Retrospective analysis of adverse effects associated with pyrethrins-containing products

The Pyrethrins Stewardship Program (PSP) was established to better understand adverse effects following exposure to pyrethrins-containing insecticide products. Running from April 2010 through December 2016, symptomatic dermal and inhalation exposures were entered into Phase I of the PSP and analyzed for exposure details and nature of the effects reported. Phase II consisted of an in-depth telephone interview using an enhanced questionnaire to investigate additional exposure details. Phase III scored the association between exposure and reported effects. Based on the data collected and analyzed, we conclude that: (1) Both in absolute number and relative to the wide distribution and use by consumers, adverse respiratory or dermal events after product exposure were rare; (2) Most outcomes for the reported events involving either dermal or respiratory effects were of minor severity and self-limiting; (3) None of the data collected and analyzed indicate that pyrethrins-containing products, including those formulated with synthetic pyrethroids and/or synergists, pose a significant risk of serious dermal or respiratory reactions even in cases where the exposed individual reported having allergies or asthma; (4) No additional label warnings or other mitigation techniques are warranted with pyrethrins-containing products formulated with or without synthetic pyrethroids and/or synergists.

Resistensi Aedes aegypti Terhadap Insektisida: Studi pada Insektisida Rumah Tangga

Dengue hemorrhagic fever is a public health problem in Pekanbaru. It is transmitted by Aedes aegypti mosquitoes. The use of insecticides to kill vectors is a common practice. It is often used in outbreaks by fogging and daily use of insecticides in households. Household insecticides contain a variety of active ingredients such as organophosphates, carbamates, synthetic pyrethroids, and their combinations. This study aims to determine the sensitivity of Ae. aegypti mosquitoes from various household insecticides. This research was descriptive research by conducting a susceptibility test from World Health Organization. Adult mosquitoes were obtained from the breeding of larvae collected from dengue-endemic areas in Pekanbaru. Three types of insecticides are widely distributed in the market consisting of insecticides X with the active ingredient cypermethrin, transfluthrin, and imiprothrin, insecticide Y containing transfluthrin, and insecticide Z containing pralethrin and sifluthrin. Each insecticide was exposed to an adult mosquito by applying insecticides to filter paper and exposed for 1 hour and observed after 24 hours. The death of mosquitoes in the three types of insecticides is less than 80%. Based on the WHO criteria mortality of less than 80% showed a resistant mosquito. This tendency of resistance is probably caused by long-term continuous use.

Exposure to Sub-Lethal Doses of Permethrin Is Associated with Neurotoxicity: Changes in Bioenergetics, Redox Markers, Neuroinflammation and Morphology

Permethrin (PERM) is a member of the class I family of synthetic pyrethroids. Human use has shown that it affects different systems, with wide health dysfunctions. Our aim was to determine bioenergetics, neuroinflammation and morphology changes, as redox markers after subacute exposure to PERM in rats. We used MDA determination, protein carbonyl assay, mitochondrial O2 consumption, expression of pro-inflammatory cytokines and a deep histopathological analysis of the hippocampus. PERM (150 mg/kg and 300 mg/kg body weight/day, o.v.) increased lipoperoxidation and carbonylated proteins in a dose-dependent manner in the brain regions. The activities of antioxidant enzymes glutathione peroxidase, reductase, S-transferase, catalase, and superoxide dismutase showed an increase in all the different brain areas, with dose-dependent effects in the cerebellum. Cytokine profiles (IL-1β, IL-6 and TNF-α) increased in a dose-dependent manner in different brain tissues. Exposure to 150 mg/kg of permethrin induced degenerated and/or dead neurons in the rat hippocampus and induced mitochondrial uncoupling and reduction of oxidative phosphorylation and significantly decreased the respiratory parameters state 3-associated respiration in complex I and II. PERM exposure at low doses induces reactive oxygen species production and imbalance in the enzymatic antioxidant system, increases gene expression of pro-inflammatory interleukins, and could lead to cell damage mediated by mitochondrial functional impairment.

Toxic Effect Of Cypermethrin On Enzymes In Freshwater Fish Oreochromis Mossambicus (Tilapia)

In agriculture, excessive use of various pesticides had increased in developing countries. These pesticides may be highly toxic, not only to aquatic organisms like fishes but also to humans. In recent years, synthetic pyrethroids were developed for major uses in various agriculture practices and public health purposes. We aim to find the toxic Effect of Cypermethrin on Freshwater Fish Oreochromis mossambicus (Tilapia). The fish Oreochromis mossambicus were exposed for 30 days to various sub lethal concentrations (1/10, 1/20, and 1/30) of cypermethrin. After completion of a 30 days exposure, the fish Oreochromis mossambicus was sacrificed and tissue samples of muscle, liver, and kidney were analyzed. Decreased value of ALP, ACP, and Increased value of AST, ALT was observed in all the sub lethal exposure of cypermethrin on treated freshwater fish Oreochromis mossambicus at 30 days on comparing with the control group. High variation of AST and ALT were observed in the liver at 1/10th concentration of cypermethrin and elevated variation of ALP and ACP was observed in the liver at 1/10th concentration of sub lethal level for 30 days exposure. While comparing with the control group, the effects of cypermethrin on experimental fish showed increased levels of AST, ALT in the tissues of muscle, liver, and kidney of O. mossambicus, and the level of ACP and ALP were found in a decreased manner. Increased levels of ALT and AST activity observed in freshwater fishes may be due to the reduction of metabolic activity and concentration of ACP and ALP in various tissues due to cellular necrosis. In the present study, we found that the effect of cypermethrin alters the activity of various enzymes in freshwater fish Oreochromis mossambicus. It is concluded from this study that exposure to cypermethrin affects the enzyme activities of fish.

A Review on Non-target Toxicity of Deltamethrin and Piperonyl Butoxide: Synergist

Deltamethrin and piperonyl butoxide two synthetic pyrethroids, when used in a combination it produces synergistic effect. This two insecticide has found to be widely used in the management of mosquito, housefly and other insects to control the various vector born diseases. In this review we assessed the toxic effect of deltamethrin and piperonyl butoxide on beneficial organisms commonly available in the ecosystem. It was found to be toxic to fish, honey bees the prime pollinators of crop plant; earthworm is also susceptible at a lethal concentration for a particular exposure. As far the birds are concerned, they have a less toxic risk in lower concentration of exposure. The alterations obtained in the hematological, biochemical and histopathological studies, further conclude that it can cause environment hazards and toxic to the non-targeted organisms. This investigation gives an insight into the combined toxicological profile of deltamethrin and PBO for better risk assessment and safe use of pyrethroids and their synergist in non-targeted organisms.

Insecticides Susceptibility Status of Malaria Vectors in a High Malaria Endemic Tribal District Gadchiroli (Maharashtra) of India

Background and Objective: The current study was undertaken to determine insecticide susceptibility of malaria vectors in various villages of high malaria endemic PHCs of Gadchiroli district of Maharashtra. Methods: Adult malaria vectors were collected from the human dwellings/ cattle sheds of 156 villages of 18 malaria endemic PHCs. Susceptibility tests were carried out for different insecticides against An. culicifacies and An. fluviatilis mosquitoes as per the World Health Organization (WHO) procedure. Cone bioassays were also done to assess the quality and efficacy of indoor residual spray. Results:An. fluviatilis could be collected from 23 villages only and all the populations were fully susceptible to synthetic pyrethroid (deltamethrin) while being tolerant to organophosphorous (malathion). Susceptibility of An. culicifacies from 156 villages indicated that only 3 populations of An. culicifacies were resistant to deltamethrin while 57 populations were fully susceptible and other 96 populations were tolerant to deltamethrin. Resistance was recorded in 25 populations of An. culicifacies against malathion and 30 populations were tolerant to malathion insecticide. Remaining populations of An. fluviatilis and An. culicifacies were highly resistant to organochlorine. Results of cone bioassay revealed the mortality ranged from 32.5-51.1% on cemented and 27.5-43.3% on the mud wall sprayed with lambda cyhalothrin. Conclusion: The current study indicates that resistance has developed to synthetic pyrethroids in the major malaria vector An. culicifacies. Therefore, there is an urgent need for the evaluation of new insecticide molecules for better control of malaria vectors.

Multi-Year Mass-Trapping With Autocidal Gravid Ovitraps has Limited Influence on Insecticide Susceptibility in Aedes aegypti (Diptera: Culicidae) From Puerto Rico

Mass-trapping has been used to control outbreaks of Aedes aegypti (Linnaeus) (Diptera: Culicidae) in Puerto Rico since 2011. We investigated the effect of multi-year, insecticide-free mass trapping had on the insecticide susceptibility profile of Ae. aegypti. Eggs collected in southern Puerto Rico were used to generate F1 populations that were tested for susceptibility to permethrin, sumethrin, bifenthrin, deltamethrin, and malathion according to CDC bottle bioassays protocols. All populations of Ae. aegypti were resistant to the synthetic pyrethroids and mosquitoes from two locations were partially resistant to malathion. Population genetic analysis, using a double digest restriction sites associated DNA sequencing (ddRADseq) approach, indicated a large amount of migration between study sites effectively homogenizing the mosquito populations. Mass-trapping using noninsecticidal autocidal gravid ovitraps did not restore susceptibility to five active ingredients that are found in commercial insecticides. Migration between communities was high and would have brought outside alleles, including resistant alleles to the treatment communities. Further investigation suggests that household use of commercially available insecticide products may continue to select for resistance in absence of public health space spraying of insecticides.

Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16

Tetramethrin is a pyrethroid insecticide that is commonly used worldwide. The toxicity of this insecticide into the living system is an important concern. In this study, a novel tetramethrin-degrading bacterial strain named A16 was isolated from the activated sludge and identified as Gordonia cholesterolivorans. Strain A16 exhibited superior tetramethrin degradation activity, and utilized tetramethrin as the sole carbon source for growth in a mineral salt medium (MSM). High-performance liquid chromatography (HPLC) analysis revealed that the A16 strain was able to completely degrade 25 mg·L−1 of tetramethrin after 9 days of incubation. Strain A16 effectively degraded tetramethrin at temperature 20–40 °C, pH 5–9, and initial tetramethrin 25–800 mg·L−1. The maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) were determined to be 0.4561 day−1, 7.3 mg·L−1, and 75.2 mg·L−1, respectively. The Box–Behnken design was used to optimize degradation conditions, and maximum degradation was observed at pH 8.5 and a temperature of 38 °C. Five intermediate metabolites were identified after analyzing the degradation products through gas chromatography–mass spectrometry (GC-MS), which suggested that tetramethrin could be degraded first by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and its subsequent metabolism. This is the first report of a metabolic pathway of tetramethrin in a microorganism. Furthermore, bioaugmentation of tetramethrin-contaminated soils (50 mg·kg−1) with strain A16 (1.0 × 107 cells g−1 of soil) significantly accelerated the degradation rate of tetramethrin, and 74.1% and 82.9% of tetramethrin was removed from sterile and non-sterile soils within 11 days, respectively. The strain A16 was also capable of efficiently degrading a broad spectrum of synthetic pyrethroids including D-cyphenothrin, chlorempenthrin, prallethrin, and allethrin, with a degradation efficiency of 68.3%, 60.7%, 91.6%, and 94.7%, respectively, after being cultured under the same conditions for 11 days. The results of the present study confirmed the bioremediation potential of strain A16 from a contaminated environment.