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The Challenge of Parasite Control
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Many alternatives to DDT exist and insecticides are still widely used to reduce vector density. Examples include the organophosphates like malathion and the pyrethroids. Organophosphates work by inhibiting acetylcholinesterases (enzymes that hydrolyze the neurotransmitter acetylcholine) in insects. Pyrethroids, similar to compounds produced by pyrethrum flowers, act in a manner similar to DDT in that they disrupt sodium ion channel proteins on neurons. Many of these compounds, however, raise some of the same issues as DDT. Organophosphates are toxic to humans and other animals. Pyrethroids, generally harmless to humans, are toxic to aquatic organisms.
Aedes-aegypti organophosphate resistance detection in the Rawasari subdistrict of Central Jakarta, Indonesia, as an effort for dengue hemorrhagic fever vector control
Published in Ade Gafar Abdullah, Isma Widiaty, Cep Ubad Abdullah, Medical Technology and Environmental Health, 2020
A. Hardjanti, I. Indrawati, E. Donanti, H. Wibowo, Z. Zulhasril
Organophosphate is an acetylcholinesterase inhibitor. Acetylcholinesterase is an enzyme that hydrolyzes acetylcholine to become acetic and choline. Organophosphate reacts with the active part of this enzyme and blocks its functions. The level of acetylcholine in nerve synapses will increase, causing a persistent postsynaptic stimulus. Acetylcholine is present in all nervous systems, including the autonomic nervous system, and acts as a neurotransmitter in sympathetic and parasympathetic nerve ganglion.
Chemical injuries
Published in Jan de Boer, Marcel Dubouloz, Handbook of Disaster Medicine, 2020
Organophosphate compounds are commonly used as pesticides but can also be used as chemical warfare agents. The toxicity seen with these agents is due to inhibition of acetylcholinesterase, which causes accumulations of acetylcholine at cholinergic synapses, accounting for a cholinergic crisis with a variety of central and peripheral neurologic manifestations. Increased muscarinic activity produces activation of all the exocrine glands causing lacrimation, salivation, perspiration and excessive secretion by the bronchial and intestinal glands and stimulation of the pancreas, bronchospasm, sinus bradycardia, miosis and involuntary contractions of the muscles of the gastrointestinal tract causing abdominal cramps, vomiting, diarrhea and involuntary urination. Pulmonary symptoms are most marked after an inhalation exposure. Nicotine effects include those involving the skeletal muscles, including the muscles of the respiratory system as reflected by fasciculations and fibrillation and weakness followed by paralysis but also hypertension and tachycardia. Central nervous system effects are confusion, anxiety, restlessness, agitation, insomnia, ataxia, drowsiness, convulsions, coma and paralysis of respiratory centres10,13,21,23. Both central respiratory depression and the ventilatory compromise produced by bronchospasm, hypersecretion and respiratory muscle weakness are the most life-threatening manifestations13,21,23.
Removal of malathion insecticide from aqueous solution by the integration of persulfate process and magnetite nanoparticles loaded on carbon (Fe3O4@CNT) in the presence of ultraviolet radiation
Published in Toxin Reviews, 2022
Malektaj Eskandari makvand, Sima Sabzalipour, Mahboobeh Cheraghia, Neda Orak
The use of pesticides plays a substantial role in the widespread control of weeds. In this regard, the organophosphate compounds are the largest and most diverse group of available pesticides, involving more than 50% of the world's registered pesticides. Certain pesticides can enter the air and then the surface of water and soil sources as rainfalls. Nowadays, a traditional pesticide named malathion has been employed to control weeds in farms (Köck-Schulmeyer et al.2013). Malathion, as one of the most widely used organophosphate toxins, has destructive effects on the human nervous system through its contact and digestive, smoking, and non-systemic properties. Regarding its low cost and optimal performance, it is one of the most prevalent substances to control weeds in the world.
Pyrethroid based pesticides – chemical and biological aspects
Published in Critical Reviews in Toxicology, 2021
Anandha Rao Ravula, Suresh Yenugu
OPs or esters of phosphoric acid are ecologically good alternatives to OCs as they are not persistent in the environment. The most common of this class is glyphosate, a weedicide. The other OPs include malathion, parathion, dimethoate and chlorpyrifos. Global usage of organophosphate insecticides is more than 30% and according to Environmental Protection Agency (EPA) reports, more than 50% of total OPs are used in many crops, particularly cotton and corn in USA (Edwards 2006). In insects and mammals, OPs affect neuromuscular transmission by interfering with acetylcholinesterase (AChE) in cholinergic synapsis via phosphorylation of this enzyme resulting in excess accumulation of acetylcholine (Ach). This leads to death due to asphyxia, loss of respiratory control and over stimulation in cholinergic pathways (Reigart and Roberts 2013). Apart from neurotoxicity, they are also associated with aberrations in insulin secretion, metabolism, mitochondrial function and endocrine function (Nicolopoulou-Stamati et al. 2016).
Transient receptor potential ankyrin 1 (TRPA1)-mediated toxicity: friend or foe?
Published in Toxicology Mechanisms and Methods, 2020
Mohaddeseh Sadat Alavi, Ali Shamsizadeh, Gholamreza Karimi, Ali Roohbakhsh
Organophosphates are commonly used as insecticides in many countries (Balali-Mood et al. 2012). The organophosphate-mediated delayed neuropathy (OPIDN) often leads to ataxia, paresthesia, and paralysis that occurs in the late stages of acute poisoning or after repeated exposures to organophosphates such as malathion, phoxim, chlorpyrifos, and fenthion (Jamal et al. 2002). Malathion, in an experimental model of OPIDN, induced nerve injuries and ataxia similar to tri-ortho-cresyl phosphate (TOCP). Both compounds also activated TRPA1. TRPA1 gene ablation or treatment with HC030031, as a selective TRPA1 antagonist, reduced the damages that were induced by malathion or TOCP (Ding et al. 2017). Duloxetine and ketotifen, which have apparent TRPA1 inhibitory activity, showed neuroprotective effects against OPIDN as well. The researchers suggested that TRPA1 was the major mediator of OPIDN (Ding et al. 2017).