Carbofuran

Carbofuran is one of the most toxic carbamate pesticides. It is marketed under the trade names Furadan, by FMC Corporation and Curaterr 10 GR, by Bayer, among several others. It is used to control insects in a wide variety of field crops, including potatoes, corn and soybeans. It is a systemic insecticide, which means that the plant absorbs it through the roots, and from there the plant distributes it throughout its organs where insecticidal concentrations are attained. Carbofuran also has contact activity against pests.

Carbofuran
Carbofuran
Carbofuran
Names
IUPAC name
2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate
Other names
Furadan, Curater, Furacarb
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.014.867
KEGG
UNII
Properties
C12H15NO3
Molar mass 221.256 g·mol−1
Appearance White, crystalline solid
Density 1.18 g/cm3
Melting point 151 °C (304 °F; 424 K)[1]
Boiling point 313.3 °C (595.9 °F; 586.5 K)
320 mg/L[2]
Solubility Highly soluble in N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, methylene chloride, cyclohexanone, benzene, and xylene[3]
log P 2.32 (octanol/water)[4]
Hazards
Flash point 143.3 °C (289.9 °F; 416.4 K)
Lethal dose or concentration (LD, LC):
8–14 mg/kg (oral, rat)
19 mg/kg (oral, dog)
NIOSH (US health exposure limits):
PEL (Permissible)
 none[5]
REL (Recommended)
 TWA 0.1 mg/m3[5]
IDLH (Immediate danger)
 N.D.[5]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Carbofuran usage has increased in recent years because it is one of the few insecticides effective on soybean aphids, which have expanded their range since 2002 to include most soybean-growing regions of the United States. The main global producer is the FMC Corporation.

Carbofuran exhibits toxicity mediated by the same mechanism as that of the notorious V-series nerve agents and presents a risk to human health. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the United States Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.[6]

Chemistry

The technical or chemical name of carbofuran is 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate, and its CAS Number is 1563-66-2.[7] It is manufactured by the reaction of methyl isocyanate with 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

Bans

Carbofuran is banned in Canada and the European Union.[8]

In 2008, the United States Environmental Protection Agency (EPA) announced that it intended to ban carbofuran.[9] In December of that year, FMC Corp., the sole US manufacturer of carbofuran, announced that it had voluntarily requested that the EPA cancel all but six of the previously allowed uses of that chemical as a pesticide. With this change, carbofuran usage in the United States would be allowed only on corn, potatoes, pumpkins, sunflowers, pine seedlings and spinach grown for seed.[10] However, in May 2009, the EPA canceled all food tolerances, an action which amounts to a de facto ban on its use on all crops grown for human consumption.[11]

Kenya is considering banning carbofuran,[12] but it is legal to buy over-the-counter in Kenya.[13]

Toxicity to vertebrates

Carbofuran is highly toxic to vertebrates with an oral LD50 of 8–14 mg/kg in rats[14] and 19 mg/kg in dogs.

Carbofuran is known to be particularly toxic to birds. In its granular form, a single grain will kill a bird. Birds often eat numerous grains of the pesticide, mistaking them for seeds, and then die shortly thereafter. Before the granular form was banned by the EPA in 1991,[15] it was blamed for millions of bird deaths per year. the liquid version of the pesticide is less hazardous to birds since they are not as likely to ingest it directly, but it is still very hazardous.

Carbofuran has been illegally used to intentionally poison wildlife not only in the US, Canada and Great Britain; poisoned wildlife have included coyotes, kites, golden eagles and buzzards. Secondary fatal poisoning of domestic and wild animals has been documented,[16][17] specifically raptors (bald eagles and golden eagles), domestic dogs, raccoons, vultures and other scavengers. In Kenya, farmers are using carbofuran to kill lions and other predators.[13][18]

In a number of publicized incidents worldwide, carbofuran has also been used to poison domestic pets.[19][20][21]

Illegally smuggled carbofuran is used on 90% of marijuana grown illegally on public land in California.[22][23][24] These illegal, carbofuran-contaminated California marijuana grows appear to be the source for the majority of marijuana consumed in states where marijuana hasn't been legalized.[25]

Carbofuran is an endocrine disruptor and a probable reproduction/development intoxicant.[14] At low-level exposures, carbofuran may cause transient alterations in the concentration of hormones. These alterations may consequently lead to serious reproductive problems following repeated exposure.[26][27] When exposed in utero or during lactation, a decrease in sperm motility and sperm count along with an increase in percent abnormal sperm was observed in rats at 0.4 mg/kg dose level.[28] In one study, the exposure of rats to sublethal amounts of carbofuran decreased testosterone by 88%, while the levels of progesterone, cortisol, and estradiol were significantly increased (1279%, 202%, and 150%, respectively).[27]

Toxicity to humans

Carbofuran has one of the highest acute toxicities to humans of any insecticide widely used on field crops (only aldicarb and parathion are more toxic). Most carbofuran is applied by commercial applicators using closed systems with engineered controls so there is no exposure to it in preparation. However in developing countries, occupational exposure to the Carbofuran and resultant carbofuran-serum protein labeling has been reported that impacts human health and well-being.[29] Since its toxic effects are due to its activity as a cholinesterase inhibitor it is considered a neurotoxic pesticide. A recent study reports that carbofuran is a structural mimic of the neurohormone melatonin and could directly bind to MT2 melatonin receptor (Ki = 1.7 uM).[30] Disruption of melatonin signaling could impact the circadian rhythm balance and is linked to elevated risk of developing diabetes.[31]

Health scare in Thailand

Due to nonregistration of 4 carcinogenic chemicals used on crops not listed in the Dangerous Substances Act of Thailand, vegetables with residues of methomyl, carbofuran, dicrotophos, and EPN were taken off supermarket shelves in July 2012.[32]

Death of Lions in Kenya

In 2009, the CBS television news magazine 60 Minutes ran an exposé discussing the use of Furadan by Kenyan farmers as a poison to kill African lions. The piece suggested that Furadan was a serious threat to the future of the lion population in Africa.[18] FMC has commented on this issue through the media and their websites including furadanfacts.com.[33] They engaged with government officials, NGOs and others to try and resolve the illegal use of pesticides to kill wildlife. The company took action to stop the sale of this product and instituted a buyback program in East Africa when it was determined that the illegal and intentional misuse of chemicals against wildlife could not be controlled by education or stewardship programs alone.[34][35] Despite this, however, National Geographic stated in 2018 that carbofuran "is still very much available" in Kenya.[36]

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gollark: NO

See also
  • Dutch standards

References
  1. Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. pp. 3–94. ISBN 978-0-8493-0594-8.
  2. Sharom MS, Miles JRW, Harris CR, McEwen FL (1980). "Behaviour of 12 Insecticides in soil and aqueous suspensions of soil and sediment". Water Res. 14 (8): 1095–1100. doi:10.1016/0043-1354(80)90158-X.
  3. US EPA/OPPTS; Reregistration Eligibility Decisions (REDs) Database on Carbofuran (1563-66-2). EPA-738-R-06-031. August 2006.
  4. Hansch, C.; Leo, A.; D. Hoekman (1995). Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society. p. 101.
  5. NIOSH Pocket Guide to Chemical Hazards. "#0101". National Institute for Occupational Safety and Health (NIOSH).
  6. "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (July 1, 2008 ed.). Government Printing Office. Archived from the original (PDF) on February 25, 2012. Retrieved October 29, 2011. Cite journal requires |journal= (help)
  7. "Carbofuran". National Institute for Occupational Safety and Health. Archived from the original on June 18, 2019. Retrieved November 13, 2019.
  8. UNEP/FAO/RC/CRC/11/6 section 2.2.3 of the European Union notification
  9. US EPA (31 July 2008). "Carbofuran Cancellation Process". US EPA. Retrieved 11 August 2008.
  10. Erickson, Britt E. (January 5, 2009). "Manufacturer Drops Carbofuran Uses". Chemical & Engineering News. Vol. 87 no. 1. p. 18. Archived from the original on November 12, 2019. Retrieved November 12, 2019.
  11. "EPA Bans Carbofuran Pesticide Residues on Food". Environmental News Service. 11 May 2009. Retrieved 5 June 2009.
  12. "unknown". tradingmarkets.com. Archived from the original on 2012-06-29.
  13. Mynott, Adam (18 June 2008). "Insecticide 'killing Kenya lions'". BBC News. Archived from the original on 12 June 2018.
  14. "Page about Carbofuran in the IUPAC's database". IUPAC - International Union of Pure and Applied Chemistry. IUPAC.
  15. "Carbofuran". Retrieved 7 September 2012.
  16. Wobeser et al. 2004. Secondary poisoning of eagles following intentional poisoning of coyotes with anticholinesterase pesticides in Western Canada. Journal of Wildlife Diseases 40(2):163-172.
  17. The Federal Wildlife Officer, Volume 10, No. 2, Summer 1996
  18. "Poison Takes Toll On Africa's Lions". 60 Minutes. CBS News. 2009-03-26. Archived from the original on 2018-06-13.
  19. Dewhurst, Patrick (May 26, 2011). "Alarm over new pet poison". Cyprus Mail. Archived from the original on May 28, 2011.
  20. Vušović, A. (2011-02-25). "Psi u naselju Braće Jerković otrovani pesticidima". Blic (in Serbian). Archived from the original on 2016-03-05.
  21. Grobler, Riann (August 3, 2019). "As many as 1 000 dogs poisoned per week in SA". News24. Archived from the original on August 4, 2019. Retrieved November 12, 2019.
  22. Thompson, Don (August 28, 2018). "Toxic pesticides found at most illegal California pot farms". Associated Press. Archived from the original on November 12, 2019.
  23. McDaniel, Piper (August 29, 2019). "Illegal cannabis farms still scarring public lands, two years after Prop. 64". Los Angeles Times. Archived from the original on November 6, 2019.
  24. Westervelt, Eric (November 12, 2019). "Illegal Pot Operations In Public Forests Are Poisoning Wildlife And Water". Morning Edition. NPR. Retrieved November 12, 2019 – via WNYC.
  25. Chun, Rene (January–February 2019). "Ending Weed Prohibition Hasn't Stopped Drug Crimes". The Atlantic. Archived from the original on May 30, 2019.
  26. Lau, TK; Chu, W; Graham, N (June 2007). "Degradation of the endocrine disruptor carbofuran by UV, O3 and O3/UV". Water Science and Technology. 55 (12): 275–80. doi:10.2166/wst.2007.416. PMID 17674859.
  27. Goad, Ryan T.; Goad, John T.; Atieh, Bassam H.; Gupta, Ramesh C. (2004). "Carbofuran-induced endocrine disruption in adult male rats". Toxicology Mechanisms and Methods. 14 (4): 233–9. doi:10.1080/15376520490434476. PMID 20021136.
  28. Pant, N; Shankar, R; Srivastava, SP (May 1997). "In utero and lactational exposure of carbofuran to rats: effect on testes and sperm". Human & Experimental Toxicology. 16 (5): 267–72. doi:10.1177/096032719701600506. PMID 9192206.
  29. Rehman, Tanzila; Khan, Mohd M.; Shad, Muhammad A.; Hussain, Mazhar; Oyler, Benjamin L.; Shad, Muhammad A.; Goo, Young Ah.; Goodlett, David R. (2016-09-22). "Detection of Carbofuran-Protein Adducts in Serum of Occupationally Exposed Pesticide Factory Workers in Pakistan". Chemical Research in Toxicology. 29 (10): 1720–1728. doi:10.1021/acs.chemrestox.6b00222. ISSN 0893-228X. PMID 27657490.
  30. Popovska-Gorevski, Marina; Dubocovich, Margarita L.; Rajnarayanan, Rajendram V. (2017-02-20). "Carbamate Insecticides Target Human Melatonin Receptors". Chemical Research in Toxicology. 30 (2): 574–582. doi:10.1021/acs.chemrestox.6b00301. ISSN 0893-228X. PMC 5318275. PMID 28027439.
  31. "Extramural Papers of the Month". National Institute of Environmental Health Sciences. Retrieved 2017-04-26.
  32. "Cancer-causing chemical residues found in vegetables". Bangkok Post. 12 July 2012. Archived from the original on 12 November 2019. Retrieved 7 September 2012.
  33. "Furadan Facts > Home". Archived from the original on 2016-05-03. Retrieved 2016-05-08.
  34. Todt, Ron (2009-03-29). "Pa. pesticide maker vows steps to protect lions". USA Today. Associated Press. Archived from the original on 2016-05-12.
  35. "Furadan Facts > Home". Archived from the original on 2014-03-17. Retrieved 2009-03-30.
  36. Dobb, Edwin (August 2018). "Why Poison Is a Growing Threat to Africa's Wildlife". National Geographic. Photographs by Charlie Hamilton James. Retrieved November 12, 2018.
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