Fipronil

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Fipronil
Fipronil structure.png
Fipronil-3D-sticks.png
Identifiers
CAS number 120068-37-3 YesY
PubChem 3352
ChemSpider 3235 YesY
UNII QGH063955F YesY
KEGG D01042 YesY
ChEBI CHEBI:5063 YesY
ChEMBL CHEMBL101326 YesY
ATCvet code QP53AX15
Jmol-3D images Image 1
Properties
Molecular formula C12H4Cl2F6N4OS
Molar mass 437.15 g/mol
Density 1.477-1.626 g/cm³
Melting point 200.5 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Fipronil is a broad-use insecticide that belongs to the phenylpyrazole chemical family. Fipronil is a broad-spectrum insecticide that disrupts the insect central nervous system by blocking GABA-gated chloride channels and glutamate-gated chloride (GluCl) channels, resulting in central nervous system toxicity. This causes hyperexcitation of contaminated insects' nerves and muscles. Specificity of fipronil on insects may come from a better efficacy on GABA receptor, but also because GluCl channels do not exist in mammals.[1]

Effects[edit]

Fipronil is a slow acting poison. When used as bait, it allows the poisoned insect time to return to the colony or harborage. In cockroaches, the feces and carcass can contain sufficient residual pesticide to kill others in the same nesting site[citation needed]. In ants, the sharing of the bait among colony members assists in the spreading of the poison throughout the colony[citation needed]. With the cascading effect, the projected kill rate is about 95% in three days for ants and cockroaches[citation needed]. Fipronil serves as a good bait toxin not only because of its slow action, but also because most, if not all, of the target insects do not find it offensive or repulsive.[citation needed]

Toxic baiting with fipronil has also been shown to be extremely effective in locally eliminating German wasps (commonly called yellow jackets in North America). All colonies within foraging range are completely eliminated within one week.[2][3][4]

Wildlife impacts include the following:

  • Fipronil is highly toxic to fish and aquatic invertebrates. Its tendency to bind to sediments and its low water solubility may reduce the potential hazard to aquatic wildlife.[5]
  • Fipronil is toxic to bees and should not be applied to vegetation when bees are foraging.[5]
  • Fipronil has been found to be highly toxic to upland game birds, but is practically nontoxic to waterfowl and other bird species. One of the metabolites of fipronil has a higher toxicity to birds than the parent compound itself.[6]

Fipronil is also used as the active ingredient in flea control products for pets, field pest control for corn, golf courses and commercial turf, although flea populations appear to be developing a genetic resistance to its effects.[7]

Pharmacodynamics[edit]

Fipronil acts by binding to allosteric sites of GABAA receptors and GluCl receptors (of insects) as an antagonist (a form of noncompetitive inhibition). This prevents the opening of chloride ion channels normally encouraged by GABA, reducing the chloride ions' ability to lower a neuron's membrane potential. This results in an overabundance of neurons reaching action potential and likewise CNS toxicity via over-stimulation.[8][9][10][11]

Acute oral LD50 (rat) 97 mg/kg
Acute dermal LD50 (rat) >2000 mg/kg

In animals and humans, fipronil poisoning is characterized by vomiting, agitation, and seizures, and can usually be managed through supportive care and early treatment of seizures, generally with benzodiazepine use.[12][13]

Discovery and use[edit]

Fipronil was discovered and developed by Rhône-Poulenc between 1985 and 1987, and placed on the market in 1993 under the US Patent No. US 5,232,940 B2. Between 1987 and 1996, fipronil was evaluated on more than 250 insect pests on 60 crops worldwide, and crop protection accounted for about 39% of total fipronil production in 1997. Since 2003, BASF holds the patent rights for producing and selling fipronil-based products in many countries.

Fipronil is or has been used in these manners:

  • Marketed under the names Termidor, Ultrathor, and Taurus in Africa and Australia, fipronil effectively controls termite pests, and was shown to be effective in field trials in these countries.[14]
    • Termidor has been approved for use against the Rasberry crazy ant in the Houston, Texas area, under a special "crisis exemption" from the Texas Department of Agriculture and the Environmental Protection Agency. The chemical is only approved for use in Texas counties experiencing "confirmed infestations" of the newly discovered ant species.[15] Use of Termidor is restricted to certified pest control operators in the following states: Alaska, Connecticut, Nebraska, South Carolina, Massachusetts, Indiana, New York, and Washington State.[16]
  • In the UK, provisional approval for five years has been granted for fipronil use as a public hygiene insecticide.[14]
  • Fipronil is the main active ingredient of Frontline TopSpot, Fiproguard, Flevox and PetArmor (used along with S-methoprene in the 'Plus' versions of these products); these treatments are used in fighting tick and flea infestations in dogs and cats. It may also be used in humans if placed on ankles, wrist or neck to prevent ticks.[17]
  • In New Zealand fipronil has been used in a trial to control wasps, which are a threat to indigenous biodiversity.[4]

Ecological toxicity[edit]

Fipronil is highly toxic for crustaceans, insects and zooplankton,[18] as well as bees, termites, rabbits, the fringe-toed lizard and certain groups of gallinaceous birds. It appears to reduce the longevity and fecundity of female braconid parasitoids. It is also highly toxic to many fish, though its toxicity varies with species. Conversely, the substance is relatively innocuous to passerines, wildfowl and earthworms.

Few studies of effects on wildlife have been conducted, but studies of the nontarget impact from emergency applications of fipronil as barrier sprays for locust control in Madagascar showed adverse impacts of fipronil on termites, which appear to be very severe and long-lived. There were also indications of adverse effects in the short term on several other invertebrate groups, one species of lizard (Trachylepis elegans) and several species of birds (including the Madagascar bee-eater).

Nontarget effects on some insects (predatory and detritivorous beetles, some parasitic wasps and bees) were also found in field trials of fipronil for desert locust control in Mauritania, and very low doses (0.6-2.0 g a.i./ha) used against grasshoppers in Niger caused impacts on nontarget insects comparable to those found with other insecticides used in grasshopper control. The implications of this for other wildlife and ecology of the habitat remain unknown, but appear unlikely to be severe.[14]

In May 2003, the French Directorate-General of Food at the Ministry of Agriculture determined that a case of mass bee mortality observed in southern France was related to acute fipronil toxicity. Toxicity was linked to defective seed treatment, which generated dust. In February 2003, the Ministry decided to temporarily suspend the sale of BASF crop protection products containing fipronil in France.[19] The seed treatment involved has since been forbidden.[citation needed] Fipronil was used in a broad spraying to control locusts in Madagascar in a program that began in 1997.[20]

Colony collapse disorder[edit]

Fipronil is one of the main chemical causes blamed for the spread of colony collapse disorder among bees. It has been found by the Minutes-Association for Technical Coordination Fund in France that even at very low nonlethal doses for bees, the pesticide still impairs their ability to locate their hive, resulting in large numbers of forager bees lost with every pollen-finding expedition.[21] A 2013 report by the European Food Safety Authority identified fipronil as a "a high acute risk to honeybees when used as a seed treatment for maize and on July 16, 2013 the EU voted to ban the use of Fipronil on corn and sunflowers within the EU. The ban took effect at the end of 2013."[22][23]

Toxicity[edit]

Fipronil is classed as a WHO Class II moderately hazardous pesticide, and has a rat acute oral LD50 of 97 mg/kg.

It has moderate acute toxicity by the oral and inhalation routes in rats. Dermal absorption in rats is less than 1% after 24 h and toxicity is considered to be low. It has been found to be very toxic to rabbits.

The photodegradate MB46513 or desulfinylfipronil, appears to have a higher acute toxicity to mammals than fipronil itself by a factor of about 10.[24]

Toxicity on humans has been tested in few studies, more commonly involving human cells which were used in carcinogenicity studies, but with no adverse effects. Yet, fipronil has been classified by the EPA as a Group C (possible human) carcinogen based on an increase in thyroid follicular cell tumors in both sexes of the rat. Furthermore, fipronil is considered slightly irritating to the skin, while moderately irritating to the eyes in both humans and animals. There is no evidence that it causes birth defects.[25]

Two Frontline TopSpot products were determined by the New York State Department of Environmental Conservation to pose no significant exposure risks to workers applying the product. However, concerns were raised about human exposure to Frontline spray treatment in 1996, leading to a denial of registration for the spray product. Commercial pet groomers and veterinarians were considered to be at risk from chronic exposure via inhalation and dermal absorption during the application of the spray, assuming they may have to treat up to 20 large dogs per day.[14] Fipronil is not volatile, so there is little likelihood of humans being exposed to this compound in the air.[25]

See also[edit]

References[edit]

  1. ^ Raymond-Delpech V, Matsuda K, Sattelle BM, Rauh JJ, Sattelle DB (2005) Ion channels: molecular targets of neuroactive insecticides. Places on dogs and cars will protect against flea and tic infestation. Humans may also use Frontline Plus by placing it on areas where ticks could jump, like ankles, wrists and neck.Invert Neurosci: 1-15.
  2. ^ Paula Sackmann, Mauricio Rabinovich and Juan Carlos Corley J. Econ. Entomol. (2001). "Successful Removal of German Yellowjackets (Hymenoptera: Vespidae) by Toxic Baiting." (PDF). pp. 94(4):811–816. 
  3. ^ "Short and long-term control of Vespula pensylvanica in Hawaii by fipronil baiting". 
  4. ^ a b "Revive Rotoiti Autumn 2011". Department of Conservation. 2011. Retrieved 11 April 2012. 
  5. ^ a b "Fipronil". National Pesticides Communication Network. p. 3. Retrieved 19 June 2012. 
  6. ^ United States Environmental Protection Agency Office of Prevention, Pesticides and Toxic Substances (1996). "Fipronil. May 1996. New Pesticide Fact Sheet. US EPA Office of Prevention, Pesticides and Toxic Substances.". 
  7. ^ Maddison, Jill E.; Page, Stephen W. (2008). Small Animal Clinical Pharmacology (Second ed.). Elsevier Health Sciences. p. 229. ISBN 9780702028588. 
  8. ^ Cole, L. M.; Nicholson, R. A.; Casida, J. E. Action of Phenylpyrazole Insecticides at the GABA-Gated Chloride Channel. Pestic. Biochem. Physiol. 1993, 46, 47-54.
  9. ^ Ratra, G. S.; Casida, J. E. GABA receptor subunit composition relative to insecticide potency and selectivity. Toxicol. Lett. 2001, 122, 215-222.
  10. ^ WHO. Pesticide Residues in Food - 1997: Fipronil; International Programme on Chemical Safety, World Health Organization: Lyon, 1997.
  11. ^ Olsen RW, DeLorey TM (1999). "Chapter 16: GABA and Glycine". In Siegel GJ, Agranoff BW, Fisher SK, Albers RW, Uhler MD. Basic neurochemistry: molecular, cellular, and medical aspects (Sixth ed.). Philadelphia: Lippincott-Raven. ISBN 0-397-51820-X. 
  12. ^ Ramesh C. Gupta (2007). Veterinary Toxicology. pp. 502–503. ISBN 978-0-12-370467-2. 
  13. ^ Mohamed F, Senarathna L, Percy A, Abeyewardene M, Eaglesham G, Cheng R, Azher S, Hittarage A, Dissanayake W, Sheriff MH, Davies W, Buckley NA, Eddleston M., Acute human self-poisoning with the N-phenylpyrazole insecticide fipronil--a GABAA-gated chloride channel blocker, J Toxicol Clin Toxicol. 2004;42(7):955-63.
  14. ^ a b c d e f g "Fipronil". Pesticides News 48: 20. 2000. 
  15. ^ "Rasberry Crazy Ant". Texas A&M. 2008-04-12. Retrieved 20012-08-06. 
  16. ^ "Termidor SC". Retrieved 2012-08-06. 
  17. ^ "Frontline Plus Flea Treatment". Retrieved 2010-05-03. 
  18. ^ "Ecotoxicity for Fipronil". Retrieved 2010-05-03. 
  19. ^ Elise Kissling, BASF SE (2003). "BASF statement regarding temporary suspension of sales of crop protection products containing fipronil in France". 
  20. ^ June 2000 BBC News story "Anti-locust drive 'created havoc'".
  21. ^ "Colony Collapse Disorder linked to Fipronil". Retrieved 2010-06-17. 
  22. ^ "EFSA assesses risks to bees from fipronil". 27 May 2013. Retrieved 29 May 2013. 
  23. ^ Carrington, Damian (16 July 2013). "EU to ban fipronil to protect honeybees". The Guardian (London). 
  24. ^ "Fipronil insecticide: Novel photochemical desulfinylation with retention of neurotoxicity". 
  25. ^ a b "Health and Environmental Aspects of Fipronil (TERMIDOR) Use in Tree Termite Eradication". Retrieved 2010-05-03. 

External links[edit]