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Insecticides
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
The pyrethroid insecticides are derived from the naturally occurring compound pyrethrum, from the dried flower heads of the yellow flower Chrysanthemum cineriaefolium.* The synthetic acid-alcoholic esters are categorized into several classes of the active ingredients; namely, pyrethrins types I and II.† Pyrethrum flowers have been used as insecticides for centuries, particularly by Caucasian tribesmen and Armenians. The powdered form was introduced into the United States in 1855, after which its importation expanded tremendously. Type I pyrethrins include allethrine, permethrin, and cismethrin; type II pyrethrins include fenvalerate, deltamethrin, and cypermethrin. The compounds (0.17–0.33%) are combined with piperonyl butoxide or n-octyl-dicycloheptane dicarboximide (2–4%) in therapeutic nonprescription pediculocide preparations for the treatment of lice, tick, and mite infestation.‡ Pyrethrins are noted for their quick “knock-down” effect on flying insects, particularly flies and mosquitoes. The products are available in lotions, sprays, and shampoos for skin or scalp applications as well as for removal from furniture and bedding material.
Catalog of Herbs
Published in James A. Duke, Handbook of Medicinal Herbs, 2018
Pyrethrum is cultivated for the dried inflorescences which furnish on insecticide, used in manufacture of insecticides and parasiticides, in live stock sprays, meat processing, ointments for scabies, and aerosol sprays against fleas, flies, lice, and mosquitos. Pyrethrum use evolved in Iran, and was introduced into Europe and the U.S. in the 19th century. Kerosene extracts are usually used, but mixing pyrethrum with sesame-oil synergists reduces the cost while enhancing toxicity of pyrethrins, and requires less pyrethrum per unit kill. Toxicity to higher animals is minimal, so that pyrethrum is an excellent insect deterrent for use around foods. Smoke of burning flowers is as effective as the powder in keeping down insects.2 The flower has shown antibiotic activity against mycobacterium tuberculosis.1 Rarely cultivated as border plant; common in botanical gardens. Recent interest in organic or “natural” pesticides has stimulated interest in, e.g., combinations of pyrethrum, rotenone, and ryania.
Rationale and technique of malaria control
Published in David A Warrell, Herbert M Gilles, Essential Malariology, 2017
David A Warrell, Herbert M Gilles
In malaria control programmes, the common formulations of pyrethrum are: 0.2–0.4 per cent dusts; 0.1–0.4 per cent solutions in kerosene or petroleum distillate; as aerosol insect sprays (synergists are included in the formulations). The pattern of use of pyrethrum is very wide. It is applied as thermal fogs, mists for non-residual control by repetitive application in kitchens, food stores, factories etc. where toxic residual insecticides cannot be used. Thermal fogs of 0.02 per cent pyrethrins with 0.4 per cent piperonyl butoxide are used for fly control. Ultra-low-volume (ULV) sprays are used against mosquitoes, houseflies and tsetse flies. Pyrethrum is repellent to mosquitoes; thus, it is used in insect repellent creams and mosquito coils. Pyrethrins have a very low toxicity for warm-blooded animals, but are toxic to fish; however, their persistence in water is brief.
Orbital giant cell myositis is an unusual and potentially lethal cause of bilateral ophthalmoplegia – A case report and literature review
Published in Orbit, 2022
Rachel Jui-Chi Chang, Vivian Kuang, Joos Meyer, Ewan Chang, Samuel J Roberts-Thomson, Penny McKelvie, Thomas G Hardy, Zelda S Pick
Vitiligo is found in 3/11 patients, and rheumatoid arthritis in 1/11,2 suggesting an autoimmune process. Many autoimmune conditions including thymoma are associated with giant cell myocarditis.17 Experimental rat models showed that autoimmunisation with cardiac myosin leads to the development of GCM.18 The exact aetiology is unclear, but giant cell myocarditis is thought to be due to dysregulation mediated by T cells. This has been proposed to be triggered by infections such as Coxsackie virus21 or drug hypersensitivity.22 Our patient reported use of the pesticide pyrethrum one week prior to onset of orbital inflammatory symptoms. Pyrethroids act on sodium channels and cause prolonged depolarisation in insects. They can cause paraesthesia from neurotoxicity in humans, allergic reactions including asthma, and are noted to alter immune response.23,24 Chronic exposure has been shown to cause hypersensitivity pneumonitis with granuloma on lung biopsy.25 In addition, there is also evidence that risperidone can contribute to immune dysregulation by upregulating cytokines.26
Metabolism of deltamethrin and cis- and trans-permethrin by rat and human liver microsomes, liver cytosol and plasma preparations
Published in Xenobiotica, 2019
Laura Hedges, Susan Brown, Audrey Vardy, Edward Doyle, Miyoung Yoon, Thomas G. Osimitz, Brian G. Lake
Pyrethroids are a class of synthetic insecticides that are derived from the structures of the six active insecticide components (Pyrethrins I and II) of Pyrethrum extract, which is obtained from the dried and ground flowers of Chrysanthemum cinerariaefolium (Bhat, 1995; Elliott, 1995). Like natural pyrethrins, synthetic pyrethroids modulate nerve axon sodium channels in insects, resulting in neurotoxic effects (Gammon et al., 2012; Soderlund et al., 2002; Soderlund, 2012). Although synthetic pyrethroids exhibit a low oral toxicity to mammals, they have been shown to produce neurotoxic effects, with toxicity being considered to be due to the parent pyrethroid and not to any subsequent metabolites (Lawrence & Casida, 1982; Rickard & Brodie, 1985; Soderlund et al., 2002; Tsuji et al., 2012). Potency for producing acute neurotoxicity varies between different pyrethroids, with deltamethrin (DLM) being more potent than permethrin (Tsuji et al., 2012).
Genetic improvement of pyrethrum (Tanacetum cinerariifolium Sch. Bip.) through gamma radiation and selection of high yield stable mutants through seven post-radiation generations
Published in International Journal of Radiation Biology, 2021
Raj Kishori Lal, Chandan Singh Chanotiya, Pankhuri Gupta, Anand Mishra, Madan Mohan Gupta
The genus Chrysanthemum, which belongs to the family ‘Asteraceae’, is a natural source of insecticides that is nontoxic to plants and higher animals. Because of their extensive uses in agriculture, the flowers are also in high demand. It is a para-medicinal plant that produces pyrethrins used as a natural pesticide (Munro 1961; Parlevliet 1974). The amounts of pyrethrum powder used in insecticides are nontoxic to plants and higher animals; thus, these insecticides are commonly used for edible plants in household and livestock sprays as well as in dust (Dove 1958; Fine 1963; Rao et al. 1983; Lal 2015). The synthetic pyrethroids like permethrin, decamethrin, or deltamethrim are highly lipophylic so that, they do not directly penetrate in contact with insects by spraying. The use of natural pyrethrins is, therefore, the most viable tool for pest control. Because of slow biodegradability and lurking dangers of environmental pollution associated with synthetic pesticides, there is a need to explore the natural sources of insecticides, especially for the control of domestic insect pests for health care (Tuikong 1984; Bhat and Menary 1986; Singh and Sharma 1989; Lal et al. 2013). Pyrethrins extracted from pyrethrum flowers are well known for considerable efficacy against domestic and field insect pests (Bhat and Pandita 1977; Casida 1980; Singh et al. 1987). The United Republic of Tanzania produced 90% over 6,986 tonnes of the world's pyrethrum. Other countries like Papua New Guinea 1,150 tonnes, Kenya 350 tonnes and Italy 300 tonnes also produce pyrethrum flowers. Production in Tanzania and Ecuador is also significant. Currently, the world's major producing countries are Kenya, Tasmania, and Australia (Lal et al. 2014; Freemont et al. 2016).