Clinical manifestations and diagnosis of acute pyrethroid poisoning

Systematic review of clinical manifestations, management and outcome following accidental ingestion of liquid mosquito repellent vaporiser in children

BACKGROUND

Pyrethroid-based mosquito repellents are widely used to control mosquito-borne diseases. Liquid mosquito-repellent vaporisers are effective modes of pyrethroid delivery but can also pose significant health risks if ingested or used improperly.

OBJECTIVE

This systematic review was performed to assess the demographic distribution, clinical presentation, management strategies and outcomes in children resulting from accidental ingestion of liquid mosquito repellent vaporiser.

METHODS

The study adheres to the reporting standards outlined in the PRISMA Statement for Systematic Reviews and was prospectively registered with PROSPERO (record # CRD42023413937) to enhance transparency and minimise reporting bias. A comprehensive search was conducted on PubMed, Scopus and Google Scholar using specific MeSH terms related to insecticides, mosquito repellents, pyrethroids, ingestion, poisoning, toxicity and prevention. The reference lists of the included studies were also reviewed for additional relevant articles. The inclusion criteria involved studies published in peer-reviewed journals between 2000 and 2023 that focused on children under 18 years old with a history of mosquito-repellent ingestion based on primary data.

RESULTS

Twelve studies met the inclusion criteria; these were primarily case reports from India, China and the UAE. Male children were predominantly affected, and symptoms included vomiting, convulsions, cough and respiratory distress. Management primarily involved supportive and symptomatic measures, including atropine for salivation and antiepileptic drugs for seizures. Respiratory support was provided for respiratory complications.

CONCLUSION

Despite the known risks and diverse presentations of pyrethroid poisoning caused by liquid mosquito repellent vaporiser in children, the limited substantial evidence in the literature underscores the urgent need for comprehensive research to refine management approaches and enhance preventive measures.

Towards quantifying atmospheric dispersion of pesticide spray drift in Yuma County Arizona

While pesticide vapor and particles from agricultural spray drift have been reported to pose a risk to public health, limited baseline ambient measurements exist to warrant an accurate assessment of their impacts at community-to-county-wide scale. Here, we present an initial modeling investigation of the transport and deposition of applied pesticides in an agricultural county in Arizona (Yuma County), to provide initial estimates on the corresponding enhancements in ambient levels of these spray drifts downwind of application sites. With a 50 × 50 km domain, we use the dispersion model CALPUFF with meteorology from the Weather Research and Forecasting (WRF) to investigate the spatiotemporal distribution of pesticide abundance due to spray drift from a representative sample of nine application sites. Data records for nine application days in September and October 2011, which are the peak months of pesticide application, were retroactively simulated for 48-h for all nine application sites using an active ingredient lambda-cyhalothrin, which is a commonly-used pesticide in the county. Twenty-one WRF/CALPUFF simulations were conducted with varying emissions, chemical lifetime, deposition rate, application height, and meteorology inputs, allowing for an ensemble-based analysis on the possible ranges in modeled abundance. Our results show that dispersion of vapors released at time of application heavily depends on prevailing meteorology, particularly wind speed and direction. Dispersion is limited to thin plumes that are easily transported out of the domain. The ensemble-mean vapor concentrations of the 48-h average (> 90 percentile domain-wide) range from 0.2 nanograms (ng)/m3 to 200 ng/m3, and the peak can be as high as 1000 ng/m3 near the application sites. Pesticide particles are mainly deposited within 1-2 km from the application sites at an average rate of 106 ng/km2/h but vary with particle mean diameter and standard deviation. While these findings are generally consistent with reported ambient levels in the literature, the associated ensemble-spread on these estimates are in the same order of magnitude as their ensemble-mean. At the two nearby communities downwind of these sites, we find that peak vapor concentrations are less than 50 ng/m3 with exposure times of less than an hour, as approximately 99.4% of the vapors are advected out and 99.5% of the particles deposit within the domain. Results of this study indicate pesticide spray drift from a sample of application sites and representative days in Fall may have a limited impact on neighboring communities. However, we strongly suggest that field measurements should be collected for model validation and more rigorous investigation of the actual scale of these impacts when the bulk of pesticide applications across the county, variation in active pesticide ingredients, and potential resuspension of deposited particles are considered.

Acute cypermethrin and other pyrethroid poisoning - An organophosphate-like poisoning: A case report and review

Background

South Africa is one of the largest importers of pesticides in Africa. Pesticides play an integral role in food security and ensuring economic survival. Cypermethrin is a type II pyrethroid and is commonly and widely used as an insecticide. Poisoning arises from exposure through inhalation, skin contact or ingestion. Its toxic effects manifest predominantly as neurological and gastrointestinal symptoms. Severe pyrethroid poisonings are rare but can present as an organophosphate-like toxidrome. This poses a diagnostic conundrum.

Case report

This case concerns a 36-year-old male from a rural town in the Eastern Cape province of South Africa, who was diagnosed with intentional cypermethrin poisoning after a suicide attempt. He was initially diagnosed as a suspected organophosphate poisoning with coma. He made a full recovery after mechanical ventilation and symptomatic treatment with a low dose muscarinic antagonist, atropine sulphate.

Conclusions

With the ease of over-the-counter procurement, cypermethrin and other pyrethroid poisonings pose an increasing diagnostic dilemma to frontline and critical care personnel. This case report intends to raise awareness about the organophosphate-like toxidrome at presentation and the potential complications of high dose atropine treatment, commonly used to treat organophosphate poisoning. The treatment of cypermethrin is largely supportive with dermal decontamination of skin as an essential component. Low dose atropine may be utilized if required.

Human Poisoning with Chlorpyrifos and Cypermethrin Pesticide Mixture: Assessment of Clinical Outcome of Cases Admitted in a Tertiary Care Hospital in Taiwan

Background and Purpose

There is an overall paucity of data regarding the human toxicity of chlorpyrifos and cypermethrin pesticide mixture. Both organophosphate and pyrethroid insecticides are metabolized by carboxylesterases. Thus, its pesticide combination, organophosphates may boost the toxicity of pyrethroids via inhibited its detoxification by carboxylesterases. This study examined the clinical course, laboratory tests, and outcomes of patients with chlorpyrifos, cypermethrin or their pesticide mixture poisoning, and to determine what association, if any, might exist between these findings.

Patients and Methods

Between 2000 and 2021, 121 patients poisoned with chlorpyrifos, cypermethrin, or their pesticide mixture were treated at Chang Gung Memorial Hospital. Patients were categorized as chlorpyrifos (n=82), cypermethrin (n=27) or chlorpyrifos and cypermethrin (n=12) groups. Demographic, clinical, laboratory and mortality data were collected for analysis.

Results

The patients experienced a broad range of clinical symptoms, including aspiration pneumonia (44.6%), salivation (42.5%), acute respiratory failure (41.3%), acute kidney injury (13.9%), seizures (7.5%), hypotension (2.6%), etc. Leukocytosis (12,700±6600 /uL) and elevated serum C-reactive protein level (36.8±50.4 mg/L) were common. The acute respiratory failure rate was 41.3%, comprising 48.8% in chlorpyrifos, 11.1% in cypermethrin as well as 58.3% in chlorpyrifos and cypermethrin poisoning. Patients with chlorpyrifos and cypermethrin pesticide mixture poisoning suffered higher rates of acute respiratory failure (P=0.001) and salivation (P=0.001), but lower Glasgow Coma Scale score (P=0.011) and serum cholinesterase level (P<0.001) than other groups. A total of 17 (14.0%) patients expired. The mortality rate was 14.0%, including 17.1% in chlorpyrifos, 3.7% in cypermethrin as well as 16.7% in chlorpyrifos and cypermethrin poisoning. No significant differences in mortality rate were noted (P=0.214).

Conclusion

Chlorpyrifos pesticide accounted for the major toxicity of the pesticide mixture. While the data show a higher rate of respiratory failure in the chlorpyrifos and cypermethrin pesticide mixture group than others, other measures of toxicity such as mortality and length of stay were not increased.

Lambda-cyhalothrin ingestion: an infrequent yet concerning presentation of pyrethroid poisoning

Introduction and importance

Lambda-cyhalothrin is a type II pyrethroid compound commonly used as a pesticide, with the potential to cause life-threatening toxicity in humans. Furthermore, among cases of pesticide poisoning in Nepal, organophosphates are most frequently implicated.

Case presentation

A 40-year-old female presented to our hospital after ingesting a pesticide compound with suicidal intent. She also admitted to alcohol intoxication and exhibited symptoms of confusion, abdominal pain, nausea, and vomiting. An atropine challenge test yielded negative results. Therefore, conservative management was continued. It was discovered later that the ingested pesticide was lambda-cyhalothrin. The patient's condition eventually improved with supportive treatment.

Clinical discussion

Several reports have highlighted the overlapping clinical features between organophosphorus and pyrethroid poisoning. In some cases of pyrethroid poisoning, misdiagnosis as organophosphorus poisoning has occurred, leading to the inappropriate administration of atropine. In our case, initial management was challenging owing to the lack of accurate information about the ingested compound. On further evaluation, cholinergic clinical features were absent and the atropine challenge test was negative. This was suggestive of nonorganophosphorus compound poisoning.

Conclusion

This case illustrates that managing pesticide poisoning becomes challenging when the nature of the pesticide is unknown. Patients suffering from poisoning caused by pyrethroid compounds like lambda-cyhalothrin can present with features resembling organophosphorus poisoning. In such circumstances, a comprehensive clinical evaluation should guide the management. Clinical features and an atropine challenge test can aid in differentiating organophosphorus from nonorganophosphorus compound poisoning. This distinction facilitates therapeutic decision-making, including the consideration of atropine administration.

Acute Pneumonitis Associated With the Inhalation of Pyrethroid-Based Domestic Insecticides

We report a 72-year-old female who presented to our hospital with a worsening cough and dyspnea that had emerged a week earlier following the accidental inhalation of a significant quantity of spray-type imiprothrin (a synthetic pyrethroid)-based insecticide in her bathroom. She exhibited acute respiratory failure necessitating 4 L/minute of nasal oxygen at maximum. Chest CT images showed diffuse centrilobular ground-glass opacities with mosaic attenuation and consolidation areas in the lower lobes of both lungs. The patient was diagnosed with acute pneumonitis due to insecticide inhalation, and her symptoms improved following methylprednisolone pulse and alpha-tocopherol therapy. Generally, the accidental inhalation of aerosolized pyrethroids does not induce significant respiratory symptoms, and case reports on pulmonary toxicity related to pyrethroid inhalation are scarce. This case report underscores the need to include inhaled pyrethroid insecticides in the differential diagnosis of patients with acute pneumonitis and suggests that methylprednisolone and alpha-tocopherol therapy can be beneficial for treating this condition.

The role of pyrethroid derivatives in autophagy and apoptosis crosstalk signaling and potential risk for malignancies

Pyrethroids and its derivatives widespread and uncontrolled continuous use has influenced multiple deleterious effects resulting in as a potential risk factor causing damage to the organ systems. Allethrin and prallethrin are extensively used yet their influences on human primary cells are very limited or under reported. The potential mechanisms by which allethrin and prallethrin modulates human primary cells, especially the molecular mechanisms or interconnectivity of autophagy-apoptosis, their clinical relevance in human subjects or patients are not well defined. In this current study, we've furnished the evidence that both allethrin and prallethrin user samples significantly induced Ccl2 mRNA expression, increased amount of reactive oxygen intermediate, inhibited membrane bound enzymes and altered membrane fluidity. Pyrethroid derivative users had induced levels of lipid peroxidation and induced binding activities of transcription factors(tfs) like CEBP-β and NF-AT. Pyrethroid derivatives induced autophagy, elicited intracellular Ca2+ concentration, calcineurin and regulated proapoptotic genes, DAPK1, Bim. Our current study presumably comprises the initial investigation of a very new mechanism of pyrethroid derivatives-moderated programed cell death in various cell sets or types, like human primary cells where-in this is a late event, is documented. Hence, current research-study might be significant in the various pyrethroid derivatives-allied hematological-related cancers and immunosuppressant or auto-immune disorders. In the foremost instance, we present data stating that pyrethroid derivatives induces multiple cell signaling cascades, like CEBP-β, NF-AT, ERK and MAPK having a role in autophagy thereby; synchronously effectively impact on the apoptosis, therefore causing hematological tumors and toxic or immune related disorders.

Cardiotoxicity of pyrethroids: molecular mechanisms and therapeutic options for acute and long-term toxicity

Pyrethroids (PY) are synthetic pesticides used in many applications ranging from large-scale agriculture to household maintenance. Their classical mechanisms of action are associated with binding to the sodium channel of insect neurons, disrupting its inactivation, ensuring their use as insecticides. However, PY can also lead to toxicity in vertebrates, including humans. In most toxicological studies, the impact of PY on heart function is neglected. Acute exposure to a high dose of PY causes enhancement of the late sodium current (INaL), which impairs the action potential waveform and can cause severe cardiac arrhythmias. Moreover, long-term, low-dose exposure to PY displays oxidative stress in the heart, which could induce tissue remodeling and impairment. Isolated and preliminary evidence supports that, for acute exposure to PY, an antiarrhythmic therapy with ranolazine (an INaL blocker), can be a promising therapeutic approach. Besides, heart tissue remodeling associated with low doses and long-term exposure to PY seems to benefit from antioxidant therapy. Despite significant leaps in understanding the mechanical details of PY intoxication, currently, few studies are focusing on the heart. In this review, we present what is known and what are the gaps in the field of cardiotoxicity induced by PY.

Interaction of Synthetic Pyrethroid Insecticide Deltamethrin with Human Alpha-2-Macroglobulin: Spectroscopic and Molecular Docking Studies

Background:

Deltamethrin (DLM) is a commercial insecticide of the synthetic pyrethroid family that is used to control disease-causing insects and vectors. When humans are exposed to the fumes or aerosols of DLM, it enters the body via cuticular absorption and reacts with proteins and other biomolecules.

Objective:

Alpha-2-macroglobulin (α2M) is a serum proteinase inhibitor that also carries out receptor- mediated endocytosis of extracellular substances. This study was done to decipher the structural and functional alterations of α2M by DLM.

Method:

Various spectroscopic techniques, including UV absorption and fluorescence spectroscopy, binding studies, and molecular docking, were used to characterize the interaction of DLM with α2M. The affinity constant was calculated from the Stern-Volmer equation using fluorescence data.

Results:

The UV-Vis and fluorescence spectral studies indicated the formation of a complex between α2M and DLM. Thermodynamically, the interaction was found to be spontaneous with ΔG = -4.23 kcal/mol. CD spectra suggested a change in the secondary structure of the protein from β to α helical content with increasing concentration of DLM. The molecular docking study by Autodock Vina established the interaction of DLM with Glu-926, Ala-1103, Ala-1108, Val-1116, Asn-1159, Glu-1220, Leu-1261, Thr-1272, Ile-1390, Pro-1391, Lys-1393, Val-1396, Lys-1397, Thr-1408, Glu-1409, Val-1410, Ser-1411, Ser-1412, and Asn-1413 with an improved docking score of -6.191 kcal/mol. The binding was carried out in the vicinity of the receptor-binding domain at the C-terminal of α2M.

Conclusion:

The decrease in the functional activity and structural changes of protein after binding with DLM has a significant effect on human α2M. The information may be useful for exploring the role of DLM in a clinical chemistry laboratory.

The insecticide β-Cyfluthrin induces acute arrhythmic cardiotoxicity through interaction with NaV1.5 and ranolazine reverses the phenotype

β-Cyfluthrin, a class II Pyrethroid, is an insecticide used worldwide in agriculture, horticulture (field and protected crops), viticulture, and domestic applications. β-Cyfluthrin may impair the function of biological systems; however, little information is available about its potential cardiotoxic effect. Here, we explored the acute toxicity of β-Cyfluthrin in isolated heart preparations and its cellular basis, using isolated cardiomyocytes. Moreover, β-Cyfluthrin effects on the sodium current, especially late sodium current (INa-L), were investigated using HEK-293 cells transiently expressing human NaV1.5 channels. We report that β-Cyfluthrin raised INa-L in a dose-dependent manner. β-Cyfluthrin prolonged the repolarization of the action potential and triggered oscillations on its duration. Cardiomyocytes contraction and calcium dynamics were disrupted by the pesticide with a marked incidence of non-electronic stimulated contractions. The antiarrhythmic drug Ranolazine was able to reverse most of the phenotypes observed in isolated cells. Lastly, ventricular premature beats and long QT intervals were found during β-Cyfluthrin exposure, and Ranolazine was able to attenuate them. Overall, we demonstrated that β-Cyfluthrin can cause significant cardiac alterations and Ranolazine ameliorated the phenotype. Understanding the insecticides' impacts upon electromechanical properties of the heart is important for the development of therapeutic approaches to treat cases of pesticides intoxication.

Clinical presentation of type 1 and type 2 pyrethroid poisoning in humans

BACKGROUND

It is unclear if the clinical presentation of poisoning with type 1 and type 2 pyrethroid compounds is different. This study was undertaken to detail the clinical profile and outcome of patients presenting with pyrethroid poisoning and to quantify serum pyrethroid levels.

PATIENTS AND METHODS

In this prospective study, patients were categorised as poisoning with type 1 pyrethroids or type 2 pyrethroids. Blood samples were sent for compound identification and quantification. Clinical features and outcomes were compared between the two groups. Factors associated with moderate and severe toxicity were explored using univariate logistic regression analysis and presented as odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Type 1 pyrethroids were implicated in 16 patients and type 2 in 43 patients. The incidence of nausea and vomiting (81.2% vs. 81.3%) and tremor (37.5% vs. 32.6%) were similar in type 1 and type 2 poisoning; paraesthesia (6.2% vs. 32.6%, p = 0.04), hypersalivation (0% vs. 20.9%, p = 0.04), seizures (0% vs. 7%, p = 0.29) and depressed sensorium (0% vs. 18.6%, p = 0.03.) were observed more frequently in type 2 pyrethroid poisoning. Pyrethroids were detected in the serum samples of 24 patients; quantification was possible in 22 patients in whom serum levels ranged from 1.1 to 453 μg/ml. The compounds were undetectable in 35 patients. Two patients (lambda-cyhalothrin poisoning and cypermethrin poisoning) required intubation for low sensorium and respiratory distress. The median (interquartile range) duration of hospitalization was 12 (12-24) hours. All patients survived. Factors associated with moderate and severe toxicity included ingestion of a type 2 pyrethroid, lambda-cyhalothrin (OR 7.81, 95%CI 1.55-39.37, p = 0.01) and volume ingested (OR 1.01, 95%CI 1.00-1.02, p = 0.02).

CONCLUSION

Patients with pyrethroid poisoning present predominantly with mild to moderate symptoms. Paraesthesia and hypersalivation are more frequent in type 2 poisoning. A favourable outcome can be expected.

Household pesticide exposure: an online survey and shelf research in the Metropolitan Region of Rio de Janeiro, Brazil

This study aimed to estimate household pesticide exposure in adult individuals in the Metropolitan Region of Rio de Janeiro, Brazil, and to verify the accessibility of these products in local and online businesses. The data were collected by an online questionnaire (1,015 responses) and a shelf survey in physical and online stores. Among the responses analyzed, 87.5% used pesticides in the previous year, most of which against mosquitoes (64.7%). The most common application method was aerosol spray (38.1%), and the most frequent places of use were bedrooms (29.7%) and living rooms (22.1%). About 30% of respondents reported invasion of pests, and the most common pests were ants (79.1%) and cockroaches (40.4%). Service area (71.6%) and kitchen (17.5%) were the most common storage locations. Approximately 91% of those who lived with children aged under 18 used pesticides. The use of chemical group of pyrethroids prevailed (81.6%), and 90.8% of the reportedly used products are class II [55.7% (highly toxic)] or class III [35.1% (medium toxic)]. The most significant amount of purchased products was in the pest category, followed by mosquitoes. More variety of products were available in online stores than in physical stores. The high exposure of the population to pesticides at household is a public health issue and confirms the need for studies that better assess the risks and consequences of chronic and low-dose exposure to these substances. It is essential to inform the population about the uncertainties and potential risks of indiscriminate use so that they can choose whether to use pesticides in their households.

An 80-Year-Old Woman with Alzheimer Disease and Accidental Poisoning with Pyrethroid Pesticide Successfully Treated with Intravenous Lipid Emulsion

Patient: Female, 80-year-old

Final Diagnosis: Poisoning

Symptoms: Seizure

Medication: —

Clinical Procedure: —

Specialty: Critical Care Medicine

Subacute poisoning with bifenthrin increases the level of interleukin 1ß in mice kidneys and livers

Background

Bifenthrin is a pyrethroid. Chronic exposure of humans to the pesticide occurs. Reports about immunotoxicity and proinflammatory effect of pyrethroids were published. The aim of the article was to check if subacute poisoning with bifenthrin affects proinflammatory interleukin 1ß and tumor necrosis factorα (TNFα) in kidneys, livers and the function of these organs.

Methods

Thirty two female mice were used. They were divided into 4 groups: controls, mice receiving 1.61 mg/kg bifenthrin for 28 days (group 1), 4.025 mg/kg (2), 8.05 mg/kg (3). On day 29 they were sacrificed, blood, livers and kidneys were obtained. Creatinine concentration and alanine transaminase (ALT) activity were estimated in the blood sera. Interleukin1ß and TNFα concentrations in the organs were measured.

Result

Mean interleukin 1ß concentration in the livers of controls was 53 pg/ml, in group 1- 54 pg/ml, 2- 59 pg/ml, 3- 99 pg/ml (p < 0.05 vs controls). It was accompanied by significant increase in ALT activity in group 3 vs controls (p < 0.05). In the control kidneys interleukin 1ß was 3.9 pg/ml, group 1–6.8 pg/ml, 2–9.8 pg/ml and 3- 11 pg/ml. Statistically significant difference between group 1, 2 and 3 vs controls was found. There was no significant differences among the groups in TNFα concentrations neither in the livers nor kidneys.

Conclusion

Subacute poisoning with bifenthrin significantly increases interleukin 1ß concentration in livers and kidneys in a dose-proportionate level. It is accompanied by ALT activity increase. It confirms nephrotoxic and hepatotoxic and pro-inflammatory effect of bifenthrin in non-target organisms.

Effects of pyrethroids on brain development and behavior: Deltamethrin

Deltamethrin (DLM) is a Type II pyrethroid pesticide widely used in agriculture, homes, public spaces, and medicine. Epidemiological studies report that increased pyrethroid exposure during development is associated with neurobehavioral disorders. This raises concern about the safety of these chemicals for children. Few animal studies have explored the long-term effects of developmental exposure to DLM on the brain. Here we review the CNS effects of pyrethroids, with emphasis on DLM. Current data on behavioral and cognitive effects after developmental exposure are emphasized. Although, the acute mechanisms of action of DLM are known, how these translate to long-term effects is only beginning to be understood. But existing data clearly show there are lasting effects on locomotor activity, acoustic startle, learning and memory, apoptosis, and dopamine in mice and rats after early exposure. The most consistent neurochemical findings are reductions in the dopamine transporter and the dopamine D1 receptor. The data show that DLM is developmentally neurotoxic but more research on its mechanisms of long-term effects is needed.

Severe dyspnea and uncontrolled seizures following meperfluthrin poisoning: a case report

Background

Meperfluthrin is a novel sanitary cyhalothrin insecticide invented in China and has increasingly been used to produce liquid mosquito repellents. Oral meperfluthrin poisoning in human has rarely been reported. Here, we reported a case of meperfluthrin poisoning by ingestion of a meperfluthrin-based liquid mosquito repellent in a 16-month-old infant.

Case presentation

A 16-month-old boy with a history of accident ingestion of meperfluthrin was admitted to our hospital’s emergency department. He exhibited severe dyspnea, and lung radiograph showed multiple patchy and cord-like high-density shadows bilaterally in a short time. He also suffered 35 min of seizures which were finally controlled by the intravenous infusion of propofol. He was diagnosed with meperfluthrin poisoning, status epilepticus and severe pneumonia. After treated with methylprednisolone, aerosolized beclomethasone dipropionate, anti-infection, and some critical supportive therapy, the patient was in good health and showed no symptoms during 12 months of follow-up.

Conclusions

Meperfluthrin poisoning is rare. Oral meperfluthrin poisoning shows neurotoxic effects and pulmonary toxicity. Controlling seizures rapidly and ensuring an adequate oxygen supply are critical to the successful treatment.

Case Report: Fatal Neurotoxicity Following Resmethrin Poisoning in a Child

Resmethrin, a type I pyrethroid insecticide, can activate sodium channels, causing neurotoxicity in both mammals and insects. Possible routes of poisoning include inhalation, dermal contact and ingestion. There are no specific symptoms for resmethrin poisoning. Until now, no antidote has been available for resmethrin. Resmethrin poisoning is rarely reported in children. Here, we report a fatal case of resmethrin poisoning that might have been caused by accidental ingestion by a 26-month-old child. He presented with neurotoxic symptoms that included vomiting, recurrent seizures, and coma. The cranial CT showed extensive lesions of low intensity in the bilateral white matter, thalamus, brainstem, and cerebellum. Lumbar punctures showed increased intracranial pressure (ICP > 25 mmHg). Cerebrospinal fluid (CSF) tests revealed that protein was elevated to 289.2 mg/dL without pleocytosis. Resmethrin was detected in his blood by liquid chromatography-mass spectrometry, which confirmed the diagnosis of resmethrin poisoning. The child developed brain stem herniation and then was declared brain dead at the 77th h after admission. Resmethrin poisoning can be fatal, and it requires immediate diagnosis and treatment. Previous studies reported that cranial CT and CSF analyses were all normal in patients with pyrethroid poisoning. This case might extend the knowledge of neuroimaging and CSF analysis in children with resmethrin poisoning.

Induced alteration of rat erythrocyte membrane with effect of pyrethroid based compounds

The effects of tetramethrin and prallethrin exposure on plasma total proteins, free amino acids, albumins, urea, urea nitrogen, uric acid, creatinine were tested. Serum SGOT, SGPT and lipid profile, antioxidants super oxide dismutase (SOD), catalase, GSH, G-Px, phospholipids, cholesterol, C/P ratio in membranes of erythrocyte and membrane fluidity were analyzed. The reason of the study were analyzed to examine the possessions of mosquito repellent pyrethroid (MRP) based compounds tetramethrin and prallethrin exposure on plasma profile, antioxidant status of erythrocyte membrane, membrane fluidity in male Wistar rats. We tested chronically for three months exposure every day (continuously for 8-10 h per day by inhalation) of tetramethrin and prallethrin markedly available (MRP) repellents treated on male Wistar rats. Our results confirmed that tetrarmethrin and prallethrin treatment effect of plasma profile alterations, and lipid homeostasis mechanism in Red Blood cells (RBCs). Tetramethrin and prallethrin treatment significantly increased in erythrocyte membrane phospholipids and decreased levels of cholesterol with no change of protein content, increased C/P ration levels. Inhalation of tetramethrin and prallethrin stimulate plasma biophysical and biochemical modify SGOT, SGPT, erythrocyte membrane cholesterol and phospholipid levels, individual phospholipids and membrane fluidity of exposure rats compared to controls.

An epigenome-wide association study of ambient pyrethroid pesticide exposures in California's central valley

BACKGROUND

Pyrethroid pesticide use is increasing worldwide, although the full extent of associated health effects is unknown. An epigenome-wide association study (EWAS) with exploratory pathway analysis may help identify potential pyrethroid-related health effects.

METHODS

We performed an exploratory EWAS of chronic ambient pyrethroid exposure using control participants' blood in the Parkinson's Environment and Genes Study in the Central Valley of California (N = 237). We estimated associations of living and working near agricultural pyrethroid pesticide applications in the past 5 years (binary) with site-specific differential methylation, and used a false discovery rate (FDR) cut off of 0.05 for significance. We controlled for age, sex, education, cell count, and an ancestral marker for Hispanic ethnicity. We normalized methylation values for Type I/II probe bias using Beta-Mixture Quantile (BMIQ) normalization, filtered out cross-reactive probes, and evaluated for remaining bias with Surrogate Variable Analysis (SVA). We also evaluated the effects of controlling for cell count and normalizing for Type I/II probe bias by comparing changes in effect estimates and p-values for the top hits across BMIQ and GenomeStudio normalization methods, and controlling for cell count. To facilitate broader interpretation, we annotated genes to the CpG sites and performed gene set overrepresentation analysis, using genes annotated to CpG sites that were associated with pyrethroids at a raw p < 0.05, and controlling for background representation of CpG sites on the chip. We did this for both a biological process context (Gene Ontology terms) using missMethyl, and a disease set context using WebGestalt. For these gene set overrepresentation analyses we also used an FDR cut off of 0.05 for significance of gene sets.

RESULTS

After controlling for cell count and applying BMIQ normalization, 4 CpG sites were differentially methylated in relation to pyrethroid exposures. When using GenomeStudio's Illumina normalization, 415 CpG sites were differentially methylated, including all four identified with the BMIQ method. In the gene set overrepresentation analyses, we identified 6 GO terms using BMIQ normalization, and 76 using Illumina normalization, including the 6 identified by BMIQ. For disease sets, we identified signals for Alzheimer's disease, leukemia and several other cancers, diabetes, birth defects, and other diseases, for both normalization methods. We identified minimal changes in effect estimates after controlling for cell count, and controlling for cell count generally weakened p-values. BMIQ normalization, however, resulted in different beta coefficients and weakened p-values.

CONCLUSIONS

Chronic ambient pyrethroid exposure is associated with differential methylation at CpG sites that annotate to a wide variety of disease states and biological mechanisms that align with prior research. However, this EWAS also implicates several novel diseases for future investigation, and highlights the relative importance of different background normalization methods in identifying associations.

Mechanism underlying hooked resurgent-like tail currents induced by an insecticide in human cardiac Nav1.5

Voltage-gated sodium channels are responsible not only for the fast upstroke of the action potential, but they also modify cellular excitability via persistent and resurgent currents. Insecticides act via permanently opening sodium channels to immobilize the animals. Cellular recordings performed decades ago revealed distinctly hooked tail currents induced by these compounds. Here, we applied the classical type-II pyrethroid deltamethrin on human cardiac Nav1.5 and observed resurgent-like currents at very negative potentials in the absence of any pore-blocker, which resemble those hooked tail currents. We show that deltamethrin dramatically slows both fast inactivation and deactivation of Nav1.5 and thereby induces large persistent currents. Using the sea anemone toxin ATx-II as a tool to prevent all inactivation-related processes, resurgent-like currents were eliminated while persistent currents were preserved. Our experiments suggest that, in deltamethrin-modified channels, recovery from inactivation occurs faster than delayed deactivation, opening a brief window for sodium influx and leading to hooked, resurgent-like currents, in the absence of an open channel blocker. Thus, we now explain with pharmacological methods the biophysical gating changes underlying the deltamethrin induced hooked tail currents. SUMMARY: The pyrethroid deltamethrin induces hooked resurgent-like tail currents in human cardiac voltage-gated Nav1.5 channels. Using deltamethrin and ATx-II, we identify additional conducting channel states caused by a faster recovery from inactivation compared to the deltamethrin-induced delayed deactivation.

Bioallethrin-induced generation of reactive species and oxidative damage in isolated human erythrocytes

Bioallethrin is an insecticide that is widely used to control mosquitoes, fleas and cockroaches. The widespread use of bioallethrin has resulted in both occupational and non-occupational human exposure. Bioallethrin enters blood, regardless of the route of exposure, where it can interact with erythrocytes. We have studied the effect of bioallethrin on isolated human erythrocytes under in vitro conditions. Erythrocytes were incubated with increasing concentrations of bioallethrin (10-200 μM) for 4 h at 37 °C. Several biochemical parameters were analyzed in bioallethrin treated and untreated (control) cells. Incubation of erythrocytes with bioallethrin increased protein oxidation, lipid peroxidation and depleted sulfhydryl group content. Membrane damage was evident from cell lysis, osmotic fragility, inhibition of bound enzymes and transmembrane electron transport system. Bioallethrin also increased hemoglobin oxidation, heme degradation and the release of free iron moiety. This will decrease the oxygen transporting ability of blood. Bioallethrin treatment altered the specific activities of antioxidant enzymes and diminished the antioxidant power of cells. Scanning electron microscopy showed that bioallethrin treatment also altered erythrocyte mophology. Almost all changes were in a bioallethrin concentration dependent manner. The cytotoxicity of bioallethrin is probably mediated by reactive oxygen and nitrogen species whose formation was significantly enhanced in treated erythrocytes. Thus bioallethrin enhances the generation of reactive species which cause oxidative damage of cell components in human erythrocytes.

The safety and applicability of synthetic pyrethroid insecticides for aircraft disinsection: A systematic review

BACKGROUND

Air travel contributes to the global spread of vectors and vector-borne infections. Although WHO provides guidance on methods for disinsection of aircraft, there is currently no harmonized or standardized decision-making process to decide when disinsection of an aircraft should be conducted. It is however compulsory for flights arriving in certain countries. Concerns have been expressed about the usefulness of disinsection for preventing the international spread of vectors and vector-borne diseases via air travel and possible toxicity for passengers and flight crew.

METHODS

We performed a systematic literature review using the databases PubMed, Embase, Medline, Scopus and CINAHL to evaluate all research findings about the applicability and safety of chemical-based, aircraft disinsection. Official reports from the WHO were also screened. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and meta-analysis (PRISMA) statement. The literature search strategy included "disinsection, airplane/plane/aviation/aircraft" and several other search items including d-phenothrin, permethrin, insecticide. Papers in English, French and German were reviewed. Reports of adverse events attributed to the disinsection of aircraft were also searched. AMP and PS screened all papers of relevance and agreed on a final selection.

RESULTS

Our search resulted in 440 papers of possible relevance. After screening, we included a total of 25 papers in this systematic review. Ten papers reported possible human toxicity and 17 papers addressed the applicability of disinsection and 2 papers addressed both topics. Chemical disinsection at recommended insecticide concentrations was found to be highly effective against a broad range of arthropods. Three papers reported passenger or crew illness possibly associated with insecticide spraying in passenger cabins - one describing a single passenger, the other two papers describing occupational illness of 12 and 33 aircrew members respectively, possibly due to aircraft disinsection. Another paper evaluating exposure of flight attendants to permethrin found higher levels of urinary metabolites in those working in planes that had recently been sprayed but this could not be linked to adverse health outcomes.

CONCLUSION

Our analysis confirmed that disease vectors are carried on international flights and can pose a threat particularly to island populations and certain airport hub areas. Disinsection with permethrin or d-phenothrin was shown to be highly effective against vectors. Despite several hundred million passenger and crew exposures to chemical disinsection, very few proven cases of toxicity have been reported. There is limited evidence linking exposure to insecticide spraying with negative health impact.

The Effect of Body Composition and Energy Expenditure on Permethrin Biomarker Concentrations Among US Army National Guard Members

OBJECTIVE

To examine relationships between percent body fat (%BF) and total energy expenditure (TEE) on permethrin exposure among Army National Guard (ARNG) Soldiers wearing permethrin-treated uniforms.

METHODS

ARNG members (n = 47) participated in a 9-day study. Repeated body composition (height, weight, %BF) measurements and daily urine samples, analyzed for permethrin and N,N-diethyl-meta-toluamide (DEET) metabolites, were collected. TEE was determined via doubly labeled water protocol. Linear mixed and regression models were used for analyses.

RESULTS

Neither %BF nor TEE were significantly associated with permethrin or DEET biomarkers. However, a significant interaction effect (F = 10.76; P = 0.0027) between laundering history and %BF was observed; 10% higher %BF was significantly associated with 25% higher permethrin biomarker concentrations among those wearing uniforms washed less than or equal to 25 (compared with more than 25) times.

CONCLUSIONS

Uniform laundering history significantly affects the association between %BF and permethrin-treated uniform exposure.

Clinical effects from household insecticide: pyrethroid or organophosphate toxicity?

A 54-year-old man with a history of schizophrenia presented to the emergency room for weakness with associated lacrimosis, drooling, nausea, emesis, diarrhoea, diplopia and burning sensation on his skin that began 6 hours after spraying five cans of Raid on his carpet. He was noted to have miotic pupils and hyperactive bowel sounds. Given the clinical presentation, the patient was diagnosed with organophosphate (OP) toxicity. After being admitted, he developed symptoms associated with his OP toxicity and was successfully treated with atropine and pralidoxime. Most Raid products contain pyrethroids; however, both OPs and pyrethroids are available in commercial pesticides and patients may misidentify ingestions. There are limited data reporting the toxicity of pyrethroid overdose in humans and to guide its subsequent treatment. It is crucial to keep a low threshold for diagnosing and treating patients with acute onset of symptoms suspicious for an OP or pyrethroid toxidrome.

A label-free optical whole-cell Escherichia coli biosensor for the detection of pyrethroid insecticide exposure

There is a growing need for low-cost, portable technologies for the detection of threats to the environment and human health. Here we propose a label-free, optical whole-cell Escherichia coli biosensor for the detection of 3-phenoxybenzoic acid (3-PBA), a biomarker for monitoring human exposure to synthetic pyrethroid insecticides. The biosensor functions like a competitive ELISA but uses whole-cells surface displaying an anti-3-PBA VHH as the detection element. When the engineered cells are mixed with 3-PBA-protein conjugate crosslinking that can be visually detected occurs. Free 3-PBA in samples competes with these crosslinks, leading to a detectable change in the output. The assay performance was improved by coloring the cells via expression of the purple-blue amilCP chromoprotein and the VHH expression level was reduced to obtain a limit of detection of 3 ng/mL. The optimized biosensor exhibited robust function in complex sample backgrounds such as synthetic urine and plasma. Furthermore, lyophilization enabled storage of biosensor cells for at least 90 days without loss of functionality. Our whole-cell biosensor is simple and low-cost and therefore has potential to be further developed as a screening tool for monitoring exposure to pyrethroids in low-resource environments.

Accidental Pyrethroid Ingestion in Toddler: Near-Fatal Atypical Presentation and Successful Recovery

We are reporting a case of pyrethroid poisoning with atypical presentation in a 21-month-old toddler who was transferred to us from a peripheral center. Signs and symptoms at presentation were predominantly of cardiopulmonary dysfunction contrary to more common presenting features of gastrointestinal and neurological impairment. The reason for this seems to be the aspiration pneumonitis as a consequence of vomiting induced by parents at home, rather than the toxin itself even though a rather rapid progression of lung injury does not rule out the possibility. He had developed decreased level of consciousness and increased work of breathing after ingestion, which had progressed to Acute Respiratory Distress Syndrome, septic shock, and multi organ failure. He even had a brief cardiac arrest with Return of Spontaneous Circulation after 5 min of cardiopulmonary resuscitation, immediately after arrival at our unit, which seemed more likely to be a consequence of inappropriate management during transfer of the child. In addition to antibiotics and vasopressors, he required high frequency oscillatory ventilation and prone positioning initially, and lung-protective conventional ventilation later. His cardiopulmonary status improved gradually and he was successfully extubated after 12 days. Other organ systems also showed complete recovery. Even though Magnetic Resonance Imaging of brain done a few days after cardiac arrest showed features suggestive of hypoxic-ischemic encephalopathy he showed complete neurological recovery. He was thriving well at three-month follow-up with no neurological deficits, good exercise tolerance, and normal renal and liver function. Atypical presentation of pyrethroid poisoning is associated with significant morbidities and there seems to no reliable parameters in children to identify the risk of the same. Considering that there is no specific antidote, prompt, and aggressive supportive therapy is necessary for a favorable outcome. This case highlights several important aspects in the care of the pediatric patient after ingestion of insecticides. First, attempt to induce emesis, especially outside of a healthcare facility is not only ineffective but also highly dangerous, and should not be done. Second, unstable patients require inter and intrahospital transfer by experienced and trained personnel; and lastly, management for these complex and atypical cases should be done as early as possible in a center which is equipped to provide high level of circulatory and ventilatory support while prioritizing neuro-protective measures, and neurologic recovery and rehabilitation.

Pyrethroid Poisoning

Introduction

Pyrethroid compounds are widely used as insecticides. These compounds not only have a versatile application, but also have favourable toxicological profiles with high selectivity and toxicity to insects and low toxicity to humans. Despite this, there have been several reports of toxicity to humans in both occupational exposure and deliberate ingestional poisoning.

Classical presentation and treatment

Two classical syndromic presentations are described. Type I syndrome is characterised predominantly by tremors and is seen with exposure to type I pyrethroids. Type II pyrethroids, which are structurally modified type I pyrethroids with the addition of a cyano group, can result in type II syndrome characterized by choreo-athetosis and salivation. Mega-dose poisoning and mixed poisoning, particularly with organophosphorus compounds, is associated with significant toxicity and death. Treatment is supportive and symptomatic. A favourable outcome can be expected in most patients.

How to cite this article

Ramchandra AM, Chacko B, Victor PJ. Pyrethroid Poisoning. Indian J Crit Care Med 2019;23(Suppl 4):S267–S271.

Dose reconstruction in workers exposed to two major pyrethroid pesticides and determination of biological reference values using a toxicokinetic model

A toxicokinetic model has been optimized to describe the time profiles of common biomarkers of exposure to permethrin and cypermethrin: trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids (trans-DCCA) and 3-phenoxybenzoic acid (3-PBA). The model then served to reproduce urinary time courses in exposed agricultural workers and predict corresponding absorbed doses. It allowed for the prediction of the main routes of exposure in workers during the study period. Modeling showed that simulating exposure mostly by the oral route, during the 3-day biomonitoring period, provided best-fits to the urinary time courses of most workers. This is compatible with an inadvertent oral exposure during work. According to best-fit scenarios, absorbed doses in workers reconstructed with the model reached a maximum of 2.4 µg/kg bw/day and were below the absorbed dose limits associated with an exposure to the reference dose values established by the U.S. Environmental Protection Agency (0.06 and 0.25 mg/kg bw/day for cypermethrin and permethrin, respectively) and the Acceptable Operator Exposure Level set by the European Commission (0.06 mg/kg bw/day for cypermethrin). Modeling was further used to derive biological reference values for cypermethrin and permethrin exposure. Respective values of 7 and 29 nmol/kg bw/day of trans-DCCA, and 3 and 13 nmol/kg bw/day of 3-PBA were obtained. None of the workers presented values above these biological reference values.

Role of body composition and physical activity on permethrin urinary biomarker concentrations while wearing treated military uniforms

Wearing of permethrin treated clothing is becoming more prevalent in military and outdoor occupational and recreational settings, as a personal protection measure against vector borne diseases transmitted through arthropods (e.g., malaria, Lyme disease). The goal of the study was to prospectively examine permethrin exposure among new U.S. Army recruits who had just been issued permethrin-treated uniforms over a 10-week military training period and whether individual body composition (percent body fat, %BF) and physical workload (total energy expenditure, TEE) influenced the exposure. Exposure was assessed by quantification in urine of three permethrin metabolites, 3-phenoxybenzoic acid (3-PBA), and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid. Although there was individual variability, urinary concentrations and estimated dose levels decreased over the 10-week period. Mixed models demonstrated that 10% higher %BF was significantly associated with 4.42% higher 3-PBA concentrations and a 10% higher daily TEE was significantly associated with a 10.57% higher 3-PBA concentrations. Additional factors influencing exposure included sex, number of uniform launderings, and wear- time (hours per previous day).

A Case of Pyrethroid Poisoning with Clinical Presentation Mimicking Organophosphate Poisoning

We report an 89-year-old retired farmer with prolonged bradycardia and hypotension after pyrethroid insecticides ingestion in a suicidal attempt. This patient also had a clinical manifestation mimicking organophosphate poisoning, included confusion, lacrimation and salivation. He required intensive care support, atropine and inotrope infusions treatments. Only metabolites of synthetic pyrethroid insecticides (3-phenoxybenzoic acid and 3-phenoxybenzaldehyde) were detected in the urine sample. In the serum toxicology screening, specific analysis for organophosphate pesticides was negative. He eventually recovered without major sequela. (Hong Kong j.emerg.med. 2016;23:47-51)

The insect repellents: A silent environmental chemical toxicant to the health

In recent years, a large number of insect repellents have been developed with the idea of consumer benefits. In addition to already known advantageous application of insect repellents, there is increasing concern about the potential toxicity in environment leading to health caused by random use of these compounds. An increasing number of evidence suggests that insect repellents may trigger undesirable hazardous interactions with biological systems with a potential to generate harmful effects including intermediate metabolites. Biotransformation followed by bioaccumulation (vice e versa) may be an important phenomenon for toxic response of this chemicals. In this review, we have summarized the current state of knowledge on the insect repellent toxicity, including biochemical pathway alteration under in vitro and in vivo conditions considering different classes of organisms, from lower to higher vertebrate. Furthermore, we have tried to incorporate the effects of insect repellent in light of some clinical reports. We hope this review would provide useful information on potential side effects of uncontrolled use of insect repellents.

Safety of insecticide-treated mosquito nets for infants and their mothers: randomized controlled community trial in Burkina Faso

Background

Insecticide-treated bed nets (ITNs) are now the main tool for malaria prevention in endemic areas. Synthetic pyrethroids are the only group of insecticides recommended by the World Health Organization for the use on ITNs. There are only few studies which have specifically investigated potential adverse effects of frequent exposure to ITNs in the vulnerable group of young infants and their mothers.

Methods

This study was nested into a large randomized controlled ITN effectiveness trial. Ninety newborns and their mothers were selected from the study population for participation. Together with their mothers they were protected with ITNs from birth (group A, n = 45) or from age 6 months (group B, n = 45) and followed up for 18 weeks (daily visits in the first 4 weeks, weekly visits thereafter). Potential side effects related to synthetic pyrethroids (deltamethrin) exposure were systematically investigated by trained field staff. The frequency and duration of respective symptoms was compared between the two study groups.

Results

A total of 180 participants (90 mothers and 90 infants) were followed up over the study period without any loss to follow up. There were no significant differences in the frequency and duration of side effects between the two study groups, except that the frequency of headache was significantly higher in group A compared to group B mothers (p = 0.01).

Conclusions

The study provides further evidence for ITNs being sufficiently safe in children and even in newborns. The association with headache in mothers could be explained by them handling the ITNs more intensely or it could be a chance finding.

The initial hyperglycemia in acute type II pyrethroid poisoning

This retrospective observational case series study was conducted to describe the clinical feature of acute type II pyrethroid poisoning, and to investigate whether hyperglycemia at presentation can predict the outcome in patients with type II pyrethroid poisoning. This study included 104 type II pyrethroid poisoned patients. The complication rate and mortality rate was 26.9% and 2.9% in type II pyrethroid poisoned patients. The most common complication was respiratory failure followed by acidosis and hypotension. In non-diabetic type II pyrethroid poisoned patients, patients with complications showed a higher frequency of hyperglycemia, abnormalities on the initial X ray, depressed mentality, lower PaCO2 and HCO3- levels, and a higher WBC and AST levels at the time of admission compared to patients without complication. Hyperglycemia was an independent factor for predicting complications in non-diabetic patients. Diabetic patients had a significantly higher incidence of complications than non-diabetic patients. However, there was no significant predictive factor for complications in patients with diabetes mellitus probably because of small number of diabetes mellitus. In contrast to the relatively low toxicity of pyrethroids in mammals, type II pyrethroid poisoning is not a mild disease. Hyperglycemia at presentation may be useful to predict the critical complications in non-diabetic patients.

Time profiles and toxicokinetic parameters of key biomarkers of exposure to cypermethrin in orally exposed volunteers compared with previously available kinetic data following permethrin exposure

Biomonitoring of pyrethroid exposure is largely conducted but human toxicokinetics has not been fully documented. This is essential for a proper interpretation of biomonitoring data. Time profiles and toxicokinetic parameters of key biomarkers of exposure to cypermethrin in orally exposed volunteers have been documented and compared with previously available kinetic data following permethrin dosing. Six volunteers ingested 0.1 mg kg(-1) bodyweight of cypermethrin acutely. The same volunteers were exposed to permethrin earlier. Blood samples were taken over 72 h after treatment and complete timed urine voids were collected over 84 h postdosing. Cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids (trans- and cis-DCCA) and 3-phenoxybenzoic acid (3-PBA) metabolites, common to both cypermethrin and permethrin, were quantified. Blood and urinary time courses of all three metabolites were similar following cypermethrin and permethrin exposure. Plasma levels of metabolites reached peak values on average ≈ 5-7 h post-dosing; the elimination phase showed mean apparent half-lives (t½ ) for trans-DCCA, cis-DCCA and 3-PBA of 5.1, 6.9 and 9.2 h, respectively, following cypermethrin treatment as compared to 7.1, 6.2 and 6.5 h after permethrin dosing. Corresponding mean values obtained from urinary rate time courses were peak values at ≈ 9 h post-dosing and apparent elimination t½ of 6.3, 6.4 and 6.4 h for trans-DCCA, cis-DCCA and 3-PBA, respectively, following cypermethrin treatment as compared to 5.4, 4.5 and 5.7 h after permethrin dosing. These data confirm that the kinetics of cypermethrin is similar to that of permethrin in humans and that their common biomarkers of exposure may be used for an overall assessment of exposure.

The neurotoxicity of organochlorine and pyrethroid pesticides

Organochlorine and pyrethroid compounds represent an old and a new class, respectively, of insecticides. Organochlorines such as DDT, dieldrin, or chlordecone, have been banned, primarily because of environmental issues. DDT is still used in certain countries to fight malaria-bearing mosquitoes, while lindane still finds some limited used against head lice. In contrast, pyrethroids find widespread use because of their efficacy, low environmental persistence, and relatively low mammalian toxicity. Like all insecticides, organochlorines and pyrethroids target the nervous system of insects and of nontarget species. All pyrethroids and DDT interact with the sodium channel; by keeping it open longer, they increase the likelihood of action potentials developing, thus creating a condition of hyperexcitability, whose main clinical sign is tremors. Most other organochlorines (except chlordecone), as well as certain (type II) pyrethroids, block the chloride channels of the GABA-A receptor, and cause seizures. Evidence of an association between exposure to organochlorine and pyrethroid insecticides and neurodegenerative diseases (e.g., Parkinson's disease) is weak, at best.

Synthesis and characterization of molecularly imprinted polymer embedded composite cryogel discs: application for the selective extraction of cypermethrins from aqueous samples prior to GC-MS analysis

Molecularly imprinted particles embedded composite cryogel discs specific for α-cypermethrin and β-cypermethrin were prepared.

In vitro metabolism of cis- and trans-permethrin by rat liver microsomes, and its effect on estrogenic and anti-androgenic activities

Permethrin is a widely applied broad-spectrum pyrethroid insecticide that consists of a mixture of cis- and trans-isomers. We examined the changes of estrogenic and anti-androgenic activities resulting from metabolism of the isomers. Both cis- and trans-permethrin were hydrolyzed to 3-phenoxybenzyl alcohol (PBAlc) by rat liver microsomes, but the extent of hydrolysis of trans-permethrin was much greater than that of the cis-isomer. In the presence of NADPH, PBAlc was further transformed to 4'-hydroxylated PBAlc (4'-OH PBAlc), 3-phenoxybenzaldehyde (PBAld) and 3-phenoxybenzoic acid (PBAcid). cis-Permethrin, but not trans-permethrin, also afforded its 4'-hydroxylated derivative (4'-OH cis-permethrin). trans-Permethrin was an anti-androgen, but also showed weak estrogenic activity, while cis-permethrin was a weak estrogen and a weak anti-androgen. After incubation with rat liver microsomes in the presence of NADPH, cis-permethrin but not trans-permethrin was metabolically activated for estrogenic activity. On the other hand, estrogenic activity of trans-permethrin was not changed, but its anti-androgenic activity was enhanced after incubation. 4'-OH PBAlc and PBAlc showed estrogenic activity, while PBAld and PBAlc showed anti-androgenic activity. PBAcid showed neither activity. 4'-OH cis-permethrin showed both estrogenic and anti-androgenic activities. Overall, our results indicate that permethrin is metabolically activated for estrogenic and anti-androgen activities, and the microsomal transformation of permethrin to 4'-OH cis-permethrin, 4'-OH PBAlc and PBAlc contributes to the both metabolic activations.

A novel toxicokinetic modeling of cypermethrin and permethrin and their metabolites in humans for dose reconstruction from biomarker data

To assess exposure to pyrethroids in the general population, one of most widely used method nowadays consists of measuring urinary metabolites. Unfortunately, interpretation of data is limited by the unspecified relation between dose and levels in biological tissues and excreta. The objective of this study was to develop a common multi-compartment toxicokinetic model to predict the time courses of two mainly used pyrethroid pesticides, permethrin and cypermethrin, and their metabolites (cis-DCCA, trans-DCCA and 3-PBA) in the human body and in accessible biological matrices following different exposure scenarios. Toxicokinetics was described mathematically by systems of differential equations to yield the time courses of these pyrethroids and their metabolites in the different compartments. Unknown transfer rate values between compartments were determined from best fits to available human data on the urinary excretion time courses of metabolites following an oral and dermal exposure to cypermethrin in volunteers. Since values for these coefficients have not yet been determined, a mathematical routine was programmed in MathCad to establish the possible range of values on the basis of physiological and mathematical considerations. The best combination of parameter values was then selected using a statistic measure (reliability factor) along with a statistically acceptable range of values for each parameter. With this approach, simulations provided a close approximation to published time course data. This model allows to predict urinary time courses of trans-DCCA, cis-DCCA and 3-PBA, whatever the exposure route. It can also serve to reconstruct absorbed doses of permethrin or cypermethrin in the population using measured biomarker data.

Pyrethroid as a Substance of Abuse

This is a case of a 22-year-old Hispanic male with a history of bipolar disorder and methamphetamine dependence who was admitted after presenting with suicidal ideations by slashing his throat with a machete. The patient had been smoking and inhaling “processed” pyrethroid for about eight weeks as an inexpensive methamphetamine substitute. He reported experiencing a “rush” similar to methamphetamine after using pyrethroid from liquid insecticide that had been heated (electrocuted) or sprayed on hot metal sheets until it crystallized. The patient presented with no significant physical markings or findings but claimed to have his suicidal ideations precipitated by concerns of ill effects of pyrethroid on his health. He also had positive urine drug screen for methamphetamine, which he admitted to using on the day of admission. We conclude that it is important for physicians to maintain a high level of suspicion for alternate and uncommon substances of abuse as well as risks for suicidal tendencies in these patients.

Characterization of α-cypermethrin exposure in Egyptian agricultural workers

Pyrethroids are neurotoxic insecticides that exert their effects by prolonging the open time of sodium channels, which increases the duration of neuronal excitation. α-cypermethrin (αCM) is derived from the 8-stereoisomers that together make up the pyrethroid cypermethrin, which is one of the most common pyrethroids being used in agriculture throughout the world. The objective of this study was to characterize the occupational exposure to αCM in a cohort of Egyptian agriculture workers (n=37) before, during and after 6-10 consecutive days of application of αCM to cotton fields. Daily spot urine specimens were collected and analyzed by GC-MS NCI for the αCM metabolites 3-phenoxybenzoic acid (3-PBA) and cis-3-(2',2'-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA). Prior to αCM application, median urinary levels of 3-PBA (4.59nmol/g creatinine) were greater than cis-DCCA (0.33nmole/g creatinine) demonstrating low background exposures to pyrethroids. During the application period for αCM, median urinary levels of both biomarkers increased (13.44nmol 3-PBA/g creatinine and 7.76nmol cis-DCCA/g creatinine) and ranged from 2.3-93.96nmol 3-PBA/g creatinine and 0.09-90.94nmol cis-DCCA/g creatinine, demonstrating that workers had a wide range of exposures to αCM. The data also demonstrate that pesticide applicators had greater exposures to αCM than workers who play a supporting role in the seasonal application of pesticides on the cotton crop. Urinary cis-DCCA and 3-PBA concentrations were elevated at 7-11 days after the cessation of αCM application, compared to baseline levels. This study is the first to use these biomarkers to quantify occupational exposures specifically to αCM. This urinary biomarker data will be useful for estimating daily internal dose, comparing exposures across job categories within the Egyptian pesticide application teams, and for modeling human exposures to αCM.