Dimethoate

Dimethoate is a general use insecticide for combatting insects such as aphids, mites, beetles, weevils, and leafhoppers. Dimethoate is formulated as emulsifiable concentrates or wettable powders to be applied primarily as foliar sprays. The majority of the approximately 800.000 kg (1.8 million pounds) of dimethoate used annually in the U.S. is accounted for by applications on alfalfa, wheat, cotton, and corn crops. In 2005, dimethoate usage was cancelled in the U.S. for use on apples, broccoli raab, cabbage, collards, grapes, head lettuce, and spinach due to being identified as significant dietary risk contributors.{{cite web | publisher = Environmental Protection Agency | date = October 2008 | title = Revised Interim Reregistration Eligibility Decisions for Dimethoate | id = EPA-HQ-OPP-2005-0084 | work = US Environmental Protection Agency Office of Pesticide Programs | url = https://archive.epa.gov/pesticides/reregistration/web/pdf/dimethoate_ired_revised.pdf }} Dimethoate also has applications as a form of botfly and mite control in livestock.{{cite encyclopedia | vauthors = Mirajkar N, Pope CN | chapter = Dimethoate |date= January 2005 | title = Encyclopedia of Toxicology | edition = Second |pages=47–49 | veditors = Wexler P |place=New York |publisher=Elsevier |doi=10.1016/b0-12-369400-0/00330-6 |isbn=978-0-12-369400-3 }} As of 2000, dimethoate is cancelled for usage in residential and non-agriculture applications in the U.S{{Cite web |date=2021-09-09 |title= Dimethoate Biomonitoring Summary | work = U.S. Centers for Disease Control and Prevention |url=https://www.cdc.gov/biomonitoring/DimethoateOmethoate_BiomonitoringSummary.html |access-date=2023-10-29 |language=en-us}}

Dimethoate is relatively non-persistent, but highly mobile in the environment due to its high solubility in water and low adsorption in soil.{{cite book | vauthors = Van Scoy A, Pennell A, Zhang X | chapter = Environmental Fate and Toxicology of Dimethoate | title = Reviews of Environmental Contamination and Toxicology Volume 237 | volume = 237 | pages = 53–70 | date = 2016 | pmid = 26613988 | doi = 10.1007/978-3-319-23573-8_3 | publisher = Springer International Publishing | isbn = 978-3-319-23573-8 | place = Cham | veditors = de Voogt WP }} The half-life of dimethoate in soil has been shown to range from 2.5 to 31 days depending on the type of soil and its moisture content. The half-life of dimethoate is shorter in moist soil due the action of microbial degradation. Breakdown of dimethoate by hydrolysis in water is highly dependent on temperature and pH, with the half-life ranging from 12 to 423 days.

Exposure of the general population to dimethoate and its breakdown product omethoate can happen through consumption of contaminated food or water. Workers involved in the application or manufacture of dimethoate are typically exposed through contact with skin, or through inhalation of aerosols and dust.

In mammals, dimethoate has an LD50 of 150 mg/kg bodyweight in mice and 400 mg/kg bodyweight in rats. Acute exposure through oral, dermal, or inhalation routes can cause symptoms such as diarrhea, nausea, sweating, blurred vision, difficulty breathing, and slowed heartbeat. Relapse situations where the patient appears to have stabilized before getting worse have been associated with higher exposure doses. Respiratory ailments, cholinesterase inhibitor exposure, impaired cholinesterase production, or liver malfunction can play a role in potentiating toxicity.

Chronic exposure to dimethoate can result in symptoms such as disorientation, irritability, impaired memory and concentration, nightmare, and speech difficulties. Chronic exposure as also been associated with nausea, loss of appetite, and malaise. Under normal conditions the chances of teratogenic, mutagenic, or carcinogenic effects from chronic exposure are low.

The Queensland fruit fly, or Bactrocera tryoni, is a tephritid fly species that has caused more than $28.5 million a year in damage to Australian fruit crops. In order to combat infestation, farmers treated crops with dimethoate and fenthion.{{Cite journal | vauthors = Lloyd AC, Hamacek EL, Kopittke RA, Peek T, Wyatt PM, Neale CJ, Eelkema M, Gu H | display-authors = 6 |date=May 2010 |title=Area-wide management of fruit flies (Diptera: Tephritidae) in the Central Burnett district of Queensland, Australia |url=http://era.daf.qld.gov.au/id/eprint/1678/ |journal=Crop Protection |volume=29 |issue=5 |pages=462–469 |doi=10.1016/j.cropro.2009.11.003 |issn=0261-2194}} In 2011 the Australian Pesticides and Veterinary Medicines Authority (APVMA) banned the use of dimethoate containing products on food producing plants in home gardens, as well as on a variety of fruits, berries, cucurbits, and vegetables.{{Cite web |title=Dimethoate chemical review |website=Australian Pesticides and Veterinary Medicines Authority |url=http://apvma.gov.au/dimethoate |access-date=2023-10-29 |language=en-AU}} In September 2023, due to concerns that dimethoate and omethoate levels were exceeding acceptable maximum residue limits on avocados and mangoes, the APVMA issued a 12-month suspension notice on the use of dimethoate containing compounds as a post-harvest dip to control fruit flies on certain tropical fruits, including avocados and mangoes.{{Cite web |title=Notice of suspension – certain dimethoate products and labels | work = Gazette | volume = 19 | date = 19 September 2023 |url=http://apvma.gov.au/node/117571 |access-date=2023-10-29 |publisher = Australian Pesticides and Veterinary Medicines Authority |language=en-AU}}{{Cite news | vauthors = Morris N |date=2023-09-22 |title=This neurotoxin is now suspended from use on mangoes and avocados after harvest, so why not oranges? |language=en-AU |work=ABC News |url=https://www.abc.net.au/news/2023-09-23/dimethoate-use-suspended-on-mangoes-avocados-post-harvest/102758696 |access-date=2023-10-29}}

Dimethoate is sold under various trade names, including Cygon, De-fend, Rogor, Rogodan, Rogodial, Roxion, Dimetate, Devigon, Dicap, Dimet, and B-58.{{cite journal | vauthors = Padmasheela NC, Delvi MR | title = Effect of Dimethoate (Rogor 30% EC) on the brain neurosecretory cells of third instar grubs of Oryctes rhinoceros L. (Coleoptera : Scarabaeidae) | journal = Journal of Environmental Biology | volume = 25 | issue = 4 | pages = 451–455 | date = October 2004 | pmid = 15907075 }}{{Cite web |work = Ravensdown | title = Rogor |url=https://www.ravensdown.co.nz/products/agrochemicals/rogor}}{{Cite web |title=Insecticides_acaricides B-58 | Detailed description, photo , growing, buy |url=http://semenaopt.com/en/Insecticides_acaricides/B-58/605675/ | work = SemenaOpt.com }}

In late October 2020 a Bulgarian farmer, a previous jackpot winner of the national 'toto' lottery drank a glass of the Russian B-58 brand, as of early November 2020 he is hospitalised in a comatose condition, he has a history of psychiatric issues but it is currently unknown whether the incident was accidental or intentional.{{Cite web | vauthors = Maskruchka A |url=https://www.24chasa.bg/novini/article/9181521|title=Остава тежко състоянието на тотомилионера, натровил се с Б-58 | trans-title = The condition of the milldionaire who poisoned himself with B-58 remains serious | language = Bulgarian | date = 12 February 2020 | work = 24 Chasa }}

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• [https://www.epa.gov/sites/production/files/2015-06/documents/dimethoate-035001_2015-06-29_txr0057168.pdf EPA Report on Dimethoate] {{Webarchive|url=https://web.archive.org/web/20151015131501/http://www2.epa.gov/sites/production/files/2015-06/documents/dimethoate-035001_2015-06-29_txr0057168.pdf |date=2015-10-15 }}

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