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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

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

Diphacinone

Trade and Other Names: Common names include diphacin (Italy and Turkey), ratindan (in the former U.S.S.R.), dipazin, diphenadione, and diphenacin. Trade names include Diphacine, Ditrac, Gold Crest, Kill-Ko, P.C.Q., Promar, Ramik, Rat Killer, Rodent Cake, and Tomcat.

Regulatory Status: Diphacinone is an highly toxic compound in EPA Toxicity Class I. All formulations of diphacinone are Restricted Use Pesticides (RUPs). RUPs may be purchased and used only by certified applicators. The Signal Word required on products containing diphacinone varies, depending on the type of formulation: DANGER applies to the technical material, WARNING to concentrate formulations, and CAUTION to bait formulations.

Chemical Class: Not Available

Introduction: Diphacinone is a rodenticide bait used for control of rats, mice, voles, and other rodents. It is available in meal, pellet, wax block, and liquid bait formulations, as well as in tracking powder and concentrate formulations. It may also be used as a anticonvulsant drug under the name of diphenadione. It has also been used successfully in controlling vampire bats, a vector for rabies.

Formulation: It is available in meal, pellet, wax block, and liquid bait formulations, as well as in tracking powder and concentrate formulations.

Toxicological Effects:

• Acute toxicity: Diphacinone is highly toxic by ingestion, with oral LD50 values of 0.3 to 7 mg/kg in rats, 3.0 to 7.5 mg/kg in dogs, 14.7 mg/kg in cats, 150 mg/kg in pigs, 50 to 300 mg/kg in mice, and 35 mg/kg in rabbits [1,172]. It is highly toxic by skin exposure, with reported dermal LD50 values of less than 200 mg/kg in rats, 340 mg/kg in mice, and greater than 3.6 mg/kg in rabbits [1,172]. It is not reported to be a skin or eye irritant in rabbits, nor a skin sensitizer in guinea pigs [1,172]. The 4-hour inhalation LC50 of diphacinone in rats of less than 2 mg/L also indicates high toxicity [1,173]. Diphacinone works by inhibition of liver-synthesized coagulation proteins, leading to internal hemorrhaging [172]. If the dose is sufficient, this may result in death [172]. Effects exhibited in test animals during acute LD50 testing included labored breathing, muscular weakness, excitability, congested blood flow to the lungs, and irregular heartbeats. Other signs of poisoning include spitting of blood, bloody urine or stools, and widespread bruising or bleeding into the joints [172]. Use in humans as an anticoagulant drug has been apparently discontinued, possibly due to its structural similarity to another compound (phenindone). Phenindone was noted to pose risks of hepatitis with jaundice, damage to kidneys, severe skin irritation, and and massive tissue swelling [172]. The use history of diphacinone indicates that it produced no adverse health effects except occasional nausea and some hemorrhagic effects that persisted for 6 to 10 days [172]. In other case reports, the anticoagulant effects are reported to persist for several weeks to months [8].
• Chronic toxicity: No permanent or life-threatening effects occurred in humans on recommended dose regimes of an initial 20 mg dose (ca. 0.29 mg/kg in a 70 kg human), followed by successive 2 to 4 mg daily doses (ca. 0.03 to 0.06 mg/kg/day in a 70 kg person) for several days to weeks [172]. All test animals exposed at dietary levels of 0.1 and 0.2 mg/kg/day in a 21-day study showed fatal massive internal hemorrhaging, although at doses of 0.05 mg/kg/day, they were unaffected [172]. In a 90-day study in which rats were given dietary doses of 0.002 to 0.025 mg/kg/day, single rats in each of the 0.003 and 0.013 mg/kg/day dose groups died from internal hemorrhage, but the others remained unaffected by treatment [172]. The effects due to chronic exposure are similar to those which may be expected from acute exposure, but animal studies and human use experience suggest that there is a level of chronic exposure at which no adverse health effects may occur. The available studies also suggest that some individuals in any population may be much more succeptible to effects than others. These individuals may include those with poor nutritional status and/or Vitamin K deficiency, liver or kidney disorders, or infectious diseases [8].
• Reproductive effects: No data are currently available [8].
• Teratogenic effects: No data are currently available [8].
• Mutagenic effects: Diphacinone was not mutagenic in the Ames test [1,172]. No other data regarding mutagenic effects are currently available [1,174].
• Carcinogenic effects: No data are currently available
• Organ toxicity: The principal target of diphacinone is the blood (specifically the clotting factors), but effects on the liver, kidneys, heart, and musculature have been seen, probably as secondary effects.

• Fate in humans and animals: Rats eliminated 70% of the administered oral dose via the feces and 10% in the urine within 8 days [172]. A similar pattern of elimination occurred in mice [172]. Animal studies indicate that little metabolism takes place, and that diphacinone which is not eliminated may concentrate to varying degrees in the liver, kidneys, and lungs [8,172]. The half-life of diphacinone in humans is 15 to 20 days [8]. It was determined that cattle dosed with the compound as an anti-bat measure were safe to use for dairy and/or meat production [8].

Ecological Effects:

• Effects on birds: Diphacinone is slightly toxic to birds. The oral LD50 for diphacinone in mallard ducks is 3158 mg/kg [1,8], and in bobwhite quail is 1630 mg/kg [8].
• Effects on aquatic organisms: Diphacinone is moderately toxic to fish species. The 96-hour LC50 for technical diphacinone in channel catfish is 2.1 mg/L, in bluegills is 7.6 mg/L, and in rainbow trout is 2.8 mg/L [1,174]. The 48-hour LC50 in Daphnia, a small freshwater crustacean, is 1.8 mg/L [174].
• Effects on other organisms: Studies with cattle indicate a high degree of tolerance for the compound, hence its use against vampire bats preying on cattle in Latin America [8].

Environmental Fate:

• Breakdown in soil and groundwater: Diphacinone has a low potential to leach in soil [173].
• Breakdown in water: Diphacinone is rapidly decomposed in water by sunlight [172].
• Breakdown in vegetation: No data are currently available.

Physical Properties:

• Appearance: Technical diphacinone is an odorless, pale yellow powder [1].
• Chemical Name: 2-(diphenylacetyl)indan-1,3-dione [1]
• CAS Number: 82-66-6
• Molecular Weight: 340.38
• Water Solubility: 0.3 mg/L; almost
• Solubility in Other Solvents: v.s. in acetone, acetic acid, toluene, xylene, and chloroform [1]
• Melting Point: 145-147 C [1]
• Vapor Pressure: 13.7 nPa @ 25 C (technical) [1]
• Partition Coefficient: Not Available
• Adsorption Coefficient: Not Available

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Hacco, Inc.
P.O. Box 7190
537 Atlas Ave.
Madison, WI 53707

• Phone: 608-221-6200
• Emergency: 800-642-4699
  

References:

References for the information in this PIP can be found in Reference List Number 10

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.