Furadan

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Carbofuran
Identifiers
CAS number 1563-66-2 YesY
PubChem 2566
ChemSpider 2468 YesY
UNII SKF77S6Y67 YesY
KEGG C14291 YesY
ChEBI CHEBI:34611 YesY
Jmol-3D images Image 1
Properties
Molecular formula C12H15NO3
Molar mass 221.25 g mol−1
Appearance White, crystalline solid
Density 1.18 g/cm3
Melting point

151 °C, 424 K, 304 °F ([4])

Boiling point

313.3 °C, 586 K, 596 °F

Solubility in water 320 mg/L[1]
Solubility Highly soluble in N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile, methylene chloride, cyclohexanone, benzene, and xylene[2]
log P 2.32 (octanol/water)[3]
Hazards
Flash point 143.3 °C (289.9 °F)
LD50 8–14 mg/kg (oral, rat)
19 mg/kg (oral, dog)
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.

In 2008, the United States Environmental Protection Agency (EPA) announced that it intends to ban carbofuran.[5] 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 6 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.[6] 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.[7]

Kenya is considering banning carbofuran,[8] but it is legal to buy over-the-counter in Kenya.[9]

It was reported in 2012 that whilst Wildlife Minister in the UK, Richard Benyon, who owns both pheasant and grouse shoots, refused a request from other MPs that possession of carbofuran should be made a criminal offence.[10] Green Party MP Caroline Lucas was quoted as saying: "The minister's shocking refusal to outlaw the possession of a poison used only by rogue gamekeepers to illegally kill birds of prey would be inexplicable were it not for his own cosy links to the shooting lobby."[10]

Toxicity to vertebrates

Carbofuran is highly toxic to vertebrates with an oral LD50 of 8–14 mg/kg in rats 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,[11] 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. The EPA announced on July 25, 2008 that it intends to ban all forms in the US.[12] The ban requires that no residue be present on domestic or imported foods.[13]

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.[9][16]

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

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.

Carbofuran is also a powerful endocrine disruptor that can cause transient alterations in the concentration of many hormones in animals and humans even at extremely low doses. These alterations may consequently lead to serious reproductive problems following repeated exposure.[19][20] 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).[19]

Carbofuran can also be toxic to testes in sublethal amounts. A decrease in sperm motility, sperm count along with increase in percent abnormal sperm was observed at 0.4 mg/kg dose level.[21]

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

External links

  • FuradanFacts.com
  • CDC - NIOSH Pocket Guide to Chemical Hazards - Carbofuran
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