Fipronil Residues Research Articles

Enantioselectivity and residue analysis of fipronil in tea (Camellia sinensis) by ultra-performance liquid chromatography Orbitrap mass spectrometry

ABSTRACTThis study aimed to determine the residues of fipronil, metabolites, and enantiomers in tea (Camellia sinensis) during tea planting and green tea manufacture. An AD-RH chiral column was used to separate the fipronil enantiomers. During tea planting, the half-lives of the sum of fipronil and metabolites were similar to those of fipronil, which were 2.37 and 3.88 days for tea shoots and mature leaves, respectively. The residues of fipronil and its metabolites increased 2.3–3.6-fold during green tea manufacture. The values for the processing factors of fipronil and metabolites ranged from 1.0 to 2.1. A slightly significant enantioselectivity of (R)- and (S)-fipronil was observed during tea planting and green tea manufacturing. The residue pattern indicated that fipronil should not be applied in tea gardens due to its long persistence. The maximum residual limits of fipronil and metabolites at 2 μg kg−1 were considered optimal.

Multi-compartmental toxicokinetic modeling of fipronil in tilapia: Accumulation, biotransformation and elimination.

Bioaccumulation and biotransformation are critical processes modifying toxicity of easily metabolizable chemicals to aquatic organisms. In this study, tissue-specific accumulation, biotransformation and elimination of a current-use pesticide fipronil in tilapia (Oreochromis niloticus) were quantified by combining in vivo measurements and a newly developed multi-compartmental toxicokinetic model. Waterborne fipronil was taken up via gills and metabolized rapidly and solely to fipronil sulfone. Significant decrease of fipronil residues in liver and intestine during exposure period strongly suggested the induction of metabolism in these two organs. Significant transport of fipronil and fipronil sulfone in the liver-bile-intestine system implied that hepatobiliary excretion and enterohepatic re-absorption played important roles in fipronil metabolism and system circulation of the parent compound and the metabolite. The multi-compartmental model quantitatively described the highly dynamic inter-compartmental transport and rapid branchial clearance of fipronil in fish. Modeling results also suggested that uptake and biotransformation were the stronger driving forces for the inter-compartmental transport of fipronil in fish than the inherent partitioning capacity. Overall, our findings highlight the importance of biotransformation on internal disposition of fipronil in fish, which helps to improve aquatic toxicity assessment of this pesticide.

Fipronil-induced toxic effects in zebrafish (Danio rerio) larvae by using digital gene expression profiling

Fipronil residue has caused widespread concern around the world, especially after the recent “toxic eggs” event in seven European countries. To evaluate the effects of fipronil on vertebrates, zebrafish larvae were used as an animal model to examine the lethal effect, developmental phenotypes at high doses, and possible mechanisms of toxicity by employing digital gene expression (DGE) profiling at environmentally relevant doses. The results of acute toxicity test indicated that treatment with fipronil from 75 h post-fertilization (hpf) led to the death of larvae with a 96-h LC50 value of 459 μg/L, as well as abnormal development including bent spine and shortened body length. Besides, we obtained high-quality-sequencing DGE profilings at fipronil concentrations of 0.5, 5, and 50 μg/L, respectively. The results revealed that 44 differentially expressed genes, 10 GO terms, and 3 KEGG pathways were overlapped among the three concentrations. MIDN, one of the 44 differentially expressed genes, showed dose-dependent responses at the transcriptional level, indicating that it was possibly a potential biomarker to reflect fipronil toxicity in zebrafish. Furthermore, we presumed that the changing transcriptional level of AP-1 family was possibly a reason for bent spine and shortened body length in larvae exposed to fipronil. Concurrently, altered abundance of transcripts of the ELOVL family in a key step of fatty acid elongation could possibly lead to the accumulation of long-chain fatty acids. Collectively, our results suggested that exposure to fipronil caused lethal and developmental toxicity in zebrafish larvae, and demonstrated the need for a comprehensive understanding of the potential mechanisms of fipronil toxicity due to fipronil's frequent presence in the environment and its potential threat to human health.

Occurrence of residues of fipronil and other acaricides in chicken eggs and poultry muscle/fat.

Following the detection of fipronil residues in eggs resulting from a misuse of non‐approved veterinary medicinal products in poultry farms against red mites, an ad‐hoc monitoring programme was set up in the EU. Member States have provided results for 5,439 samples of eggs and chicken muscle/fat which were analysed for fipronil and a number of additional active substances which were proposed by the European Commission to be monitored in view of potential misuse in poultry farms against red mites. The report summarises the data sampled during the period 1 September 2017 to 30 November 2017 and reported to EFSA. It provides an overview on the results with regard to frequency of occurrence and compliance with the legal limits. The results are presented by country of origin, by type of food product, and by the active substances analysed.

Green Silver Nanoparticles for Enhancing the Phytoremediation of Soil and Water Contaminated by Fipronil and Degradation Products

Fipronil has been associated with neurotoxicity, carcinogenicity, endocrine disruption, persistence in soil, and low uptake by plants and is a potential groundwater contaminant. Fipronil degradation by silver nanoparticles (AgNPs) from medicinal plant extracts was investigated in spiked water. Also, remediation capacity of soil contaminated by fipronil under the combined application of green AgNPs and phytoremediation was investigated. Brassica-AgNps, Ipomoea-AgNps, Camellia-AgNps, and Plantago-AgNps in water solution significantly reduced fipronil residues by 95.45, 90.15, 63.65, and 63.48%) during 2 days of treatment as compared with 18.42% in untreated water without AgNps. Fipronil amide and fipronil-desulfenyl metabolites were detected in water under the influence of AgNps. The contribution of Brassica-AgNps, Plantago-AgNps, Ipomoea-AgNps, and Camellia-AgNps to the dissipation of fipronil in the soil were 68.8, 54.64, 43.75, and 30.99%, respectively, compared with 10.14% by Plantago major alone through 6 days. Low uptake and translocation of fipronil by P. major roots and leaves were seen in flooded soil alone or under the influence of AgNps within 6 days of treatment. However, the resulting fipronil amide product accumulates in large quantities in P. major roots and leaves. These results show that AgNps and P. major play a major role for the remediation of fipronil contaminated water and in flooded soil, while P. major played an important role for remediation the polar break product, fipronil-amide as phytoremediation.

Fipronil recognition by the FA1 site of human serum albumin.

Fipronil is a broad-spectrum pesticide widely used in agriculture, horticulture, and forestry. Because fipronil can cause a variety of toxic effects in animals and humans, its use is authorized as a pesticide in veterinary medicinal products for pets, but not for the treatment of livestock animals whose products are intended for consumption. Recently, however, the presence of fipronil residues has been detected in the eggs and meat of layer hens from farms located in different European countries. Given the relevance of fipronil toxicity for human health, it is important to gain information concerning its fate in the human body, including its binding mode to human serum albumin (HSA), the most abundant protein in plasma. Here, the inhibition of heme-Fe(III) binding to the fatty acid site 1 (FA1) of HSA by fipronil is reported. Docking simulations support functional data, indicating that the FA1 site is the preferential cleft for fipronil recognition by HSA. The affinity of fipronil for HSA (Kf =1.9×10-6 M, at pH 7.3, and 20.0°C) may be relevant in vivo. Indeed, HSA could play a pivotal role in fipronil transport and scavenging, thus reducing the pesticide-free plasmatic levels, with consequent reduced systemic toxicity. In turn, fipronil binding to the FA1 site of HSA could impair the recognition of endogenous and exogenous molecules.

‘Hydraulic Trench’ Termiticide Injections Eliminate Termites from Buildings

Termidor®H•P ‘High Precision Injection System’ technology was used to create termiticide-treated ‘Hydraulic Trenches’ in soil around perimeters of six termite-infested buildings. Termidor®H•P II High Precision Termiticide was applied at locations around the buildings where using the Hydraulic Trench mode was not practical. The H•P System ‘Standard Application’ mode was used to apply termiticide using drilling and rodding methods, thereby ensuring complete continuous termiticide treatment to soil around building perimeters. Treated soil around one of the buildings was sampled for fipronil residue. Soil classifications were pH-neutral sandy-loam topsoil underlain with a sandy-clay-loam base. Residue analyses within the 30.5-cm-deep soil profile found fipronil concentrations lethal to termites in both soil types. No termite activity was detected within the six buildings at 3-, 6-, 12-, or 24-months after treatments.

Analysis of fipronil and metabolites residues distrubution in eggs

Objective: To compare the residual distribution of fipronil and its metabolites in white and yellow egg, and to analyze the residual changes of fipronil and its metabolites in raw and cooked samples, regarding the risk assessment of fipronil and its metabolites via consuming egg for different age groups. Methods: The white egg and yellow egg were isolated from 10 egg samples containing fipronil residues. Samples were extracted with acetonitrile and purified, and determined by liquid chromatography-high resolution mass spectrometry. The chromatographic analysis was performed on a BEH C(18) column with 0.1% acetic acid and acetonitrile as mobile phase with gradient elution, and external standard calibration was used for quantification. The negative ion acquisition mode was applied and quantitative analysis was carried out by using Full Scan/ddms2 model. Results: The results showed that fipronil sulfone was the main residue detected in eggs; The content of fipronil sulfone in white egg was between 2.5 and 59.9 μg/kg, the median was 16.1 μg/kg; and the content of fipronil sulfone in yellow egg ranged from 81.5 and 1 526.0 μg/kg, with a median of 390.0 μg/kg. The ratio of fipronil sulfone in yellow egg to white egg ranged from 8.0 and 14.6. Compared with that observed in fresh egg, after heating or cooking, the content ratio of fipronil sulfone residue between cooked samples and raw samples from yellow egg was between 0.80 and 0.96, the median was 0.90; and the ratio from white egg ranged from 0.65 to 1.06, the median was 0.83. The conversion coefficient of fipronil sulfone (f) between white egg and yellow egg was 3.1. Conclusion: Yellow egg is a major intake source of fipronil and metabolites residues, and there is no obvious change for fipronil sulfone residue in eggs after heating or cooking. The conversion coefficient of fipronil sulfone (f) between white egg and yellow egg lays the foundation for assessing the health risks of fipronil and metabolites residues through yellow egg intake in special population.

Disappearance and hazard quotient of chlorpyrifos-methyl, fipronil, and imidacloprid insecticides from dates

Control strategies of red palm weevil (RPW) mainly depend on the use of insecticides. However, the residue of insecticides in dates might cause poisoning risk to the consumers. Therefore, the present study aimed to measure the disappearance rates of the extensively applied insecticides on date palm trees. Residues of chlorpyrifos-methyl (CPM), fipronil (FIP), and imidacloprid (IMD) insecticides in and/or on dates were extracted and cleaned-up using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The residues of CPM, FIP, and IMD were determined by GC-FPD, GC-ECD, and HPLC, respectively. Recoveries of CPM, FIP, and IMD ranged from 86.3 to 98.2%. CPM on dates degraded faster than FIP and IMD. However, after 21 days of the last spray application, 74, 50, and 67% of CPM, FIP, and IMD disappeared, respectively. Residues of CPM and IMD insecticides posed no risk quotient, but FIP caused a risk to humans, depending on the consumption pattern of dates. Insecticides with a fast degradation pattern should be incorporated into the management strategy of RPW to reduce the amount on residues in dates.

Determination of fipronil and its metabolites in eggs and egg products with gas chromatography-negative chemical ionization-mass spectrometry

A method was established for the determination of fipronil and its metabolites in eggs and egg products with gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS). The targets were extracted from samples with acetonitrile, and followed by a simple cleanup step known as dispersive solid-phase extraction QuEChERS. The extracts were determined by GC-NCI-MS, and quantified by external standard method with matrix correction standard curves. The recoveries were in the range of 87.0% to 99.3% at four spiked levels (0.1, 2.0, 4.0 and 20.0 μg/kg), and all RSDs were not more than 12.7% for the four analytes. The linearity of the method was good between 0.005 and 0.10 mg/L, and all LOQs were less than 0.10 μg/kg. So this method can be used to determine the residues of fipronil and its metabolites in eggs and egg products.

Safety Evaluation of Parastar® Plus in Dogs and Assessment of Transferable Residue of Fipronil and Cyphenothrin from Dogs to Humans.

Dogs are easily infested with fleas, ticks, and other ectoparasites serving as vectors for transmitting bacterial, viral, and parasitic diseases. Therefore, the use of ectoparasiticides is inevitable and important. The present investigation was undertaken with two specific objectives: one, to evaluate the safety of fipronil and cyphenothrin in dogs after topical application of Parastar® Plus, and two, to determine the transferable residue of these insecticides from dogs to humans. Six healthy, adult dogs (medium length hair, weighing between 20.5 and 27.3 kg) received topical application of Parastar® Plus (2.68 mL; fipronil, 9.8%, and cyphenothrin, 5.2%) on the back between the shoulder blades. At predetermined intervals, dogs were given a full physical exam, and residues of fipronil and cyphenothrin were determined in dog blood and cotton glove extracts using GC/MS. Fipronil and cyphenothrin peaks eluted at 7.453 and 9.913 min, correspondingly, and the compounds were confirmed based on characteristic ions. At no time was fipronil or cyphenothrin residue detected in blood samples. In glove extracts, residues of fipronil and cyphenothrin were maximally present at 24-h posttreatment (43.84 ± 5.69 and 59.26 ± 8.97 ppm, respectively). By 48 h, the residue levels sharply declined (16.89 ± 2.82 and 17.98 ± 2.07 ppm, respectively). The insecticides’ residues were detected in insignificant amounts after 1 week (5.69 ± 2.16 and 10.00 ± 1.51 ppm, respectively), and only in trace amounts after 2 weeks. At no time did any dog show side effects, except itching at the site of Parastar® Plus application. The findings suggest that Parastar® Plus was safe for dogs, and transferable residues of fipronil and cyphenothrin were minimal, posing very little or no health concern to pet owners or veterinary personnel. Of course, veterinary personnel, who handle many dogs daily, may require proper protection to avoid cumulative exposure.

Rapid and sensitive detection of fipronil and its metabolites in edible oils by solid-phase extraction based on humic acid bonded silica combined with gas chromatography with electron capture detection.

Solid-phase extraction based on humic acid bonded silica followed by gas chromatography with electron capture detection was developed to determine fipronil and its metabolites in edible oil. To achieve the best extraction performance, we systematically investigated a series of solid-phase extraction parameters. Under the optimized conditions, the method was validated according to linearity, recovery, and precision. Good linearities were obtained with R(2) more than 0.9996 for all analytes. The limits of detection were between 0.3 and 0.5 ng/g, and the recoveries ranged from 83.1 to 104.0% at three spiked concentrations with intra- and interday relative standard deviation values less than 8.7%. Finally, the proposed method was applied to determine fipronil and its metabolites in 11 edible oil samples taken from Wuhan markets. Fipronil was detectable in four samples with concentrations ranging from 3.0 to 5.2 ng/g. In China, the maximum residue limits of fipronil in some vegetables and maize are 20 and 100 ng/g (GB/T 2763-2014), respectively. The residues of fipronil and its metabolites in commercial edible oils might exhibit some potential threat to human health as a result of high consumption of edible oil as part of daily intake.

Persistence of fipronil residues in Eucalyptus seedlings and its concentration in the insecticide solution after treatment in the nursery.

Eucalyptus seedlings are normally protected from underground termites (Isoptera: Termitidae) by immersing them in insecticide solutions. Fipronil (phenylpyrazole) is the most frequently used product to protect seedlings in the field for up to 6 months after application. This is performed just prior to planting. However, the persistence of this product in seedlings that are treated and subjected to irrigation several days prior to planting has not yet been evaluated. This study aims to quantify the fipronil concentration in the substratum and roots of the seedlings treated and subjected to irrigation for up to 56 days prior to planting and to quantify this insecticide concentration in the solutions, without continuous stirring, for 120 min. The quantitative determination of fipronil in the seedlings and in the insecticide solution was done by high-performance liquid chromatography (HPLC) with an ultraviolet (UV) detector. It was found that irrigation up to 56 days, performed in the nurseries, did not decrease the fipronil concentration in the seedlings. The absence of stirring reduced the fipronil concentration in the insecticide solution, necessitating a homogenization system to maintain the recommended concentration of this product, to effectively treat the eucalyptus seedlings. The seedling treatment with fipronil can be conducted strictly in the nursery, reducing cost and environmental risks.

Distribution of pesticides in dust particles in urban environments

In regions with a mild climate, pesticides are often used around homes for pest control. Recent monitoring studies have linked pesticide use in residential areas to aquatic toxicity in urban surface water ecosystems, and suggested dust particles on paved surfaces as an important source of pesticides. To test the hypothesis that dust on hard surfaces is a significant source of pesticides, we evaluated spatial and temporal patterns of current-use insecticides in Southern California, and further explored their distribution as a function of particle sizes. Pyrethroid insecticides were detected in dust from the driveway, curb gutter and street at 53.5–94.8%, with median concentrations of 1–46 ng g−1. Pyrethroid residues were uniformly distributed in areas adjacent to a house, suggesting significant redistribution. The total levels of pyrethroids in dust significantly (p < 0.01) decreased from October to February, suggesting rainfalls as a major mechanism to move pesticide residues offsite. Fipronil as well as its degradation products, were detected at 50.6–75.5%, and spatial and temporal patterns of fipronil residues suggested rapid transformations of fipronil to its biologically active intermediates. Moreover, pyrethroids were found to be enriched in fine particles that have a higher mobility in runoff than coarse particles. Results from this study highlight the widespread occurrence of pesticides in outdoor dust around homes and the potential contribution to downstream surface water contamination via rain-induced runoff.

Potential of some soil amendments in reducing leaching of fipronil to groundwater

The efficacy of different soil amendments in reducing the leaching of fipronil to groundwater was examined in soil columns under laboratory conditions. The polyvinyl chloride columns were sequentially filled with soils of different depths simulating natural conditions. Different soil amendments namely fresh cow dung (FCD) slurry @ 0.5 t ha−1, farmyard manure @ 5.0 t ha−1, press mud compost @ 5.0 t ha−1, cereal straw @ 5.0 t ha−1 and gypsum @ 5.0 t ha−1 were applied on the top soil. The application of farmyard manure, cereal straw and gypsum decreased the soil pH, and except FCD, all the amendments increased the electrical conductivity of the soil. Among different soil amendments, press mud compost and cereal straw were the most effective in reducing leaching of the fipronil to groundwater. Fipronil residues in soil columns after leaching indicated that all soil amendments effectively increased the retention of fipronil in soil; however, press mud compost and cereal straw also dissipated higher amount of fipronil. The results also revealed a higher retention of applied fipronil with lower degradation and leaching under application of 0.5 t FCD ha−1 as organic amendment in soil in comparison with the unamended soil.

Analytical method for determination of fipronil and its metabolites in vegetables using the QuEChERS method and gas chromatography/mass spectrometry.

An easy, simple, and efficient analytical method was validated for the determination of residues of fipronil and its metabolites in different vegetables comprising brinjal, cabbage, capsicum, cauliflower, okra, and tomato. The Quick, Easy, Cheap, Rugged and Safe method was used for the extraction and cleanup of fipronil and its metabolites on these vegetables. Final clear extracts of ethyl acetate were concentrated under vacuum and reconstituted into acetone, and residues were determined by GC/MS with an Rtx-5 capillary column. The retention times of desulfinyl, sulfide, fipronil, sulfone, and amide were 11.8, 15.8, 16.4, 19.7, and 24.1 min, respectively. The average recoveries obtained for fipronil and its metabolites at different spiking levels were determined to be above 85% in all samples. The repeatability and reproducibility in different matrixes ranged from 1.36 to 5.42 and 1.75 to 4.53%, respectively, for fipronil and its metabolites. The LOQ of this method was 0.01 mg/kg and LOD was 0.003 mg/kg.

Determination of residues of fipronil and its metabolites in cauliflower by using gas chromatography-tandem mass spectrometry.

Fipronil is a widely used insecticide with a well-described toxicological pathway. Recently it has been widely used in India to control vegetable pests. The present study has been carried out to observe the persistence pattern of fipronil and its metabolites-fipronil sulfone, fipronil sulfide, fipronil desulfinyl in cauliflower and soil so as to know the potential risk if any to consumers and environment. Fipronil was applied @ 56 g a.i. ha(-1). Samples of cauliflower and soil were collected periodically; processed using QuEChERS method and analyzed by GCMS/MS. In cauliflower, residues of fipronil and its metabolites reached below detectable level before 30 days of application whereas in soil about 95% of total fipronil residues got degraded within same time period. Washing and washing followed by cooking or boiling was found effective in reducing residues. A safe waiting period of 15 days is therefore suggested before consuming cauliflower.

Effects of Types of Washing and Peeling in Relation to Pesticide Residues in Tomatoes

Tomatoes are widely consumed and most often without cooking, therefore it is important to estimate the reduction of residues using simple washing procedures. An experiment was carried out to evaluate the effects of household processing such as: washing with water, washing with 10% of vinegar solution and washing with 10% of sodium bicarbonate solution on pesticide residue levels of acetamiprid, azoxystrobin, diflubenzuron, dimethoate, fipronil, imidacloprid, procymidone and thiamethoxam, in spiked tomato samples. The amount of residue remaining in the peel and pulp was also investigated. The pesticide residues were monitored using the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and analysed by liquid chromatography tandem mass spectrometry method (LC-MS/MS) in dynamic multiple-reaction monitoring mode (DMRM). The effect of the number of washing treatments (n = 3) and control, with six replicates, differed significantly for all pesticides evaluated (n = 8), but despite washing, fipronil residues were not removed from the tomato samples. Overall, washing with water or other solutions, and peeling before consumption are shown to reduce pesticide residues in tomatoes.

Residues and dissipation of fipronil and metabolites in Pomegranate fruits

Field and laboratory studies on residues and dissipation of fipronil and metabolites in pomegranate fruits were conducted during 2010 at the Pesticide Residue Analysis Laboratory, Department of Entomology, Mahatma Phule Krishi Vidyapeeth, Rahuri, Ahmednagar (M.S.) India. The studies revealed that residues of fipronil persisted up to 3 and 5 days in arils, 7 and 10 days in whole fruits and 10 and 14 days in peel of pomegranate fruits at recommended and higher doses, respectively. The metabolites showed interesting mode of dissipation. How to view point the article : Kadam, D.R., Deore, B.V. and Umate, S.M. (2014). Residues and dissipation of fipronil and metabolites in Pomegranate fruits. J. Plant Protec., 7(2) : 456-461.

Effect of paste processing on residue levels of imidacloprid, pyraclostrobin, azoxystrobin and fipronil in winter jujube

The changes of imidacloprid, pyraclostrobin, azoxystrobin and fipronil residues were studied to investigate the carryover of pesticide residues in winter jujube during paste processing. A multi-residue analytical method for winter jujube was developed based on the QuEChERS approach. The recoveries for the pesticides were between 87.5% and 116.2%. LODs ranged from 0.002 to 0.1 mg kg–1. The processing factor (Pf) is defined as the ratio of pesticide residue concentration in the paste to that in winter jujube. Pf was higher than 1 for the removal of extra water, and other steps were generally less than 1, indicating that the whole process resulted in lower pesticide residue levels in paste. Peeling would be the critical step for pesticide removal. Processing factors varied among different pesticides studied. The results are useful to address optimisation of the processing techniques in a manner that leads to considerable pesticide residue reduction.