Dichlorvos

Dichlorvos is effective against mushroom flies, aphids, spider mites, caterpillars, thrips, and whiteflies in greenhouses and in outdoor crops. It is also used in the milling and grain handling industries and to treat a variety of parasitic worm infections in animals and humans. It is fed to livestock to control botfly larvae in manure. It acts against insects as both a contact poison and an ingested poison. It is available as an aerosol and soluble concentrate. It is also used in pet flea collars and "no-pest strips" in the form of a pesticide-impregnated plastic; this material has been available to households since 1964 and has been the source of some concern, partly due to misuse.{{cite book |vauthors= Gillett JW, Harr JR, Lindstrom FT, Mount DA, St Clair AD, Weber LJ |chapter= Evaluation of human health hazards on use of dichlorvos (DDVP), especially in resin strips |title= Residue Reviews |volume= 44 |pages= 115–59 |date= 1972 |pmid= 4576326 |doi= 10.1007/978-1-4615-8491-9_6 |isbn= 978-0-387-05863-4}}

Dichlorvos is a colourless liquid{{RömppOnline|ID=RD-04-01285|Name=Dichlorvos|Datum=2014-02-07}} with aromatic odour. Its density is {{convert|1.425|g/cm3|g/in3|abbr=on}} at {{convert|25|C|F}},{{GESTIS|Name=Dichlorvos|ZVG=12500|CAS=62-73-7|Date=2017-01-10}} melting point below {{convert|−60|C|F}} and a boiling point of {{convert|140|C|F}} at 27 hPa. Dichlorvos is soluble in water.

Dichlorvos, like other organophosphate insecticides, inhibits acetylcholinesterase, associated with the nervous systems of insects. Evidence for other modes of action, applicable to higher animals, have been presented.{{cite journal |vauthors= Pancetti F, Olmos C, Dagnino-Subiabre A, Rozas C, Morales B |title= Noncholinesterase effects induced by organophosphate pesticides and their relationship to cognitive processes: implication for the action of acylpeptide hydrolase |journal= Journal of Toxicology and Environmental Health, Part B |volume= 10 |issue= 8 |pages= 623–30 |date= December 2007 |pmid= 18049927 |doi= 10.1080/10937400701436445 |bibcode= 2007JTEHB..10..623P |citeseerx= 10.1.1.334.9406}}{{cite journal |vauthors= Booth ED, Jones E, Elliott BM |title= Review of the in vitro and in vivo genotoxicity of dichlorvos |journal= Regulatory Toxicology and Pharmacology |volume= 49 |issue= 3 |pages= 316–26 |date= December 2007 |pmid= 17936460 |doi= 10.1016/j.yrtph.2007.08.011}} It is claimed to damage DNA of insects.{{cite journal |vauthors= Espeland M, Irestedt M, Johanson KA, Akerlund M, Bergh JE, Källersjö M |title= Dichlorvos exposure impedes extraction and amplification of DNA from insects in museum collections |journal= Frontiers in Zoology |volume= 7 |pages= 2 |date= January 2010 |pmid= 20148102 |pmc= 2819063 |doi= 10.1186/1742-9994-7-2 |doi-access= free }}

The United States Environmental Protection Agency has reviewed the safety data of dichlorvos several times.{{cite journal |vauthors= Mennear JH |title= Dichlorvos: a regulatory conundrum |journal= Regulatory Toxicology and Pharmacology |volume= 27 |issue= 3 |pages= 265–72 |date= June 1998 |pmid= 9693077 |doi= 10.1006/rtph.1998.1217}} In 1995 a voluntary agreement was reached with the supplier, Amvac Chemical Corporation, which restricted the use of dichlorvos in many, but not all, domestic uses, all aerial applications, and other uses.{{cite web |title=Dichlorvos (DDVP): Deletion of Certain Uses and Directions |url=https://www.federalregister.gov/documents/1995/04/19/95-9166/dichlorvos-ddvp-deletion-of-certain-uses-and-directions |publisher=U.S. Environmental Protection Agency: Office of Pesticide Programs |ref=Docket Control Number OPP-38511 |pages=19580–19581 |date=April 19, 1995 |quote=Docket Control Number OPP-38511}} Additional voluntary cancellations were implemented in 2006, 2008, and 2010. Major concerns focus on acute and chronic toxicity and the fact that this pesticide is prevalent in urban waterways.{{cite news|url=https://www.nytimes.com/2014/09/12/us/pesticide-levels-in-waterways-have-dropped-reducing-the-risks-to-humans.html|title=Pesticide Levels in Waterways Have Dropped, Reducing the Risks to Humans |date=11 September 2014 |newspaper=The New York Times | vauthors = Wines M }} A 2010 study found that each 10-fold increase in urinary concentration of organophosphate metabolites was associated with a 55% to 72% increase in the odds of ADHD in children.{{cite news |url=https://www.medscape.com/viewarticle/721892 |title=Organophosphate Pesticides Linked to ADHD | vauthors = Brooks M |date=May 17, 2010 |work=Medscape}}{{cite journal |vauthors= Bouchard MF, Bellinger DC, Wright RO, Weisskopf MG |title= Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides |journal= Pediatrics |volume= 125 |issue= 6 |pages= e1270-7 |date= June 2010 |pmid= 20478945 |pmc= 3706632 |doi= 10.1542/peds.2009-3058 |url= |doi-access= free}}{{cite magazine |url=https://www.scientificamerican.com/article/slow-acting/ |title=Slow-Acting |magazine=Scientific American | vauthors = Raeburn P |volume=295 |issue=2 |pages=26 |date=August 14, 2006 |doi=10.1038/scientificamerican0806-26 |doi-access=free}}

Between 2000 and 2013, thirty-one cases of acute dichlorvos pest strip-related illness were reported to the National Institute for Occupational Safety and Health (NIOSH) sentinel system. 65% of the 31 cases involved DDVP misuse contrary to instructions and safety labels.{{Cite magazine |last=Pearson |first=Gwen |title=CDC Warning on Misuse of Pest Strips |url=https://www.wired.com/2014/01/cdc-warning-misuse-pest-strips/ |access-date=2024-03-14 |magazine=Wired |language=en-US |issn=1059-1028}} Common violations included pest strip use in occupied, poorly-ventilated living areas (e.g., kitchens, bedrooms), lack of skin protection, cutting and tearing strips, and using a heater and fan to accelerate vapor dissemination from strips.

Dichlorvos can be produced by dehydrochlorinating trichlorfon in an aqueous alkali at 40-50 °C. It is also produced by the reaction of trimethyl phosphate and chloral.{{Cite web |last=Okoroiwu |first=Henshaw Uchechi |date=August 2018 |title=Interdisciplinary toxicology |pmc=6829687 }} As of 1990, it was produced in Argentina, Brazil, Germany, India, Israel, Japan, the Republic of Korea, Mexico, the USA, Switzerland, Sweden, Spain, and the Netherlands.{{Citation |last=to Humans |first=IARC Working Group on the Evaluation of Carcinogenic Risks |title=Dichlorvos |date=1991 |work=Occupational Exposures in Insecticide Application, and Some Pesticides |url=https://www.ncbi.nlm.nih.gov/books/NBK499685/ |access-date=2024-03-14 |publisher=International Agency for Research on Cancer |language=en |pmid=1842580}}

Dichlorvos enters the air, water, and soil when it is used and manufactured. It also can enter the environment when waste containing dichlorvos is disposed of in landfills. Dichlorvos is soluble in water, so it dissolves when it enters a body of water. Dichlorvos evaporates into the air easily, but is broken down by water vapor such as humidity. It does not bind to soil, but dichlorvos is broken down slower in soil than in the air. The broken down products are far less harmful than dichlorvos is. Dichlorvos is not stored in plants, animals, or humans.{{Cite web |title=Dichlorvos {{!}} Public Health Statement {{!}} ATSDR |url=https://wwwn.cdc.gov/TSP/PHS/PHS.aspx?phsid=595&toxid=111#:~:text=The%20U.S.%20EPA%20has%20determined,people%20exposed%20to%20this%20level. |access-date=2024-03-14 |website=wwwn.cdc.gov}}

People can be exposed to dichlorvos in the workplace by breathing it in, skin absorption, swallowing it, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for dichlorvos exposure in the workplace as 1 mg/m³ over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1 mg/m³ over an 8-hour workday. At levels of 100 mg/m³, dichlorvos is immediately dangerous to life or health (IDLH).

Different physicochemical methods have been developed for the removal of DDVP from contaminated environments, and microbial degradation is regarded as a promising method to solve several harmful residuals caused by DDVP. The biodegradation mechanism of many OPs has been studied deeply, especially for the methyl parathion, whose degradation genes and enzymes were cloned and purified. There is a need to select more useful strains, since only a few bacteria have been studied thoroughly in relation to the functional enzymes and genes.{{Cite journal |last1=Zhang |first1=Yuming |last2=Zhang |first2=Wenping |last3=Li |first3=Jiayi |last4=Pang |first4=Shimei |last5=Mishra |first5=Sandhya |last6=Bhatt |first6=Pankaj |last7=Zeng |first7=Daxing |last8=Chen |first8=Shaohua |date=January 2021 |title=Emerging Technologies for Degradation of Dichlorvos: A Review |journal=International Journal of Environmental Research and Public Health |language=en |volume=18 |issue=11 |pages=5789 |doi=10.3390/ijerph18115789 |doi-access=free |issn=1660-4601 |pmc=8199373 |pmid=34071247}}

Since it is an acetylcholinesterase inhibitor, symptoms of dichlorvos exposure include weakness, headache, tightness in chest, blurred vision, salivation, sweating, nausea, vomiting, diarrhea, abdominal cramps, eye and skin irritation, miosis (pupil constriction), eye pain, runny nose, wheezing, laryngospasm, cyanosis, anorexia, muscle fasciculation, paralysis, dizziness, ataxia, convulsions, hypotension (low blood pressure), and cardiac arrhythmias.{{PGCH|0202}}

It is also known to affect DNA replication in bacteria.{{cite journal |title=Preferential Effect of Dichlorvos(Vapona) on Bacteria Deficient in DNA Polymerase |url=https://cancerres.aacrjournals.org/content/canres/33/3/458.full.pdf |journal=Cancer Research}}

Acute Effects

Dichlorvos is irritating to the skin. The substance may affect the nervous system by inhibiting cholinesterase. The effects of exposure may be delayed but a high level could be fatal. Medical observation is indicated{{Cite web |title=ICSC 0690 - DICHLORVOS |url=https://www.ilo.org/dyn/icsc/showcard.display?p_card_id=0690&p_version=2&p_lang=en |access-date=2024-03-14 |website=www.ilo.org}}

Tests involving acute exposure of rats, mice, and rabbits have demonstrated that dichlorvos has high to extremely acute toxicity from oral or dermal exposure and extremely acute toxicity from inhalation{{Cite web |publisher=EPA |date=January 2000 |title=Dichlorvos |url=https://www.epa.gov/sites/default/files/2016-09/documents/dichlorvos.pdf |website=EPA's integrated risk information system (IRIS)}}

Long-Term Effects

Prolonged contact with skin may cause dermatitis and skin sensitization. If drinking water contaminated by dichlorvos is ingested long-term it may cause oral cancer.

Reproductive/Developmental Effects

There is no information available on the reproductive or developmental effects of dichlorvos in humans. In studies conducted with rat models, birth defects in fetal rats were observed. Mouse models also demonstrated sperm abnormalities. However, studies with other animal subjects found no birth defects.{{Cite web |date=January 2000 |title=Dichlorvos |url=https://www.epa.gov/sites/default/files/2016-09/documents/dichlorvos.pdf |access-date=March 14, 2024}}

Dichlorvos is mentioned in John Brunner's science fiction novel The Sheep Look Up. One of the book's many vignettes tells of a woman who nearly dies, having taken barbiturates and gone to sleep in a closed room where a fly-killing strip doused with the material was placed.{{Cite book|title=The Sheep Look Up| vauthors = Brunner J |publisher=Ballantine Books|year=1972|isbn=978-0-06-010558-7|location=New York|pages=220|lccn=72-79705}}

• Metrifonate (converts into dichlorvos)
• Naled (can convert into dichlorvos)

{{Reflist}}

• [http://extoxnet.orst.edu/pips/dichlorv.htm Extension Toxicology Network - Pesticide Information Profiles - Dichlorvos] (last maintained 1996)
• [https://www.cdc.gov/niosh/npg/npgd0202.html CDC - NIOSH Pocket Guide to Chemical Hazards]
• [https://web.archive.org/web/20110930163127/http://www.apvma.gov.au/products/review/completed/dichlorvos.php Australian Pesticides & Veterinary Medicines Authority Chemical Review Program - Dichlorvos]
• [https://web.archive.org/web/20070928060619/http://www.amvac-chemical.com/media/pdf/products/msds/nuvan_7.pdf Material Safety Data Sheet (MSDS) for Dichlorvos]
• {{cite journal |vauthors= Raeburn P |title= Slow-acting |journal= Scientific American |volume= 295 |issue= 2 |pages= 26 |date= August 2006 |pmid= 16866280 |doi= 10.1038/scientificamerican0806-26 |bibcode= 2006SciAm.295b..26R}}
• [http://news.bbc.co.uk/2/hi/uk_news/1939569.stm BBC News: Insecticide ban amid cancer fears]

{{Anthelmintics}}

{{Anti-arthropod medications}}

{{Acetylcholine metabolism and transport modulators}}

Category:Acetylcholinesterase inhibitors

Category:IARC Group 2B carcinogens

Category:Organochlorides

Category:Organophosphate insecticides