Pyrethroid Insecticides: Poisoning Syndromes, Synergies, and Therapy
BACKGROUND: Pyrethroid insecticides are widely used, but there have been relatively few reports of systemic poisoning. These reports have, however, shown that pharmacotherapy is difficult and that the duration of poisoning can be unexpectedly long. Pyrethroids are ion channel toxins prolonging neuronal excitation, but are not directly cytotoxic. Two basic poisoning syndromes are seen. Type I pyrethroids produce reflex hyperexcitability and fine tremor. Type II pyrethroids produce salivation, hyperexcitability, choreoathetosis, and seizures. Both produce potent sympathetic activation. Local effects are also seen: skin contamination producing paresthesia and ingestion producing gastrointestinal irritation. The slow absorption of pyrethroids across the skin usually prevents systemic poisoning, although a significant reservoir of pyrethroid may remain bound to the epidermis. Carboxyesterase inhibitors can enhance pyrethroid toxicity in high-dose experimental studies. Hence, the unauthorized pyrethroid/organophosphate mixtures marketed in some developing countries may precipitate human poisoning. Pyrethroid paresthesia can be treated by decontamination of the skin, but systemic poisoning is difficult to control with anticonvulsants. Pentobarbitone, however, is surprisingly effective as therapy against systemic type II pyrethroid poisoning in rats, probably due to its dual action as a chloride channel agonist and a membrane stabilizer.
Available from: Terezinha Souza
- "In addition, all aforementioned classes of insecticides are shown to be toxic to humans. Organochlorines are either known carcinogens or endocrine disruptors (Longnecker et al., 1997), organophosphate poisoning leads to cholinergic syndrome (Marrs, 1993) and intoxication by pyrethroids results in neurotoxicity and induction of seizures (Ray and Forshaw, 2000). Such effects are not "
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ABSTRACT: Nowadays, dengue fever is considered the most important arbovirosis worldwide and its control is still based upon combating the vector Aedes aegypti. Besides monitoring of mosquito populations resistant to conventional insecticides, the search for new environmentally safe insecticides and conduction of molecular studies focusing on the elucidation of mode of action and possible resistance mechanisms are considered the key for a sustainable management of the mosquito vector. Thus, the present work aimed to assess changes in protein expression of 3rd-instar larvae of Ae. aegypti after exposure to the natural insecticide m-pentadecadienyl-phenol. Bidimensional electrophoresis followed by mass spectrometry resulted in identification of 12 proteins differentially expressed between control and treated groups. Larvae exposed to the toxic compound for 24h showed elevated detoxification response (glutathione-SS-transferase), increased levels of stress-related proteins (HSP70) as well as evidence of lysosome stabilization to enable survival. Furthermore, expression of proteins involved in protection of peritrophic membrane and metabolism of lipids indicated systemic effect of toxic effects in treated larvae.
Copyright © 2015. Published by Elsevier B.V.
Available from: Sarah Greish
- "choreoathetosis, and seizures. Both types produce potent sympathetic activation (Ray and Forshaw 2000). Residues of all targeted pesticides were detected in our study, with the exception of methomyl and oxamyl. "
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ABSTRACT: The objective of this study was to assess pesticide residues in tomatoes, cucumbers, peppers, strawberries, and potatoes collected from local markets in Ismailia, Egypt, and to assess dietary intake and health risk implications of pesticide residues through food consumption. Vegetable selection was based on their popularity and consumption. Selection of pesticides was based on their impact on humans, and on their heavy use. The majority of the analyzed samples contained detectable levels of pesticides. Residues of some organophosphorus pesticides, including malathion, ethion, and profenofos and some pyrethroid pesticides such as fenpropathrin and cypermethrin were found in some samples at concentration equal to or exceeding their European Union's maximum residue limits (EU-MRLs). The fungicide bupirimate detected in potato samples exceeded the EU-MRL by 1500%. Phentohate and profenofos were the most frequently detected pesticides in 30 and 27% of analyzed samples, respectively. Data were used to estimate the potential health risks associated with exposure to these pesticides by ingestion of food. Estimated daily intakes (EDIs) of pesticides ranged from 0.03% to 40% of the acceptable daily intakes (ADIs), depending on pesticide concentration and vegetable consumption. Overall, the EDIs of the different pesticides from vegetable consumption are not considered a public health problem.
Available from: Anindya Sundar Bhunia
- "Moreover, during monsoon and flood, agricultural run-off laden with cypermethrin and fenvalerate often contaminates the natural habitat of molluscs and expected to create toxicity in them. Toxicity of pyrethroids is well reported in mammal  but their toxicity in molluscs is not studied in detail. Molluscs, in general, lack adaptive immunity and antibody and depend on innate immune system to combat invading parasites, pathogens and toxin exposure . "
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ABSTRACT: Bellamya bengalensis (Gastropoda: Prosobranchia) and Lamellidens marginalis (Bivalvia: Eulamellibranchiata) are the molluscs of Indian freshwater ecosystem and important biological resources. These edible species bear economical, ecological, nutritional and medicinal importance. Natural habitat of these organisms is under the ecological threat of contamination by cypermethrin and fenvalerate, the common pyrethroid pesticides of India. Hemocytes are chief immunoeffector cells of molluscs which exhibit responsiveness against environmental toxins and perform diverse immunological functions including phagocytosis, encapsulation and cytotoxicity. Experimental exposure of cypermethrin and fenvalerate resulted in significant shift in density and morphological damage in hemocytes of B. bengalensis and L. marginalis respectively. Pyrethroid induced fragility and destabilization of hemocyte lysosomal membrane was recorded and proposed as an indication of toxin induced stress in molluscs. Apoptosis is an immunologically important cellular response which is modulated by environmental toxins. Pyrethroid exposure suppressed the physiological level of apoptosis and necrosis in hemocytes of B. bengalensis and L. marginalis indicating possible impairment of apoptosis mediated immunoprotection. Differential responses of B. bengalensis and L. marginalis hemocytes may be due to species specificity, toxin specificity, nonidentical immune strategies of Gastropoda and Bivalvia, specific habitat preference and related ecological niches.
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