Bifenthrin

Lead Editor

Overview


Bifenthrin is an insecticide used heavily in the control of red imported fire ants. Due to its high toxicity to aquatic organisms, it is listed as a restricted use pesticide, although it can be purchased for residential use in lower concentrations. It has a very low solubility in water and tends to bind to soil, which minimizes runoff into water sources. It may also be marketed as Talstar, Bifenthrine, Brigade, Capture, Torant, Zipak, FMC 54800, and OMS3024 (#EXTOXNET).

Chemical Description


Bifenthrin is chemically classified as a pyrethroid. It is a waxy solid, with a color ranging from an off-white to a pale tan, with a slightly sweet odor. It is mostly insoluble in water. Commercially, it is available as emulsifiable concentrates, wettable powders, granules, flowable concentrates, and pellets (#EPA). Bifenthrin is not naturally synthesized.

Bifenthrin tends to bind tightly with soil (#CDPR). In soil, it has a half-life of 7 days to 8 months, depending on soil type and aeration (#EXTOXNET).

Uses


Bifenthrin is used regularly as an insecticide to target red imported fire ants. Other target species are aphids, worms, ants, gnats, moths, beetles, grasshoppers, mites, midges, spiders, ticks, yellow jackets, maggots, thrips, caterpillars, flies, and fleas (#EPA). It is often used in orchards, nurseries, and homes (#CDPR). Agriculturally, it is registered for use on greenhouse ornamentals and cotton (#EXTOXNET). It is used extensively on some crops, including corn. Roughly 70% of all US-grown hops and raspberries are treated with bifenthrin (#EPA).

Human Health Effects


People may be exposed to bifenthrin through ingestion or skin contact, although dermal absorption has little to no risks beyond mild discomfort. Ingestion is moderately toxic for mammals. Bifenthrin, as with other pyrethroids, overstimulates electrical signals in nerve cells. This may cause tremors and paralysis. However, in the body, bifenthrin is broken down and excreted quickly. In a seven-day study on rats, excess bifenthrin was found accumulated in high-fat tissues, including skin and ovaries of females. The EPA listed bifenthrin as a developmental toxicant in the toxics release inventory (#PANNA). The EPA has also identified bifenthrin as a class C carcinogen, meaning that it is a possible human carcinogen (#EXTOXNET).

Symptoms associated with exposure to pyrethroid compounds include skin and eye irritation, irritability to sound or touch, abnormal facial sensation, sensation of prickling, tingling, or creeping on skin, numbness, headache, dizziness, nausea, vomiting, diarrhea, salivation, and fatigue. At very high levels of exposure, muscle twitching and fluid accumulation in the lungs may occur (#PANNA).

Environmental Health Effects


Bifenthrin disrupts the nervous system and causes paralysis in insects. It has a moderate toxicity to mammals. For rats, the LD50 of females is 54mg/kg, and in males is 70mg/kg. Bifenthrin is also moderately toxic to birds. The LD50 of mallard ducks is 1280ppm, and 4450ppm for bobwhite quail. It has a very high toxicity for fish and other aquatic species. The LD50 is 0.00015 mg/l for rainbow trout, 0.00035 mg/l for bluegill, and 0.0016 mg/l for Daphnia. Bifenthrin is also toxic to non-target bees (#EXTOXNET).

Although it does not pose a high risk for mammals and birds, bifenthrin may accumulate in the food chain and harm high-level predators. Bifenthrin has a low potential for ground water contamination, although bifenthrin bound to sediment could contaminate runoff (#CDPR). Bifenthrin is not absorbed into plants, and has a low mobility in most types of soil (#EXTOXNET).

Regulation


Bifenthrin is a restricted use pesticide, meaning that it can only be sold and used by Certified Pesticide Applicators (#CDPR). However, some products for unrestricted residential use, which have lower bifenthrin concentrations, are legally sold.

Precautionary Notes


Although unsoluble in water, bifenthrin is highly toxic to aquatic organisms and should be used with caution near water sources. Otherwise, the risks to aquatic species are somewhat offset by the hydrophobic property of bifenthrin (#CDPR). It may be absorbed through skin, although this has low risk for humans.

References



California Department of Pesticide Regulation. Environmental Fate of Bifenthrin. (December 1999). http://www.cdpr.ca.gov/docs/emon/pubs/fatememo/bifentn.pdf [Accessed 7-06-10].


Environmental Protection Agency. Bifenthrin Summary Document. (June 2010). http://www.regulations.gov/search/Regs/home.html [Accessed 7-09-10].


Extension Toxicology Network. Pesticide Information Profiles - Bifenthrin. (1996). http://extoxnet.orst.edu/pips/bifenthr.htm [Accessed 6-30-10].


Pesticide Action Network North America. Bifenthrin. http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC32863 [Accessed 7-07-10].

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