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.

Influence of land use on chlorpyrifos and persistent organic pollutant levels in honey bees, bee bread and honey: Beehive exposure assessment

This work reports the spatial and temporal variations on the dynamics of OCPs, PCBs, PBDEs and chlorpyrifos in honey bee, bee bread and honey samples, as well as soil and flowers from the surrounding areas, considering, different land uses. Honey bee samples showed the highest pollutant levels, with a predominance of the industrial contaminants over pesticides. Chlorpyrifos showed the highest concentration during the application period in almost all samples from the soybean field (S2), in concordance with its current use. By other hand, the recalcitrant compounds such as, DDTs, BDE #47 and also light PCBs exhibited the highest levels in beehive samples from the field adjacent to urban disposal waste (S3). In both soils and flower samples a prevalence of obsolete compounds over chlorpyrifos was observed, and the 6-CB predominated among the homologous groups of PCBs These results highlights the importance of soils as sink of these persistent contaminants, which became available depending on environmental conditions. Results revealed that the land uses and seasonal variations have directly impacted on the levels of agrochemicals, PCBs and PBDEs found in the beehive matrixes. This survey provides novel evidence about the current situation of pollution on honey bee colonies under temperate climates and contributes to the knowledge of this poor studied topic in Argentina.

Response of Trichogramma spp. (Hymenoptera: Trichogrammatidae) to Insecticides at Concentrations Sublethal to Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)

Trichogramma japonicum Ashmead (Hymenoptera: Trichogrammatidae) and Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) are important parasitoids of Lepidopteran pests and are used for biological control in rice fields. In this study, the response of two of these parasitoids to four insecticides (chlorpyrifos, chlorantraniliprole, emamectin benzoate, and spinosad) were evaluated at target sublethal concentrations (TSC10 and TSC25, representing the LC10 and LC25 to the target pest) of the important rice pest, Cnaphalocrocis medinalis (Guenée). Each of the insecticides led to the mortality of adult T. japonicum and T. dendrolimi at TSC10 and TSC25, whereas no significant differences in the mortality of T. japonicum between TSC10 of chlorantraniliprole and control groups occurred. The parasitic capacity increased at F0 of T. japonicum at the two TSCs of spinosad treated host eggs, whereas the TSC10 was lower for emamectin benzoate at F1 for T. japonicum. The TSCs of chlorpyrifos treated host eggs negatively influenced the emergence rates of T. japonicum at F1. Emamectin benzoate with TSC10 reduced the female ratio of T. japonicum at F1. For T. dendrolimi, the TSCs of chlorpyrifos treated host eggs negatively influenced the emergence rates at F1. These findings indicate that T. japonicum and T. dendrolimi are affected by insecticides at TSCs, and among the four insecticides, chlorantraniliprole had the lowest mortality rates for T. japonicum and T. dendrolimi at TSCs.

Single or combined exposure to chlorpyrifos and cypermethrin provoke oxidative stress and downregulation in monoamine oxidase and acetylcholinesterase gene expression of the rat's brain

The extensive uses of organophosphates and pyrethroids have made it necessary to investigate the neurotoxicity of their combination as they may implicate in the neurodegenerative syndromes. Monoamine oxidase-A (MAO-A) and acetylcholinesterase (AChE) gene expression in the rat brain were evaluated after independent and combined intoxications with chlorpyrifos and cypermethrin. Twenty-four mature male rats were equally distributed into four groups. The first one was kept as a control group, whereas the second, third and fourth were orally gavage with chlorpyrifos (16.324 mg/kg), cypermethrin (25.089 mg/kg) and their combination (9.254 mg/kg), respectively, for 4 weeks. As compared to the control group, intoxications with chlorpyrifos and/or cypermethrin revealed significant (P < 0.05) declines in the levels of brain neurotransmitters (dopamine and serotonin) plus the enzymatic activities of MAO-A, AChE and sodium-potassium adenosine triphosphatase. The mRNA genes expression of MAO-A and AChE have also confirmed the enzymatic actions. Moreover, the oxidative injury recorded as the levels of malondialdehyde and nitric oxide markedly increased (P < 0.01), while the total thiol content reduced and the histopathological outcomes have confirmed these impacts. In conclusion, chlorpyrifos and cypermethrin revealed antagonistic inhibitions on the brain MAO-A and AChE gene regulation through neurotransmission deteriorations and oxidative damage, which could describe their contributions in the neuropathological progressions.

Importance of functional classification in the use of carabids for the environmental risk assessment of the GE crops and other agricultural practices

Carabids (Coleoptera: Carabidae) seem to be suitable bioindicators of the environmental impacts of novel agrotechnologies, including deployment of the genetically engineered (GE) crops. In this article, we describe our effort to employ carabids in the environmental risk assessment (ERA). GE maize MON88017, its near-isogenic hybrid nontreated or treated with the soil insecticide chlorpyrifos, and two reference hybrids were used to compare three different ways how to utilize carabids in ERA. The analysis of abundance of all captured carabids or of the most abundant carabid species did not disclose any differences between the treatments. The analysis based on the categories of functional traits revealed distinct features of some treatments and proved suitable for ERA because it permitted field data transportability in spite of different species compositions. Our results indicate that GE maize has no detrimental environmental effect. On the other hand, we found significant trends toward lower abundance and lower species number (including analysis of all carabid species together) in plots treated with the insecticide, and some tendencies to higher abundance and higher species number in plots sown with the reference hybrid PR38N86. Using functional group indicators allows identification of unintended changes in ecological functions of agroecosystem and comparability across geographies. We recommend data evaluation at the level of the categories of functional traits in ERA of GE crops and other agricultural practices.

Effects of predator cues and pesticide resistance on the toxicity of a (bio)pesticide mixture

BACKGROUND

Populations of target species are typically exposed to pesticide mixtures and natural stressors such as predator cues, and are increasingly developing resistance to single pesticides. Nevertheless, we have poor knowledge whether natural stressors and the presence of pesticide resistance shape mixture toxicity. We tested the single and combined effects of the pesticide chlorpyrifos and the biopesticide Bacillus thuringiensis israelensis (Bti) on the survival of the Southern house mosquito (Culex quinquefasciatus, Say) and whether these effects were magnified by synthetic predator cues of Notonecta water bugs and differed between a chlorpyrifos-resistant (Ace-1R) and non-resistant (S-Lab) strain.

RESULTS

Single exposure to Bti caused mortality in both strains (S-Lab ∼27%, Ace-1R ∼41%) and single exposure to chlorpyrifos caused only mortality in the S-Lab strain (∼33%), while predator cues did not induce mortality. The chlorpyrifos-resistant strain was 1.5-fold more sensitive to Bti, indicating a cost of resistance. The interaction types between chlorpyrifos and Bti (additive), between chlorpyrifos and predator cues (additive), and between Bti and predator cues (synergistic) were consistent in both strains. Despite predator cues making Bti approximately 8% more lethal, they did not change the additive interaction between Bti and chlorpyrifos in their mixture in either strain.

CONCLUSION

These results indicate that the resistance against chlorpyrifos was not partly lifted when chlorpyrifos exposure was combined with Bti and predator cues. Identifying the interaction type within pesticide mixtures and how this depends on natural stressors is important to select control strategies that give a disadvantage to resistant individuals compared to non-resistant individuals. © 2019 Society of Chemical Industry.

Carnosic acid alleviates chlorpyrifos-induced oxidative stress and inflammation in mice cerebral and ocular tissues

Chlorpyrifos is an organophosphate pesticide whose exposure leads to inhibition of acetylcholinesterase (AChE) enzyme and induces oxidative stress, inflammation, and neurotoxicity. The current study was designed to evaluate the efficacy of carnosic acid (CA) in ameliorating CPF-induced cytotoxicity in mice brain and eye tissues. We allocated 40 male Swiss albino mice to receive DMSO 1% solution, oral CA 60 mg/kg/day bw, CPF 12 mg/kg/day bw via gastric gavage, or CPF plus CA at 30 and 60 mg/kg/day bw. Carnosic acid was administered once/day for 14 days, while CPF was administered in the last 7 days of the experiment. Biochemical analysis showed that CPF administration was associated with significant increases in the serum concentrations of interleukin-1β, IL-6, and tumor necrosis factor-α, while it was associated with significant reductions in serum AChE levels in mice. Moreover, CPF-intoxicated mice exhibited significantly higher levels of malondialdehyde and nitric oxide in the brain and eye tissues. However, they had significantly lower levels of reduced glutathione, glutathione peroxidase, superoxide dismutase, and catalase in comparison with normal controls. Pretreatment with CA at 30 and 60 mg/kg/day bw for 14 days significantly alleviated all the aforementioned CPF-induced alterations in a dose-dependent manner; more frequent restorations of the normal control ranges were observed in the higher dose group. In conclusion, CA offers a neuroprotective effect against CPF-induced oxidative stress and inflammation and should be further studied in upcoming experimental and clinical research.

Biomarkers of occupational exposure to pesticides: Systematic review of insecticides

INTRODUCTION

Pesticides are widely used around the world, and rural workers have greater risk of poisoning. The use of biomarkers for insecticides can contribute to the diagnosis and prevention of poisoning.

OBJECTIVE

To identify, in the scientific literature, the biomarkers of occupational exposure to insecticides of different insecticide classes.

METHODS

The PubMed, Lilacs and Embase databases were analyzed using a systematic search strategy and in accordance with the criteria established by the PRISMA methodology. Articles with information related to the use of biomarkers to identify active ingredients, or insecticide metabolites, or effects on the human biological matrices were analyzed.

RESULTS

A total of 840 studies was found, and 30 met the selection criteria. The search identified 118 results for insecticide biomarkers, of which 45% were of exposure, 42% of effect, and 14% of susceptibility. Additionally, 78 were possible biomarkers, and only 67 confirmed to be different biomarkers for insecticides. Acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and 3,5,6-trichloro-2-pyridinol (TCP-y), specific for Chlorpyrifos, were among the most common biomarkers identified; however, most metabolites found were non-specific.

CONCLUSION

Various insecticide biomarkers were mentioned; nonetheless, only a few are specific and used to identify the wide range of insecticides to which farm workers are exposed.

Analytical protocol for determination of endosulfan beta, propham, chlorpyrifos, and acibenzolar-s-methyl in lake water and wastewater samples by gas chromatography-mass spectrometry after dispersive liquid-liquid microextraction

This study describes the development of a sensitive and accurate dispersive liquid-liquid microextraction strategy for the preconcentration and determination of selected pesticides in wastewater and lake water samples by gas chromatography-mass spectrometry. Determination of these pesticides at high accuracy and precision is important because they can be still be found in environmental samples. The type of extraction solvent and type of disperser solvent were optimized using the univariate approach. Furthermore, a Box-Behnken experimental design was used to set up a working model made up of 18 combinations of three variables, tested at three levels. The parameters fitted into the design model were volume of extraction solvent, disperser solvent volume, and mixing period. Analysis of variance was used to evaluate the experimental data to determine the significance of extraction variables and their interactions, before selecting optimum extraction conditions. The method was then applied to aqueous standard solutions between 2.0 and 500 μg L^-1, and the limit of detection (LOD) and quantification (LOQ) values obtained for the analytes were between 0.37-2.8 and 1.2-9.4 μg L^-1, respectively. The percent recoveries were calculated in the range of 92-114 and 96-110% for wastewater and lake water, respectively. These results validated the accuracy and applicability of the method to the selected matrices.

Investigating the relationship between synergistic effects and diversity of four widely used agricultural pesticides by using bacterial species in liquid culture medium

Interactive effects of mixtures of pesticides on bacteria are rarely investigated. The aim of this study was to investigate the cumulative, synergistic, and antagonistic effects of four widely used agricultural pesticides including deltamethrin, diazinon, chlorpyrifos, and 2,4-dichlorophenoxyacetic acid (2,4-D) on Pseudomonas, Aeromonas, and Bacillus bacteria. The reduction of alamar blue, as an indicator of bacterial activity, was measured using a spectrophotometer at 600-nm wavelength. Data were analyzed using SPSS 24.0 software. The binary mixtures of pesticides had mainly antagonistic and additive effects, but quadruple mixtures of pesticides had synergistic effects on all of the three bacterial species. In the mixtures of pesticides, increasing the number of compounds leads to more synergistic effects.

Characterization of Nanostructured Silica as Carrier for Insecticides Deltamethrin, Pyriproxyfen, and Chlorpyrifos and Testing the Insecticidal Efficacy Against Trogoderma granarium (Coleoptera: Dermestidae) Larvae

Nanostructured silica can be used as a carrier of pesticides to enhance stability and controlled release of agrochemicals with an effective concentration on target pests. Silica nanoparticles (SNPs) were synthesized by sol–gel process and employed as a carrier of three different insecticides including deltamethrin, pyriproxyfen, and chlorpyrifos. The SNPs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis and the insecticides-loaded in SNPs were characterized by transmission electron microscopy (TEM). The toxicity of insecticides alone and loaded in SNPs was evaluated against small and large larvae of Trogoderma granarium Everts on concrete surfaces. The immediate mortality was counted after 1, 3, and 7 d of exposure, and then surviving individuals were transferred to untreated surfaces for seven more days, with delayed mortality was recorded. Small larvae were more susceptible than large ones on all insecticide treatments. In addition, insecticides loaded in silica nanoparticles were more effective when compared with application of the insecticides alone. For immediate mortality, deltamethrin loaded in SNPs was the most efficient treatment causing 70.5% mortality on small and 55.5% mortality on large larvae after 7 d of exposure to the highest concentration. Pyriproxyfen loaded in SNPs caused low immediate mortality, but the mortality increased in delayed count indicated that the insecticide could control the larvae even after they have been removed from treated surfaces. It can be concluded that loading insecticides in SNPs could significantly increase their insecticidal efficiency, but this increase was compound-dependent.

Monitoring insecticide resistance and diagnostics of resistance mechanisms in Bemisia tabaci Mediterranean (Q biotype) in China

Bemisia tabaci is one of notorious agricultural insect pests in China, and the strategies of management largely depend on application of insecticides. In order to assess levels of resistance in field populations of B. tabaci to six insecticides including abamectin, cyantraniliprole, pymetrozine, imidacloprid, chlorpyrifos and bifenthrin, we monitored the susceptibility to all tested insecticides in five field populations across China and the results indicated that field populations of B. tabaci have developed various levels of resistance to each chemical agent. Furthermore, para-type voltage gated sodium channel mutations (L925I and T929V) and acetylcholinesterase ace1 mutation (F331W) were confirmed, and expression levels of CYP6CM1, CYP4C64, GSTd7 and ABCG3 were detected for investigating mechanisms of imidacloprid resistance in the five field-collected populations. The results showed that, in all tested populations, frequencies of F331W were 100%, and the frequencies of the L925I and T929V were in the range of 28.5 to 47.0% and 11.0 to 53.5%, respectively. Moreover, CYP6CM1 and CYP4C64 were significantly overexpressed in two tested populations, respectively, and GSTd7 was significantly overexpressed in one population. No overexpression of ABCG3 was observed in all the populations. Above results provided valuable insight into the current status of insecticide resistance and could be contributed to design strategies of management for B. tabaci.

Preferential flow modelling of chlorpyrifos leaching in two arid soils of irrigated agricultural production areas in Argentine Patagonia

An analysis was made of the transport and fate of the organophosphate pesticide chlorpyrifos in productive soils from the Alto Valle of the Río Negro in Argentine Patagonia. The climate of the region is arid, so traditional fruit production is under flood irrigation. The soils in the floodplain are predominantly Aridisols with textures ranging from sandy loam to clay loam. The calibration was performed with water table data and chlorpyrifos concentration in the soil horizons. Field experiments made with Brilliant Blue FCF at the profile scale enabled the parametrisation of the dual-permeability model MACRO. The model calibration was evaluated by a comparison of observed and simulated data and statistics. The simulation of the groundwater table depth was satisfactory and the chlorpyrifos leaching revealed a different pattern in the two soil types studied. The sandy loam texture soil produced more percolation of irrigation water, but the clay loam soil produced greater leaching of chlorpyrifos under similar application conditions, presumably due to preferential flow under non-equilibrium conditions. Productive management alternatives to reduce leaching into the underlying unconfined aquifer were simulated. Among these, the incorporation of organic matter was the best alternative.

Differential effects of azinphos-methyl and chlorpyrifos on polyamine oxidative metabolism during the embryonic development of Rhinella arenarum and its relation to oxidative stress

The organophosphorus pesticides azinphos-methyl (AZM) and chlorpyrifos (CPF) exert their toxic action by inhibition of acetylcholinesterase, but non-target processes such as polyamine metabolism can also be affected. Our objective was to evaluate the effects of different concentrations of AZM (0.5-, 2- and 9 mg L^-1) and CPF (0.5- and 1 mg L^-1) on polyamine oxidative metabolism along Rhinella arenarum embryonic development and to explore its relationship to oxidative stress. Free and conjugated polyamines were measured by HPLC. The activity of spermine oxidase (SMOX), N¹-acetylpolyamine oxidase (PAOX) and diamine oxidase (DAO) were measured through kinetic spectrofluorometry. Free putrescine and spermine were significantly increased in open mouth embryos exposed to AZM. Free polyamine levels were not affected by CPF exposure. In embryos exposed to AZM, DAO was increased in tail bud stage and SMOX was increased in open mouth stage, while embryos exposed to CPF showed an increase of PAOX activity in tail bud stage and a decrease of DAO and SMOX activity in open mouth stage. Polyamine levels and oxidative degradation enzymes respond differently if R. arenarum embryos are exposed to AZM or CPF, despite that both insecticides belong to the same chemical family. The early increase of DAO and PAOX would play a protective role to guarantee the normal progression of embryonic development. The increased production of reactive species might contribute to an oxidative stress situation generated by exposure to the insecticides and to the alteration of the antioxidant defense system. In tail bud stage embryos, PAOX and SMOX were positively correlated to acetylcholinesterase activity and reduced glutathione levels (GSH), and negatively correlated to the antioxidant enzymes catalase (CAT) and glutathione S-transferase (GST). In complete operculum embryos, a negative correlation between antioxidant parameters and polyamine levels and polyamine oxidative metabolism was observed, except for SMOX, which showed a low positive correlation with CAT and GSH and a negative correlation to PAOX and DAO. We suggest the use of DAO and PAOX as biomarkers of exposure to AZM and CPF, respectively, as they respond earlier than the classical biomarker acetylcholinesterase.

Chronic health risk comparison between China and Denmark on dietary exposure to chlorpyrifos

Chlorpyrifos is one of the most heavily used pesticides in domestic and agricultural insect prevention globally. Given the potential neurotoxicity of chlorpyrifos and its high detection rates in food and drinking water, health risks attributable to chlorpyrifos residue in Chinese drinking water and food in both China and Denmark were assessed in this study. Mixed left-censored handling models were used to deal with the non-detected values in chlorpyrifos concentrations. Results show that chronic exposure imputed to chlorpyrifos residue is much lower than the reference dose, and will thus not pose appreciable health risk to the consumer. Compared to the total exposure from chlorpyrifos in drinking water and food sources, chronic exposure from drinking water sources in China accounts for 0-4.4%. Health risk owing to chlorpyrifos in food within China is 6-7-fold higher than in Denmark, and this coincides with the fact that all application of chlorpyrifos is banned in Denmark, in contrast to China. However, the Danish consumers are still exposed from imported food items. The main health risk contributors in China are the food groups of Grains and grain-based products and Vegetable and vegetable products, while the main chronic health risk contributor in Denmark is the food group of imported fruit and fruit products.

Frequently encountered pesticides can cause multiple disorders in developing worker honey bees

Pesticide exposure is regarded as a contributing factor to the high gross loss rates of managed colonies of Apis mellifera. Pesticides enter the hive through contaminated nectar and pollen carried by returning forager honey bees or placed in the hive by beekeepers when managing hive pests. We used an in vitro rearing method to characterize the effects of seven pesticides on developing brood subjected dietary exposure at worse-case environmental concentrations detected in wax and pollen. The pesticides tested included acaricides (amitraz, coumaphos, fluvalinate), insecticides (chlorpyrifos, imidacloprid), one fungicide (chlorothalonil), and one herbicide (glyphosate). The larvae were exposed chronically for six days of mimicking exposure during the entire larval feeding period, which is the worst possible scenario of larval exposure. Survival, duration of immature development, the weight of newly emerged adult, morphologies of the antenna and the hypopharyngeal gland, and gene expression were recorded. Survival of bees exposed to amitraz, coumaphos, fluvalinate, chlorpyrifos, and chlorothalonil was the most sensitive endpoint despite observed changes in many developmental and physiological parameters across the seven pesticides. Our findings suggest that pesticide exposure during larvae development may affect the survival and health of immature honey bees, thus contributing to overall colony stress or loss. Additionally, pesticide exposure altered gene expression of detoxification enzymes. However, the tested exposure scenario is unlikely to be representative of real-world conditions but emphasizes the importance of proper hive management to minimize pesticide contamination of the hive environment or simulates a future scenario of increased contamination.