Carbofuran

Carbofuran
Names
IUPAC name
2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate
Other names
Furadan, Curater, Furacarb
Identifiers
1563-66-2 YesY
ChEBI CHEBI:34611 YesY
ChEMBL ChEMBL416081 YesY
ChemSpider 2468 YesY
Jmol interactive 3D Image
KEGG C14291 YesY
PubChem 2566
UNII SKF77S6Y67 YesY
Properties
C12H15NO3
Molar mass 221.26 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)
US health exposure limits (NIOSH):
none[5]
TWA 0.1 mg/m3[5]
N.D.[5]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Carbofuran is one of the most toxic carbamate pesticides. It is marketed under the trade names Furadan, by FMC Corporation and Curater, 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 here the plant distributes it throughout its organs where insecticidal concentrations are attained. Carbofuran also has contact activity against pests.

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 U.S. The main global producer is the FMC Corporation.

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. 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.[6]

In 2008, the United States Environmental Protection Agency (EPA) announced that it intends to ban carbofuran.[7] In December of that year, FMC Corp., the sole US manufacturer of carbofuran, announced that it had voluntarily requested that the United States Environmental Protection Agency cancel all but six of the previously allowed uses of that chemical as a pesticide. With this change, carbofuran usage in the US would be allowed only on maize, potatoes, pumpkins, sunflowers, pine seedlings and spinach grown for seed.[8] However, in May 2009 EPA cancelled all food tolerances, an action which amounts to a de facto ban on its use on all crops grown for human consumption.[9]

Kenya is considering banning carbofuran,[10] but it is legal to buy over-the-counter in Kenya.[11]

Toxicity to vertebrates

Carbofuran is highly toxic to vertebrates with an oral LD50 of 8–14 mg/kg in rats[12] 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 U.S. Environmental Protection Agency in 1991,[13] 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 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,[14][15] 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.[11][16]

In a number of publicized incidents worldwide, carbofuran has also been used to poison domestic pets.[17][18]

Carbofuran is an endocrine disruptor and a probable reproduction/development intoxicant.[12] 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.[19][20] When exposed in utero or during lactation, a decrease in sperm motility, sperm count along with increase in percent abnormal sperm was observed in rats at 0.4 mg/kg dose level.[21] 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).[20]

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). A quarter teaspoon (1 mL) can be fatal. Most carbofuran is applied by commercial applicators using closed systems with engineered controls so there is no exposure to it in preparation. Since its toxic effects are due to its activity as a cholinesterase inhibitor it is considered a neurotoxic pesticide.

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.[22]

See also

References

  1. ↑ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 3–94. ISBN 0-8493-0594-2.
  2. ↑ Sharom MS; et al. (1980). Water Res 14: 1095–1100. Missing or empty |title= (help)
  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. 1 2 3 "NIOSH Pocket Guide to Chemical Hazards #0101". National Institute for Occupational Safety and Health (NIOSH).
  6. ↑ UNEP/FAO/RC/CRC/11/6 section 2.2.3 of the European Union notification
  7. ↑ US EPA (31 July 2008). "Carbofuran Cancellation Process". US EPA. Retrieved 11 August 2008.
  8. ↑ Chemical & Engineering News, 5 January 2009, "Manufacturer drops Carbofuran uses", p. 18
  9. ↑ "EPA Bans Carbofuran Pesticide Residues on Food". Environmental News Service. 11 May 2009. Retrieved 5 June 2009.
  10. ↑ "unknown". tradingmarkets.com.
  11. 1 2 Mynott, Adam (18 June 2008). "Insecticide 'killing Kenya lions'". BBC news.
  12. 1 2 "Page about Carbofuran in the IUPAC's database". IUPAC - International Union of Pure and Applied Chemistry. IUPAC.
  13. ↑ "Carbofuran". Retrieved 7 September 2012.
  14. ↑ 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.
  15. ↑ The Federal Wildlife Officer, Volume 10, No. 2, Summer 1996
  16. ↑ "Poison Takes Toll on Africa's Lions". CBS 60 Minutes.
  17. ↑ "Alarm over new pet poison". Cyprus Mail. May 26, 2011.
  18. ↑ "Psi u naselju Braće Jerković otrovani pesticidima" (in Serbian). Blic Online. 2011-02-25.
  19. ↑ Lau, TK; Chu, W; Graham, N (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.
  20. 1 2 Goad, RT; Goad, JT; Atieh, BH; Gupta, RC (2004). "Carbofuran-induced endocrine disruption in adult male rats". Toxicology mechanisms and methods 14 (4): 233–9. doi:10.1080/15376520490434476. PMID 20021136.
  21. ↑ Pant, N; Shankar, R; Srivastava, SP (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.
  22. ↑ "Cancer-causing chemical residues found in vegetables". Bangkok Post. 12 July 2012. Retrieved 7 September 2012.

External links

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