbuthylazine, and for desethyl-terbuthylazine the Temkin and Dubinin-Radushkevich models were better. The adsorption capacities obtained under dynamic conditions were comparable with batch results. For column adsorption modeling the Bohart-Adams, Wolborska, Thomas and Yoon-Nelson models were used. The proposed microspheres can be reused easily with no significant decrease in adsorption capacity by using ethanol as eluent in the desorption.

Understanding the origins of herbicides metabolites in an agricultural watershed through their spatial and seasonal variations

The aim of this study is to understand the spatial and seasonal variations of persistent herbicides metabolites and to determine their origins in the Vilaine River watershed, Britany-France. Improving knowledge on herbicides metabolites sources and seasonality is important for drinking water resource management. Data were collected at 13 sampling stations during five sampling campaigns in 2016 and 2017. Relations between water quality parameters, herbicides and metabolites were analyzed using statistical methods. The influence of land use and wastewater treatment plants (WWTP) on streams water quality has been identified. Cluster Analysis revealed that two groups of sampling stations can be described as "urban" with stations downstream the urban area and as "agricultural" with stations located downstream of the watershed. Chloroacetamids metabolites have been associated together with nitrates and agricultural areas as could be expected. Thus, the drinking water treatment plant located in the estuary of the Vilaine River is exposed to high metolachlor ESA and nitrate loads all year long. Aminomethylphosphonic acid (AMPA) is associated to anthropogenic urban contamination and nutrient loads. AMPA has its major sources in both glyphosate and phosphonate detergents issued from WWTP. This can help to adapt surface water treatment process and water management policies concerning herbicides metabolites.

Neonicotinoids, fipronil, chlorpyrifos, carbendazim, chlorotriazines, chlorophenoxy herbicides, bentazon, and selected pesticide transformation products in surface water and drinking water from northern Vietnam

Studies on the occurrence of emerging pesticides in surface and drinking water in Vietnam are limited. In this study, lake water (n = 7), river water (n = 1), tap water (n = 46), and bottled water (n = 3) collected from Hanoi and other four provinces in northern Vietnam were analyzed for selected pesticides (including insecticides such as neonicotinoids, fipronil, and chlorpyrifos; fungicide carbendazim; herbicides such as atrazine, terbuthylazine, simazine, 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid, and bentazon) and some of their degradates by liquid chromatography-tandem mass spectrometry. Carbendazim (median: 86.7 ng/L) and triazines (49.3 ng/L) were the major pesticides found in lake water samples, followed by neonicotinoids and their degradation products (15.1 ng/L), chlorpyrifos and its degradate (13.4 ng/L), fipronil and its degradates (3.76 ng/L), chlorophenoxy acid herbicides (2.10 ng/L), and bentazon (0.62 ng/L). Triazines (164 ng/L) were the major pesticides in river water. Higher concentrations (median: 39.3 ng/L; range: 1.20-127) of selected pesticides were found in tap water from Hanoi than those from four other provinces studied (5.49 ng/L; 4.73-66.8 ng/L). Bottled water samples collected from Hanoi contained lower concentrations of pesticide residues (median: 3.54 ng/L, range: 2.18-8.09) than those of tap water samples. The calculated risks from pesticide exposure through ingestion of tap water by the general populations were low. However, fipronil concentrations in lake water exceeded the benchmark value recommended for freshwater in the United States or the Netherlands. Degradation of acetamiprid into desmethyl-acetamiprid was found in lake water.

A nationwide study of the occurrence and distribution of atrazine and its degradates in tap water and groundwater in China: Assessment of human exposure potential

Despite frequent detection of atrazine (ATZ) and its degradates (including hydroxyatrazine, ATZ-OH; deethylatrazine, DEA; deisopropylatrazine, DIA; and deethyldeisopropylatrazine, DACT) in a variety of water bodies, documentation of their occurrence and distribution in tap water in China is still scarce. A nationwide survey about ATZ and its degradates (ATZs) in tap water from 31 provinces in 7 regions of mainland China and Hong Kong was conducted during June 2019. At least one of the analytes was found in all the water samples (n = 884). The median sum concentrations of ATZs (ΣATZs) was 21.0 ng/L (range: 0.02 ng/L-3.04 μg/L). The predominant compounds of ATZs in tap water were ATZ and DEA, with a detection frequency of 99.5% and 98.0%, respectively, followed by ATZ-OH (87.3%), DACT (84.0%), and DIA (78.1%). Significant regional variations (p < 0.05) were found in the concentrations of ATZs in tap water, and the highest concentration of ΣATZs (median: 254 ng/L, range: 0.44 ng/L-3.04 μg/L) was found in Northeastern China, followed by Eastern (37.2 ng/L, 0.02-706 ng/L), Northern (30.2 ng/L, 0.04-317 ng/L), Central (29.3 ng/L, 0.04-256 ng/L), Southern (25.0 ng/L, 0.04-297 ng/L), Southwestern (17.2 ng/L, 0.02-388 ng/L), and Northwestern China (3.22 ng/L, 0.06-214 ng/L). The level of ΣATZs in groundwater from rural area of China was about 1/3 of that found in tap water. ATZs cannot be removed by boiling tap water. The highest estimated daily intake of ΣATZs (248 ng/kg-body weight/day) was found in the infant population of Changchun, Jilin, Northeastern China.

Mobility monitoring of two herbicides in amended soils: A field study for modeling applications

This paper reports the mobility and total balance of chlorotoluron (CTL), flufenacet (FNC) and bromide ion (Br^-) throughout a sandy soil profile after the application of spent mushroom substrate (SMS) and green compost (GC). Obtaining mobility dataset is crucial to simulate the herbicides' fate under amended soil scenarios by application pesticide leaching models with regulatory application (FOCUS models). The application of organic residues is nowadays increased to improve the crop yields and there is a gap in the simulations of this kind of amended scenarios. A two-year field experiment involving unamended soil (S) and SMS- or GC-amended soil plots was conducted. CTL, FNC, and Br^- were annually applied and their residual concentrations were determined in soil profiles (0-100 cm) regularly sampled. In all the treatments the order of mobility is followed as FNC < CTL < Br^-. SMS and GC increased herbicide retention in the top 10 cm by the higher organic carbon (OC) content than the unamended soil, and their ability to increase the soil's water-holding capacity and to decrease water percolation. Simultaneously dissolved organic carbon (DOC) content facilitated herbicide transport being it favoured by the initial soil moisture content and the rainfall shortly after the chemicals' initial application. Over the first year, residual amounts (<2.6%) of Br^-, CTL and FNC were leached down to 90-100 cm depth in the three treatments. However, over the second year low CTL and FNC amounts (<1.0%) reached the bottom layer only in S + SMS although high Br^- concentrations did so in the three treatments (<20%). According to the total balance of Br^-, CTL, and FNC in the soil profiles other processes (degradation, mineralisation, bound residues formation, and/or crop uptake) different from leaching below 1 m depth might play a key role in their dissipation especially in the amended soil profiles. SMS and GC are likely to be used as organic amendments to preserve the soil and water quality but in the case of SMS, its higher DOC content could imply a higher potential risk for groundwater contamination than GC.

Mechanism and kinetics of diuron oxidation by hydroxyl radical addition reaction

Diuron is a phenyl urea herbicide used to control weeds in agricultural lands. The degradation of diuron in the atmosphere takes place dominantly via reaction with OH radicals. In this work, the OH addition reaction of diuron has been studied by using density functional theory methods M06-2X, ωB97X-D and MPWB1K with 6-31G(d,p) basis set. The calculated thermochemical parameters show that OH addition reaction occurs favourably at C₂ position of diuron. The rate constant is calculated for the favourable initial reaction pathway by using canonical variational transition state theory with small curvature tunnelling (SCT) correction over the temperature range of 200-1000 K. The reaction of initially formed diuron-OH adduct intermediate with O₂ leads to the formation of peroxy radical intermediate. The reaction of peroxy radical intermediate with HO₂ and NO_x (x = 1, 2) radicals is studied in detail. The results obtained from time-dependent density functional theory (TDDFT) calculations show that the intermediates and products formed from oxidation of diuron can be easily photolyzed in the sunlight. This study provides thermodynamical and kinetic data for the atmospheric oxidation of diuron by OH radical addition reaction and demonstrates the atmospheric chemistry of diuron and its derivatives.

Endocrine Disruptors in Water and Their Effects on the Reproductive System

Anthropogenic contaminants in water can impose risks to reproductive health. Most of these compounds are known to be endocrine disrupting chemicals (EDCs). EDCs can impact the endocrine system and subsequently impair the development and fertility of non-human animals and humans. The source of chemical contamination in water is diverse, originating from byproducts formed during water disinfection processes, release from industry and livestock activity, or therapeutic drugs released into sewage. This review discusses the occurrence of EDCs in water such as disinfection byproducts, fluorinated compounds, bisphenol A, phthalates, pesticides, and estrogens, and it outlines their adverse reproductive effects in non-human animals and humans.

Phytoremediation and detoxification of xenobiotics in plants: herbicide-safeners as a tool to improve plant efficiency in the remediation of polluted environments. A mini-review

Phytoremediation is a widely studied and applied technology, based on the use of plants and their associated microorganisms to decontaminate polluted sites. In recent years, different strategies have been investigated to improve the phytoremediation efficiency of the selected plants. In this context, some studies have shown that herbicide-safeners, chemicals applied to crops to enhance their tolerance to herbicides, can increase the phytoremediation of soils and water polluted by organic and inorganic contaminants. Safeners, by inducing the xenobiotic detoxification and the antioxidant metabolism in plants, can enhance their removal potential in the cleaning process. In this review, after a short survey of phytoremediation technologies and the biochemical mechanisms activated by plants to tolerate and detoxify heavy metals and herbicides, the use of herbicide-safeners as a tool to increase the phytoremediation performance is reviewed and discussed.

Mapping the Photochemistry of European Mid-Latitudes Rivers: An Assessment of Their Ability to Photodegrade Contaminants

The abiotic photochemical reactions that take place naturally in sunlit surface waters can degrade many contaminants that pose concern to water bodies for their potentially toxic and long-term effects. This works aims at assessing the ability of European rivers to photoproduce reactive transient intermediates, such as HO^• radicals and the excited triplet states of chromophoric dissolved organic matter (³CDOM*), involved in pollutant degradation. A photochemical mapping of the steady-state concentrations of these transients was carried out by means of a suitable modeling tool, in the latitude belt between 40 and 50°N. Such a map allowed for the prediction of the photochemical lifetimes of the phenylurea herbicide isoproturon (mostly undergoing photodegradation upon reaction with HO^• and especially ³CDOM*) across different European countries. For some rivers, a more extensive dataset was available spanning the years 1990–2002, which allowed for the computation of the steady-state concentration of the carbonate radicals (CO₃^•−). With these data, it was possible to assess the time trends of the photochemical half-lives of further contaminants (atrazine, ibuprofen, carbamazepine, and clofibric acid). The calculated lifetimes were in the range of days to weeks, which might or might not allow for efficient depollution depending on the river-water flow velocity.

Development of a Multiresidue Method for Endocrine-Disrupting Pesticides by Solid Phase Extraction and Determination by UHPLC-MS/MS from Drinking Water Samples

A rapid and efficient method based on solid phase extraction and liquid chromatography–tandem mass spectrometry was validated, allowing the determination of the endocrine-disrupting herbicides (acetochlor, alachlor, amitrole and atrazine), fungicides (carbendazim, triadimefon, penconazole and propiconazole), and insecticides (carbaryl and carbofuran) in drinking water. Low method detection limits (0.01–0.64 ng/L) and method quantification limits (0.03–2.13 ng/L) were obtained with satisfactory recoveries and precision for the endocrine-disrupting pesticides. The method was applied for real drinking water samples collected in the area of the city of Hangzhou (Zhejiang, China); the results showed that carbendazim, atrazine and acetochlor were detected in the drinking water samples and acetochlor was the most detected analyte.

Anthropogenic contaminants of high concern: Existence in water resources and their adverse effects

Existence of anthropogenic contaminants (ACs) in different environmental matrices is a serious and unresolved concern. For instance, ACs from different sectors, such as industrial, agricultural, and pharmaceutical, are found in water bodies with considerable endocrine disruptors potency and can damage the biotic components of the environment. The continuous ACs exposure can cause cellular toxicity, apoptosis, genotoxicity, and alterations in sex ratios in human beings. Whereas, aquatic organisms show bioaccumulation, trophic chains, and biomagnification of ACs through different entry route. These problems have been found in many countries around the globe, making them a worldwide concern. ACs have been found in different environmental matrices, such as water reservoirs for human consumption, wastewater treatment plants (WWTPs), drinking water treatment plants (DWTPs), groundwaters, surface waters, rivers, and seas, which demonstrate their free movement within the environment in an uncontrolled manner. This work provides a detailed overview of ACs occurrence in water bodies along with their toxicological effect on living organisms. The literature data reported between 2017 and 2018 is compiled following inclusion-exclusion criteria, and the obtained information was mapped as per type and source of ACs. The most important ACs are pharmaceuticals (diclofenac, ibuprofen, naproxen, ofloxacin, acetaminophen, progesterone ranitidine, and testosterone), agricultural products or pesticides (atrazine, carbendazim, fipronil), narcotics and illegal drugs (amphetamines, cocaine, and benzoylecgonine), food industry derivatives (bisphenol A, and caffeine), and personal care products (triclosan, and other related surfactants). Considering this threatening issue, robust detection and removal strategies must be considered in the design of WWTPs and DWTPs.

Electrochemical removal of Terbuthylazine:Boron-Doped Diamond anode coupled with solid polymer electrolyte

Terbuthylazine (TBA) has replaced atrazine in many EU countries, becoming one of the most frequently detected pesticides in natural waters. TBA is a compound of emerging concern, due to its persistence, toxicity and proven endocrine disruption activity to wildlife and humans. Techniques applied in water treatment plants remove only partially this herbicide and poor attention is given to the generation and fate of by-products, although some of them have demonstrated an estrogenic activity comparable to atrazine. This paper summarizes the environmental occurrence of TBA and its main metabolite desethylterbuthylazine and reports the performance of an innovative electrochemical cell equipped with a solid polymer electrolyte (SPE) sandwiched between a Ti/RuO₂ cathode and a Boron-Doped Diamond anode, operating at constant current, in the treatment of an aqueous solution of TBA. The herbicide removal in the first 30 min of treatment increases from 42% to 92% as the applied current is increased from 100 to 500 mA. The rate of degradation at 500 mA decreases between 30 and 60 min, with a final abatement of 97%. An 89% removal was reached at 100 mA when the initial TBA concentration was raised from 0.1 to 4 mg L^-1 and less than 1% of the herbicide was converted in desethylterbuthylazine and minor metabolites. No chemicals are needed, no sludge is produced. Further research is encouraged, as this technology may be promising for the achievement of a zero-discharge removal of different emerging pollutants as pesticides, pharmaceuticals and personal care products.

Veterinary pharmaceutical residues from natural water to tap water: Sales, occurrence and fate

Veterinary pharmaceuticals (VPs) increasingly used in animal husbandry have led to their presence in aquatic environments -surface water (SW) or groundwater (GW) - and even in tap water. This review focuses on studies from 2007 to 2017. Sixty-eight different veterinary pharmaceutical residues (VPRs) have been quantified worldwide in natural waters at concentrations ranging from nanograms per liter (ng L^-1) to several micrograms per liter (μg L^-1). An extensive up-to-date on sales and tonnages of VPs worldwide has been performed. Tetracyclines (TCs) antibiotics are the most sold veterinary pharmaceuticals worldwide. An overview of VPRs degradation pathways in natural waters is provided. VPRs can be degraded or transformed by biodegradation, hydrolysis or photolysis. Photo-degradation appears to be the major degradation pathway in SW. This review then reports occurrences of VPRs found in tap water, and presents data on VPRs removal in drinking water treatment plants (DWTPs) at each step of the process. VPRs have been quantified in tap water at ng L^-1 concentration levels in four studies of the eleven studies dealing with VPRs occurrence in tap water. Overall removals of VPRs in DWTPs generally exceed 90% and advanced treatment processes (oxidation processes, adsorption on activated carbon, membrane filtration) greatly contribute to these removals. However, studies performed on full-scale DWTPs are scarce. A large majority of fate studies in DWTPs have been conducted under laboratory at environmentally irrelevant conditions (high concentration of VPRs (mg L^-1), use of deionized water instead of natural water, high concentration of oxidant, high contact time etc.). Also, studies on VPRs occurrence and fate in tap water focus on antibiotics. There is a scientific gap on the occurrence and fate of antiparatic drugs in tap waters.

Terbuthylazine and desethylterbuthylazine: Recent occurrence, mobility and removal techniques

The herbicide terbuthylazine (TBA) has displaced atrazine in most of EU countries, becoming one of the most regularly used pesticides and, therefore, frequently detected in natural waters. The affinity of TBA for soil organic matter suggests prolonged contamination; degradation leads to the release of the metabolite desethylterbuthylazine (DET), which has higher water solubility and binds more weakly to organic matter compared to the parent compound, resulting in higher associated risk for contamination of groundwater resources. Additionally, TBA and DET are chemicals of emerging concern because of their persistence and toxicity towards aquatic organisms; moreover, they are known to have significant endocrine disruption capacity to wildlife and humans. Conventional treatments applied during drinking water production do not lead to the complete removal of these chemicals; activated carbon provides the greatest efficiency, whereas ozonation can generate by-products with comparable oestrogenic activity to atrazine. Hydrogen peroxide alone is ineffective to degrade TBA, while UV/H₂O₂ advanced oxidation and photocatalysis are the most effective processes for oxidation of TBA. It has been determined that direct photolysis gives the highest degradation efficiency of all UV/H₂O₂ treatments, while most of the photocatalytic degradation is attributed to OH radicals, and TiO₂ solar-photocatalytic ozonation can lead to almost complete TBA removal in ∼30 min. Constructed wetlands provide a valuable buffer capacity, protecting downstream surface waters from contaminated runoff. TBA and DET occurrence are summarized and removal techniques are critically evaluated and compared, to provide the reader with a comprehensive guide to state-of-the-art TBA removal and potential future treatments.

A review on environmental monitoring of water organic pollutants identified by EU guidelines

The contamination of fresh water is a global concern. The huge impact of natural and anthropogenic organic substances that are constantly released into the environment, demands a better knowledge of the chemical status of Earth's surface water. Water quality monitoring studies have been performed targeting different substances and/or classes of substances, in different regions of the world, using different types of sampling strategies and campaigns. This review article aims to gather the available dispersed information regarding the occurrence of priority substances (PSs) and contaminants of emerging concern (CECs) that must be monitored in Europe in surface water, according to the European Union Directive 2013/39/EU and the Watch List of Decision 2015/495/EU, respectively. Other specific organic pollutants not considered in these EU documents as substances of high concern, but with reported elevated frequency of detection at high concentrations, are also discussed. The search comprised worldwide publications from 2012, considering at least one of the following criteria: 4 sampling campaigns per year, wet and dry seasons, temporal and/or spatial monitoring of surface (river, estuarine, lake and/or coastal waters) and ground waters. The highest concentrations were found for: (i) the PSs atrazine, alachlor, trifluralin, heptachlor, hexachlorocyclohexane, polycyclic aromatic hydrocarbons and di(2-ethylhexyl)phthalate; (ii) the CECs azithromycin, clarithromycin, erythromycin, diclofenac, 17α-ethinylestradiol, imidacloprid and 2-ethylhexyl 4-methoxycinnamate; and (iii) other unregulated organic compounds (caffeine, naproxen, metolachlor, estriol, dimethoate, terbuthylazine, acetaminophen, ibuprofen, trimethoprim, ciprofloxacin, ketoprofen, atenolol, Bisphenol A, metoprolol, carbofuran, malathion, sulfamethoxazole, carbamazepine and ofloxacin). Most frequent substances as well as those found at highest concentrations in different seasons and regions, together with available risk assessment data, may be useful to identify possible future PS candidates.

Substructure-activity relationship studies on antibody recognition for phenylurea compounds using competitive immunoassay and computational chemistry

Based on the structural features of fluometuron, an immunizing hapten was synthesized and conjugated to bovine serum albumin as an immunogen to prepare a polyclonal antibody. However, the resultant antibody indicated cross-reactivity with 6 structurally similar phenylurea herbicides, with binding activities (expressed by IC₅₀ values) ranging from 1.67 µg/L to 42.71 µg/L. All 6 phenylurea herbicides contain a common moiety and three different substitutes. To understand how these three different chemical groups affect the antibody-phenylurea recognition activity, quantum chemistry, using density function theory (DFT) at the B3LYP/6-311++ G(d,p) level of theory, was employed to optimize all phenylurea structures, followed by determination of the 3D conformations of these molecules, pharmacophore analysis, and molecular electrostatic potential (ESP) analysis. The molecular modeling results confirmed that the geometry configuration, pharmacophore features and electron distribution in the substituents were related to the antibody binding activity. Spearman correlation analysis further elucidated that the geometrical and electrostatic properties on the van der Waals (vdW) surface of the substituents played a critical role in the antibody-phenylurea recognition process.

Habitat fragmentation caused by contaminants: Atrazine as a chemical barrier isolating fish populations

Information on how atrazine can affect the spatial distribution of organisms is non-existent. As this effect has been observed for some other contaminants, we hypothesized that atrazine-containing leachates/discharges could trigger spatial avoidance by the fish Poecilia reticulata and form a chemical barrier isolating upstream and downstream populations. Firstly, guppies were exposed to an atrazine gradient in a non-forced exposure system, in which organisms moved freely among the concentrations, to assess their ability to avoid atrazine. Secondly, a chemical barrier formed by atrazine, separating two clean habitats (extremities of the non-forced system), was simulated to assess whether the presence of the contaminant could prevent guppies from migrating to the other side of the system. Fish were able to avoid atrazine contamination at environmentally relevant concentrations (0.02 μg L^-1), below those described to cause sub-lethal effects. The AC₅₀ (atrazine concentration causing avoidance to 50% of the population) was 0.065 μg L^-1. The chemical barrier formed by atrazine at 150 μg L^-1 (concentration that should produce an avoidance around 82%) caused a reduction in the migratory potential of the fish by 47%; while the chemical barrier at 1058 μg L^-1 (concentration that produces torpidity) caused a reduction in the migratory potential of the fish by 91%. Contamination by atrazine, besides driving the spatial distribution of fish populations, has potential to act as a chemical barrier by isolating fish populations. This study includes a novel approach to be integrated in environmental risk assessment schemes to assess high-tier contamination effects such as habitat fragmentation and population displacement and isolation.

Dissipation dynamics of terbuthylazine in soil during the maize growing season

Ever since terbuthylazine (TBA) replaced atrazine in herbicide crop treatment, its much greater persistence has raised considerable environmental concern. The aim of our field experiment was to establish the dissipation dynamics of TBA and its degradation product desethylterbuthylazine (DET) in soil over five months of maize growth. We applied TBA as part of pre-emergent treatment in the regular and double-the-regular amounts. Soil samples were collected periodically at the following depths: 0-10 cm, 10-20 cm, 20-30 cm, and 30-50 cm. For TBA and DET soil residue analysis we used microwave-assisted extraction with methanol, followed by HPLC-UV/DAD. Regardless of the application rate, more than 80 % of the applied TBA dissipated from the first 50 cm of soil in the two months after herbicide application and 120 mm of rainfall. Three months later (at maize harvest), less than 4 % of total TBA remained in the soil, mostly in the top 20 cm rich with organic carbon on which TBA is likelier to adsorb. The loss of TBA from soil coincided with the rise in DET, especially the top soil layers, during the periods of low rainfall and highest soil temperatures. This points to biodegradation as the main route of TBA dissipation in humic soils. The applied amount had no significant effect on TBA dissipation in the top (humic) layers, but in the layers with less than 1 % of organic carbon, it was higher when the doublethe- regular dose was applied.

Seasonal distribution of herbicide and insecticide residues in the water resources of the vineyard region of La Rioja (Spain)

Pesticides are needed to maintain high production in the vineyard area of La Rioja (Spain), and monitoring their spatial distribution is a priority for preserving the quality of natural resources. Accordingly, the purpose of this work was to conduct a study to evaluate the presence and seasonal distribution of herbicide and insecticide residues in ground and surface waters in this region. The monitoring network comprised 12 surface waters and 78 groundwaters, covering the three subareas (63,593ha) into which the vineyard region is divided. The quality of natural waters was examined through the analysis of twenty-two herbicides, eight of their main degradation products, and eight insecticides. Pesticides were extracted by solid-phase extraction, and analysed by gas chromatography-mass spectrometry or by liquid-chromatography-mass spectrometry. The results reveal the presence of most of the herbicides and insecticides included in the study in one or more of the samples collected during the four campaigns. The herbicide terbuthylazine and its metabolite desethylterbuthylazine were the compounds more frequently detected (present in >65% of the samples across all the campaigns). Other compounds detected in >50% of the samples in one sampling campaign were the herbicides fluometuron, metolachlor, alachlor and ethofumesate. Insecticides were present in a small number of samples, with only pirimicarb being detected in >25% of the samples in March and June campaigns. The results reveal that the sum of compounds detected (mainly herbicides) was higher than 0.5μgL^-1 in >50% of the samples, especially in the campaigns with the highest application of these compounds. A possible recovery of the quality of the waters was detected outside the periods of crop cultivation, although more monitoring programmes are needed to confirm this trend with a view to preventing and/or maintaining the sustainability of natural resources.

Multiple Pesticides Detoxification Function of Maize (Zea mays) GST34

ZmGST34 is a maize Tau class GST gene and was found to be differently expressed between two maize cultivars differing in tolerance to herbicide metolachlor. To explore the possible role of ZmGST34 in maize development, the expression pattern and substrate specificity of ZmGST34 were characterized by quantitative RT-PCR and heterologous expression system, respectively. The results indicated that the expression level of ZmGST34 was increased ∼2-5-fold per day during the second-leaf stage of maize seedling. Chloroacetanilide herbicides or phytohormone treatments had no influence on the expression level of ZmGST34, suggesting that ZmGST34 is a constitutively expressed gene in maize seedling. Heterologous expression in Escherichia coli and in Arabidopsis thaliana proved that ZmGST34 can metabolize most chloroacetanilide herbicides and increase tolerance to these herbicides in transgenic Arabidopsis thaliana. The constitutive expression pattern and broad substrate activity of ZmGST34 suggested that this gene may play an important role in maize development in addition to the detoxification of pesticides.