Pulmonary effects of deltamethrin inhalation: an experimental study in rats

Morphometric Evaluation of the Recurrent Laryngeal Nerve of Wistar Rats Exposed to Pesticides

The literature has been shown that exposition by inhalation to chemical compounds can cause vocal disorders and dysphagia in humans, in addition to other symptoms that are manifested according to the type, concentration and duration of exposure to the substance. Cypermethrin and dichlorvos are pesticides widely used in agriculture, public health, veterinary, and home environments. Despite the scientific evidence that cypermethrin and dichlorvos can cause neurodegenerative damage and motor alterations, there are no studies evaluating the toxic effects of these pesticides on the morphology of structures responsible for vocal mobility, especially to the Recurrent Laryngeal Nerve (RLN). Considering the association between vocal disorders in humans and variations in RLN and morphometry, the aim of this study was to evaluate the possible alterations in the microstructure of RLN secondary to subchronic exposure to cypermethrin (pyrethroid) and dichlorvos (organophosphate) in Wistar rats. The experimental protocol (approved by CEUA-UFCSPA: 321/15 and 323/15) consisted of 15 male Wistar rats, allocated in 3 groups: Control (n = 5, exposed to water), Cypermethrin (n = 5, exposed to cypermethrin - 1/10 of the inhalation median lethal concentration [LC50] - 0.25 mg/L) and dichlorvos (n = 5, exposed to dichlorvos - 1/10 of the LC50 - 1.5 mg/L). Inhalation exposure was performed for 4 hours, 5 times per week, for 6 weeks. The nerves were collected, histologically processed and analyzed using morphometric parameters measured using ZEN 2.6 (Zeiss - Germany). The cypermethrin and dichlorvos groups showed significant changes (P < 0.001, ANOVA) in the g-ratio and in the thickness of the myelin sheath of the RLN when compared to the control animals, however, none of the other parameters evaluated showed statistically significant differences. These findings indicate that repeated inhalation exposure to commercial products of cypermethrin and dichlorvos is able to modify the structure of the RLN and possibly generating vocal changes and / or dysphagia.

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.

Paediatric lung injury due to accidental ingestion of meperfluthrin: a case report

Background

It is common for children to accidentally ingest chemical drugs with different degrees of toxicity. Meperfluthrin is a highly effective and easy-to-use pyrethroid pesticide with low toxicity. It is widely used in electric mosquito coils. This type of electric mosquito coil is used in daily life, which increases the chance of exposure among children and, consequently, may lead to accidental ingestion. There are only few reports of meperfluthrin poisoning causing lung injury in children. We report a rare clinical case of lung injury wherein a child ingested meperfluthrin orally.

Case presentation

We report the case of a 1-year-old boy who accidentally swallowed an electric mosquito coil containing meperfluthrin and developed cough and fever. The patient’s parents observed him swallowing the electric mosquito coil (Qiangshou®). Although he was stopped, the child had already swallowed approximately 10 ml of the liquid. According to the instructions, it contained 9 mg/ml of meperfluthrin, thus, it was assumed that he ingested meperfluthrin at a dose of approximately 90 mg. Computed tomography (CT) of his lungs showed uneven brightness in both lungs with multiple spots, scaly shadows, and mesh. Density of the shadows indicated lung parenchymal and interstitial lung disease. Lung tidal function tests indicated obstructive ventilation dysfunction. After evaluation and treatment, his cough drastically reduced, his fever disappeared, and his lung CT findings showed improvement. Therefore, accidental ingestion of meperfluthrin led to acute lung injury in a paediatric patient. Because of prompt treatment, his lung lesions recovered well.

Conclusions

Meperfluthrin causes airway mucosal damage and hypersensitivity. Lung CT and lung tidal function measurements can be used to monitor changes in the condition. Presently, there is a lack of specific detoxification drugs for meperfluthrin poisoning. Thus, the focus of treatment is to protect the airway mucosa and reduce inflammatory reactions.

Severe pulmonary toxicity associated with inhalation of pyrethroid-based domestic insecticides (Bop/Sapolio): a case series and literature review

PURPOSE OF REVIEW

The current review focuses on serious pulmonary toxicity after inhalation of over the counter available pyrethroid-based insecticides. Pyrethroid is a synthetic product of pyrethrin, which in turn is the active ingredient of pyrethrum, a flower extract.

RECENT FINDINGS

On the contrary, a large gap of knowledge exists in the association of interstitial lung disease (ILD) with pyrethroids. So far, two cases of ILD, one associated with pyrethrin and one associated with pyrethrum, were described. Existing literature on both other (pulmo)toxic effects of pyrethroids in human and animals is summarized.

SUMMARY

We present three cases of severe pulmonary toxicity after inhalation of pyrethroid-based insecticides demanding hospitalization and oxygen therapy. One of these cases died. Although a causal relationship was hard to establish, these cases all demonstrated an obvious history of (repeated) pyrethroid exposure associated with ILD. Moreover, other causes of ILD as well as infections were excluded. Furthermore, studies in mammals as well as aquatic animals confirm (pulmonary) toxicity of pyrethroids. The occurrence of toxicity is dose-dependent but also associated with individual susceptibility. Therefore, we would like to acknowledge that awareness of potential hazards of commercially available insecticides containing pyrethroids to both medical physicians and the public is mandatory.

Nontransient third-degree heart block and persistent respiratory findings as sequelae of acute occupational exposure to pyrethroids insecticide

We present the case of a worker with occupational exposure to a pyrethroid insecticide who acutely developed nontransient third-degree heart block. In 2000, a 57-year-old male truck driver on his delivery route was accidentally exposed to pyrethroid insecticide being sprayed for West Nile virus containment. Both the driver and his vehicle were coated with the spray. The exposure was prolonged because he did not change his clothes until after his shift ended and he used the same contaminated truck for a week. Within days, he presented with a third-degree heart block, for which he was emergently treated, and a pacemaker was placed. He had no past history of arrhythmias. In the weeks thereafter, he also developed reactive airway dysfunction syndrome (RADS). In the second decade following the exposure, the patient replaced his pacemaker, confirming the permanent nature of his heart block. In addition to the persistence of his exposure-related RADS, he developed restrictive lung disease and was diagnosed with pulmonary interstitial fibrosis in the absence of established risk factors. The patient died in October 2019 from respiratory illness. Most previous reports of pyrethroid-related disorders are limited to acute exposures, in which transient symptoms predominate. To our knowledge, this is the first report of an exposed worker experiencing permanent third-degree heart block, as well as persistent respiratory findings, as possible short- and long-term sequelae of pyrethroid exposure.

Oxidative stress and neuromodulatory effects of deltamethrin and its combination with insect repellents in rats

Deltamethrin (DEL) and other synthetic repellents like N,N-diethyl benzamide (DEB), N,N-diethyl phenylacetamide (DEPA), and N,N-diethyl meta toluamide (DEET) are widely used due their high efficacy against mosquitoes. We evaluated the safe dose on exposure to insecticide and insect repellent individually and in combination in Wistar rats. Rats were administrated with individual chemicals DEL, DEB, DEPA, and DEET and in combination of DEL along DEB, DEPA, and DEET. The reduced glutathione and its detoxifying enzymes were significantly increased in DEL treated rats. Serotonin, dopamine, and noradrenaline were increased in DEL alone and its combination groups. Histopathology revealed that DEL and along with other insect repellants can cause lung toxicities. This study suggests that DEL in combination with other insect repellents showed antagonistic effect against oxidative stress, and there was no significant toxicological effect in the combination groups. The insect repellents with DEL cause less toxic effect and is safe for use.

Suicide after inhaling a pyrethrins containing insecticide spray

Pesticide self-poisoning is rare in developed countries. We report a suicide case after inhalation of a pyrethrins containing insecticide spray. The patient presented at the emergency department with respiratory failure. Despite mechanical ventilation, he developed severe pulmonary inflammation with a systemic inflammatory response syndrome and died 5 days later. Studies reporting on acute pyrethrins or pyrethroids insecticide poisoning in both occupational and non-occupational cases usually describe mild and self-limiting respiratory symptoms as the predominant symptom. Severe or fatal cases of pyrethrins or pyrethroids poisoning are very rare. Patients with asthma or allergies are apparently more at risk for severe symptoms. In these cases, early and aggressive treatment with bronchodilatators, steroids, antihistamines and epinephrine should be considered.

Exploration of toxicological impacts following acute and sub-chronic exposure to ethyl anthranilate-loaded mosquito repellent patch

In the recent years, growing concern about the potential toxicity of synthetic repellents has led to the development of environmentally safe non-toxic insect control methods. Present investigation explores the toxicological impacts of ethyl anthranilate-loaded mosquito repellent patch (EAMRP) on respiratory system following acute and sub-chronic inhalation exposure in Wistar rats. Lungs parameters such as enhanced pause, tidal volume, respiration rate, inspiration time, and expiration time were determined using whole body plethysmograph. X-ray, scanning electron microscopy and histology were utilized to study the morphology and microscopical architecture of lungs. Hematological and serum biochemical markers were estimated. Cytokines such as IL-1β, IL-2, and IL-12 were also estimated in bronchoalveolar lavage fluid using ELISA kits. Finally, acute oral and dermal toxicity studies were carried out to study the accidental or intentional poisoning due to the ingestion and skin contact of EAMRP, respectively. The findings demonstrate that inhalation exposure to EAMRP did not pose any significant dose related toxicity in above mentioned experiments. Further, no appreciable toxicity was observed in both acute oral and dermal exposure. Thus, these results revealed the non toxic nature of EAMRP in preclinical studies. Hence, EAMRP can be used successfully as an alternative to existing synthetic repellents without any potential health hazards.

Oral exposure of deltamethrin and/or lipopolysaccharide (LPS) induced activation of the pulmonary immune system in Swiss albino mice

The deltamethrin, a synthetic pyrethroid, is used worldwide and has been linked with several type of acute toxicity. However, effect of low level of deltamethrin alone or in combination with the microbial antigen on pulmonary system is not understood. Lipopolysaccharide (LPS) was used as antigen which is a key inflammatory component of gram-negative bacteria, which induces a distinctive pattern of cytokine release that regulates inflammation. The aim was to determine whether chronic exposure to a low level of deltamethrin alone or in combination with LPS impair the lung response in adult male Swiss albino mice. The mice were orally exposed to different doses of deltamethrin (0.1, 0.05, 0.005, 0.001 mg/kg bwt) and then immunized with LPS at the 60th day. None of the treatment groups contained residues of deltamethrin above the limits of quantification. Deltamethrin combined with LPS challenge caused significant lymphocytosis and neutropenia in group 1 (0.1 mg/kg) mice (P < 0.05). The highest dose of deltamethrin exposure (0.1 mg/kg bwt) alone altered the total cell count significantly in blood and total leukocyte count (TLC) and macrophage count in bronchoalveolar lavage fluid. Microscopic pulmonary damage was evaluated by H&E staining and EM which indicated that two higher doses of deltamethrin, i.e., 0.1 and 0.05 mg/kg bwt, distinctly increased inflammatory cell infiltration and caused alveolar septa thickening and leukocyte infiltration into the alveolar septum (septal cell infiltration) in the lungs. Deltamethrin exposure alone and/or with endotoxin revealed different degrees of immunopositive reaction for Toll-like receptor 4 (TLR4) and pro-inflammatory cytokine-like tumor necrosis factor-alpha (TNFα) in different parts of the lungs. The expression of TLR4 and TNFα in the lung tissue was more pronounced in two higher dose groups. Thus, chronic low-level deltamethrin exposure may impair the main pro-inflammatory response in the lungs which is more pronounced in combination with LPS. Further research is required in direction of the mechanism of action of deltamethrin on the immune cell lineage and their differentiation.

Deltamethrin-Induced Hepatotoxicity and Virgin Olive Oil Consumption: An Experimental Study

BACKGROUND

Deltamethrin (DM) is a synthetic pyrethroid insecticide which can lead to pathological effects in mammals through oxidative stress. On the other hand, virgin olive oil (VOO) is a rich source of phenolic compounds with antioxidants. The aim of the present study was to determine the protective effects of VOO against DM-induced hepatotoxicity.

METHODS

Thirty-six mice were randomly separated into 4 groups: vehicle group, VOO group, DM group, and DM plus VOO group. Immunohistochemistry of PARP, COX-2, and caspase-3 with the biochemical analysis of malondialdehyde and total antioxidant capacity levels were performed in the liver samples 5 weeks after gavaging. Statistical analysis was performed using SPSS, version 15. The data were compared between the groups using the Tukey multiple comparison tests and the analysis of the variance. A P value <0.05 was considered significant.

RESULTS

The malondialdehyde level in the liver was increased in the DM group (71.18±0.01), whereas it was significantly (P=0.001) decreased after VOO administration in the DM plus VOO group (39.59±2.43). While the total antioxidant capacity level in the liver was decreased in the DM group (3.05±0.05), it was significantly increased (P=0.03) after VOO administration in the DM plus VOO group (3.95±0.04). A greater expression of caspase-3 (P=0.008), COX-2 (P =0.004), and PARP (P 0.006) could be detected in the DM group, while it was significantly (P=0.009) attenuated in the DM plus VOO group. Also, the degeneration of hepatocytes, which was detected in the DM group, was attenuated after VOO consumption.

CONCLUSIONS

VOO exerted protective effects against DM-induced hepatotoxicity, which might be associated with its anti-apoptotic, anti-inflammatory, and antioxidative properties.

Autism genes are selectively targeted by environmental pollutants including pesticides, heavy metals, bisphenol A, phthalates and many others in food, cosmetics or household products

The increasing incidence of autism suggests a major environmental influence. Epidemiology has implicated many candidates and genetics many susceptibility genes. Gene/environment interactions in autism were analysed using 206 autism susceptibility genes (ASG's) from the Autworks database to interrogate ∼1 million chemical/gene interactions in the comparative toxicogenomics database. Any bias towards ASG's was statistically determined for each chemical. Many suspect compounds identified in epidemiology, including tetrachlorodibenzodioxin, pesticides, particulate matter, benzo(a)pyrene, heavy metals, valproate, acetaminophen, SSRI's, cocaine, bisphenol A, phthalates, polyhalogenated biphenyls, flame retardants, diesel constituents, terbutaline and oxytocin, inter alia showed a significant degree of bias towards ASG's, as did relevant endogenous agents (retinoids, sex steroids, thyroxine, melatonin, folate, dopamine, serotonin). Numerous other suspected endocrine disruptors (over 100) selectively targeted ASG's including paraquat, atrazine and other pesticides not yet studied in autism and many compounds used in food, cosmetics or household products, including tretinoin, soy phytoestrogens, aspartame, titanium dioxide and sodium fluoride. Autism polymorphisms influence the sensitivity to some of these chemicals and these same genes play an important role in barrier function and control of respiratory cilia sweeping particulate matter from the airways. Pesticides, heavy metals and pollutants also disrupt barrier and/or ciliary function, which is regulated by sex steroids and by bitter/sweet taste receptors. Further epidemiological studies and neurodevelopmental and behavioural research is warranted to determine the relevance of large number of suspect candidates whose addition to the environment, household, food and cosmetics might be fuelling the autism epidemic in a gene-dependent manner.

Virgin olive oil ameliorates deltamethrin-induced nephrotoxicity in mice: A biochemical and immunohistochemical assessment

Objective

A major class of synthetic pyrethroid insecticide, deltamethrin (DM), can elicit pathophysiological effects through oxidative stress in non-targeted organisms such as mammals. There is accumulating evidence that virgin olive oil (VOO), a rich source of polyphenolic components, have anti-oxidant, anti-inflammatory, and anti-apoptotic properties. This study aimed to determine the protective and ameliorative effects of VOO against DM-induced nephrotoxicity.

Methods & materials

Mice were randomly divided into four equal groups: DM group, DM plus VOO group, VOO group, and vehicle group. Five weeks after gavaging, kidney samples were taken for biochemical assessment of malondialdehyde (MDA), glutathione (GSH) and catalase (CAT), and for immunohistochemical assessment of caspase-3, cyclooxygenase-2 (cox-2) and poly (ADP-ribose) polymerase (PARP).

Results

The MDA level in kidney was increased in the DM group, which was significantly decreased after VOO administration in the DM plus VOO group. The GSH level and CAT activiy in kidney were decreased in the DM group, which were significantly increased after VOO administration in the DM plus VOO group. Greater expression of caspase-3, cox-2, and PARP could be detected in the DM group, which was significantly attenuated in the DM plus VOO group. Also, the histopathological changes which were detected in the DM group attenuated after VOO consumption.

Conclusion

Virgin olive oil exerted protective effects against deltamethrin-induced nephrotoxicity, which might be associated with its anti-apoptotic, anti-inflammatory, and anti-oxidative properties.

[Pulmonary nodules and arachnophobia]

Pulmonary nodules are a common reason for consultation and their investigation must always exclude a possible neoplastic cause. This means that, in addition to a thorough history, investigations may be necessary which are sometimes invasive and therefore potentially a cause of iatrogenic harm. The toxic aetiologies for pulmonary nodules are rare. We report a case of a patient with pulmonary nodules occurring predominantly in the right lung, about 1cm in diameter, non-cavitating without calcification, and sometimes surrounded by a peripheral halo. The nodules were a chance finding during preoperative evaluation. After a comprehensive review, a reaction to an inhaled irritant was the preferred hypothesis, specifically overuse of a compound insecticide containing, in addition to the propellant gas and solvent type hydrocarbon - a mixture of piperonyl butoxide, of esbiothrine and permethrin. Removal of this led to the complete disappearance of nodules. Pathological examination identified bronchiolitis obliterans with organising pneumonia accompanied by non-necrotizing granulomas and lipid vacuoles.

Veterinary Pesticides

Veterinary pesticides are used to treat a range of parasitic conditions in companion and farm animals. These products are based on a number of different compounds with different modes of action and different spectra of toxicity. The older agents include the synthetic pyrethroids and organophosphorus compounds, while the newer examples include, for example, representatives of the insect growth promoters, the neonicotinoids, and the oxadiazones. For many of these compounds, toxicity is associated with their pharmacological activity or mode of action. Thus the synthetic pyrethroids and the organophosphorus compounds exert neurotoxic effects. For others, toxicity may be associated with mechanisms that are independent of their mode of action. When used according to the manufacturer's instructions, these products are generally safe and efficacious. However, accidental contamination and misuse can lead to toxicity in operators and treated animals. These compounds are important in the treatment of parasitic disease in animals and their regulation and uses are based on favourable risk-benefit outcomes.