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EXTOXNET PIP-PARAQUAT http://extoxnet.orst.edu/pips/paraquat.htm EXTOXNET Extension Toxicology Network Pesticide Information Profiles A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program. EXTOXNET primary files maintained and archived at Oregon State University Revised June 1996 Paraquat Trade and Other Names: Product names include Crisquat, Cyclone, Dextrone, Dexuron, Gramoxone Extra, Herbaxone, Ortho Weed and Spot Killer, and Sweep. The compound may be found in formulations with many other herbicides, including simazine and diquat dibromide. Regulatory Status: Paraquat is a highly toxic compound in EPA toxicity class I. Products containing it must be is labeled with the Signal Words DANGER- POISON. Paraquat is a Restricted Use Pesticide (RUP). RUPs may be purchased and used only by certified applicators. Chemical Class: quaternary nitrogen compound Introduction: Paraquat is a quaternary nitrogen herbicide widely used for broadleaf weed control. It is a quick-acting, nonselective compound, that destroys green plant tissue on contact and by translocation within the plant. It has been employed for killing marijuana in the U.S. and in Mexico. It is also used as a crop desiccant and defoliant, and as an aquatic herbicide. Formulation: Not Available Toxicological Effects: • Acute toxicity: Paraquat is highly toxic via ingestion, with reported oral LD50 values of 110 to 150 mg/kg in rats, 50 mg/kg in monkeys, 48 mg/kg in cats, and 50 to 70 mg/kg in cows [8,87]. The toxic effects of paraquat are due to the cation, and the halogen anions have little toxic effects [87]. The dermal LD50 in rabbits is 236 to 325 mg/kg, indicating moderate toxicity by this route [58,87]. The 4-hour inhalation LC50 is greater than 20 mg/L for the technical grade of the compound [87]. It causes skin and eye irritation in rabbits (severe for some of the formulated products) and also has caused skin sensitization in guinea pigs in some formulations [87]. Effects due to high acute exposure to paraquat may include excitability and lung congestion, which in some cases leads to convulsions, incoordination, and death by respiratory failure [87]. If swallowed, burning of the mouth and throat often occurs, followed by gastrointestinal tract 1 of 4 2/20/2008 2:04 PM