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The information in this profile may be out-of-date.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

Dicofol

Trade and Other Names: Trade names include Acarin, Cekudifol, Decofol, Dicaron, Dicomite, Difol, Hilfol, Kelthane, and Mitigan.

Regulatory Status: The EPA has classified dicofol as toxicity class II - moderately toxic, and toxicity class III - slightly toxic, depending on the formulation. Products containing dicofol bear the Signal Word WARNING or CAUTION, depending on the formulation. Products containing dicofol are designated General Use Pesticides (GUPs).

Chemical Class: organochlorine

Introduction: Dicofol is an organochlorine miticide used on a wide variety of fruit, vegetable, ornamental and field crops. Dicofol is manufactured from DDT. In 1986, use of dicofol was temporarily canceled by the EPA because of concerns raised by high levels of DDT contamination. However, it was reinstated when it was shown that modern manufacturing processes can produce technical grade dicofol which contains less than 0.1% DDT.

Formulation: Not Available

Toxicological Effects:

• Acute toxicity: Dicofol is moderately toxic to practically nontoxic and may be absorbed through ingestion, inhalation, or skin contact. Symptoms of exposure include nausea, dizziness, weakness, and vomiting from ingestion or respiratory exposure, skin irritation or rash from dermal exposure, and conjunctivitis from eye contact. Poisoning may affect the liver, kidneys, or the central nervous system. Overexposure by any route may cause nervousness and hyperactivity, headache, nausea, vomiting, unusual sensations, and fatigue. Very severe cases may result in convulsions, coma, or death from respiratory failure [44,45]. Dicofol is a moderate skin and eye irritant [17,45]. Since dicofol is stored in fatty tissues, intense activity or starvation may mobilize the pesticide, resulting in the reappearance of toxic symptoms long after actual exposure [17]. The oral LD50 for dicofol in rats is 575 to 960 mg/kg, in rabbits and guinea pigs is 1810 mg/kg, and in mice is 420 to 675 mg/kg. The dermal LD50 in rats is 1000 to 5000 mg/kg, and in rabbits is between 2000 and 5000 mg/kg. The inhalation LC50 (4-hour) in rats is greater than 5 mg/L [9,7,45].
• Chronic toxicity: In a 2-year dietary study with rats, liver growth, enzyme induction, and other changes in the liver, adrenal gland, and urinary bladder were observed at doses of 2.5 mg/kg/day and above. Effects on the liver, kidney, and adrenals, and reduced body weights were observed at doses of 6.25 mg/kg/day and above in a 3-month dietary study with mice [45]. When dicofol was fed to rats for 3 months, fewer than half of the animals survived a 75 mg/kg/day dose. Liver enzyme induction was observed at 75 mg/kg/day and above. Decreased body weights, decreased cortisone levels, and toxic changes in the liver, adrenal glands, and kidneys were noted at 25 mg/kg/day. Similar results were observed in a 3-month feeding study with mice [44]. When dogs were fed dicofol for 3 months, 2 two out of 12 survived at 25 mg/kg/day. Poisoning symptoms and effects on the liver, heart, and testes were observed at the 7.5 mg/kg/day dose [44]. When dicofol was fed to dogs, 4.5 mg/kg/day for 1 year caused toxic effects on the liver. Long-term dermal exposure of rats to dicofol as an emulsifiable concentrate formulation also produced toxic effects on the liver [44].
• Reproductive effects: Reproductive effects in rat offspring have been observed only at doses high enough to also cause toxic effects on the livers, ovaries, and feeding behavior of the parents. Rats fed diets containing dicofol through two generations exhibited adverse effects on the survival and/or growth of newborns at 6.25 and 12.5 mg/kg/day [44].
• Teratogenic effects: No teratogenic effects were observed when rats were given up to 25 mg/kg/day on days 6 through 15 of pregnancy [44].
• Mutagenic effects: Five separate laboratory tests have shown that dicofol is not mutagenic [44,45].
• Carcinogenic effects: No evidence of carcinogenicity was observed in when rats were fed up to 47 mg/kg/day for 78 weeks. A 2-year oncogenicity study in mice showed an increased incidence of liver tumors in male mice at dietary concentration levels of 13.2 and 26.4 mg/kg/day [45]. It is unlikely that dicofol poses a carcinogenic risk to humans.
• Organ toxicity: Chronic exposure to dicofol can cause damage to the kidney, liver, and heart. Prolonged or repeated exposure to dicofol can cause the same effects and symptoms as acute exposure [17]. Prolonged or repeated skin contact can cause moderate skin irritation and/or sensitization of the skin [45].

• Fate in humans and animals: Dicofol is converted in rats to the metabolites 4,4'-dichloro-benzophenone and 4,4'-dichlorodicofol [2,46]. Studies of the metabolism of dicofol in rats, mice, and rabbits have shown that ingested dicofol is rapidly absorbed, distributed primarily to fat, and readily eliminated in feces. When mice were given a single oral dose of 25 mg/kg dicofol, approximately 60% of the dose was eliminated within 96 hours, 20% in the urine, and 40% in the feces. Concentrations in body tissues peaked between 24 and 48 hours following dosing, with 10% of the dose found in fat, followed by the liver and other tissues. Levels in tissues other than fat declined sharply after the peak. When rats were given a single oral dose of 50 mg/kg of dicofol, all but 2% of the dose was eliminated within 192 hours, with peak concentrations in body tissues occurring between 24 and 48 hours after dosing [44].

Ecological Effects:

• Effects on birds: Dicofol is slightly toxic to birds. The 8-day dietary LC50 is 3010 ppm in bobwhite quail, 1418 ppm in Japanese quail, and 2126 ppm in ring-necked pheasant. Eggshell thinning and reduced offspring survival were noted in the mallard duck, American kestrel, ring dove, and screech owl [45].
• Effects on aquatic organisms: Dicofol is highly toxic to fish, aquatic invertebrates, and algae. The LC50 is 0.12 mg/L in rainbow trout, 0.37 mg/L in sheepshead minnow, 0.06 mg/L in mysid shrimp, 0.015 mg/L in shell oysters, and 0.075 mg/L in algae [45].
• Effects on other organisms: Dicofol is not toxic to bees [9].

Environmental Fate:

• Breakdown in soil and groundwater: Dicofol is moderately persistent in soil, with a half-life of 60 days [14,46]. Dicofol is susceptible to chemical breakdown in moist soils [12]. It is also subject to degradation by UV light. In a silty loam soil, its photodegradation half-life was 30 days. Under anaerobic soil conditions, the half-life for dicofol was 15.9 days [46]. Dicofol is practically insoluble in water and adsorbs very strongly to soil particles. It is therefore nearly immobile in soils and unlikely to infiltrate groundwater. Even in sandy soil, dicofol was not detected below the top 3 inches in standard soil column tests. It is possible for dicofol to enter surface waters when soil erosion occurs [46,14].
• Breakdown in water: Dicofol degrades in water or when exposed to UV light at pH levels above 7. Its half-life in solution at pH 5 is 47 to 85 days. Because of its very high absorption coefficient (Koc), dicofol is expected to adsorb to sediment when released into open waters [12].
• Breakdown in vegetation: In a number of studies, dicofol residues on treated plant tissues have been shown to remain unchanged for up to 2 years [46].

Physical Properties:

• Appearance: Pure dicofol is a white crystalline solid. Technical dicofol is a red-brown or amber viscous liquid with an odor like fresh-cut hay [9,45].
• Chemical Name: 2,2,2-trichloro-1,1-bis(y-chlorophenyl)ethanol [9]
• CAS Number: 115-32-2
• Molecular Weight: 370.51
• Water Solubility: 0.8 mg/L @ 25 C [9]
• Solubility in Other Solvents: s. in most organic solvents [9]
• Melting Point: 78.5-79.5 C for pure dicofol [1,5]; 50 C for technical dicofol [9,45]
• Vapor Pressure: Negligible at room temperature [9,45]
• Partition Coefficient: 4.2788 [9,45]
• Adsorption Coefficient: 5000 (estimated) [14]

Exposure Guidelines:

• ADI: 0.002 mg/kg/day [27]
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Rohm and Haas Co.
Agricultural Chemicals
100 Independence Mall West
Philadelphia, PA 19106

• Phone: 215-592-3000
• Emergency: Not Available
  

References:

References for the information in this PIP can be found in Reference List Number 6

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.