Simultaneous determination of atrazine and metabolites (DIA and DEA) in natural water by multivariate electronic spectroscopy

Contribution of differential alteration in oxidative stress and anti-oxidation related molecular signals to toxicity difference between atrazine and its main metabolites in nematodes

As a widely used herbicide, atrazine and its two main metabolites of deethylatrazine (DEA) and deisopropylatrazine (DIA) pose an exposure risk for both human beings and animals in the environment. In this study, Caenorhabditis elegans was selected as an in vivo model to compare the toxicity between atrazine and its main metabolites. Upon exposure from the larval stage L1 to adult day 3, both DEA and DIA showed less toxicity on locomotion and reproduction compared with atrazine at concentration of 0.001, 0.01 0.1 and 1 mg/L for parental generation. In addition, exposure to DEA and DIA at concentration of 0.1 mg/L also induced less transgenerational toxicity on locomotion than exposure to atrazine for both parental generation and offspring of F1-F4. Accordingly, exposure to DEA and DIA caused less ROS production and alteration in the expression of some genes (mev-1, gas-1, and clk-1) governing oxidative stress compared to atrazine. Meanwhile, DEA and DIA lead to less increase in expression of superoxide dismutase genes (sod-2 and sod-3) and SOD-3::GFP than atrazine. Moreover, atrazine and its two main metabolites differentially activated the daf-16 encoding FOXO transcriptional factor in insulin signaling pathway during the control of downstream target of SOD-3. Overall, our results highlighted the important role of oxidative stress and anti-oxidation related molecular signals in mediating toxicity of atrazine, DEA and DIA, which provided a novel explanation for the different toxicity between atrazine and its main metabolites.

Atrazine and Diuron Effects on Survival, Embryo Development, and Behavior in Larvae and Adult Zebrafish

Atrazine and Diuron are widely used herbicides. The use of pesticides contaminates the aquatic environment, threatening biodiversity and non-target organisms such as fish. In this study, we investigated the effects of acute exposure for 96 h hours to atrazine and diuron commercial formulations in zebrafish (Danio rerio, wild-type AB) embryos and larvae and adult stages. We observed a significant concentration-dependent survival decrease and hatching delays in animals exposed to both herbicides and in the frequency of malformations compared to the control groups. Morphological defects included cardiac edema, tail reduction, and head malformation. At 7 days post-fertilization (dpf), atrazine exposure resulted in a reduction in the head length at 2, 2.5, and 5 mg/L and increased the ocular distance at 1, 2, 2.5, and 5 mg/L atrazine when compared to controls. At the same age, diuron increased the ocular distance in animals exposed to diuron (1.0 and 1.5 mg/L) and no effects were observed on the head length. We also evaluated a behavioral repertoire in larvae at 7 dpf, and there were no significant differences in distance traveled, mean speed, time in movement, and thigmotaxis for atrazine and diuron when animals were individually placed in a new environment. The cognitive ability of the larvae was tested at 7 dpf for avoidance and optomotor responses, and neither atrazine nor diuron had significant impacts when treated groups were compared to their corresponding controls. Adults’ behavior was evaluated 7 and 8 days after the end of the acute herbicide exposure. Exploration of a new environment and associated anxiety-like parameters, social interaction, and aggressiveness were not altered. Our results highlight the need for further studies on the sublethal effects of both herbicides and the consideration of the effects of commercial formulas vs. isolated active ingredients. It also emphasizes the need to take sublethal effects into consideration when establishing the environmental limits of residues.

Isotherm and Electrochemical Properties of Atrazine Sensing Using PVC/MIP: Effect of Porogenic Solvent Concentration Ratio

Widespread atrazine use is associated with an increasing incidence of contamination of drinking water. Thus, a biosensor using molecularly imprinted polymers (MIPs) was developed to detect the amount of atrazine in water to ensure prevention of exposure levels that could lead to reproductive effects in living organisms. In this study, the influence of the porogen on the selectivity of MIPs was investigated. The porogen plays a pivotal role in molecular imprinting as it affects the physical properties and governs the prepolymerization complex of the resulting polymer, which in turn firmly defines the recognition properties of the resulting molecularly imprinted polymer (MIP). Therefore, bulk MIPs against atrazine (Atr) were synthesized based on methacrylic acid (MAA) as a functional monomer and ethyleneglycol dimethacrylate (EGDMA) as a crosslinker; they were prepared in toluene and dimethyl sulfoxide (DMSO). The imprinting factor, binding capacity, and structural stability were evaluated using the respective porogenic solvents. Along with the characterization of the morphology of the obtained polymers via SEM and BET analysis, the kinetic and adsorption analyses were demonstrated and verified. The highest imprinting factor, binding capacity, and the highest structural stability were found to be on polymer synthesized in a medium of MAA and EGDMA, which contained 90% toluene and 10% DMSO as porogen. Moreover, the response for Atr concentrations by the PVC-based electrochemical sensor was found to be at a detection limit of 0.0049 μM (S/N = 3). The sensor proved to be an effective sensor with high sensitivity and low Limit of Detection (LOD) for Atr detection. The construction of the sensor will act as a baseline for a fully functionalized membrane sensor.

Efficient enrichment and analysis of atrazine and its degradation products in Chinese Yam using accelerated solvent extraction and pipette tip solid-phase extraction followed by UPLC-DAD

The Chinese Yam (Dioscorea opposita) is cultivated widely in China. However, there are potential safety risks associated with herbicide residues in Chinese Yam because of its characteristics and unregulated use of pesticides. We developed an efficient sample preparation technique for simultaneous analysis of atrazine and its degradation products in Chinese Yam using accelerated solvent extraction and pipette tip solid-phase extraction followed by UPLC-DAD analysis. Molecularly imprinted polymer (MIP) were used as the adsorbent material. Method performance was evaluated and our results showed the limit of quantification was 1-3 μg/ kg, with recoveries in the range 79.2-103.8%. When compared with other methods, this method provided superior performance in terms of sensitivity, accuracy, and precision. This method is, therefore, expected to be useful in supervised residue analysis.

Comprehensive investigation of pesticides in Brazilian surface water by high resolution mass spectrometry screening and gas chromatography-mass spectrometry quantitative analysis

In this work, a comprehensive investigation on the occurrence of pesticides in the Paraná 3 hydrographic basin of Paraná State, Brazil, was made by application of wide-scope screening based on ultra-high performance liquid chromatography (LC) and gas chromatography (GC) both coupled to quadrupole time-of-flight mass spectrometry (QTOF MS). The use of two complementary techniques, such as GC-QTOF MS and LC-QTOF MS, allowed screening a large number of compounds with different polarity and volatility. This screening approach was applied to 17 samples, enabling the detection of fifty-two pesticides and six metabolites. In a second step, an specific research was made on the herbicide atrazine, one of the most frequent compounds in samples, and its major transformation products (TPs), which were quantitatively analyzed by dispersive liquid-liquid microextraction (DLLME) followed by GC-MS measurement. Twenty-one agricultural streams from the Paraná 3 hydrographic basin were sampled twice in 2017, each time along six successive weeks. Additional samples were also collected after rain events exceeding 10 mm. In total, 407 samples were quantitatively analyzed by DLLME/GC-MS. Atrazine concentrations did not exceed the maximum permitted concentration of 2 μg L^-1 according to Brazilian legislation, and only one surface water sample, collected after precipitation events, was slightly above this value (2.89 μg L^-1). The maximum concentrations for the TPs desethylatrazine and deisopropylatrazine were 0.80 and 1.22 μg L^-1, respectively. Based on the quantification results, a map was produced showing the occurrence of atrazine and its TPs in the area under study. This is the first time that the presence of agrochemicals is evaluated in the Paraná 3 hydrographic basin.

Occurrence, control and fate of contaminants of emerging concern in environmental compartments in Brazil

This is the first review to present data obtained in Brazil over the years regarding contaminants of emerging concern (CEC) and to contrast it with contamination in other countries. Data gathered indicated that caffeine, paracetamol, atenolol, ibuprofen, cephalexin and bisphenol A occur in the μg L^-1 range in streams near urban areas. While endocrine disruptors are frequently detected in surface waters, highest concentrations account for 17α-ethynylestradiol and 17β-estradiol. Organochlorine pesticides are the most frequently found and persistent in sediments in agricultural regions. Moreover, in tropical agricultural fields, pesticide volatilization and its implications to ecosystem protection must be better investigated. The reality represented here for Brazil may be transposed to other developing countries due to similarities related to primitive basic sanitation infrastructure and economic and social contexts, which contribute to continuous environmental contamination by CEC. Municipal wastewater treatment facilities in Brazil, treat up to the secondary stage and lead to limited CEC removal. This is also true for other nations in Latin America, such as Argentina, Colombia and Mexico. Therefore, it is an urgent priority to improve sanitation infrastructure and, then, the implementation of tertiary treatment shall be imposed.

Spatiotemporal distributions of Cu, Zn, metribuzin, atrazine, and their transformation products in the surface water of a small plain stream in eastern China

The intensive use of fertilizers and pesticides in agriculture has led to widespread nonpoint source pollution in surface waterbodies. In this work, the occurrence and distribution of nonpoint source metals (Cu and Zn) and herbicides (metribuzin; atrazine; and its degradates, including desethyl atrazine (DEA), desisoproylatrazine (DIA), and deethyldeisopropylatrazine (DEDIA)) in the surface water of the Baima River, which is located in a region noted for its intense agricultural activities, were investigated during a high water period in August and a low water period in October. The results showed that the heavy metals and herbicides investigated were detected frequently in the surface water of the river during the two periods. The average concentrations of Cu during the high water period and low water period were 9.3 (0-20.7) and 8.7 (0-15.55) μg/L, and the average concentrations of Zn during the two periods were 11.4 (6.65-22.15) and 10.6 (7.55-15.15) μg/L, respectively. The concentrations of atrazine were higher than those of metribuzin, which ranged from 0.07 to 1.12 μg/L during the high water period and 0.01-0.74 μg/L during the low water period. The total concentrations of atrazine and its transformation products in 60.00% of the samples during the high water period exceeded the maximum contaminant level (MCL) of 3 μg/L for the drinking water criteria in the USA, and 33.33% of the samples exceeded the MCL during the low water period. The spatial and temporal distributions of nonpoint source pollutants along the Baima River were influenced by land use and hydrogeomorphic settings. The ecotoxicological risk assessment indicated that atrazine and DIA have moderate risks to aquatic environment in Baima River.

Development of a liquid-phase microextraction based on the freezing of a deep eutectic solvent followed by HPLC-UV for sensitive determination of common pesticides in environmental water samples

In this research, a new extraction method based on liquid-phase microextraction and the freezing of deep eutectic solvent has been developed for the determination of pesticides in water prior to their analysis by HPLC-UV.

Reduced expression of selective immune-related genes in silver catfish (Rhamdia quelen) monocytes exposed to atrazine

The effect of atrazine (ATZ) and its metabolites on aquatic vertebrate species has been a matter of concern to researchers and environmentalist. In this study we exposed head kidney monocytes to sublethal concentrations of atrazine (1 and 10 μg/ml^-1), corresponding to 1% and 10% of the LC_50-96h, to evaluate the expression of immune-related genes central to immune stimulation. The mRNA levels of TNF-α, Mieloperoxidase and Mx genes were significantly reduced following 24 h exposure to both concentrations of ATZ. The mRNA levels of iRAK4 were reduced only at the higher ATZ concentration and the mRNA levels of IL-1β were not affected. The results reported here support our previous findings on the immunosuppressive effect of ATZ indicating its potential to interfere with the expression of immune-related genes, and strengthen the need to regulate ATZ usage aiming to preserve animal and human health.

Factors affecting formation of deethyl and deisopropyl products from atrazine degradation in UV/H2O2 and UV/PDS

Formation of deethyl products (DEPs) (i.e., atrazine amide and deethylatrazine) and deisopropyl product (i.e., deisopropylatrazine (DIA)) from parent atrazine (ATZ) degraded in UV/H₂O₂ and UV/PDS processes under various conditions was monitored.

Immunotoxic effects of atrazine and its main metabolites at environmental relevant concentrations on larval zebrafish (Danio rerio)

Atrazine (ATZ) and its main metabolites, i.e., diaminochlorotriazine (DACT), deisopropylatrazine (DIP), and deethylatrazine (DE), have been widely detected in surface water around the world. In the present study, to determine their immunotoxic effects, zebrafish during the early developmental stage were exposed to ATZ and its main metabolites at environmental concentrations (30, 100, 300 μg L^-1). It was observed that ATZ, DACT, DIP and DE selectively induced the transcription of immunotoxic related genes including Tnfα, Il-1β, Il-6, Il-8, Cxcl-clc and Cc-chem in larval zebrafish. Pretreatment with ATZ and its metabolites also changed the immune response of larval zebrafish to LPS and E. coli challenge, which was indicated by the alternation in the mRNA levels of some cytokines. In addition, 300 μg L^-1 ATZ and DACT exposure could also increase the release of tryptase into water, indicating that they increased the anaphylactoid reaction in the larval zebrafish. According to these results, both of ATZ and its metabolites exposure could cause the immunotoxicity in larval zebrafish. Thus, we thought that the ecological risks of the metabolites of ATZ on aquatic organisms could not be ignored.

Evaluation of flow injection analysis method with spectrophotometric detection for the determination of atrazine in soil extracts

A method for determining atrazine in soil extracts was evaluated by flow injection analysis with spectrophotometric detection. The method is based on the reaction of atrazine with pyridine in an acid medium followed by the reaction with NaOH and sulfanilic acid. Several analytical conditions were previously studied and optimized. Under the best conditions of analysis, the limits of detection and quantification were 0.15 and 0.45 mg L(-1), respectively, for a linear response between 0.50 and 2.50 mg L(-1), and a sampling throughput of 21 determinations per hour. Using the standard addition method, the maximum relative standard deviation of 17% and recovery values between 80 and 100% were observed for three extracts from soil samples with different composition. The proposed method is simple, low-cost and easy to use, and can be employed for studies involving atrazine in soil samples or for screening of atrazine in soils.

Atrazine and its main metabolites alter the locomotor activity of larval zebrafish (Danio rerio)

Atrazine (ATZ) and its main chlorometabolites, i.e., diaminochlorotriazine (DACT), deisopropylatrazine (DIP), and deethylatrazine (DE), have been widely detected in aquatic systems near agricultural fields. However, their possible effects on aquatic animals are still not fully understood. In this study, it was observed that several developmental endpoints such as the heart beat, hatchability, and morphological abnormalities were influenced by ATZ and its metabolites in different developmental stages. In addition, after 5 days of exposure to 30, 100, 300 μg L(-1) ATZ and its main chlorometabolites, the swimming behaviors of larval zebrafish were significantly disturbed, and the acetylcholinesterase (AChE) activities were consistently inhibited. Our results also demonstrate that ATZ and its main chlorometabolites are neuroendocrine disruptors that impact the expression of neurotoxicity-related genes such as Ache, Gap43, Gfap, Syn2a, Shha, Mbp, Elavl3, Nestin and Ngn1 in early developmental stages of zebrafish. According to our results, it is possible that not only ATZ but also its metabolites (DACT, DIP and DE) have the same or even more toxic effects on different endpoints of the early developmental stages of zebrafish.