Dichlorvos concentrations

Dichlorvos is a particularly versatile organophosphate since it can be incorporated as a plasticizer into polyvinyl chloride resin pellets and can be released slowly from the undigestible pellets as they pass through the digestive tract. This allows for a therapeutic concentration against parasites all along the digestive tract. 

Prepared by bulk polymerization, an MIP for the detection of dicrotophos based on the Eu3+ complex has recently been presented [58]. The authors used reversible addition fragmentation chain transfer (RAFT) polymerization followed by ring closing methathesis (RCM) to obtain the star MIP with arms made out of block copolymer. The star MIP containing Eu3+ exhibited strong fluorescence when excited at 338 nm with a very narrow emission peak (half width -10 nm) at 614 nm. This MIP was sensitive to dicrotophos in the range of 0-200 ppb, but showed saturation above this limit. Cross-reactivity of this MIP was evaluated with respect to structurally similar compounds dichlorvos, diazinon and dimethyl methylphosphonate. In these tests no optical response of the polymer was detected even at concentrations much higher than the initial concentration of dicrotophos (>1000 ppb). 

Early results indicate a high sensitivity for pesticide detection, with the system being capable of detecting dichlorvos at concentrations as low as 1 x 10-17M and parathion and azinphos both at concentrations as low as 1 x 10-16M [40]. 

Biocides most often found in the indoor environment are chlorinated hydrocarbons like chlordane, DDT, dieldrin, lindane, heptachlor and methoxychlor, pyrethroids like cyfluthrin, cypermethrin, and permethrin, organophosphates like chlorpyrifos, diazinon, dichlorvos, isofenfos, and malathion, carbamates like ben-diocarb, carbaryl and propoxur and chlorophenols like pentachlorophenol (PCP), chlorocresol (4-chloro-3-methylphenol) and o-phenylphenol. Residues formed in house dust may vary in different countries (Butte, 2003), but biocides like chlorpyrifos, DDT, methoxychlor, permethrin, pentchlorophenol and propoxur seem to be the active compounds in biocide formulations even in different continents, as they are found equally in house dust samples form Germany and the USA (Becker et al., 2002 Butte, 2003 Camann, Colt and Zuniga, 2002). Concentrations of biocides in house dust are mostly in the milligram per kilogram range, they seldom exceed a microgram per cubic meter in indoor air. 

Uses Dichlorvos is a colorless to amber liquid with a mild chemical odor. The USEPA has classified it under RUP, and hence it should be purchased and used only by certified applicators. Dichlorvos is used primarily to control household insects such as flies, aphids, spider mites, caterpillars, and thrips. The chemical also is used therapeutically against parasitic worm infections in dogs, livestock, and humans. The mechanism of action appears to be a contact poison and stomach poison in insects caused by interference with cholinesterase, a neurologic enzyme that is important to nerve transmissions. It is used as a fumigant and has been used to make pet collars and pest strips. It is available as an aerosol and a soluble concentrate.28 44... 

T ichlorvos (DDVP, dichlorovinyldimethyl phosphate) was first syn-thesized in the late 1940s, but active investigation of its insecticidal properties was not initiated until 1954. Investigations at that time revealed that low concentrations of the vapor of dichlorvos were toxic to adult mosquitoes and flies and that there appeared to be a relatively wide margin of safety between the insecticidal dose and the concentration required to affect man. 

Table IV. Concentration of Dichlorvos in Air of Homes in which Vapona Resin Vaporizers Were Installed...

Because of its high vapor pressure, dichlorvos is useful in the control of insects in closed spaces (e.g., warehouses, greenhouses, animal shelters, homes, and restaurants). It is available in oil solutions, emu-Isifiable concentrates, aerosols, and baits. Therapeutically, dichlorvos is used as a broad-spectrum anthelmintic (for destroying or expelling intestinal worms). It is also used as a feed through larvicide to control botfly larvae in the manure. It is primarily used for insect control. Dichlorvos is also a breakdown product of the organophosphorus pesticide trichlorfon (metrifonate). 

Under most conditions, dichlorvos is not detectable in any tissues. Dichlorvos is not stored in tissues, it does not accumulate in secretions (e.g., milk), and it is below detection levels in the blood of various species at exposure levels in excess of 10 times those effective for insect control. At exceptionally high concentrations (90mgm or about 2000 times normal exposure levels), dichlorvos was detectable in various tissues of the rat. 

Organophosphate Dimpylate (diazinon) Dichlorvos Fenitrothion Fenthion Phosmet (dogs) Fleas, ticks Solution (spot on) collars aerosol spray liquid concentrate (sponge on)... 

Various OPC inhibit both CarbE and AChE at similar concentrations ranging from 1 to 1000 nmol/1. CBDP, dichlorvos, DFP and paraoxon show higher... 

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