Cyfluthrin is a synthetic (type 2) pyrethroid insecticide that has both contact and stomach poison action. It is a non-systemic chemical used to control cutworms, ants, silverfish, cockroaches, termites, grain beetles, weevils, mosquitoes, fleas, flies, corn earworms, tobacco budworm, codling moth, European corn borer, cabbageworm, loopers, armyworms, boll weevil, alfalfa weevil, Colorado potato beetle, and many others. Its primary agricultural uses have been for control of chewing and sucking insects on crops such as cotton, turf, ornamentals, hops, cereal, corn, deciduous fruit, peanuts, potatoes, and other vegetables. Cyfluthrin is also used in public health situations and for structural pest control. (5)
belongs to the class of organic compounds known as pyrethroids. These are organic compounds similar to the pyrethrins. Some pyrethroids containing a chrysanthemic acid esterified with a cyclopentenone (pyrethrins), or with a phenoxybenzyl group.
Both type I and type II pyrethroids exert their effect by prolonging the open phase of the sodium channel gates when a nerve cell is excited. They appear to bind to the membrane lipid phase in the immediate vicinity of the sodium channel, thus modifying the channel kinetics. This blocks the closing of the sodium gates in the nerves, and thus prolongs the return of the membrane potential to its resting state. The repetitive (sensory, motor) neuronal discharge and a prolonged negative afterpotential produces effects quite similar to those produced by DDT, leading to hyperactivity of the nervous system which can result in paralysis and/or death. Other mechanisms of action of pyrethroids include antagonism of gamma-aminobutyric acid (GABA)-mediated inhibition, modulation of nicotinic cholinergic transmission, enhancement of noradrenaline release, and actions on calcium ions. They also inhibit calium channels and Ca2+, Mg2+-ATPase. (7, 8, 4)
Metabolism
The initial step in cyfluthrin biotransformation is ester hydrolysis, giving a 3-phenoxy-4-fluorobenzyl alcohol intermediate and the permethric acid fraction. After ester hydrolysis, the 3-phenoxy-4-fluorobenzyl alcohol moiety is oxidized to the free metabolite 3-phenoxy-4-fluorobenzoic acid. This metabolite can then either be conjugated with glycine to form 3-phenoxy-4-fluorohippuric acid or hydroxylated to give 4'-hydroxy-3-phenoxy-4-fluorobenzoic acid. The metabolites as well as a small pert of the unmetabolized compound are excreted in the urine in the feces. (4, 2)
At high doses, signs of poisoning attributable to cyfluthrin include profuse salivation and pulmonary edema, clonic seizures, opisthotonos (i.e., the spine is bent forward such that a supine body rests on its head and heels), coma, and death. At lower doses, commonly observed effects include paresthesia and erythema. As for other type 2 pyrethroids, cyfluthrin produces a severe syndrome characterized by salivation and choreoathetosis. (6)
Symptoms
Following dermal exposure to cyfluthrin, feelings of numbness, itching, burning, stinging, tingling, or warmth may occur, that could last for a few hours. Dizziness, headache, nausea, muscle twitching, reduced energy, and changes in awareness can result from inhalation or ingestion of large amounts of cyfluthrin. Paralysis can occur after exposure. (4)
Treatment
Following oral exposure, the treatment is symptomatic and supportive and includes monitoring for the development of hypersensitivity reactions with respiratory distress. Provide adequate airway management when needed. Gastric decontamination is usually not required unless the pyrethrin product is combined with a hydrocarbon. Following inhalation exposure, move patient to fresh air. monitor for respiratory distress. If cough or difficulty breathing develops, evaluate for respiratory tract irritation, bronchitis, or pneumonitis. Administer oxygen and assist ventilation as required. Treat bronchospasm with inhaled beta2 agonist and oral or parenteral corticosteroids. In case of eye exposure, irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility. If the contamination occurs through dermal exposure, Remove contaminated clothing and wash exposed area thoroughly with soap and water. A physician may need to examine the area if irritation or pain persists. Vitamin E topical application is highly effective in relieving parenthesis. (3)
