Phytoremediation of cadmium-trichlorfon co-contaminated water by Indian mustard (Brassica juncea): growth and physiological responses.

In this study, the morphological and physiological responses of Brassica juncea to the stresses of Cadmium (Cd) and trichlorfon (TCF), and the phytoremediation potential of B. juncea to Cd and TCF were investigated under hydroponics. Results showed that Cd exhibited strong inhibition on biomass and root morphology of B. juncea as Cd concentration increased. The chlorophyll a fluorescence intensity and chlorophyll content of B. juncea decreased with the increased Cd concentration, whereas the malondialdehyde and soluble protein contents and superoxide dismutase activity increased. TCF with different concentrations showed no significant influence on these morphological and physiological features of B. juncea. The biomass and physiological status of B. juncea were predominantly regulated by Cd level under the co-exposure of Cd and TCF. B. juncea could accumulate Cd in different plant parts, as well as showed efficient TCF degradation performance. A mutual inhibitory removal of Cd and TCF was observed under their co-system. The present study clearly signified the physiological responses and phytoremediation potential of B. juncea toward Cd and TCF, and these results suggest that B. juncea can be used as an effective phytoremediation agent for the Cd-TCF co-contamination in water.

Combined pollution of heavy metals and pesticides in agricultural water systems is a common phenomenon. In previous phytoremediation studies, limited information is available on the co-contamination of heavy metals and pesticides. In this study, we aimed to investigate the concentration-dependent morphological and physiological characteristics of B. juncea under single and co-stress of Cd and trichlorfon (TCF), and the phytoremediation ability of B. juncea to remove Cd and TCF through hydroponic experiment. B. juncea exhibited efficient removal performance of Cd and TCF alone and simultaneous exposure of both pollutants, indicating that B. juncea is an effective phytoremediation agent for the Cd-TCF co-contaminated water.

Assessing the effect of ß-glucan diets on innate immune response of tilapia macrophages against trichlorfon exposure: an in vitro study.

The widespread use of pesticides in some areas where fish species such as tilapia are farmed may cause damage to the environment and affect commercial fish and therefore, human health. Water leaching with the pesticide trichlorfon, during the fumigation season in the field, can affect water quality in fish farms and consequently affect fish health. At the same time, the use of immunomodulatory compounds such as ß-glucan supplied in the diet has become widespread in fish farms as it has been shown that improves the overall immune response. The present research examines the immunomodulatory impacts observed in macrophages of Nile tilapia (Oreochromis niloticus) after being fed a diet supplemented with ß-glucan for 15 days, followed by their in vitro exposure to trichlorfon, an organophosphate pesticide, at concentrations of 100 and 500 µg mL-1 for 24 h. The results showed that ß-glucan diet improved the viability of cells exposed to trichlorfon and their antioxidant capacity. However, ß-glucan did not counteract the effects of the pesticide as for the ability to protect against bacterial infection. From the present results, it can be concluded that ß-glucan feeding exerted a protective role against oxidative damage in cells, but it was not enough to reduce the deleterious effects of trichlorfon on the microbicidal capacity of macrophages exposed to this pesticide.

The Combined Use of Copper Sulfate and Trichlorfon Exerts Stronger Toxicity on the Liver of Zebrafish.

In aquaculture, copper sulphate and trichlorfon are commonly used as disinfectants and insecticide, sometimes in combination. However, improper use can result in biotoxicity and increased ecological risks. The liver plays a crucial role in detoxification, lipid metabolism, nutrient storage, and immune function in fish. Selecting the liver as the main target organ for research helps to gain an in-depth understanding of various aspects of fish physiology, health, and adaptability. In the present study, zebrafish were exposed to Cu (0.5 mg/L) and Tri (0.5 mg/L) alone and in combination for 21 days. The results demonstrate that both Cu and Tri caused hepatocyte structure damage in zebrafish after 21 days of exposure, with the combination showing an even greater toxicity. Additionally, the antioxidant and immune enzyme activities in zebrafish liver were significantly induced on both day 7 and day 21. A transcriptome analysis revealed that Cu and Tri, alone and in combination, impacted various physiological activities differently, including metabolism, growth, and immunity. Overall, Cu and Tri, either individually or in combination, can induce tissue damage by generating oxidative stress in the body, and the longer the exposure duration, the stronger the toxic effects. Moreover, the combined exposure to Cu and Tri exhibits enhanced toxicity. This study provides a theoretical foundation for the combined use of heavy metal disinfectants and other drugs.

Developmental Neurotoxicity of Trichlorfon in Zebrafish Larvae.

Trichlorfon is an organophosphorus pesticide widely used in aquaculture and has potential neurotoxicity, but the underlying mechanism remains unclear. In the present study, zebrafish embryos were exposed to trichlorfon at concentrations (0, 0.1, 2 and 5 mg/L) used in aquaculture from 2 to 144 h post fertilization. Trichlorfon exposure reduced the survival rate, hatching rate, heartbeat and body length and increased the malformation rate of zebrafish larvae. The locomotor activity of larvae was significantly reduced. The results of molecular docking revealed that trichlorfon could bind to acetylcholinesterase (AChE). Furthermore, trichlorfon significantly inhibited AChE activity, accompanied by decreased acetylcholine, dopamine and serotonin content in larvae. The transcription patterns of genes related to acetylcholine (e.g., ache, chrna7, chata, hact and vacht), dopamine (e.g., drd4a and drd4b) and serotonin systems (e.g., tph1, tph2, tphr, serta, sertb, htrlaa and htrlab) were consistent with the changes in acetylcholine, dopamine, serotonin content and AChE activity. The genes related to the central nervous system (CNS) (e.g., a1-tubulin, mbp, syn2a, shha and gap-43) were downregulated. Our results indicate that the developmental neurotoxicity of trichlorfon might be attributed to disorders of cholinergic, dopaminergic and serotonergic signaling and the development of the CNS.

Determination of trichlorfon using a molecularly imprinted electrochemiluminescence sensor on multi-walled carbon nanotubes decorated with silver nanoparticles.

Considering the limitations associated with existing methods for the detection of trace amounts of trichlorfon, this paper proposes a novel molecularly imprinted electrochemiluminescence (ECL) sensor for the detection of trichlorfon by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes (MWCNTs/Ag NPs) in a luminol-H2O2 ECL system. Here, trichlorfon was electropolymerized on the surface of the MWCNT/Ag NP-modified gold nanoelectrode with o-phenylenediamine to prepare the molecularly imprinted polymer-based sensor. After eluting the trichlorfon, imprinted holes for the identification of trichlorfon were retained on the sensor, which were used as signal switches to obtain different ECL intensities through the adsorption of different concentrations of trichlorfon. The ECL signal of the sensitized luminol-H2O2 was doubly enhanced by the MWCNTs/Ag and trichlorfon, improving the sensitivity of the sensor. The trichlorfon concentration was positively correlated with the enhanced ECL intensity of the sensor in the range 5.0 × 10-8-5.0 × 10-11 mol L-1, and the detection limit of trichlorfon was 3.9 × 10-12 mol L-1. Moreover, the proposed sensor was successfully applied to the detection of trichlorfon residues in real samples, and the recovery ranged between 91.8 and 109%. A molecularly imprinted electrochemiluminescence sensor for trichlorfon detection by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes in a luminol-H2O2 ECL system. The dual enhancement of the ECL signal improved the sensitivity of the sensor.

Temperature-dependent pharmacokinetics of trichlorfon in common carp (Cyprinus carpio L.) after bath immersion therapy.

The common carp (Cyprinus carpio L.) is one of the most important freshwater fish species. As C. carpio culture has escalated, bacterial and parasitic infections have become a real threat to the industry. Antibacterial and antiparasitic treatments are provided for infection control in C. carpio. However, adequate vaccines have not yet been developed. Trichlorfon (TCF), an organophosphate, is an antiparasitic agent used in aquaculture to treat external parasites. However, there are few pharmacokinetic (PK) studies on its use in fish. This study investigated the residue elimination and temperature-dependent PK characteristics of TCF in C. carpio at 15°C and 25°C after 30 mg/L TCF bath immersion for 30 min. TCF residue concentrations in plasma and muscle tissues were determined using liquid chromatography-tandem mass spectrometry and further analyzed using a noncompartmental model. Temperature significantly affected specific PK parameters. Increasing the temperature from 15°C to 25°C shortened the elimination half-life from 36.07 to 22.72 h. The time to reach the maximum plasma TCF residue concentration (Cmax ) (Tmax ) remained the same (0.5 h), but Cmax increased from 67.72 to 70.76 µg/L. The area under the plasma concentration-time curve decreased from 1,057.31 to 962.14 h∙µg/L. The muscle TCF Cmax was 446.99 µg/L with a corresponding Tmax of 0.5 h at 25°C, and 267.53 µg/L, with a corresponding Tmax of 1.0 h at 15°C. The temperature-sensitive PK parameters, such as increased in Cmax and decreased elimination and distribution rates, significantly affected the plasma TCF residue concentration and its overall exposure to increasing temperature. Temperature affected the therapeutic outcomes of TCF treatment in C. carpio and likely other freshwater fish. Therefore, proper dosing regimens should take temperature into consideration.

Chronic trichlorfon stress induces differential transcriptome expression and interferes with multifunctional pathways in the brain of Rana chensinensis.

Trichlorfon is widely used to control pest insects and various parasitic infestations in agriculture, aquaculture and human medicine. However, the long-term widespread use and overuse of trichlorfon poses risks to public and environmental health. Thus, the aim of this study was to evaluate the interference of trichlorfon on gene transcription patterns in the brain of Rana chensinensis with 4 weeks treatment under control conditions and 0.1 mg/L exposure. In total, 102,013 unigenes were obtained from the brain tissue of R. chensinensis, and 874 differentially expressed genes (DEGs) were identified. Functional annotation indicated that out of 118,643 unigenes, 45,600 (44.7%) were annotated in the Nr, Nt, the Swiss-Prot, KEGG, COG, and GO databases. The differential expression patterns of 4 genes associated with neural activity were selected and validated by quantitative polymerase chain reaction (qPCR). The results revealed that except for the canonical cholinesterase-based mechanism, trichlorfon could act on other receptors and alter certain types of neuronal ion channels as the major target sites. All of these effects ultimately cause disorders of multifunctional pathways and other neurotransmitter pathways in the host. The results further our understanding of the mechanisms underlying nontarget effects of organophosphate insecticides (OPs) through multitargets studies.

Integrated biomarker parameters response to the toxic effects of high stocking density, CuSO4, and trichlorfon on fish and protective role mediated by Angelica sinensis extract.

The present study explored the protective role of dietary the extract of Angelica sinensis (EAs) on high density, CuSO4, or trichlorfon-treated Crucian carp (Carassius auratus auratus). Firstly, the study showed that the optimum density for growth and growth inhibition was 0.49 and 0.98 fish L-1 water, respectively. Dietary EAs relieved the high density-induced growth inhibition in Crucian carp. The appropriate concentration of EAs for recovery of growth was estimated to be 4.30 g kg-1 diet in high-density fish. Moreover, high density decreased both digestive and absorptive enzyme activities and increased lipid oxidation in digestive organs, suggesting the ability of high density to induce oxidative damage. However, dietary EAs inhibited the oxidative damage through elevating ROS scavenging ability and enzymatic antioxidant activity in digestive organs. Secondly, our data demonstrated that the appropriate concentration of CuSO4 to induce the decrease in feed intake (FI) was 0.8 mg Cu L-1 water. Dietary EAs returned to FI of Crucian carp treated with CuSO4. The appropriate concentration of EAs for recovery of FI was estimated to be 4.25 g kg-1 diet. Moreover, dietary EAs suppressed the CuSO4-induced decrease in digestion and absorption capacity and increase in protein metabolism in digestive organs of Crucian carp. Finally, the present results suggested that dietary EAs inhibited the trichlorfon-induced rollover (loss of equilibrium) in Crucian carp. The appropriate concentration of EAs for inhibition of rollover was estimated to be 4.18 g kg-1 diet. Moreover, trichlorfon stimulated not only the decrease in energy metabolism but also lipid and protein oxidation, suggesting that trichlorfon caused loss of function and oxidative damage in muscles of fish. However, dietary EAs improved muscular function and inhibited oxidative damage via quenching ROS and elevating non-enzymatic and enzymatic antioxidant activity in muscles of trichlorfon-induced fish. So, EAs could be used as an inhibitor of high density, CuSO4, and trichlorfon stress in fish.

Neurotoxic effects of sublethal concentrations of cyanobacterial extract containing anatoxin-a(s) on Nauphoeta cinerea cockroaches.

The detection of cyanotoxins, such as the anatoxin-a(s), is essential to ensure the biological safety of water environments. Here, we propose the use of Nauphoeta cinerea cockroaches as an alternative biological model for the biomonitoring of the activity of anatoxin-a(s) in aquatic systems. In order to validate our proposed model, we compared the effects of a cyanobacterial extract containing anatoxin-a(s) (CECA) with those of the organophosphate trichlorfon (Tn) on biochemical and physiological parameters of the nervous system of Nauphoeta cinerea cockroaches. In brain homogenates from cockroaches, CECA (5 and 50 µg/g) inhibited acetylcholinesterase (AChE) activity by 53 ±â€¯2% and 51 ±â€¯7%, respectively, while Tn (5 and 50 µg/g) inhibited AChE activity by 35 ±â€¯4% and 80 ±â€¯9%, respectively (p < 0.05; n = 6). Moreover, CECA at concentrations of 5, 25, and 50 µg/g decreased the locomotor activity of the cockroaches, diminishing the distance travelled and increasing the frequency and duration of immobile episodes similarly to Tn (0.3 µg/g) (p < 0.05, n = 40, respectively). CECA (5, 25 and 50 µg/g) induced an increase in the leg grooming behavior, but not in the movement of antennae, similarly to the effect of Tn (0.3 µg/g). In addition, both CECA (50 µg/200 µl) and Tn (0.3 µg/200 µl) induced a negative chronotropism in the insect heart (37 ±â€¯1 and 47 ±â€¯8 beats/min in 30 min, respectively) (n = 9, p > 0.05). Finally, CECA (50 µg/g), Tn (0.3 µg/g) and neostigmine (50 µg/g) caused significant neuromuscular failure, as indicated by the monitoring of the in vivo neuromuscular function of the cockroaches, during 100 min (n = 6, p < 0.05, respectively). In conclusion, sublethal doses of CECA provoked entomotoxicity. The Tn-like effects of CECA on Nauphoeta cinerea cockroaches encompass both the central and peripheral nervous systems in our insect model. The inhibitory activity of CECA on AChE boosts a cascade of signaling events involving octopaminergic/dopaminergic neurotransmission. Therefore, this study indicates that this insect model could potentially be used as a powerful, practical, and inexpensive tool to understand the impacts of eutrophication and for orientating decontamination processes.

Effects of low doses Trichlorfon exposure on Rana chensinensis tadpoles.

Trichlorfon is an organophosphate insecticide widely used in aquaculture and agriculture. Little is known about the effects of long-term of low doses trichlorfon exposure on amphibians. In this study, we investigated the effects of low doses trichlorfon on Rana chensinensis tadpoles after exposure to 0.01, 0.1, and 1.0 mg/L trichlorfon for 2 and 4 weeks. Survival, growth, development and mortality were monitored regularly over the course of exposure. The results showed that trichlorfon led to a decrease in tadpole survival. Reductions in growth and disruptions to the development of tadpoles were observed in trichlorfon treatments. Morphological abnormalities of affected tadpoles included axial flexures, skeletal malformations and lateral kinks. Trichlorfon increased the frequency of micronucleus (MN) formation in circulating erythrocytes of tadpoles exposed for 2 weeks to 0.1 and 1.0 mg/L trichlorfon. At all concentrations, an enhanced frequency of MN formation was observed in tadpoles exposed for 4 weeks. Exposure to trichlorfon induced other nuclear abnormalities such as lobed and notched nuclei only in tadpoles exposed to 1.0 mg/L trichlorfon for 4 weeks. In addition, exposure to trichlorfon within the 0.01-1.0 mg/L range increased the genetic damage index in hepatic tissues in all treatments. Apoptosis-associated DNA fragmentation in hepatic tissues occurred in a weak ladder-like pattern. This study presents evidence of low doses trichlorfon effects on amphibians, highlighting the properties of this organophosphate insecticide that jeopardize nontarget species exposed to trichlorfon.

Transcriptome analysis of Rana chensinensis liver under trichlorfon stress.

Trichlorfon is a selective organophosphate insecticide that is widely applied in aquaculture and agriculture for control of various parasites. However, repeated and excess applications of trichlorfon often lead to water pollution and threaten non-targeted species. Our previous studies showed that trichlorfon could cause oxidative stress, lipid peroxidation and hepatic lesions in the liver of Rana chensinensis, but the related molecular mechanisms remain unclear. To explore the interference of trichlorfon in gene transcription, the differentially expressed genes in the liver of R. chensinensis exposed to trichlorfon were characterized using the RNA-seq platform. A search of all unigenes against non-redundant protein sequence (Nr), non-redundant nucleotide (Nt), Swiss-Prot, Kyoto Encyclopaedia of Genes and Genomes (KEGG), Clusters of Orthologous Groups (COG) and Gene Ontology (GO) databases resulted in 22,888, 21,719, 20,934, 16,923, 7375 and 15,631 annotations, respectively, and provided a total of 27,781 annotated unigenes. Among the annotated unigenes, 16,923 were mapped to 257 signalling pathways. A set of 3329 differentially expressed unigenes was identified by comparison of the two groups in liver. Notably, relative expression of metabolism-related genes, including both up- and down-regulated genes, were also validated by qPCR. The present study depicts the high degree of transcriptional complexity in R. chensinensis under trichlorfon stress and provides new insights into the molecular mechanisms of organophosphate insecticide toxicology. Some of these metabolism-responsive genes could be useful for understanding the toxicological mechanism of trichlorfon on non-target aquatic organisms and will contribute to the conservation of aquatic life.

Enantioseparation and enantioselective behavior of trichlorfon enantiomers in sediments.

Trichlorfon (TF), an organophosphorus insecticide, has been widely used in seawater aquaculture; it is easily degraded to the highly toxic insecticide, dichlorvos (DDVP). In this study, the enantioseparation of TF enantiomers, as well as their degradation behavior and product (DDVP) formation in mariculture pond sediments, was investigated. The results show that both TF enantiomers degrade into DDVP, which is the main degradation product. Furthermore, S-(+)-TF is preferentially degraded under natural conditions, suggesting that TF enantiomers degrade enantioselectively. Nevertheless, the degradation behavior of TF enantiomers is not enantiospecific under sterile conditions. The formation of DDVP and the enantiospecific degradation of TF enantiomers are attributed to the activities of microbes present in the sediments.

On-site preconcentration of pesticide residues in a drop of seawater by using electrokinetic trapping, and their determination by surface-enhanced Raman scattering.

The authors have developed a method for simultaneous quantification of several charged pesticides (as shown for amitrole, simazine, trichlorfon and bisultap). It is based on the use of a reduced graphene oxide-modified screen-printed electrode (RGO-SPE) and combines electrokinetic trapping (EKT) and surface-enhanced Raman scattering (SERS). When a 50 µL droplet containing negatively charged RGO and positively charged gold nanorods is placed on the SPE, the RGO and gold nanorods are selectively attracted on the surface of the SPE during EKT. This leads to the formation of sandwich-type hybrid substrates. The resulting substrates also contain Raman "hot spots" among the high-density gold nanorods. This, along with the excellent adsorption performance of RGO, makes it an excellent SERS substrate for on-site detection of the charged pesticides. The method is highly reproducible and long-term stable. The spot-to-spot variation of the intensity of the SERS is <15%, and the performance of SERS activity is maintained over a period of 6 weeks. The method works over a wide range of concentrations (0.5 nM to 4 µM) for charged pesticides under optimal conditions, with a sub-nanomolar detection limit (at a signal to noise ratio of 3). The EKT-SERS method requires only microliter volumes and takes only minutes for completion. Therefore, the method provides high sensitivity for detection while preserving the selectivity and stability required for reliable quantitative analysis. Graphical abstract A method combining electrokinetic trapping and SERS can be used for simultaneous detection of charged pesticides in a drop of seawater.

Oxidative stress and hepatotoxicity in the frog, Rana chensinensis, when exposed to low doses of trichlorfon.

Trichlorfon is an organophosphate insecticide that is widely used in aquaculture and agriculture against parasitic infestations and has caused aquatic toxicity to non-target organisms. To evaluate the effects of low doses of trichlorfon on the oxidative stress and hepatotoxicity in amphibians, Chinese brown frogs (Rana chensinensis) were exposed to trichlorfon at concentrations of 0, 0.01, 0.1, and 1.0 mg/L for 2 and 4 weeks. Then, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and the content of malondialdehyde (MDA) in hepatic tissue were examined to evaluate the effects of oxidative stress and lipid peroxidation. The histopathological alternations to the liver were observed through light and transmission electron microscopy (TEM). The results showed that SOD and CAT activities were increased in the livers of frogs exposed to various concentrations of trichlorfon. The GST activity showed no significant changes at any concentration after 2 weeks of exposure, whereas there was an initial increase after exposure to 0.1 mg/L of trichlorfon at 4 weeks. The content of MDA revealed a significant decrease after exposure. Histopathological and ultrastructural studies showed that trichlorfon induced hyalinization, vacuolation, nucleus necrosis, and cellular swelling in hepatocytes. These results suggest that low doses of trichlorfon could induce oxidative stress, lipid peroxidation, and hepatic lesions in frogs, which shows that even lower, non-lethal doses of trichlorfon are potentially toxic to amphibians.

Performance of trichlorfon degradation by a novel Bacillus tequilensis strain PA F-3 and its proposed biodegradation pathway.

The novel trichlorfon (TCF)-degrading bacterium PA F-3, identified as Bacillus tequilensis, was isolated from pesticide-polluted soils by using an effective screening and domesticating procedure. The TCF biodegradation pathways of PA F-3 were also systematically elucidated. As revealed by high-performance liquid chromatography, the TCF residues in the mineral salt medium demonstrated that PA F-3 can utilize TCF as its sole carbon source and reach the highest degradation of 71.1 % at an initial TCF concentration of 200 mg/L within 5 days. The TCF degradation conditions were optimized using response surface methodology as follows: temperature, 28 °C; inoculum amount, 4 %; and initial TCF concentration, 125 mg/L. Biodegradation treatments supplemented with exogenous carbon sources and yeast extract markedly increased the microbial dry weights and TCF-degrading performance of PA F-3, respectively. Meanwhile, five metabolic products of TCF were identified through gas chromatography/mass spectrometry, and a biodegradation pathway was proposed. Results indicated that deoxidation and dehydration (including the cleavage of the P-C phosphonate bond and the C-O bond) were the preferred metabolic reactions of TCF in this TCF-degrading bacterium.

Delayed consequences of extremely low-frequency magnetic fields and the influence of adverse environmental conditions on roach Rutilus rutilus embryos.

This study presents data collected over a 6 year period on the effects of extremely low-frequency magnetic fields (MFs) (1.4-1.6 µT, 500 Hz and 1.4-1.6 µT, 72.5 Hz) and MFs in combination with other environmental stressors (elevated temperature, 0.01 mg l(-1) trichlorfon, 0.01 mg l(-1) copper sulphate pentahydrate) on roach Rutilus rutilus embryos. Effects were studied during different stages of early development. Rutilus rutilus were raised in ponds for 4 months after exposure to MFs. The mass, standard length (LS ) and morphological characteristics of underyearlings which were exposed as embryos were recorded. An increase in embryo mortality and a decrease in LS and mass indices in underyearlings were noted after they had been exposed to a combination of MFs and different adverse environmental factors. In addition, exposure to MFs led to changes in the total number of vertebrae and the number of seismosensory system openings in the mandibular bones of underyearlings. MFs of different frequency caused both increases (500 Hz) and decreases (72.5 Hz) in morphological diversity. The stressors used in this study, however, did not increase the fluctuating asymmetry of bilateral morphological characteristics. The possible microevolutionary effects of exposure to MFs alone and in combination with other adverse environmental factors upon natural fish populations are discussed.

Dissipation kinetics, safety evaluation, and preharvest interval assessment of trichlorfon application on rice.

Nowadays, there is an urgent need for the investigation of the field dissipation and assessment of the preharvest interval for trichlorfon residues on rice. To protect consumers from potential health risks, this study can provide references for the safe application of trichlorfon in the rice fields. Results of the field dissipation study showed that the dissipation dynamic equations of trichlorfon were based on the first-order reaction dynamic equations and that the dissipation rates vary among rice plant, brown rice, rice bran, soil, and water. The 2-year field trials conducted in Yangzhou and Xiaogan suggested the interval of each application for trichlorfon on rice to be at least 7 days when 80 % trichlorfon SP was sprayed with a dose ranges between 80 and 160 a.i g/667 m(2). Additionally, the preharvest interval of the last application should be at least 15 days to ensure the amounts of residues below the maximum residue limits of trichlorfon on brown rice (0.1 mg/kg).

Modulation of dopaminergic neurotransmission induced by sublethal doses of the organophosphate trichlorfon in cockroaches.

Organophosphate (OP) insecticides have been used indiscriminately, based on their high dissipation rates and low residual levels in the environment. Despite the toxicity of OPs to beneficial insects is principally devoted to the acetylcholinesterase (AChE) inhibition, the physiological mechanisms underlying this activity remain poorly understood. Here we showed the pharmacological pathways that might be involved in severe alterations in the insect locomotion and grooming behaviors following sublethal administration of the OP Trichlorfon (Tn) (0.25, 0.5 and 1 µM) in Phoetalia pallida. Tn inhibited the acetylcholinesterase activity (46±6, 38±3 and 24±6 nmol NADPH/min/mg protein, n=3, p<0.05), respectively. Tn (1 µM) also increased the walking maintenance of animals (46±5 s; n=27; p<0.05). Tn caused a high increase in the time spent for this behavior (344±18 s/30 min, 388±18 s/30 min and 228±12 s/30 min, n=29-30, p<0.05, respectively). The previous treatment of the animals with different cholinergic modulators showed that pirenzepine>atropine>oxotremorine>d-tubocurarine>tropicamide>methoctramine induced a decrease on Tn (0.5 µM)-induced grooming increase, respectively in order of potency. Metoclopramide (0.4 µM), a DA-D2 selective inhibitor decreased the Tn-induced grooming activity (158±12 s/30 min; n=29; p<0.05). Nevertheless, the effect of the selective DA-D1 receptor blocker SCH 23390 (1.85 µM) on the Tn (0.5 µM)-induced grooming increase was significative and more intense than that of metoclopramide (54±6 s/30 min; n=30; p<0.05). Taken together the results suggest that a cross-talking between cholinergic M1/M3 and dopaminergic D1 receptors at the insect nervous system may play a role in the OP-mediated behavioral alterations.

Assessment of the genotoxic effects of organophosphorus insecticides phorate and trichlorfon in human lymphocytes.

In vitro genotoxic effects of organophosphorus insecticides Phorate (PHR) and Trichlorfon (TCF) were investigated using four genotoxicity endpoints. Different concentration ranges between 0.25-2.00 µg mL(-1) of PHR and 2.34-37.50 µg mL(-1) of TCF were applied to lymphocytes. PHR and TCF significantly increased the frequency of chromosomal aberrations (except 2.34 µg mL(-1) for TCF) and sister chromatid exchanges at all treatment times and concentrations. Most of the used concentrations induced a significant increase in the frequency of micronuclei. Furthermore, PHR and TCF significantly decreased the mitotic index at the higher concentrations after 24- and 48-h treatments. In the comet assay, PHR and TCF significantly increased the comet tail at all concentrations. However, the comet tail intensity was significantly increased at only the highest concentration of PHR and at all concentrations of TCF. According to these results, PHR and TCF possess clastogenic, mutagenic, and DNA damaging effects in human lymphocytes in vitro.

Study on an electrochromatography method based on organic-inorganic hybrid molecularly imprinted monolith for determination of trace trichlorfon in vegetables.

BACKGROUND: Organophosphorus pesticides have been widely used in agricultural production. However, the wide use of organophosphate also results in pesticide residues on the plant, which are harmful to human health because of their potential mutagenic and carcinogenic properties. Therefore, it is vital to develop a sensitive and effective analysis method to control pesticide residues. RESULTS: In this study, a novel molecularly imprinted capillary monolithic column was prepared using trichlorfon as the template molecule by combining non-hydrolytic sol-gel process with a molecular imprinting technique. The resulting material was characterized by scanning electron microscopy and Fourier transform infrared. Under capillary electrochromatography, the effects of voltage, pH, ACN content and concentration of buffer solution on the electro-osmotic flow (EOF) of imprinted capillary monolithic column were evaluated in detail. Using this prepared material as stationary phase for capillary electrochromatography, a novel method of molecularly imprinted capillary electrochromatography (MICEC) for the detection of trace trichlorfon residues in vegetables was developed. Under optimal conditions, appreciable sensitivity was achieved with a LOD (S/N = 3) of 92.5 µg kg(-1) and method quantitation limit (MQL) of 305.3 µg kg(-1), respectively. The linear ranges of the calibration graph were 0.1 µg L(-1) to 10 mg L(-1). The peak area precision (RSD) for five replicate extractions of 0.01 mg L(-1) trichlorfon standard aqueous solution was 4.5%. To evaluate the accuracy of this method, the blank cucumber and cauliflower samples spiked with trichlorfon were extracted and analyzed by this method with good recoveries, ranging from 80.2% to 95.8%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon residues in leek samples. CONCLUSION: With good properties of high sensitivity and simple pre-treatment, this MICEC method could provide a new tool for the rapid determination of trace trichlorfon residue in complex food samples.