Effect of sub-lethal doses of Bacillus thuringiensis subsp. Aizawai and deltamethrin with regard to fertility and organ toxicity in pregnant albino rats

Respiratory system: Highly exposed yet under-reported organ in pyrethrin and pyrethroid toxicity

Pyrethrin and pyrethroid are a relatively new class of pesticides with potent insecticidal properties. Pyrethrins are naturally occurring pesticides obtained from the Chrysanthemum cinerariaefolium flower, while pyrethroids are their synthetic derivatives. They are widely used as the insecticides of choice in agriculture, veterinary medicine, public health programs, and household activities. Pyrethrin, being a broad-spectrum insecticide kills a wide range of pests, while pyrethroids last longer in the environment owing to low susceptibility to sunlight, and greater stability and efficacy than parent molecules. Humans can be exposed through inhalation, ingestion, and dermal routes. Indoor usage of an insecticide poses a serious risk to human health, especially to women, children, and stay-at-home people. Although pyrethrin and pyrethroid are generally considered safe, sustained skin or inhalation exposure or direct contact with open wounds results in higher toxicity to mammals. There is a paucity of data on the impact of pyrethrin and pyrethroid on overall pulmonary health. The respiratory system, from the nose, nasal passages, airways, and bronchi to the pulmonary alveoli, is vulnerable to environmental contaminants such as pesticides because of its anatomical location as well as being a highly blood profused organ. Under and over-functioning of the respiratory system triggers diverse pathologies such as serious infections, allergies, asthma, metastatic malignancies, and auto-immune conditions. While the association between workplace-related pesticide exposures and respiratory diseases and symptoms is well documented, it is important to understand the adverse health impact of pyrethrin and pyrethroid on the general population for awareness and also for better regulation and implementation of the law.

A sub-chronic feeding study of dual toxin insect-resistant transgenic maize (CEMB-413) on Wistar rats

Genetically modified (GM) crops expressing insecticidal crystal proteins are widely accepted worldwide, but their commercial utilization demands comprehensive risk assessment studies. A 90-day risk assessment study was conducted on Wistar rats fed with GM maize (CEMB-413) expressing binary insect-resistant genes (cry1Ac and cry2Ab) at low (30%) and high (50%) dose along with a control diet group. The study used fifty Wistar rats randomly distributed in five treatment groups. Our study revealed that compared to controls, GM diet had no adverse effects on animal's health, including body weight, food consumption, clinical pathological parameters, serum hormone levels and histological parameters of testes and ovaries of rats. Differences were observed in transcripts levels of fertility related genes, but these were independent of treatment with GM diet.

Systematic Toxicity of Cypermethrin and Alterations in Behavior of Albino Rats

The present study aimed to evaluate the effect of repeatedly orally administering cypermethrin (CYP) at different doses on the behavior, hematology, and histology of adult male and female albino rats for 1 month. For this, animals have divided into four different groups and each group contained 10 animals (5 males and 5 females). Group I served as a control group and groups II, III, and IV were represented as experimental groups and treated with CYP at doses of 25, 50, and 75 mg/kg body weight/day/rat, respectively. Through the behavioral results of this study, it was observed that cypermethrin intoxication causes dose-dependent moderate to high toxicity symptoms like vomiting, decreased food consumption, thick eye discharge, rolling, tremors, loss of coordination, tilted neck, and convulsion attacks. A significant reduction in body weight of high-dose (75 mg)-treated animals, especially in females, was noticed. Similarly, hematological data also revealed that CYP exposure caused a reduction in the level of Hb, RBC, WBC, neutrophil, and other blood indices such as PCV and MCV and an increase in the lymphocyte percentage in both male and female experimental groups. Microscopic observation stated that CYP produced infiltration of cells near the central vein, hepatocyte degeneration, congestion of the central and portal veins, hemorrhage, and necrosis in liver tissue. Shrinkage of the glomerulus, necrosis in the glomerulus and renal tubules, congestion of blood cells, and hemorrhage were seen in kidney tissue. The current study suggests that hepatotoxicity and nephrotoxicity due to cypermethrin exposure were more prominent in female rats.

Bacillus thuringiensis affects reproductive capacity of adult rat offspring

We investigated the effects of B. thuringiensis-based biological insecticides, XenTari and Dipel, and deltamethrin on the reproductive development of pups of pregnant rats. Twenty 90-day-old pregnant rats were divided randomly onto four equal groups: control group (GC) administered only water; XenTari group (GX) administered 1 mg XenTari (containing Cry1Ac toxin of B. thuringiensis)/100 g body weight; Dipel group (GDi) administered 1 mg Dipel (containing Cry1Aa, Cry1Ab and Cry1Ac toxins of B. thuringiensis)/100 g body weight; and a deltamethrin group (GDe) administered 2 mg deltamethrin (0.08 ml Keshet 25EC)/kg body weight as a positive control. Insecticides were administered by gavage at doses of 1 mg/100 g/day (GX and GDi), and 2 mg/kg/day (GDe) during pregnancy and lactation. Treatment with both biologic and synthetic insecticides reduced the weight gain of the mothers. The biological insecticides reduced the number, weight and length, and increased malformation and mortality of the offspring. In female offspring for all three groups administered insecticides, opening of the vagina was delayed, metestrus was increased and estrogen and progesterone levels were reduced compared to proestrus, estrus and metestrus of the cycle. The ovaries of female offspring of all three groups administered insecticides contained numerous tertiary and atretic follicles, few corpora lutea, primary and secondary follicles, and reduced estrogen receptors compared to controls. In male offspring, all three groups exposed to insecticides exhibited reduced testosterone levels. Histopathological changes in the testes including vacuolation and desquamation of the seminiferous epithelium were observed only in the GX and GDi groups. The number of androgen receptors was reduced significantly in the testes and testicular morphometry revealed reduced tubule diameter, height of the seminiferous epithelium and total tubule length compared to the control. The biological insecticides, XenTari and Dipel, administered in sublethal doses to pregnant rats, caused reproductive changes in the offspring similar to those of the insecticide, deltamethrin.

Renal and hepatic changes in the offspring of rats that received biological insecticides during pregnancy and lactation

Bacillus thuringiensis insecticides have been considered safe, being an alternative to the use of synthetic insecticides. However, studies have shown the effects of Bt Cry toxins on various organs, compromising their functions. The objective of this work was to test whether the administration of biological insecticides based on B. thuringiensis in pregnant rats will cause histopathological changes in the liver and kidneys, as well as in the levels of toxicity biomarkers, of their puppies in adulthood. Twenty rats, 90 days old, were used, divided into four groups: GC - Pregnant rats, GX - Pregnant rats that received XenTari®, GDi - Pregnant rats that received Dipel® and GDe - Pregnant rats that received deltamethrin. Insecticides were administered by gavage at a dosage of 1 mg/100 g/day (GX and GDi), and 2 mg/Kg/day (GDe) during pregnancy and lactation. In the animals of the groups whose matrices received the insecticides, there was a reduction in the levels of the biomarkers of toxicity alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea and creatinine, about the control group. The biological insecticides promoted histopathological changes in the liver, with the presence of portal vein, centrilobular and sinusoidal capillaries congestion, and in the kidney, presence of cortical congestion and reduction of the subcapsular space. Histochemical evaluation in the liver demonstrated a significant reduction in glycogen in the groups that received insecticides when compared to the control group, whereas for collagen fibers in both the liver and the kidneys, no differences were observed between the experimental groups. The morphometry of the liver revealed a significant reduction in the lobular parenchyma and an increase in the non-lobular parenchyma, and in the kidney, there was a reduction in the diameter and volume of the glomerulus and Bowman's capsule of the animals whose matrices received both biological and synthetic insecticides. Thus, it is concluded that the biological insecticides XenTari® and Dipel® in sublethal doses in pregnant rats promote changes in the liver and kidney of the offspring similar to the insecticide deltamethrin, which extend into adulthood.

Effects of pyrethroid insecticides on hypothalamic-pituitary-gonadal axis: A reproductive health perspective

Pyrethroids, a class of ubiquitous insecticides, have been recognized as endocrine-disrupting chemicals (EDCs). A lot of studies have implied the endocrine-disrupting effects of pyrethroids on the hypothalamic-pituitary-gonadal (HPG) axis. However, there are few review articles regarding the effects of pyrethroids on the HPG axis of mammal and human, especially new research progress made in this area. The present review sums up the effects of pyrethroids on the HPG axis-related reproductive outcomes, including epidemiological investigations based on human biomonitoring, animal studies and in vitro tests. Mechanisms have described that the endocrine-disrupting effects of pyrethroids on mammal can be mediated via the interaction with steroid receptors, the direct action on ion channels and signaling molecules. Finally, we summarize the current research gaps and suggest future directions in this topic.

Safety of Natural Insecticides: Toxic Effects on Experimental Animals

Long-term application and extensive use of synthetic insecticides have resulted in accumulating their residues in food, milk, water, and soil and cause adverse health effects to human and ecosystems. Therefore, application of natural insecticides in agriculture and public health sectors has been increased as alternative to synthetic insecticides. The question here is, are all natural insecticides safe. Therefore, the review presented here focuses on the safety of natural insecticides. Natural insecticides contain chemical, mineral, and biological materials and some products are available commercially, e.g., pyrethrum, neem, spinosad, rotenone, abamectin, Bacillus thuringiensis (Bt), garlic, cinnamon, pepper, and essential oil products. It can induce hepatotoxicity, renal toxicity, hematotoxicity, reproductive toxicity, neurotoxicity, and oxidative stress. It can induce mutagenicity, genotoxicity, and carcinogenicity in mammals. Some natural insecticides and active compounds from essential oils are classified in categories Ib (Highly hazardous) to U (unlikely toxic). Therefore, the selectivity and safety of natural insecticides not absolute and some natural compounds are toxic and induce adverse effects to experimental animals. In concussion, all natural insecticides are not safe and the term "natural" does not mean that compounds are safe. In this respect, the term "natural" is not synonymous with "organic" and not all-natural insecticide products are acceptable in organic farmers.

Effect of pyrethroids on female genital system. Review

Pyrethroids have been associated with a range of toxicological effects on various organs in animals.Recent animal studies suggest that neurodevelopmental, reproductive, and immunological effects may result following exposure to some pyrethroids at levels below those that induce overt signs of neurotoxicity. A variety of pyrethroids and their metabolites have the potential to affect the reproductive system. Dose-dependent effects on reproduction are associated with exposure across pyrethroid types. In mammals, permethrin and tetramethrin and cypermethrin have been found to be associated with adverse effects at high doses. Fenvalerate, deltamethrin, cypermethrin, caused morphometric and structural changes in the female genital organs. These pyrethroids affect ovulation, cause atresia of follicles, decrease the number of follicular cells, oocytes and corpora lutea and induce vesicular atrophy of the endometrial glands. The potential hormonal activity of pyrethroids showed that certain pyrethroids and their metabolites have multiple effects on the endocrine system. The level of steroid hormones, such as progesterone and estradiol, was inhibited. The pyrethorids may have the potential to mimic estrogens or to inhibit estrogen action. Some metabolites of pyrethroids, in particular permethrin and cypermethrin, are more likely to interact with the cellular estrogen receptors than the parent pyrethroids. Though several pyrethroids posses low toxicity, some pyrethroids, such as deltamethrin, cypermethrin, fenvalerate and bifenthrin have showed considerable toxicity.

Deltamethrin-induced oxidative stress and mitochondrial caspase-dependent signaling pathways in murine splenocytes

Deltamethrin (DLM) is a well-known pyrethroid insecticide used extensively in pest control. Exposure to DLM has been demonstrated to cause apoptosis in various cells. However, the immunotoxic effects of DLM on mammalian system and its mechanism is still an open question to be explored. To explore these effects, this study has been designed to first observe the interactions of DLM to immune cell receptors and its effects on the immune system. The docking score revealed that DLM has strong binding affinity toward the CD45 and CD28 receptors. In vitro study revealed that DLM induces apoptosis in murine splenocytes in a concentration-dependent manner. The earliest markers of apoptosis such as enhanced reactive oxygen species and caspase 3 activation are evident as early as 1 h by 25 and 50 µM DLM. Western blot analysis demonstrated that p38 MAP kinase and Bax expression is increased in a concentration-dependent manner, whereas Bcl 2 expression is significantly reduced after 3 h of DLM treatment. Glutathione depletion has been also observed at 3 and 6 h by 25 and 50 µM concentration of DLM. Flow cytometry results imply that the fraction of hypodiploid cells has gradually increased with all the concentrations of DLM at 18 h. N-acetyl cysteine effectively reduces the percentage of apoptotic cells, which is increased by DLM. In contrast, buthionine sulfoxamine causes an elevation in the percentage of apoptotic cells. Phenotyping data imply the effect of DLM toxicity in murine splenocytes. In brief, the study demonstrates that DLM causes apoptosis through its interaction with CD45 and CD28 receptors, leading to oxidative stress and activation of the mitochondrial caspase-dependent pathways which ultimately affects the immune functions. This study provides mechanistic information by which DLM causes toxicity in murine splenocytes. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 808-819, 2016.

An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals

Crystal proteins (Cry) produced during the growth and sporulation phases of Bacillus thuringiensis (Bt) bacterium are known as delta endotoxins. These toxins are being used worldwide as bioinsecticides to control pests in agriculture, and some Cry toxins are used against mosquitoes to control vector transmission. This review summarizes the relevant information currently available regarding the biosafety and biological effects that Bt and its insecticidal Cry proteins elicit in mammals. This work was performed because of concerns regarding the possible health impact of Cry toxins on vertebrates, particularly because Bt toxins might be associated with immune-activating or allergic responses. The controversial data published to date are discussed in this review considering earlier toxicological studies of B. thuringiensis, spores, toxins and Bt crops. We discussed the experimental studies performed in humans, mice, rats and sheep as well as in diverse mammalian cell lines. Although the term 'toxic' is not appropriate for defining the effects these toxins have on mammals, they cannot be considered innocuous, as they have some physiological effects that may become pathological; thus, trials that are more comprehensive are necessary to determine their effects on mammals because knowledge in this field remains limited.

Immunomodulatory role of piperine in deltamethrin induced thymic apoptosis and altered immune functions

Deltamethrin (DLM), a well-known pyrethroid insecticide, is a potent immunotoxicant. In rodents, it is primarily characterized by marked thymic apoptosis. Mechanism of DLM induced thymic apoptosis in primary murine thymocytes has been recently explored. Oxidative stress and activation of caspase dependent pathways appear to be involved in the DLM induced thymic injury. Thus, for the amelioration of its effect, this study has been designed to first observe the binding affinity of piperine to immune cell receptors and its protective effects on the DLM induced immunotoxicity under in vitro condition. The docking results demonstrated that piperine has good binding affinity towards CD4 and CD8 receptors. In vitro study results have shown that piperine (1, 10 and 50 μg/ml) increased cell viability in a concentration dependent manner. The early activated markers of apoptosis such as enhanced reactive oxygen species (ROS) and caspase-3 activation by DLM was significantly reduced by piperine treatment. GSH depletion induced by DLM has been also restored by piperine treatment. At 18 h, all concentration of piperine (1, 10 and 50 μg/ml) significantly ameliorated the DLM induced apoptosis. Further, DLM induced phenotypic changes were mitigated by the piperine. In addition, piperine also restored the cytokine levels, which were suppressed by DLM treatment. These findings strongly indicate the anti-oxidative, anti-apoptotic and chemo-protective ability of piperine in the DLM induced thymic apoptosis.