Varying modalities of perinatal exposure to a pesticide cocktail elicit neurological adaptations in mice and zebrafish

Epidemiological indications connect maternal and developmental presence or exposure to pesticides with an increased risk for a spectrum of neurological trajectories. To provide pre-clinical data in support of this hypothesis, we used two distinct experimental models. First, female and male mice were fed immediately prior to mating, and the resulting pregnant dams were continously fed during gestation and lactation periods using chow pellets containing a cocktail of six pesticides at tolerable daily intake levels. Male and female offspring were then tracked for behavioral and in vivo electrophysiological adaptations. Second, a zebrafish model allowed us to screen toxicity and motor-behavior outcomes specifically associated with the developmental exposure to a low-to-high concentration range of the cocktail and of each individual pesticide. Here, we report anxiety-like behavior in aging male mice maternally exposed to the cocktail, as compared to age and gender matched sham animals. In parallel, in vivo electrocorticography revealed a decrease in gamma (40-80 Hz) and an increase of theta (6-9 Hz) waves, delineating a long-term, age-dependent, neuronal slowing. Neurological changes were not accompanied by brain structural malformations. Next, by using zebrafish larvae, we showed an increase of all motor-behavioral parameters resulting from the developmental exposure to 10 μg/L of pesticide cocktail, an outcome that was not associated with midbrain structural or neurovascular modifications as assessed by in vivo 2-photon microscopy. When screening each pesticide, chlorpyrifos elicited modifications of swimming parameters at 0.1 μg/L, while other components provoked changes from 0.5 μg/L. Ziram was the single most toxic component inducing developmental malformations and mortality at 10 μg/L. Although we have employed non-equivalent modalities and timing of exposure in two dissimilar experimental models, these outcomes indicate that presence of a pesticide cocktail during perinatal periods represents an element promoting behavioral and neurophysiological modifications. The study limitations and the possible pertinence of our findings to ecotoxicology and public health are critically discussed.

Aedes Albopictus (Diptera: Culicidae) Susceptibility Status to Agrochemical Insecticides Used in Durian Planting Systems in Southern Thailand

High rates of dengue morbidity occur in southern Thailand. The intensive application of insecticides in orchards could affect not only agricultural insect pests, but also nontarget mosquitoes or beneficial insects. In this study, the type and quantity of insecticides commonly used across durian plantations in southern Thailand were characterized, along with the population density of Aedes albopictus (Skuse) (Diptera: Culicidae). Our primary aim was to determine the susceptibility status of field-derived Ae. albopictus to typical application concentrations of four agrochemical insecticides; cypermethrin, chlorpyrifos, carbaryl, and imidacloprid. Mosquito eggs were collected from durian cultivation sites in five provinces in southern Thailand and used to generate adults for susceptibility tests. The cultivation sites were categorized into three groups based on insecticide application: intensive application of insecticides, low application of insecticides, and no application of insecticides. Twenty ovitraps were deployed for at least three consecutive days at each study site to collect mosquito eggs and to determine Ae. albopictus population density. WHO tube assays were used to determine the susceptibility of adult mosquitoes derived from field-collected eggs to selected insecticides. This represents the first report of the susceptibility status of Ae. albopictus from durian orchards in southern Thailand to agrochemical insecticides. Results showed complete susceptibility of these Ae. albopictus to chlorpyrifos, but reduced mortality following exposure to λ-cyhalothrin, carbaryl, and imidacloprid, which is suggestive of the development of resistance. These findings provide new insights into the status of insecticide susceptibility in Ae. albopictus populations, with important implications for mosquito and mosquito-borne disease control in Thailand.

Relationship between Autism Spectrum Disorder and Pesticides: A Systematic Review of Human and Preclinical Models

Autism spectrum disorder (ASD) is a complex set of neurodevelopmental pathologies characterized by impoverished social and communicative abilities and stereotyped behaviors. Although its genetic basis is unquestionable, the involvement of environmental factors such as exposure to pesticides has also been proposed. Despite the systematic analyses of this relationship in humans, there are no specific reviews including both human and preclinical models. The present systematic review summarizes, analyzes, and discusses recent advances in preclinical and epidemiological studies. We included 45 human and 16 preclinical studies. These studies focused on Organophosphates (OP), Organochlorine (OC), Pyrethroid (PT), Neonicotinoid (NN), Carbamate (CM), and mixed exposures. Preclinical studies, where the OP Chlorpyrifos (CPF) compound is the one most studied, pointed to an association between gestational exposure and increased ASD-like behaviors, although the data are inconclusive with regard to other ages or pesticides. Studies in humans focused on prenatal exposure to OP and OC agents, and report cognitive and behavioral alterations related to ASD symptomatology. The results of both suggest that gestational exposure to certain OP agents could be linked to the clinical signs of ASD. Future experimental studies should focus on extending the analysis of ASD-like behaviors in preclinical models and include exposure patterns similar to those observed in human studies.

Chlorpyrifos and Dimethoate in Water and Sediments of Agricultural Drainage Ditches in Northern Sinaloa, Mexico

In northern Sinaloa state, Mexico, little is known on organophosphate pesticide transport and fate in agricultural drainage systems. Spatial and temporal variation of chlorpyrifos and dimethoate was assessed in two agricultural drainage ditches (Buenaventura and Burrión) and risk for aquatic life was estimated. Analysis was made by high performance liquid chromatography and risk estimates were determined following international reference frameworks. In water, the highest chlorpyrifos concentration in the Buenaventura ditch was 5.49 µg L^-1, and 3.43 µg L^-1 in the Burrión ditch. Dimethoate was quantified only once in both ditches (0.44 µg L^-1 and 0.49 µg L^-1). In sediment, chlorpyrifos was quantified only in the Burrión ditch (242 µg kg^-1). Chlorpyrifos concentrations surpassed water and sediment quality criteria, representing a hazard for environmental and human health, as both ditches discharge into the Gulf of California and are used for capture of commercial species such as the grey mullet (Mugil cephalus) and cauque prawn (Macrobrachium americanum).

Biodegradation pathway of the organophosphate pesticides chlorpyrifos, methyl parathion and profenofos by the marine-derived fungus Aspergillus sydowii CBMAI 935 and its potential for methylation reactions of phenolic compounds

The indiscriminate use of organophosphate pesticides causes serious environmental and human health problems. This study aims the biodegradation of chlorpyrifos, methyl parathion and profenofos with the proposal of new biodegradation pathways employing marine-derived fungi as biocatalysts. Firstly, a growth screening was carried out with seven fungi strains and Aspergillus sydowii CBMAI 935 was selected. For chlorpyrifos, 32% biodegradation was observed and the metabolites tetraethyl dithiodiphosphate, 3,5,6-trichloropyridin-2-ol, 2,3,5-trichloro-6-methoxypyridine, and 3,5,6-trichloro-1-methylpyridin-2(1H)-one were identified. Whereas 80% methyl parathion was biodegraded with the identification of isoparathion, methyl paraoxon, trimethyl phosphate, O,O,O-trimethyl phosphorothioate, O,O,S-trimethyl phosphorothioate, 1-methoxy-4-nitrobenzene, and 4-nitrophenol. For profenofos, 52% biodegradation was determined and the identified metabolites were 4-bromo-2-chlorophenol, 4-bromo-2-chloro-1-methoxybenzene and O,O-diethyl S-propylphosphorothioate. Moreover, A. sydowii CBMAI 935 methylated different phenolic substrates (phenol, 2-chlorophenol, 6-chloropyridin-3-ol, and pentachlorophenol). Therefore, the knowledge about the fate of these compounds in the sea was expanded, and the marine-derived fungus A. sydowii CBMAI 935 showed potential for biotransformation reactions.

Rapid detection of chlorpyrifos pesticide residue in tea using surface-enhanced Raman spectroscopy combined with chemometrics

Surface enhanced Raman spectroscopy based on rapid pretreatment combined with Chemometrics was used to determine chlorpyrifos residue in tea. Au nanoparticles were used to as enhance substrate. Different dosages of PSA and NBC were investigated to eliminate the tea substrate influence. Competitive adaptive reweighted sampling (CARS) was used to optimize the characteristic peaks, and compared to full spectra variables and the experiment selected variables. The results showed that PSA of 80 mg and NBC of 20 mg was an excellent approach for rapid detecting. CARS - PLS had better accuracy and stability using only 1.7% of full spectra variables. SVM model achieved better performance with R²_p = 0.981, RMSEP = 1.42 and RPD = 6.78. Recoveries for five unknown concentration samples were 98.47 ~ 105.18% with RSD - 1.53% ~ 5.18%. T-test results showed that t value was 0.720, less than t0.05,4 = 2.776, demonstrating that no clear difference between the real value and predicted value. The detection time of a single sample is completed within 15 min. This study demonstrated that SERS coupled with Chemometrics and QuEChERS may be employed to rapidly examine the chlorpyrifos residue in tea towards its quality and safety monitoring.

Impact of dietary lipid level on esterase enzyme activities in the non-target freshwater shrimp Macrobrachium borellii exposed to chlorpyrifos

This study increases our understanding of how diet-driven phenotypic plasticity can help non-target aquatic invertebrates deal with chlorpyrifos (CPO) exposure. A bioassay was performed over 6 days with the freshwater shrimp Macrobrachium borellii. Experimental treatments included CPO-treated shrimps (10 μg L^-1) were fed with (i) a lipid-rich diet, (ii) a lipid-medium diet, or (iii) a lipid-poor diet. Control shrimps (no CPO exposure) received the same diets as detailed above. Cholinesterases and carboxylesterases were determined as an indicator of CPO exposure. Results showed that diets with a medium-to-high lipid content were important inducers of esterase activity, while shrimps exposed to CPO under a lipid-poor diet showed a significant enzymatic inhibition. This diet-dependent esterase induction suggests that the intake of fatty dietary items mitigates the esterase enzyme inhibition caused by CPO exposure.

Improving Pesticide Uptake Modeling into Potatoes: Considering Tuber Growth Dynamics

To explore pesticide uptake from soil into a growing potato, a moving-boundary dynamic model is proposed on the basis of the radical diffusion process of a chemical to a sphere. This model, which considers the logistic growth of the potato tuber, describes two hypothetical processes of chemical diffusion within a growing tuber. The model was tested in an illustrative case study for an application of chlorpyrifos. Results indicate that the distribution of chlorpyrifos concentrations along the potato radius is significantly affected by the tuber development. In comparison of our results to results from a classic model using a fixed boundary, the proposed dynamic model yields a quick and big jump for both the average concentration and bioconcentration factor (BCF) of chlorpyrifos in the potato as a result of the sigmoid expansion boundary. Overall, the dynamic model predicts that chlorpyrifos BCFs in the potato at harvest are higher than those using the classical model. In comparison of model results to measured uptake of chlorpyrifos into potato at harvest, the dynamic model shows better performance than the classical model. Our results provide a new perspective on pesticide uptake into potatoes and inform human health risk assessment for pesticides applied at different tuber growth stages.

Application to the Buñol-Cheste Aquifer (Spain)

Chlorpyrifos, Bromacil and Terbuthylazine are commonly used as insecticides and herbicides to control weeds and prevent non-desirable growth of algae, fungi and bacteria in many agricultural applications. Despite their highly negative effects on human health, environmental modeling of these pesticides in the vadose zone until they reach groundwater is still not being conducted on a regular basis. This work shows results obtained by version 5.08 of the Pesticide Root Zone Model (PRZM5) numerical model to simulate the fate and transport of Chlorpyrifos, Bromacil and Terbuthylazine between 2006 and 2018 inside the Buñol-Cheste aquifer in Spain. The model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. The simulation process was designed for a set of twelve scenarios considering four application doses for each pesticide. Results show that the maximum concentration value for every scenario exceeds the current Spanish Maximum Concentration Limit (0.1 μg/L). Numerical simulations were able to reproduce concentration observations over time despite the limited amount of available data.

Chlorpyrifos and persistent organic pollutants in feathers of the near threatened Olrog's Gull in southeastern Buenos Aires Province, Argentina

The use of bird feathers to assess environmental contamination has steadily increased in ecotoxicological monitoring programs over the past decade. The Olrog's Gull (Larus atlanticus) is a species endemic to the Atlantic coast of southern South America, constituting one of the three threatened gull species listed in the entire American continent. The aim of this study was to assess the exposure to Persistent Organic Pollutants (POPs) and chlorpyrifos in the Near Threatened Olrog's Gull through the analysis of body feathers sampled at the Mar Chiquita coastal lagoon, the main wintering area of the species in Argentina, controlling for sex and age class. Chlorpyrifos showed the highest concentrations among all contaminants and groups of individuals (X¯ = 263 ng g^-1), while among POPs the concentration of organochlorine pesticides was higher than polychlorinated biphenyls and polybrominated diphenyl ethers, likely indicating the current use of these agricultural contaminant in the region. The highest values of total POP concentrations (males X¯ = 280 ng g^-1, females X¯ = 301 ng g^-1) were found in juvenile gulls, likely as a consequence of the incorporation of pollutants during the breeding season. Subadult and adult birds showed difference between sexes in the concentration of contaminants, with higher levels in males than females. The results highlight the need to include birds of different sex and age classes in order to better understand the variation in pollutants loads. The present study provides relevant information to improve the conservation status of the Olrog's Gull and new insights about the environmental health of the Mar Chiquita coastal lagoon, Argentina, a MAB-UNESCO World Biosphere Reserve. However, there is a continued need for long-term monitoring programs focusing on this threatened species to understand the effects of pollutants on its population.

Cholinesterase characterization and effects of the environmental contaminants chlorpyrifos and carbofuran on two species of marine crabs, Carcinus maenas and Pachygrapsus marmoratus

Among the most frequent targets for toxic effects of modern pesticides, namely organophosphates and carbamates, one may find cholinesterases (ChEs). ChEs exist in a wide variety of animals and have been used actively to discriminate among the environmental effects of different pollutant groups, including the aforementioned pesticides. This study had three purposes, namely (i) identifying the ChE forms present in tissues (eyes and walking legs muscle) of two crab species, Carcinus maenas and Pachygrapsus marmoratus; to (ii) determine the in vitro toxicological effects, and (iii) compare the sensitivity of such enzymatic forms towards commonly used anti-ChE pesticides, namely the organophosphate chlorpyrifos and the carbamate carbofuran. Our results showed that there was not a clear preference for any of the tested substrates in any of the tissues from both species. Furthermore, the ChE activity was almost completely suppressed following incubation with eserine and with the specific inhibitor BW284C51 in all tissues from both species. In vitro exposure to chlorpyrifos promoted a significant decrease in ChE activity in both species. Furthermore, the ChE activity was completely suppressed following incubation with carbofuran and chlorpyrifos. These results suggest that the major ChE forms present in tissues of both crab species show intermediate structural properties and activity patterns, halfway between classic acetylcholinesterase and pseudocholinesterases. However, the sensitivity of the found forms towards ChE inhibitors was established, and the responsiveness of such forms towards common anti-ChE chemicals was established. Both tested species seem to be promising test organisms to be used in marine and coastal scenarios of putative contaminations by anti-ChE chemicals, considering the here reported patterns of response.

Insights into the microbial degradation and catalytic mechanisms of chlorpyrifos

Chlorpyrifos is extensively used worldwide as an insecticide to control various insect pests. Long-term and irregular applications of chlorpyrifos have resulted in large-scale soil, groundwater, sediment, and air pollution. Numerous studies have shown that chlorpyrifos and its major intermediate metabolite 3,5,6-trichloropyridinol (TCP) accumulate in non-target organisms through biomagnification and have a strong toxic effect on non-target organisms, including human beings. Bioremediation based on microbial metabolism is considered an eco-friendly and efficient strategy to remove chlorpyrifos residues. To date, a variety of bacterial and fungal species have been isolated and characterized for the biodegradation of chlorpyrifos and TCP. The metabolites and degradation pathways of chlorpyrifos have been investigated. In addition, the chlorpyrifos-degrading enzymes and functional genes in microbes have been reported. Hydrolases can catalyze the first step in ester-bond hydrolysis, and this initial regulatory metabolic reaction plays a key role in the degradation of chlorpyrifos. Previous studies have shown that the active site of hydrolase contains serine residues, which can initiate a catalytic reaction by nucleophilic attack on the P-atom of chlorpyrifos. However, few reviews have focused on the microbial degradation and catalytic mechanisms of chlorpyrifos. Therefore, this review discusses the deep understanding of chlorpyrifos degradation mechanisms with microbial strains, metabolic pathways, catalytic mechanisms, and their genetic basis in bioremediation.

In-depth biochemical identification of a novel methyl parathion hydrolase from Azohydromonas australica and its high effectiveness in the degradation of various organophosphorus pesticides

Organophosphorus pesticides are highly toxic phosphate compounds with the general structure of O = P(OR)₃ and threaten human health seriously. Methyl parathion hydrolase from microbial is an important enzyme to degrade organophosphorus pesticides (OPs) into less toxic or nontoxic compounds like. p-nitrophenol and diethyl phosphate. Here, a gene encoding methyl parathion hydrolase from Azohydromonas australica was firstly cloned and expressed in Escherichia coli. The recombinant hydrolase showed its optimal pH and temperature at pH 9.5 and 50 °C. Leveraging 1 mM Mn²⁺, the enzyme activity was significantly enhanced by 29.3-fold, and the thermostability at 40 and 50 °C was also improved. The recombinant MPH showed the specific activity of 4.94 and 16.0 U/mg towards methyl parathion and paraoxon, respectively. Moreover, A. australica MPH could effectively degrade various of OPs pesticides including methyl parathion, paraoxon, dichlorvos and chlorpyrifos in a few minutes, suggesting a great potential in the bioremediation of OPs pesticides.

Chemicals with increasingly complex modes of action result in greater variation in sensitivity between earthworm species

The scale of variation in species sensitivity to toxicants has been theoretically linked to mode of action. Specifically, it has been proposed there will be greater variations for chemicals with a putative specific biological target than for toxicants with a non-specific narcotic mechanism. Here we test the hypothesis that mode of action is related to variation in sensitivity in a specifically designed experiment for species from a single ecologically important terrestrial taxa, namely earthworms. Earthworm toxicity tests were conducted with five species for four chemicals, providing a series of increasingly complex modes of action: a putative narcotic polycyclic aromatic hydrocarbon (fluoranthene), and three insecticides (chlorpyrifos, cypermethrin, imidacloprid) with known neuronal receptor targets. Across all the chemicals, the standard epigeic test species Eisenia fetida and Lumbricus rubellus, were generally among the two least sensitive, while the endogenic Aporrectodea caliginosa and Megascolecidae Amynthas gracilis were generally more sensitive (never being among the two least sensitive species). This indicates a potential for bias in the earthworm ecotoxicology literature, which is dominated by studies in epigeic Lumbricidae, but contains few endogeic or Megascolecidae data. Results confirmed the lowest range of variation in sensitivities for effects on reproduction was for fluoranthene (2.5 fold). All insecticides showed greater variation for species sensitivity (cypermethrin: 7.5 fold, chlorpyrifos: 10.3 fold, imidacloprid: 31.5 fold) consistent with the specific mechanisms of the pesticides. Difference in toxicodynamics, based on mode of action specificity and receptor complexity was reflected in the magnitude of sensitivity variation. However, measurements of tissue concentrations also indicated the potential importance of toxicokinetics in explaining species sensitivity variations for chlorpyrifos and cypermethrin.

Enhanced biodegradation of organophosphorus insecticides in industrial wastewater via immobilized Cupriavidus nantongensis X1T

Chlorpyrifos is an important organophosphorus insecticide. It is highly toxic to mammals and can pollute the environment. Cupriavidus nantongensis X1^T can efficiently degrade chlorpyrifos. Immobilization technology can also improve the viability, stability and catalytic ability of bacteria. In this study, strain X1^T was, therefore, captured on various composite immobilized carriers, sodium alginate (SA), diatomite (KLG), chitosan (CTS) and polyvinyl alcohol (PVA). The four types of immobilized beads (SA, SA + KLG, SA + CTS and SA + PVA) could form a slice and honeycomb structure to capture strain X1^T. The results showed that SA + CTS (SC) was an optimal material combination for the immobilization of strain X1^T to degrade chlorpyrifos. Compared with SA-X1^T, after adding CTS, the specific surface area and adsorption capacity for chlorpyrifos were increased 3.4 and 1.7 fold, respectively. SC-X1^T could degrade 96.6% of chlorpyrifos at 20 mg/L within 24 h and the degradation rate constant was 4.8 fold greater than immobilized strain LLBD2, a well-studied chlorpyrifos-degrading strain. The immobilized beads SC-X1^T also showed a more stable and greater degradation ability than X1^T free cells for chlorpyrifos in industrial wastewater. The synergy of adsorption and degradation of immobilized strain X1^T is suitable for in-situ remediation of chlorpyrifos contaminated environment.

Novel degradation pathways for Chlorpyrifos and 3, 5, 6-Trichloro-2-pyridinol degradation by bacterial strain Bacillus thuringiensis MB497 isolated from agricultural fields of Mianwali, Pakistan

Over use of organophosphate pesticides including Chlorpyrifos (CPF) has led to contamination of soil and water resources, resulting in serious health problems in humans along with other non-target organisms. The current study was aimed to investigate Chlorpyrifos as well as 3, 5, 6-Trichloro-2-pyridinol (TCP) biodegradation tendency of bacterial strain Bacillus thuringiensis MB497 isolated from wheat/cotton fields of Dera Saleemabad, Mianwali, Pakistan, having a history of heavy Organophosphate pesticides application. HPLC analysis revealed almost 99% degradation of the spiked CPF (200 mg L^-1) in M-9 broth, soil slurry and soil microcosm by MB497 after 9 days of incubation. Strain MB497 was also able to degrade and transform TCP (28 mg L^-1), up to 90.57% after 72 h of incubation in M-9 broth. A novel compound Di-isopropyl methanephosphonate along with known products of 3, 5, 6-Trichloro-2-pyridinol (TCP), Diethyl thiophospsphate and Phosphorothioic acid were detected as metabolites of CPF by GCMS analysis. Three novel metabolites of TCP (p-Propyl phenol, 2-Ethoxy-4, 4, 5, 5-tetramethyloxazoline and 3-(2, 4, 5-Trichlorophenoxy)-1-propyne) were identified after 72 h. Based on these metabolites, new/amended metabolic pathways for CPF and TCP degradation in these bacteria has been suggested.

Combined toxic impacts of thiamethoxam and four pesticides on the rare minnow (Gobiocypris rarus)

To examine pesticide mixture toxicity to aqueous organisms, we assessed the single and combined toxicities of thiamethoxam and other four pesticides (chlorpyrifos, beta-cypermethrin, tetraconazole, and azoxystrobin) to the rare minnow (Gobiocypris rarus). Data from 96-h semi-static toxicity assays of various developmental phases (embryonic, larval, juvenile, and adult phases) showed that beta-cypermethrin, chlorpyrifos, and azoxystrobin had the highest toxicities to G. rarus, and their LC₅₀ values ranged from 0.0031 to 0.86 mg a.i. L^-1, from 0.016 to 6.38 mg a.i. L^-1, and from 0.39 to 1.08 mg a.i. L^-1, respectively. Tetraconazole displayed a comparatively high toxicity, and its LC₅₀ values ranged from 3.48 to 16.73 mg a.i. L^-1. By contrast, thiamethoxam exhibited the lowest toxic effect with LC₅₀ values ranging from 37.85 to 351.9 mg a.i. L^-1. Rare minnow larvae were more sensitive than embryos to all the pesticides tested. Our data showed that a pesticide mixture of thiamethoxam-tetraconazole elicited synergetic toxicity to G. rarus. Moreover, pesticide mixtures containing beta-cypermethrin in combination with chlorpyrifos or tetraconazole also had synergetic toxicities to fish. The majority of pesticides are presumed to have additive toxicity, while our data emphasized that the concurrent existence of some chemicals in the aqueous circumstance could cause synergetic toxic effect, leading to severe loss to the aqueous environments in comparison with their single toxicities. Thence, the synergetic impacts of chemical mixtures should be considered when assessing the ecological risk of chemicals.

A comprehensive system for detection of behavioral change of D. magna exposed to various chemicals

The purpose of the present study was to develop a sensitive and comprehensive method, based on D. magna swimming behavior, for toxicity assessment of environmental chemicals. Firstly, D. magna swimming in several chambers with different diameters were compared to determine the most suitable container, and then baseline behaviors during light/dark periods as well as reactions to light/dark switching and vibration stimulation were determined. Secondly, after exposure to sub-lethal concentrations of the selected 42 typical chemicals, which were classified into heavy metals, pesticides, fungicides and flame retardants, the alterations in the swimming parameters were evaluated. Our results indicated the 48-well plate was the most suitable chamber for behavioral monitoring of D. magna, and specific responsive patterns of D. magna neonates to light/dark switching and vibration stimulation were observed. The results of the behavioral assays of chemicals suggested that D. magna was the most sensitive to methylmercury-chloride and then to abamectin and chlorpyrifos. The three chemicals at several to dozens of ng/L significantly changed swimming behaviors of D. magna. Furthermore, the alteration in the behavioral parameters (average swimming speed, etc.) induced by the selected chemicals could be ascribed to various modes of actions, confirming the reliability and practicability of the monitoring method.

Pesticide interactions induce alterations in secondary structure of malate dehydrogenase to cause destability and cytotoxicity

Environmental exposure to pesticides increases the risk of neurotoxicity and neurodegenerative diseases. The mechanism of pesticide-induced toxicity is attributed to the increased reactive oxygen species, mitochondrial dysfunction, inhibition of key cellular enzymes and accelerated pathogenic protein aggregation. The structural basis of pesticide-protein interaction is limited to pathogenic proteins such as α-synuclein, Tau and amyloid-beta. However, the effect of pesticides on metabolic proteins is still unexplored. Here, we used rotenone and chlorpyrifos to understand the interaction of these pesticides with a metabolic protein, malate dehydrogenase (MDH) and the consequent pesticide-induced cytotoxicity. We found that rotenone and chlorpyrifos strongly bind to MDH, interferes with protein folding and triggers alteration in its secondary structure. Both pesticides showed high binding affinities for MDH as observed by NMR and LCMS. Rotenone and chlorpyrifos induced structural alterations during MDH refolding resulting in the formation of cytotoxic conformers that generated oxidative stress and reduced cell viability. Our findings suggest that pesticides, in general, interact with proteins resulting in the formation of cytotoxic conformers that may have implications in neurotoxicity and neurodegenerative diseases.

Evaluation of the efficiency of chlorpyrifos-ethyl remediation by Methylobacterium radiotolerans and Microbacterium arthrosphaerae using response of some biochemical biomarkers

This study reveals out detoxifying and antioxidant enzyme response of Gammarus pulex exposed/polluted to chlorpyrifos-ethyl insecticide before and after biodegradation/bioremediation by Methylobacterium radiotolerans and Microbacterium arthrosphaerae. Cytochrome P450 1A1, glutathione S-transferase, catalase, and superoxide dismutase activities in G. pulex exposed to chlorpyrifos-ethyl before and after bioremediation/biodegradation by these two bacteria during 24 and 96 h tested by using commercial ELISA kits. The activity of catalase enzyme was decreased depending on chlorpyrifos-ethyl before and after bioremediation/biodegradation the enzyme activity was increased repeatedly. Superoxide dismutase activity level increased after chlorpyrifos-ethyl exposure in 96 h (p > 0.05). Following bioremediation, superoxide dismutase enzyme activity decreased again during 24 h (p > 0.05) and increased during 96 h (p < 0.05). Statistical differences were not found in cytochrome P450 1A1 enzyme activity before and after the process (p > 0.05). No significant differences were determined during the activity of glutathione S-transferase in 24 h (p > 0.05). The activities of glutathione S-transferase were increased after exposure of chlorpyrifos-ethyl during 96 h. After bioremediation; the activity of glutathione S-transferase increased even more (p < 0.05). The results determined that activities of G. pulex at superoxide dismutase, catalase, and glutathione S-transferase are common biomarkers for revealing out the efficiency of bioremediation of chlorpyrifos-ethyl with these two types of soil bacteria. Graphical abstract.

The investigation of honey bee pesticide poisoning incidents in Czechia

Honey bees are major pollinators of crops with high economic value. Thus, bees are considered to be the most important nontarget organisms exposed to adverse effects of plant protection product use. The side effects of pesticides are one of the major factors often linked to colony losses. Fewer studies have researched acute poisoning incidents in comparison to the study of the sublethal effects of pesticides. Here, we compared pesticides in dead/dying bees from suspected poisoning incidents and the suspected crop source according to government protocols. Additionally, we analyzed live bees and bee bread collected from the brood comb to determine recent in-hive contamination. We used sites with no reports of poisoning for reference. Our analysis confirmed that not all of the suspected poisonings correlated with the suspected crop. The most important pesticides related to the poisoning incidents were highly toxic chlorpyrifos, deltamethrin, cypermethrin and imidacloprid and slightly toxic prochloraz and thiacloprid. Importantly, poisoning was associated with pesticide cocktail application. Almost all poisoning incidents were investigated in relation to rapeseed. Some sites were found to be heavily contaminated with several pesticides, including a reference site. However, other sites were moderately contaminated despite agricultural use, including rapeseed cultivation sites, which can influence the extent of pesticide use, including tank mixes and other factors. We suggest that the analysis of pesticides in bee bread and in bees from the brood comb is a useful addition to dead bee and suspected crop analysis in poisoning incidents to inform the extent of recent in-hive contamination.

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.

Pesticide occurrence and water quality assessment from an agriculturally influenced Latin-American tropical region

A monitoring study was carried out in three agriculturally influenced microcatchments in Costa Rica during 2012-2014, for pesticides and water quality parameters. A total of 42 pesticides were analyzed, detecting the following in water samples: two herbicides (oxyfluorfen, diuron), four insecticides (carbofuran, chlorpyrifos, oxamyl, ethion), and two fungicides (thiabendazole, carbendazim); while in sediment samples only the insecticides, chlorpyrifos and cypermethrin were found. Water quality was also assessed by the Canadian Council of Ministers of the Environment Water Quality Index and the National Sanitation Water Quality Index, the first one classified most of the sampling point as marginal and poor quality while the second one classified most of them as good quality, the most affected parameters were nitrate, phosphorous, suspended solids and organic matter content. The results suggest that the water quality in the microcatchments seems to be affected by the nearby agricultural and urban activities in the region.

Evaluation of 1-year urinary excretion of eight metabolites of synthetic pyrethroids, chlorpyrifos, and neonicotinoids

Synthetic pyrethroids, chlorpyrifos, and neonicotinoids are representatives of non-persistent insecticides ubiquitously used against insects all over the world. Their widespread use causes prevalent exposure to these compounds, which may be hazardous to human health. The insecticides have short biological half-lives and are mostly excreted in urine within 24 h after entering the human body; thus, the urinary concentration of their metabolites is highly dependent on the time elapsed between exposure and sample collection. Considering the within-day fluctuations in urinary concentration, one randomly collected sample may cause misclassification of long-term exposure. We evaluated the variability of excretion of eight insecticide metabolites in 24-h urine samples collected from 14 volunteers once or twice per month over 12 consecutive months. High detection frequency above 70% for non-specific metabolites of pyrethroid, chlorpyrifos, and neonicotinoids confirmed widespread exposure to these insecticides in the studied population. A long-term variability of exposure was assessed based on intraclass correlation coefficient (ICC). We found relatively low variability of excretion for non-specific pyrethroid metabolites and 3,5,6-trichloro-2-pyridinol (ICC > 0.75), but poor repeatability for 6-chloronicotinic acid. Constantly higher ICCs were observed for daily excretion than for unadjusted concentrations. Seasonal differences were observed for 3,5,6-trichloro-2-pyridinol and 6-chloronicotinic acid, with the highest and the lowest median concentration, respectively, in the summer. Due to high ICC values and lack of seasonal variations, one 24-h urine sample was considered sufficient to characterize long-term excretion of non-specific pyrethroid metabolites in non-occupationally exposed population. In addition, we calculated the daily intake (DI) for cypermethrin, permethrin, deltamethrin, and chlorpyrifos. The estimated DI values were mostly below the acceptable daily intake, which indicates that the evaluated exposure is non-hazardous to the population.

Insecticides cause transcriptional alterations of endocrine related genes in the brain of honey bee foragers

Bees are exposed to endocrine active insecticides. Here we assessed expressional alteration of marker genes indicative of endocrine effects in the brain of honey bees. We exposed foragers to chlorpyrifos, cypermethrin and thiacloprid and assessed the expression of genes after exposure for 24 h, 48 h and 72 h. Chlorpyrifos caused the strongest expressional changes at 24 h characterized by induction of vitellogenin, major royal jelly protein (mrjp) 2 and 3, insulin-like peptide (ilp1), alpha-glucosidase (hbg3) and sima, and down-regulation of buffy. Cypermethrin caused minor induction of mrjp1, mrjp2, mmp1 and ilp1. The sima transcript showed down-regulation at 48 h and up-regulation at 72 h. Exposure to thiacloprid caused down-regulation of vitellogenin, mrjp1 and sima at 24 h, and hbg3 at 72 h, as well as induction of ilp1 at 48 h. The buffy transcript was down-regulated at 24 h and up-regulated at 48 h. Despite compound-specific expression patterns, each insecticide altered the expression of some of the suggested endocrine system related genes. Our study suggests that expressional changes of genes prominently expressed in nurse or forager bees, including down-regulation of buffy and mrjps and up-regulation of hbg3 and ilp1 may serve as indicators for endocrine activity of insecticides in foragers.

Organophosphorus compounds biodegradation by novel bacterial isolates and their potential application in bioremediation of contaminated water

Organophosphorus compounds (OPs), the major pesticides used worldwide, comprise an environmental hazard due to their harmful toxicity. Aimed to develop a bioreactor to remediate OPs contaminated wastewater, bacteria isolated from contaminated soils were identified and their ability to degrade OPs assessed, resulting in two main isolates, Sphingomonas sp. and Brevundimonas sp. Their OP degrading activities were characterized in terms of temperature, pH and substrates acceptance, resulting in high degradation rates at 60 °C, pH 10 and towards bulky OPs such as coroxon, coumaphos, and chlorpyrifos. Sphingomonas sp. cells were immobilized and 75.4% degradation of 0.15 mM chlorpyrifos was achieved after 21 days by immobilized cells in batch system, while this OP was completely degraded within 17 h when the biocatalyst is settled in a packed bed bioreactor, with a reusability of 8 cycles. These results suggest the potential application of this system in the bioremediation of contaminated wastewater.

Characterization of a novel hyper-thermostable and chlorpyrifos-hydrolyzing carboxylesterase EstC: A representative of the new esterase family XIX

Carboxylesterases have widely been used in a series of industrial applications, especially, the detoxification of pesticide residues. In the present study, EstC, a novel carboxylesterase from Streptomyces lividans TK24, was successfully heterogeneously expressed, purified and characterized. Phylogenetic analysis showed that EstC can be assigned as the first member of a novel family XIX. Multiple sequence alignment indicated that EstC has highly conserved structural features, including a catalytic triad formed by Ser155, Asp248 and His278, as well as a canonical Gly-His-Ser-Ala-Gly pentapeptide. Biochemical characterization indicated that EstC exhibited maximal activity at pH 9.0 (Tris-HCl buffer) and 55 °C. It also showed higher activity towards short-chain substrates, with the highest activity for p-nitrophenyl acetate (pNPA2) (K_m = 0.31 ± 0.02 mM, k_cat/K_m = 1923.35 ± 9.62 s^-1 mM^-1) compared to other pNP esters used in this experiment. Notably, EstC showed hyper-thermostability and good alkali stability. The activity of EstC had no significant changes when it was incubated under 55 °C for 100 h and reached half-life after incubation at 100 °C for 8 h. Beyond that, EstC also showed stability at pH ranging from 6.0 to 11.0 and about 90% residual activity still reserved after treatment at pH 8.0 or 9.0 for 26 h, especially. Furthermore, EstC had outstanding potential for bioremediation of chlorpyrifos-contaminated environment. The recombinant enzyme (0.5 U mL^-1) could hydrolyze 79.89% chlorpyrifos (5 mg L^-1) at 37 °C within 80 min. These properties will make EstC have a potential application value in various industrial productions and detoxification of chlorpyrifos residues.

Susceptibility of Chrysoperla externa (Hagen, 1861) (Neuroptera: Crysopidae) to insecticides used in coffee crops

The coffee crop hosts pests such as mites, mealybugs, and aphids which serve as food for the predator Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae). The preservation of this chrysopid in coffee agroecosystem is very important to achieve sustainability of this agricultural sector, and can be obtained by applying low toxicity insecticides. The present study aimed to evaluate the susceptibility of C. externa to azadiracthin, chlorpyrifos, ethiprole and teflubenzuron. Predator eggs, third instar larvae, pupae and adults were exposed to insecticides by Potter tower spraying. When evaluating exposure of C. externa eggs we observed that chlorpyrifos, ethiprole and teflubenzuron reduced larvae hatching, while azadiracthin prolonged first instar duration. Meanwhile, the exposure of third instar larvae to chlorpyrifos and ethiprole caused mortality of all insects after 72 h, while azadiracthin prolonged the larval development time; we also observed that no compound allowed the formation of adults. After pupae were exposed to chlorpyrifos and teflubenzuron, it was observed a reduction on the emergence of adults, while the longevity of adults from these pupae and the evaluated reproductive parameters were reduced by all insecticides. For the bioassay with adults, chlorpyrifos, ethiprole and teflubenzuron reduced the longevity of insects, while the reproductive parameters evaluated were negatively affected after exposure to azadiracthin and teflubenzuron. It was concluded that all insecticides negatively affected at least one biological characteristic of the predator in at least one of the insect's developmental stages, requiring further research in semi-field and field conditions to prove its toxicity.

Are there any risks of the disposal of pesticide effluents in soils? Biobed system meets ecotoxicology ensuring safety to soil fauna

The biobed is a purification system, which reduces soil pollution for receiving pesticide residues from handling and washing machinery in agricultural areas. The aims of this study were (1) to assess ecotoxicity effects over time to soil fauna, posed by Lorsban^® 480 BR (Chlorpyrifos) and Dithane^® NT (Mancozeb) residues when disposed of in a biobed system compared with two subtropical soils, and (2) to assess ecotoxicity effects over time to soil fauna simulating an accidental spillage with Lorsban^® 480 BR at the biobed. A semi-field experiment was conducted for 420 days in southern Brazil, testing continuous disposal of washing pulverization tanks in biobeds, Typic Haploperox or Typic Hapludults. In addition, different biobeds received a single dose (1 L) of Lorsban^® 480 BR to simulate an accidental spillage. Chronic ecotoxicity tests were performed using Folsomia candida, Eisenia andrei, and Enchytraeus crypticus in different sampling times for both experiments. F. candida was the most sensitive species. The biobed system was able to eliminate effects from residues of both pesticides over time in all species, which did not happen in both natural soils. In accidental spillage simulation, even 420 days after contamination, F. candida did not show reproduction. The biobeds can be a feasible alternative for the disposal and treatment residues of pesticides, also for handling and washing pesticides activities. The system was efficient in promoting degradation and reducing ecotoxicity effects posed by Lorsban^® 480 BR and Dithane^® NT for soil fauna. It is a safe alternative to avoid soil contamination.

Linkage of antibiotic resistance genes, associated bacteria communities and metabolites in the wheat rhizosphere from chlorpyrifos-contaminated soil

Rhizosphere is a crucial site for the proliferation of antibiotic resistance genes (ARGs) in agricultural soil. Pesticide contamination is ubiquitous in soil, such as chlorpyrifos as one of the most commonly used pesticides. However, limited knowledge is reported about ARGs profiles changes and the driving mechanism of ARGs prevalence in rhizosphere soil after adding pesticide. In this study, irrespective of chlorpyrifos presence, the abundances of ARGs (tetM, tetO, tetQ, tetW, tetX, sul1 and sul2) and intI1 in rhizosphere soil of wheat were obviously higher than those in bulk soil. 20.0 mg·kg^-1 chlorpyrifos significantly increased the abundance of total ARGs and intI1 in bulk soil, respectively, at day 50 and 100, but not in rhizosphere soil. Rhizosphere influence on ARGs was far greater than chlorpyrifos. ARGs and intI1 abundances were higher at day 50 than ones at day 100. C/N ratio and NO₃^--N content, which were affected by rhizosphere and cultivation time, significantly explained the increased ARGs. Compared to bulk soil, rhizosphere shifted host bacteria of tetracycline resistance genes (TRGs), intI1 at genus level, and host bacteria of sul1, sul2 at phylum level. Rhizosphere simplified the linkage of ARGs, host bacteria and metabolites. Bacterial communities played important roles in the variation of ARGs and intI1, and the difference in the distribution of potential hosts between bulk and rhizosphere soil was related to metabolites abundance and composition. These results provide valuable information for understanding the linkage of ARGs, associated bacteria communities and metabolites in the wheat rhizosphere soil.

Mosquito larvae that survive a heat spike are less sensitive to subsequent exposure to the pesticide chlorpyrifos

While extreme high temperatures are an important aspect of global warming, their effects on organisms are relatively understudied, especially in ecotoxicology. Sequential exposure to heat spikes and pesticides is a realistic scenario as both are typically transient stressors and are expected to further increase in frequency under global warming. We tested the effects of exposure to a lethal heat spike and subsequently to an ecologically relevant lethal pulse exposure of the pesticide chlorpyrifos in the larvae of mosquito Culex pipiens. The heat spike caused direct and delayed mortality, and resulted in a higher heat tolerance and activity of acetylcholinesterase, and a lower fat content in the survivors. The chlorpyrifos exposure caused mortality, accelerated growth rate, and decreased the heat tolerance and the activity of acetylcholinesterase. The preceding heat spike did not change how chlorpyrifos reduced the heat tolerance. Notably, the preceding heat spike did lower the lethal effect of the pesticide, which makes an important novel finding at the interface of ecotoxicology and global change biology, and adds a new dimension to the "climate-induced toxicant sensitivity" (CITS) concept. This may be due to both survival selection and cross-tolerance, and therefore likely a widespread phenomenon. Our results emphasize the importance of including extreme high temperatures as an important transient global change stressor in ecotoxicology.

Products and mechanism of thermal decomposition of chlorpyrifos under inert and oxidative conditions

Chlorpyrifos (CPF) is a widely used pesticide; however, limited experimental work has been completed on its thermal decomposition. CPF is known to decompose into 3,5,6-trichloro-2-pyridinol (TCpyol) together with ethylene and HOPOS. Under oxidative conditions TCpyol can decompose into the dioxin-like 2,3,7,8-tetrachloro-[1,4]-dioxinodipyridine (TCDDPy). With CPF on the cusp of being banned in several jurisdictions worldwide, the question might arise as to how to safely eliminate large stockpiles of this pesticide. Thermal methods such as incineration or thermal desorption of pesticide-contaminated soils are often employed. To assess the safety of thermal methods, information about the toxicants arising from thermal treatment is essential. The present flow reactor study reports the products detected under inert and oxidative conditions from the decomposition of CPF representative of thermal treatments and of wildfires in CPF-contaminated vegetation. Ethylene and TCpyol are the initial products formed at temperatures between 550 and 650 °C, although the detection of HOPOS as a reaction product has proven to be elusive. During pyrolysis of CPF in an inert gas, the dominant sulfur-containing product detected from CPF is carbon disulfide. Quantum chemical analysis reveals that ethylene and HOPOS undergo a facile reaction to form thiirane (c-C₂H₄S) which subsequently undergoes ring opening reactions to form precursors of CS₂. At elevated temperatures (>650 °C), TCpyol undergoes both decarbonylation and dehydroxylation reactions together with decomposition of its primary product, TCpyol. A substantial number of toxicants is observed, including HCN and several nitriles, including cyanogen. No CS₂ is observed under oxidative conditions - sulfur dioxide is the fate of S in oxidation of CPF, and quantum chemical studies show that SO₂ formation is initiated by the reaction between HOPOS and O₂. The range of toxicants produced in thermal decomposition of CPF is summarised.

Ecological risk assessment of current-use pesticides in an aquatic system of Shanghai, China

The widespread use of current-use pesticides (CUPs) in modern agriculture has threatened the survival of aquatic organisms. Therefore, the residual levels, spatial distribution, and ecological risk assessment of 18 CUPs are investigated in an aquatic system of Shanghai. The aquatic system focused on a freshwater system that contains particles smaller than 0.45 μm in size, which are easily absorbed by aquatic organisms. The mean values of chlorpyrifos, napropamide, and atrazine were found to be the highest concentration CUPs, and propazine, mevinphos, ametryn, butylate, dichlorvos, ethoprop, and prometryn displayed the most significant positive correlations with each other. The concentration of the ∑₁₈CUPs was higher in the southern areas of Shanghai (generally greater than 100 ng/L), but it was relatively low in the central areas (generally smaller than 75 ng/L). Six important CUPs were identified, and the differences in the concentration contribution rates and contribution amounts among different intensive land-use types were noticeable. The ecological risk in most areas of this aquatic system of Shanghai was high. Chlorpyrifos and butachlor produced the maximum toxic unit (mTU) for daphnid and green algae, respectively, and their toxic unit contribution rates to the entire mixture toxicity were both greater than 50%. This confirms that the mixture toxicity of the CUPs to aquatic organisms in this aquatic system of Shanghai primarily resulted from a few dominant toxic pesticides. However, for each sensitive organism, there will still be a risk contribution of approximately 5%-30% due to other CUPs.

Behavioural and biochemical alterations by chlorpyrifos in aquatic insects: an emerging environmental concern for pristine Alpine habitats

This study aimed to assess how different concentrations of the insecticide chlorpyrifos (1.1, 5.24, 11, 52.4, 110, 262, 524 and 1100 ng L-1) affect the swimming behaviour of Diamesa zernyi larvae following exposure. A video tracking system was employed to analyse two swimming traits (total distance moved and average speed) of the larvae simultaneously after 3 days of exposure to the pesticide at 2 °C. The behavioural results were also interpreted according to biochemical responses to oxidative stress (OS) induced by chlorpyrifos, based on malondialdehyde (MDA) and protein carbonyl (PCC) content. Both distance and speed significantly decreased after 72 h of exposure to chlorpyrifos concentrations of ≥ 110 ng L-1, under which significant OS was detected as lipid peroxidation (level of MDA) and protein carbonylation (level of carbonyl). Analysis of altered swimming behaviour, along with MDA and carbonyl content, indicated that ≥ 110 ng L-1 contamination levels of the insecticide cause the organism to reallocate energy normally used for locomotor activity to repair cell damage, which might explain the strong impairment to locomotor performance. Locomotor performance is an ecologically relevant trait for elucidating the population dynamics of key species, with disturbance to this trait having long-term negative impacts on population and community structure. Therefore, chlorpyrifos insecticides represent a serious ecological risk for mountain aquatic species based on the detrimental effects observed in the current study, as the tested concentrations were those at which the insecticide is found in many Alpine rivers of Italy.

The protective role of spirulina and β-glucan in African catfish (Clarias gariepinus) against chronic toxicity of chlorpyrifos: hemato-biochemistry, histopathology, and oxidative stress traits

Chlorpyrifos (CPF) is an insecticide that is commonly applied in the agriculture sector. However, little is known about the protective role of Spirulina platensis (SP) and/or β-glucan (BG) on African catfish exposed to chronic CPF toxicity. The fish (95 ± 5 g, initial weight) were assigned to 5 fiberglass tanks (500 L, 50 fish/tank) where the 1st and 2nd fed the basal diet, while the 3rd, 4th, and 5th fed diets with SP, BG, and SP+BG at 0.5%, respectively. Fish in 2nd, 3rd, 4th, and 5th groups were exposed to CPF at a dose of 1.5 mg/L and fed the respective diets for 60 days. In comparison with the control group, CPF-exposed fish exhibited significantly lower (P ≤ 0.05) body weights, feed intake, red blood cells count, hemoglobin concentration, packed cell volume (PCV) (%), lymphocytes, monocytes, phagocytic activity, and phagocytic index, while feed conversion ratio, white blood cell count, and neutrophils count were significantly increased. Fish exposed to CPF also revealed a significant elevation in aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol, triglycerides, low-density lipoproteins (LDL), very-low-density lipoproteins (vLDL), glucose concentration, urea, and creatinine as well as low total proteins, albumin, globulins, and high-density lipoprotein (HDL) concentration. Fish exposed to CPF also exhibited a high concentration of malondialdehyde while glutathione content, glutathione peroxidase, and catalase activities were significantly decreased in the liver, gills, brain, and intestine tissues. Moreover, exposure to CPF resulted in higher transcription of cytochrome P450 (CYP1A-P450) gene expression than the 1st group. Histopathological investigations revealed various degrees of pathological lesions in different organs like the liver, kidney, brain, spleen, and intestine tissues. Interestingly, dietary SP supplementation either alone or combined with BG significantly ameliorated the alterations mitigated by CPF-induced organ injuries and genotoxicity. Therefore, it could be concluded that SP or/and BG are able to induce the protective consequences on health status, immunity, and antioxidative response of African catfish exposed to CPF.

Co-presence of the anionic surfactant sodium lauryl ether sulphate and the pesticide chlorpyrifos and effects on a natural soil microbial community

There is a growing concern about the simultaneous presence in the environment of different kinds of pollutants, because of the possible synergic or additive effects of chemical mixtures on ecosystems. Chlorpyrifos (CPF) is an organophosphate insecticide extensively used in agricultural practices. The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component of several commercial products, including foaming agents used in underground mechanised excavation. Both compounds are produced and sold in high amounts worldwide and can be found in the environment as soil contaminants. The persistence of SLES and CPF in agricultural soils and their possible effects on the natural microbial community was evaluated in microcosms. The experimental set consisted of soil samples containing the autochthonous microbial community and treated with only SLES (70 mg/kg), only CPF (2 mg/kg) or with a mix of both compounds. Control microcosms (without the contaminants) were also performed. Soil samples were collected over the experimental period (0, 7, 14, 21 and 28 days) and analysed for CPF, SLES and the main metabolite of CPF (3, 5, 6-trichloropyridinol, TCP). The half-life time (DT50) of each parent compound was estimated in all experimental conditions. At the same time, the abundance, activity and structure of the microbial community were also evaluated. The results showed that the co-presence of SLES and CPF did not substantially affect their persistence in soil (DT50 of 11 and 9 days with co-presence and 13 and 10 days, respectively, when alone); however, in the presence of SLES, a higher amount of the metabolite TCP was found. Interestingly, some differences were found in the bacterial community structure, abundance and activity among the various conditions.

Acute toxicity of chlorpyrifos and its metabolite 3,5,6-trichloro-2-pyridinol alone and in combination using a battery of bioassays

Acute toxicity of chlorpyrifos (CP) and its principal metabolite 3,5,6-trichloro-2-pyridinol (TCP) alone and in combination have been evaluated using a test battery comprising aquatic organisms from different trophic levels: luminescent marine bacteria Aliivibrio fischeri, freshwater unicellular alga Pseudokirchneriella subcapitata, and cladoceran Daphnia magna. As expected, D. magna was the more sensitive organism to the compounds tested, being CP more toxic than its metabolite. On the contrary, TCP was found to be more toxic than its parental compound to A. fischeri and P. subcapitata. In all cases, the mixture of CP and its metabolite was more toxic than the compounds tested separately, multiplying between 5 and 200 times CP toxicity level and up to 15 times TCP toxicity level. These results indicate that the co-existence of parent chemical and its degradation product in the environment can result in a synergic interaction involving high risk to the aquatic ecosystems. Graphical abstract.

Synergistic effect of Ficus-zero valent iron supported on adsorbents and Plantago major for chlorpyrifos phytoremediation from water

Chlorpyrifos and the metabolite 3, 5, 6-trichloro-2-pyridinol (TCP) are widespread contamination of aquatic environments especially freshwater fish. The objectives of this study were to evaluate the contribution of using Ficus zero-valent iron nanoparticles supported on adsorbents (F-Fe⁰ ad) as green nanotechnology and Plantago major as phytoremediation for removing chlorpyrifos and degradation product TCP polluted water. The shapes of F-Fe⁰ were circular, with sizes from 2.46 nm to 11.49 nm. Wheat bran (WB) showed the highest extent of removal of chlorpyrifos, while Rice straw ash (RSA) showed the lowest extent of removal. F-Fe⁰ supported on adsorbents has demonstrated faster removal toward chlorpyrifos compared with tested adsorbents or F-Fe⁰. Chlorpyrifos was removed more quickly and effectively by P. major L. plus F-Fe⁰ supported on different adsorbents (nearly 100%) than that by P. major (43.76%) or F-Fe⁰ (81.69%). The degradation product TCP was more greatly accumulated in water treated with F-Fe⁰ than that P. major alone or F-Fe⁰ supported with adsorbents and combined with P. major. Furthermore, TCP significantly accumulated in P. major roots and leaves in the water treated with F-Fe⁰ supported with adsorbents plus P. major more than that in the P. major roots and leaves alone, this is attributed to the role of F-Fe⁰ adsorbents for the degradation of chlorpyrifos to TCP, Which strongly accumulated in the P. major roots and leaves. It can be concluded that the contribution of using F-Fe⁰ supported on adsorbents, especially WB as green nanotechnology and P. major as phytoremediation would be a major role for the complete removal of chlorpyrifos from the water with a significant reduction in the toxic degradation product TCP.

Mechanism of interactions between organophosphorus insecticides and human serum albumin: Solid-phase microextraction, thermodynamics and computational approach

Organophosphates insecticides (OPs) are one of the major environmental pollutants and their interaction with human serum albumin (HSA) has been shown to have significant effects on their bioavailability which is related to toxicokinetics and toxicodynamics in human body. In this research, solid-phase microextraction methods were developed to analyse the free concentrations of three OPs (chlorpyrifos, parathion-methyl and malathion) in buffered HSA solution and that provide a useful method for the determination of binding affinity constants (K_a), binding forces and binding location. Polydimethylsiloxane fibers were selected for analysing the free concentrations of OPs, with an external calibration approach. Good linearities conducted in PBS solution were observed in the range of 0.0025-1.7 μmol L^-1 (R² = 0.9975) for chlorpyrifos, 1.0-27 μmol L^-1 (R² = 0.9974) for parathion-methyl, and 0.5-70 μmol L^-1 (R² = 0.9973)for malathion, respectively. The LODs for instrument response were 1 ng, 5 ng and 10 ng for chlorpyrifos, parathion-methyl and malathion, respectively. The K_a values for chlorpyrifos, parathion-methyl and malathion showed that they were positively correlated with hydrophobicity and negatively correlated with temperature. The OP binding sites on HSA were confirmed by site marker competition test and further proven by computational approaches. The recognition region of parathion-methyl was situated within residues 199-292 in subdomain IIA. Malathion bonded to residues 404-558 in subdomain IIIA. The mode of action between HSA-parathion-methyl and HSA-malathion is found to involve mainly by H-bonds, π-π stacking and hydrophobic effects. These results clearly demonstrate the noncovalent binding of OPs with HSA and provide new insight into solid-phase microextraction, thermodynamics and computational approaches.

TCP structure intensified the chlorpyrifos-induced decrease in testosterone synthesis via LH-LHR-PKA-CREB-Star pathway

Similar to diethylphosphate (DEP), 3,5,6-trichloro-2-pyridinol (TCP) is also a characteristic chemical substance and ultimate transformation product of chlorpyrifos (CPF) because the structure of TCP is equivalent to the trichloro pyridine structure of CPF. TCP is often used as a biomarker of CPF exposure. TCP and DEP are often detected in human blood and urine due to the widespread use of CPF. No studies have sufficiently clarified which structure contributes to the negative effect of CPF on testosterone synthesis. This study aims to explain which structure promotes the inhibitory effect of CPF on testosterone synthesis and the related influence mechanisms. After 20 weeks of exposure, the testosterone level in testes was significantly reduced by different doses of CPF (0.3 mg/kg body weight CPF and 3.0 mg/kg body weight CPF). Meanwhile, the level of testosterone synthesized by isolated primary Leydig cells was also reduced by CPF. In addition, TCP but not DEP aggravated the decrease in testosterone synthesis in isolated primary Leydig cells. On the other hand, CPF and TCP significantly decreased the levels of the Star protein, CREB phosphorylation and PKA phosphorylation, which are important in regulating testosterone synthesis. Based on these results, TCP is a key structure that mediates the CPF-induced decrease in testosterone synthesis by terminating the signal transmission of the LH-LHR-PKA-CREB-Star pathway. Thus, chemicals with the TCP structure may be potential endocrine disruptors that decrease fertility. Chemicals that can be converted to TCP or achieve a trichloro pyridine structure must be considered during reproductive toxicity risk assessment.

Biomonitoring of the hematological, biochemical and genotoxic effects of the mixture cypermethrin plus chlorpyrifos applications in bovines

External antiparasitic agents applied in bovine production represent a risk to consumers of meat products, especially if the conditions of their use are not strictly respected. The post-mortem control of residues in meat is an activity that must be updated and reinforced by the biomonitoring of live animals and the use of analytical tools to help identifying signs of early warning risks. The objective of the present study was to carry out a pre-slaughter biomonitoring approach in Aberdeen Angus cattle and crosses (n = 12) with the application of a commercial formulation of cypermethrin plus chlorpyrifos. This was performed with a single therapeutic dose applied on the backs of the cattle, through hematological, enzymatic, as well as hepatic and renal function analysis in plasma, and then quantifying the genotoxic effect on lymphocytes. Analytical measurements of plasma concentrations of cypermethrin plus chlorpyrifos at 24 h were negative and therefore a low absorption of the compounds was assumed. Measurement of acetyl cholinesterase showed no inhibition after exposure. The concentration of urea increased between 24 h and 168 h post application of the formulation, without showing any kidney damage. The rest of the parameters analyzed did not show any variations. This evaluation of hematological and biochemical effects and of cytokinesis-block micronucleus cytome assay in bovines is proposed as a pre-slaughter control of biomonitoring of the health status of animals, with a focus on food safety for meat consumers.

Toxicity evaluation of pesticide chlorpyrifos in male Japanese quails (Coturnix japonica)

In the current study, chlorpyrifos was used as a test chemical to evaluate its possible toxicological effect on birds. A total of 45 adult male Japanese quails were divided into five groups (A to E). Each group, containing 9 birds was further divided into 3 sub-groups (containing 3 birds each). Group A served as control, while all other groups and sub-groups were exposed to selected pesticide for different trial periods. Chlorpyrifos sub-lethal doses were orally administered daily at the rate of 3, 6, 9, and 12 mg/kg body weight per day to group B, C, D, and E, respectively. Birds were kept under observation for behavioral changes throughout the trial periods. Clinical signs, histological alterations, genotoxicity, and blood biochemical alterations were recorded after each 15-day trial. Mild to moderate clinical signs like staggering gait, tremors, diarrhea, dullness, less frequency of crowing, and decrease foam production were observed in group D and E throughout the study. The changes in the body weight gain and blood biochemical parameters among different groups at a given trial period were insignificant. The appearance of micronuclei in group E birds was more significant, indicating that nucleus damage was dose-dependent while to lesser extent duration-dependent. The comet assay showed significant dose- and duration-dependent DNA damage among various groups. In comparison with control group, extensive histological degenerative alterations in the liver, testes, and kidneys were observed in birds of group D and E, where mild to severe alteration like congestion, vacuolation, necrosis, apoptosis, karyopyknosis, extensive degeneration, and alteration in many cellular structures were noticeable.

Influence of Adjuvants on Pesticide Soil-Air Partition Coefficients: Laboratory Measurements and Predicted Effects on Volatilization

A solid-phase fugacity meter was used to measure the soil-air partition coefficients of three semivolatile pesticides (chlorpyrifos, pyrimethanil, and trifluralin) in the absence of additional adjuvants (K_soil-air,AI), as part of commercial formulations (K_{soil-air,formulation}), and as formulation mixtures with an additional spray adjuvant added (K_{soil-air,formulation+spray adjuvant}). Chlorpyrifos K_{soil-air,formulation} values were also measured over 15-30 °C, allowing for the change in internal energy of the phase transfer reaction (Δ_soil-airU) to be calculated and compared to the Δ_soil-airU for K_soil-air,AI from the literature. Measured K_soil-air values were then used as input parameters in a pesticide volatilization model to understand how their variability affects pesticide volatilization rates under different conditions. Initial experiments conducted at ∼24 °C indicated that all pesticides volatilized more readily in the presence of adjuvants than in their absence and that the additional spray adjuvant had minimal impact. The Δ_soil-airU values were 328 and 90 kJ/mol for chlorpyrifos in the absence and presence of formulation adjuvants, respectively, suggesting that adjuvants may weaken or disrupt intermolecular attractions between pesticide molecules and soil. At temperatures below 24.5 °C, modeled chlorpyrifos volatilization rates were higher in the presence of adjuvants than in their absence; however, the opposite occurred at temperatures above 24.5 °C.

Occupational Pesticide Use and Risk of Renal Cell Carcinoma in the Agricultural Health Study

BACKGROUND

Agricultural work and occupational pesticide use have been associated with increased risk of renal cell carcinoma (RCC), the most common form of kidney cancer. However, few prospective studies have investigated links to specific pesticides.

OBJECTIVE

We evaluated the lifetime use of individual pesticides and the incidence of RCC.

METHODS

We evaluated the associations between intensity-weighted lifetime days (IWDs) of 38 pesticides and incident RCC in the Agricultural Health Study, a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. Among 55,873 applicators, 308 cases were diagnosed between enrollment (1993-1997) and the end of follow-up (2014-2015). We estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) using Poisson regression, controlling for potential confounding factors, with lagged and unlagged pesticide exposures.

RESULTS

There was a statistically significant increased risk of RCC among the highest users of 2,4,5-T compared with never users [unlagged RR IWD Tertile  3 = 2.92 (95% CI: 1.65, 5.17; p trend = 0.001 )], with similar risk estimates for lagged exposure [20-y lag RR IWD Tertile  3 = 3.37 (95% CI: 1.83, 6.22; p trend = 0.001 )]. In 20-y lagged analyses, we also found exposure-response associations with chlorpyrifos [RR IWD Quartile  4 = 1.68 (95% CI: 1.05, 2.70; p trend = 0.01 )], chlordane [RR IWD Tertile  3 = 2.06 (95% CI: 1.10, 3.87; p trend = 0.02 )], atrazine [RR IWD Quartile  4 = 1.43 (95% CI: 1.00, 2.03; p trend = 0.02 )], cyanazine [RR IWD Quartile  4 = 1.61 (95% CI: 1.03, 2.50; p trend = 0.02 )], and paraquat [RR IWD > Median = 1.95 (95% CI: 1.03, 3.70; p trend = 0.04 )].

CONCLUSIONS

This is, to our knowledge, the first prospective study to evaluate RCC risk in relation to various pesticides. We found evidence of associations with RCC for four herbicides (2,4,5-T, atrazine, cyanazine, and paraquat) and two insecticides (chlorpyrifos and chlordane). Our findings provide insights into specific chemicals that may influence RCC risk among pesticide applicators. Confirmation of these findings and investigations of the biologic plausibility and potential mechanisms underlying the observed associations are warranted. https://doi.org/10.1289/EHP6334.

The impact of age-related sub-chronic exposure to chlorpyrifos on metabolic indexes in male rats

Chlorpyrifos (CPF), an organophosphorus pesticide (OP), has been implicated in metabolic diseases; however, the data are controversial. Rising age has been found as a main risk factor for metabolic diseases, and it has been proposed that advanced age increases susceptibility to the toxic effects of OPs. Therefore, this investigation aimed to evaluate the impact of CPF on hyperglycemia, hypercholesterolemia, and inflammation in animals with different ages. CPF (5 mg/kg) for 45 consecutive days was administered orally to male Wistar rats with different ages including 2-, 10-, and 20-month-old. The results indicated an increase in glucose and inflammatory indices, and also lipid profile was changed in the serum of aged animals in comparison with the 2-month-old animals. CPF administration amplified these parameters in the 20-month-old rats in comparison with that of aged-matched controls. The histopathological examination also indicated that CPF caused slight to moderate changes in the liver of 2-, 10-, and 20-month-old animals. Cholestasis was also observed in the CPF-administrated 20-month-old rats. In conclusion, aging may increase the susceptibility to CPF-induced metabolic disturbances in the animal models. It is proposed that advancing in age elevates the susceptibility to the metabolic effects of CPF.

Combined effects of goethite nanoparticles with metallic contaminants and an organophosphorus pesticide on Eisenia andrei

The effects of mixtures of nanoparticles (NPs) and other chemicals have been poorly studied in terrestrial invertebrates. In this study, we investigated the effects of binary mixtures of goethite (α-FeOOH) NPs and metallic (Cd and Pb) or organic (chlorpyrifos, CPF) contaminants in Eisenia andrei earthworms. We used the filter paper contact test to evaluate (i) the uptake of NPs in organisms exposed to the mixtures of NPs+Metals and NPs+CPF and (ii) the potential effects of the mixture of NPs+CPF on the CPF-induced inhibition of the biomarker enzymes acetylcholinesterase (AChE) and carboxylesterases (CES). We used the artificial soil test to deepen the study on joint effects of NPs+CPF. All compounds were applied separately and in binary mixtures. In the single exposure treatment, Fe levels decreased significantly in organisms exposed to NPs on filter paper, suggesting systemic effects aimed at eliminating Fe incorporated through NPs. Conversely, earthworms exposed to binary mixtures showed Fe levels similar (NPs+Metals) to or higher (NPs+CPF) than controls. The earthworms single exposed to NPs presented no changes in AChE and CES activities. In the artificial soil test, the only treatment that showed AChE inhibition after 72 h was single CPF exposure, while no significant changes were observed in CES activity. However, after 7-day exposure in artificial soil or 72-h exposure on filter paper, the mixture of NPs+CPF induced a similar degree of AChE and CES inhibition as single CPF exposure. All these suggested that NPs did not produce neurotoxic effects, and that the inhibition of the enzymes' activities in all cases was due to the presence of the pesticide. On the other hand, the differences in the pattern of Fe accumulation in the earthworms indicate that the presence of other contaminants in the exposure media can modify the uptake and/or the excretion of Fe and evidence the interactions that may be found in binary mixtures of metal oxide NPs and other pre-existing contaminants in the soil ecosystem.

The effect of warming on pesticide toxicity is reversed between developmental stages in the mosquito Culex pipiens

A better understanding of interactions between pesticides and warming is important to improve ecological risk assessment in a warming world. Current insights are almost exclusively based on studies that exposed animals simultaneously to both warming and a pesticide and focused on effects during the pesticide exposure period and within a single developmental stage. We studied two ignored aspects of the interplay between warming and pesticide exposure: (i) the role of delayed effects after the pesticide exposure period, and (ii) the dependence on the developmental stage. We carried out a longitudinal experiment from the egg stage to the adult stage in the mosquito Culex pipiens where we crossed a warming treatment (20 °C vs 24 °C) with 48 h exposures to the pesticide chlorpyrifos in three developmental stages (early L1 larvae, late L4 larvae and adults). Chlorpyrifos induced mild to moderate mortality in all developmental stages (10-30%). A key finding was that warming shaped the chlorpyrifos-induced mortality but in opposite directions between stages. Chlorpyrifos was 7% less toxic under warming in L1 larvae, yet more toxic under warming in L4 larvae (22%) and in adult males (33%), while toxicity did not change under warming in adult females. We hypothesize that the general, stage-specific differences in the effects of warming on body size (increased size in early larvae, decreased size in later stages) caused the reversal of the effects of warming on toxicity between stages. Previous larval exposure to chlorpyrifos caused delayed effects that strongly reduced survival to the adult stage (̰25% at 24 °C). Notably, warming also modulated these delayed mortality effects in opposite ways between developmental stages, matching the patterns of mortality during the pesticide exposure periods. Integrating the general stage-specific patterns of how warming shapes body size is important to advance our mechanistic understanding of the interactions between pesticides and warming.

Synergic effects of aerobic exercise and eugenol supplement on germ cell development and testicular tissue structure in chlorpyrifos-treated animal model

Insecticide chlorpyrifos (CPF) with increased oxidative stress, structural destruction, and hemostasis of testicular tissue leads to male infertility. The present study investigated the protective effect of exercise (Exe) and eugenol supplementation (Sup) on CPF-induced testicular spermatogenic disorders in male rats. In this experimental study, 21 adult male albino rats were divided into seven groups, control (Co: 6 weeks), CPF (6 weeks), Co + Oil (2 weeks healthy food and 4 weeks oil), Co + Dimethylsulfoxide (DMSO: 6 weeks), CPF + Sup (2 weeks CPF and 4 weeks CPF + Sup), CPF + Exe (2 weeks CPF and 4 weeks CPF + Exe), and CPF + Exe + Sup (2 weeks CPF and 4 weeks CPF + Exe + Sup) group. All treatments were done intraperitoneally (5 days a week). Exe groups were subjected to run at moderate exercise intensity for 5 days per week over 6 weeks. DMSO groups were administered to the equal volume of vehicle for 6 consecutive weeks. Finally, the animals were sacrificed with Co2 gas and then alterations in testicular histology and sperm parameters were evaluated. Protein expression of PLZF and IGFα in the CPF group showed a significant decrease compared with the control group (p ˂ 0.001 for both). It was shown that CPF + Exe + Sup (p ˂ 0.001) and CPF + Sup (p ˂ 0.01) groups had a significant increase in protein expression of PLZF, but the protein expression of IGFα showed a significant increase just in the CPF + Exe + Sup group (p ˂ 0.001). Also, CPF caused a significant decrease in Leydig counts, Sertoli cell count, spermatogonium counts, spermatocyte cell count, spermatid cell count, and tunica thickness as well as a significant increase in testicle diameter (p ˂ 0.01) and ducts diameter compared with the control group. It seems that aerobic exercise with eugenol supplementation suppresses the disruption effects of CPF on testicular tissue (cellular and structural) by increasing the antioxidant capacity and improving the secretion of sex hormones. Therefore, the aerobic exercise with supplement of the eugenol has potential therapeutic targets for male infertility that need further study.

Passive monitoring techniques to evaluate environmental pesticide exposure: Results from the Infant's Environmental Health study (ISA)

BACKGROUND

Pesticides used in agriculture may expose populations living nearby. Costa Rica is a major banana-exporting country, its production depends on extensive pesticide use.

OBJECTIVES

To evaluate environmental pesticide exposure, we measured levels of current-use pesticides in air and dust from 12 schools in Matina County, Costa Rica, with passive sampling methods.

METHODS

We selected ten proximal and two non-proximal schools and placed polyurethane foam passive air samplers outdoors at each school, during four consecutive periods. At three of these schools, we also placed an active air sampler during the first 24 h of each sampling period. We collected passive dust samples by placing a glass Petri Dish at the inside of each school. We subsequently performed a chemical analysis of 18 pesticides, using gas chromatography with mass detector.

RESULTS

With passive air samplers we detected ten different pesticides: two insecticides, two nematicides, and six fungicides, of which nine reported to be used on banana plantations. More than half of the samples contained at least five pesticides. Chlorpyrifos was detected most-frequently, in 98% of samples, followed by the nematicides etoprophos and the fungicide pyrimethanil that were both detected in 81% of samples. Chlorpyrifos concentrations were five times higher in proximal as compared to non-proximal schools: mean = 18.2 ng/m3 (range = 6.1-36.1) and mean = 3.5 ng/m3 (range= <0.5-11.4) and varied more between schools than in time (intra-class correlation coefficient = 0.80). In general, results from passive and active samplers showed similar exposure patterns; yet median concentrations tended to be higher in passive samplers. In dust samples, mostly fungicides were detected; chlorothalonil was detected most frequently, in 50% of samples.

DISCUSSION

Passive air sampling is a promising technique to characterize environmental exposure to current-use pesticides; more studies are needed to characterize the sampling rates, reproducibility and optimum sampling times for passive samplers. School environments near banana plantations are contaminated with multiple pesticides that include insecticides, nematicides, and fungicides, which is of concern.