bifenthrin and fenvalerate

To address concerns around age-related sensitivity to pyrethroids, a life-stage physiologically based pharmacokinetic (PBPK) model, supported by in vitro to in vivo extrapolation (IVIVE) was developed. The model was used to predict age-dependent changes in target tissue exposure of 8 pyrethroids; deltamethrin (DLM), cis-permethrin (CPM), trans-permethrin, esfenvalerate, cyphenothrin, cyhalothrin, cyfluthrin, and bifenthrin. A single model structure was used based on previous work in the rat. Intrinsic clearance (CLint) of each individual cytochrome P450 or carboxylesterase (CES) enzyme that are active for a given pyrethroid were measured in vitro, then biologically scaled to obtain in vivo age-specific total hepatic CLint. These IVIVE results indicate that, except for bifenthrin, CES enzymes are largely responsible for human hepatic metabolism (>50% contribution). Given the high efficiency and rapid maturation of CESs, clearance of the pyrethroids is very efficient across ages, leading to a blood flow-limited metabolism. Together with age-specific physiological parameters, in particular liver blood flow, the efficient metabolic clearance of pyrethroids across ages results in comparable to or even lower internal exposure in the target tissue (brain) in children than that in adults in response to the same level of exposure to a given pyrethroid (Cmax ratio in brain between 1- and 25-year old = 0.69, 0.93, and 0.94 for DLM, bifenthrin, and CPM, respectively). Our study demonstrated that a life-stage PBPK modeling approach, coupled with IVIVE, provides a robust framework for evaluating age-related differences in pharmacokinetics and internal target tissue exposure in humans for the pyrethroid class of chemicals.

Topics: Carboxylesterase; Cytochrome P-450 Enzyme System; Dose-Response Relationship, Drug; Humans; Kinetics; Liver; Microsomes, Liver; Models, Biological; Nitriles; Permethrin; Pharmacokinetics; Pyrethrins

The metabolism of bifenthrin (BIF), β-cyfluthrin (CYFL), λ-cyhalothrin (CYHA), cyphenothrin (CYPH) and esfenvalerate (ESF) was studied in liver microsomes, liver cytosol and plasma from male Sprague-Dawley rats aged 90, 21 and 15 days and from adult humans. Pyrethroid metabolism was also studied with some human expressed cytochrome P450 (CYP) and carboxylesterase (CES) enzymes. All five pyrethroids were metabolised by adult (90 day old) rat hepatic microsomal CYP and CES enzymes and by cytosolic CES enzymes. The pyrethroids were also metabolised by human liver microsomes and cytosol. Some species differences were observed. Pyrethroid metabolism by cytosolic CES enzymes contributes to the overall hepatic clearance of these compounds. CYFL, CYHA, CYPH and ESF were metabolised by rat plasma CES enzymes, whereas none of the pyrethroids were metabolised by human plasma. This study demonstrates that the ability of male rats to metabolise these pyrethroids by hepatic CYP and CES enzymes and plasma CES enzymes increases with age. In all instances, apparent intrinsic clearance values were lower in 15 than in 90 day old rats. All pyrethroids were metabolised by some of the human expressed CYP enzymes studied and apart from BIF were also metabolised by CES enzymes.

Topics: Animals; Carboxylesterase; Cytochrome P-450 Enzyme System; Humans; Male; Microsomes, Liver; Nitriles; Pyrethrins; Rats

This study compared four different statistical methods, involving six estimation procedures, for addressing censored left data in measuring temporal trends of eight different pyrethroids measured in sediment from a 10-year data set in a residential California stream (Pleasant Grove Creek). The statistical methods used were: the Kaplan-Meier (km) method; the robust regression on order statistics (ros using normal and log normal distributions rosln); the maximum likelihood estimation (mlen using normal and log normal distributions mleln); and a substitution method (sub) using ½ the detection limit. For five of the eight pyrethroids (bifenthrin, cyfluthrin, cypermethrin, lambda-cyhalothrin, and permethrin), the six statistical methods generally agree, with one exception, that the data set exhibit significant declining trends. In the case of bifenthrin, the slight disagreement among statistical methods only occurred for the mleln estimate that did not show a significant declining trend, whereas the other five methods did. For deltamethrin, esfenvalerate, and fenpropathrin, all six statistical methods were in agreement showing no significant trends. Possible reasons for declining sediment concentrations of pyrethroids in Pleasant Grove Creek are urban label changes effective in 2012-2015 that reduced residential use, variable annual rainfall, and more responsible homeowner use based on outreach/education programs.

Topics: Animals; California; Environmental Monitoring; Insecticides; Nitriles; Permethrin; Pyrethrins; Rivers; Water Pollutants, Chemical

Pyrethroid and carbamate resistance was evaluated in Helicoverpa armigera from 2008 to 2015. Insects were collected as eggs primarily from cultivated hosts in the major cropping areas of New South Wales and Queensland, Australia. Larvae reared from eggs were tested for resistance to fenvalerate, bifenthrin or methomyl in the F0 generation using a topical application of a discriminating dose of insecticide. In 2008-2009, resistance to fenvalerate was 71% and no resistance to bifenthrin was recorded. In the following two seasons, resistance to pyrethroids was relatively stable with fenvalerate resistance ranging from 63% to 67% and bifenthrin resistance ranging from 5.6% and 6.4% in 2009-2010 and 2010-2011, respectively. However, in 2011-2012, pyrethroid resistance had increased to 91% and 36% for fenvalerate and bifenthrin, respectively. Resistance remained above 90% for fenvalerate and above 35% for bifenthrin in the following three seasons from 2012 to 2015. In 2008-2009, methomyl resistance was 33% and declined to 22% and 15% in 2009-2010 and 2010-2011, respectively. Methomyl resistance remained at moderate levels from 2011-12 to 2014-15, ranging from 21% to 40%. Factors that influenced selection pressure of pyrethroid and carbamate insecticides and impacted resistance frequency in H. armigera may have been associated with changes in the composition of the cropping landscape. The rapid expansion of the pulse industry and the commensurate increased use of insecticide may have played a role in reselection of high-level pyrethroid resistance, and highlights the need for an urgent and strategic response to insecticide resistance management in the Australian grains industry.

Topics: Animals; Bacillus thuringiensis; Gossypium; Insecticides; Larva; Methomyl; Moths; New South Wales; Nitriles; Plants, Genetically Modified; Pyrethrins; Queensland

Twenty-nine pesticide residues in nut-planted soils from China were investigated. One organophosphate (chlorpyrifos) was detected in 5.3% soils, and the residue levels of 7.2 μg/kg to 77.2 μg/kg. The concentrations of six organochlorines (DDT, HCH, endosulfan, quintozene, aldrin and dieldrin) detected in 78.9% soils were 0.6 μg/kg to 90.1 μg/kg. The residue levels of six pyrethroids (bifenthrin, fenpropathrin, cyhalothrin, cypermethrin, fenvalerate and deltamethrin) detected in 65.8% soils were 1.5 μg/kg to 884.3 μg/kg. Triadimefon and buprofezin were found in 71.1% and 52.6% samples, respectively, with the corresponding concentrations of 9.8 μg/kg to 193.7 μg/kg and 87.9 μg/kg to 807.4 μg/kg. The multiple residues were found in 76.3% soils. A significant correlation between pesticide residues in nuts and soils was observed, with the correlation coefficient (r) 0.83 (P < 0.001). In addition, the bioconcentration factor (BCF) values for the explanation of pesticides from soils into nuts were ranged from 0.8 to 16.5. The results showed that some pesticides could accumulate in nut by the uptake effect from soil.

Topics: China; Chlorpyrifos; Dieldrin; Endosulfan; Environmental Monitoring; Hydrocarbons, Chlorinated; Nitriles; Nuts; Pesticide Residues; Pesticides; Pyrethrins; Soil; Soil Pollutants

Topics: Animals; Brazil; Chickens; Diet; Eggs; Environmental Exposure; Farms; Gas Chromatography-Mass Spectrometry; Humans; Insecticides; Nitriles; Permethrin; Pyrethrins

The aim of this study was to characterize the level and nature of the pesticide contamination received by one-sided livebearer fish (Jenynsia multidentata) from a watercourse situated within the main agricultural region of Argentina, and to assess the effects of this contamination on fish health. Juvenile one-sided livebearer fish (Jenynsia multidentata) were collected in December 2011 and March 2012 from three sites along the Pergamino River. Pesticide contamination was characterized by extracting whole fish and analytically determining thirty different pesticide molecules. The biomarkers catalase, glutathione-S-transferase, and cholinesterases were assessed. Body condition was calculated as an estimate of the amount of energy reserves possessed by the fish. Seventeen different pesticides were detected in fish tissues with 81% of captured animals containing at least one pesticide molecule. The pyrethroid insecticides fenvalerate and bifenthrin were most frequently detected, being respectively found in 41.8 and 36.4% of samples tested. Highly toxic dichlorvos and pirimiphos-methyl were detected. Differential levels of contamination could not be established amongst sites but were observed within sites amongst the two sampling dates. The months when pesticide residues were most abundant from in Site A and B corresponded to the months when body condition was at its lowest in the two sites. The inhibition of Che activity in March when body condition was reduced also points to a role of insecticide contamination in the reduction of body condition. These findings provide strong new evidence that current-used agricultural pesticides can accumulate in wild fish and impact their health and energetics.

Topics: Agriculture; Animals; Argentina; Biomarkers; Cholinesterase Inhibitors; Cholinesterases; Cyprinodontiformes; Environmental Monitoring; Insecticides; Nitriles; Pesticide Residues; Pesticides; Pyrethrins; Rivers; Water Pollutants, Chemical

High tunnels are large protective structures used for season extension of many crops, including raspberries. These structures are often covered in plastic films to reduce and diffuse ultraviolet light transmission for pest and disease control, but this may also affect the photodegradation and efficacy of pesticides applied under these tunnels. We compared the residue levels of ten insecticides under three tunnel plastics with varying levels of UV transmission and open field conditions. Raspberry plants placed in research-scale tunnels were treated with insecticides and residues on fruit and foliage were monitored for one or two weeks in early 2015 and early and late 2016. Plastics that reduce UV transmission resulted in 50% greater residues of some insecticides compared to transparent plastics, and 60% compared to uncovered tunnels. This increased persistence of residues was evident within 1 day and remained consistently higher for up to 14 days. This pattern was demonstrated for multiple insecticides, including bifenthrin, esfenvalerate, imidacloprid, thiamethoxam, and spinosad. In contrast, the insecticide malathion degraded rapidly regardless of the plastic treatment, indicating less sensitivity to photodegradation. Bioassays using insecticide-treated leaves that were under UV-blocking plastic revealed higher mortality of the invasive fruit pest, Drosophila suzukii, compared to leaves that were uncovered. This indicates that the activity of pesticides under high tunnels covered in UV-reducing plastics may be prolonged, allowing for fewer insecticide applications and longer intervals between sprays. This information can be used to help optimize pest control in protected culture berry production.

Topics: Animals; Crops, Agricultural; Drug Combinations; Insect Control; Insecticides; Longevity; Macrolides; Malathion; Neonicotinoids; Nitriles; Nitro Compounds; Oxazines; Pesticide Residues; Pyrethrins; Rubus; Thiamethoxam; Thiazoles; Ultraviolet Rays

Extreme and uncontrolled usage of pesticides produces a number of problems for vegetation and human health. In this study, the existence of organophosphates (OPs), organochlorines (OCs), pyrethroids (PYs) and fungicides (FUs) were investigated in persimmons/jujubes and their planted soils, which were collected from China. One OP (dimethoate), three OCs (DDT, quintozene and aldrin), six PYs (bifenthrin, fenpropathrin, cyhalothrin, cypermethrin, fenvalerate and deltamethrin) and two FUs (triadimefon and buprofezin) were found in 36.4% of persimmons and 70.8% of jujubes, with concentrations from 1.0 μg/kg to 2945.0 μg/kg. The most frequently detected pesticides in the two fruits were fenpropathrin in persimmons and cypermethrin in jujubes, with the detection frequencies of 30.0% and 22.7%, respectively. The residues of 4.5% (persimmon) and 25.0% (jujube) of samples were higher than the maximum residue limits (MRLs) of China. Compared with the fruits, more types of pesticides and higher residues were observed in their planted soils. The most frequently detected pesticides were HCH in persimmon soil and DDT in jujube soil, with the detection frequencies of 10.9% and 12.7%, respectively. For the tested samples, 39.1% of fruit samples and 63.0% of soil samples with multiple residues (containing more than two pesticides) were noted, even up to 8 residues in fruits and 14 residues in soils. Except for cyhalothrin, the other short-term risks for the tested pesticides in the fruits were below 10%, and the highest long-term risk was 14.13% for aldrin and dieldrin. There was no significant health risk for consumers via consumption of the two fruits.

Topics: Agriculture; China; Dieldrin; Diospyros; Environmental Monitoring; Food Contamination; Fruit; Hydrocarbons, Chlorinated; Nitriles; Pesticide Residues; Pyrethrins; Risk Assessment; Soil; Soil Pollutants; Ziziphus

A resistant strain of the Aphis glycines Matsumura (CRR) has developed 76.67-fold resistance to lambda-cyhalothrin compared with the susceptible (CSS) strain. Synergists piperonyl butoxide (PBO), S,S,S-Tributyltrithiophosphate (DEF) and triphenyl phosphate (TPP) dramatically increased the toxicity of lambda-cyhalothrin to the resistant strain. Bioassay results indicated that the CRR strain had developed high levels of cross-resistance to chlorpyrifos (11.66-fold), acephate (8.20-fold), cypermethrin (53.24-fold), esfenvalerate (13.83-fold), cyfluthrin (9.64-fold), carbofuran (14.60-fold), methomyl (9.32-fold) and bifenthrin (4.81-fold), but did not have cross-resistance to chlorfenapyr, imidacloprid, diafenthiuron, abamectin. The transcriptional levels of CYP6A2-like, CYP6A14-like and cytochrome b-c1 complex subunit 9-like increased significantly in the resistant strain than that in the susceptible. Similar trend were observed in the transcripts and DNA copy number of CarE and E4 esterase. Overall, these results demonstrate that increased esterase hydrolysis activity, combined with elevated cytochrome P450 monooxygenase detoxicatication, plays an important role in the high levels of lambda-cyhalothrin resistance and can cause cross-resistance to other insecticides in the CRR strain.

Topics: Animals; Aphids; Cytochrome P-450 Enzyme System; Esterases; Insect Proteins; Insecticide Resistance; Insecticides; Nitriles; Pyrethrins

There is an assumption that pyrethroid pesticides are converted to non-toxic metabolites by hydrolysis in mammals. However, some recent works have shown their bioaccumulation in human breast milk collected in areas where pyrethroids have been widely used for agriculture or malaria control. In this work, thirteen pyrethroids have been studied in human breast milk samples coming from areas without pyrethroid use for malaria control, such as Brazil, Colombia and Spain. The concentrations of pyrethroids ranged from 1.45 to 24.2 ng g⁻¹ lw. Cypermethrin, λ-cyhalothrin, permethrin and esfenvalerate/fenvalerate were present in all the studied samples. The composition of pyrethroid mixture depended on the country of origin of the samples, bifenthrin being the most abundant in Brazilian samples, λ-cyhalothrin in Colombian and permethrin in Spanish ones. When the pyrethroid concentrations were confronted against the number of gestations, an exponential decay was observed. Moreover, a time trend study was carried out in Brazil, where additional archived pool samples were analyzed, corresponding to years when pyrethroids were applied for dengue epidemic control. In these cases, total pyrethroid levels reached up to 128 ng g⁻¹ lw, and concentrations decreased when massive use was not allowed. Finally, daily intake estimation of nursing infants was calculated in each country and compared to acceptable WHO levels. The estimated daily intakes for nursing infants were always below the acceptable daily intake levels, nevertheless in certain samples the detected concentrations were very close to the maximum acceptable levels.

Topics: Adolescent; Adult; Agriculture; Brazil; Breast Feeding; Colombia; Environmental Exposure; Environmental Pollutants; Environmental Pollution; Female; Humans; Infant; Insecticides; Milk, Human; Mosquito Control; Nitriles; Permethrin; Pyrethrins; Spain; Young Adult

Pyrethroid resistance in Helicoverpa armigera (Hübner) field populations was investigated in Benin over several years by using third- and fourth-instar larval topicalbioassays. H. armigera was resistant to pyrethroids tested as cypermethrin, deltamethrin, bifenthrin, and fenvalerate. Pretreatment with piperonyl butoxide significantly decreased the LD50 value of cypermethrin and deltamethrin, and the resistance suppression by this synergist effect was observed. No significant decrease in the LD50 value was obtained when S,S,S-tributyl phosphoro-trithioate was applied before deltamethrin. In the field, cypermethrin's LD50 value varied, and the highest LD50 values were observed during the rainy season, the cotton, Gossypium hirsutum L., crop period, when pyrethroids are extensively used. In the dry season when there was no cotton cultivation, the lowest LD50 values were obtained. However, reversion was never total in the field; resistance did not revert to the level we observed in the susceptible strain. In the laboratory, when field populations were reared in insecticide-free conditions, resistance decreased and total reversion was observed. Results are discussed with regard to insecticide resistance fitness cost and resistance management strategies.

Topics: Animals; Benin; Drug Resistance; Gossypium; Insecta; Insecticides; Lethal Dose 50; Nitriles; Pest Control; Pyrethrins; Solanum lycopersicum

The use of pyrethroid insecticides is increasing for agriculture, commercial pest control, and residential consumer use. In addition, there is a trend toward the use of newer and more potent compounds. Little is known about the toxicity of sediment-associated pyrethroid residues to aquatic organisms, yet recent work has shown they commonly are found in aquatic sediments in the heavily agricultural Central Valley of California, USA. Minimal data exist on the sensitivity of standard sediment toxicity testing species to pyrethroids, despite two or more decades of agricultural use of these compounds. Sediment concentrations causing acute toxicity and growth impairment to the amphipod Hyalella azteca were determined for six pyrethroids in three sediments, ranging from 1.1 to 6.5% organic carbon (OC). In order of decreasing toxicity of sediment-associated residues, the compounds tested were bifenthrin (average 10-d median lethal concentration [LC50] = 0.18 microg/g OC), lambda-cyhalothrin (0.45 microg/g OC), deltamethrin (0.79 microg/g OC), esfenvalerate (0.89 microg/g OC), cyfluthrin (1.08 microg/g OC), and permethrin (4.87 microg/g OC). In a sediment containing about 1% OC, most pyrethroids, except permethrin, would be acutely toxic to H. azteca at concentrations of 2 to 10 ng/g dry weight, a concentration only slightly above current analytical detection limits. Growth typically was inhibited at concentrations below the LC50; animal biomass on average was 38% below controls when exposed to pyrethroid concentrations roughly one-third to one-half the LC50. Survival data are consistent with current theory that exposure occurs primarily via the interstitial water rather than the particulate phase. A reanalysis of previously reported field data using these toxicity data confirms that the compounds are exceeding concentrations acutely toxic to sensitive species in many agriculture-dominated water bodies.

Topics: Amphipoda; Animals; Biomass; California; Carbon; Geologic Sediments; Lethal Dose 50; Nitriles; Organic Chemicals; Permethrin; Pesticides; Pyrethrins; Water Pollutants, Chemical