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The information in this profile may be out-of-date.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

Triadimefon

Trade and Other Names: Trade names for products containing triadimefon include Acizol, Amiral, Bay MEB 6447, and Bayleton (92.6% triadimefon). The compound may also be found in formulations with other fungicides such as captan, carbendazim, folpet, dodine, and propineb [1].

Regulatory Status: Triadimefon is a General Use Pesticide (GUP). It is a moderately toxic compound in toxicity class II that carries the Signal Word WARNING on its label.

Chemical Class: triazole

Introduction: Triadimefon is a systemic fungicide in the triazole family of chemicals. It is used to control powdery mildews, rusts, and other fungal pests on cereals, fruits, vegetables, turf, shrubs, and trees. It is available in wettable powder, emulsifiable concentrate, granular, and paste forms. All data presented refer to Bayleton unless otherwise specified.

Formulation: It is available in wettable powder, emulsifiable concentrate, granular, and paste forms.

Toxicological Effects:

• Acute toxicity: Bayleton (92.6% triadimefon) has an acute oral LD50 of 300 to 600 mg/kg in rats, about 1000 mg/kg in mice, and about 500 mg/kg in rabbits and dogs [6,15]. While these LD50 values indicate lower acute toxicity than many compounds classed as moderately toxic, triadimefon is classified this way because of its potential to cause adverse chronic effects at low to moderate dose levels. Lower potency formulations of triadimefon have lower acute toxicities (higher LD50 values). Acute inhalation toxicity of the compound is moderate. The 4-hour inhalation LC50 is greater than 0.48 mg/L in rats and approximately the same in mice [6]. Acute toxicity through skin exposure is also fairly low. The LD50 values for the dermal toxicity of technical triadimefon are greater than 1000 mg/kg in rats and 2000 mg/kg in rabbits [6,15]. Studies of acute effects in rats have indicated a potential to induce neurobehavioral effects [16]. Data regarding eye and skin irritation are inconclusive [13].
• Chronic toxicity: A number of 2-year studies have indicated that there are several toxic responses to low to moderate doses of the compound. Long-term studies of triadimefon in several species (rat, mouse, dog) over a range of doses indicated a reduction in body weight, changes in red blood cell counts, an increase in blood cholesterol levels, and increased liver weights [16]. Increased liver weights may be seen as an adaptation to toxic stress, rather than a toxic endpoint related to exposure [3].
• Reproductive effects: Female rats fed up to 90 mg/kg/day of Bayleton over three generations showed a number of adverse effects. No effects were noted in the fetuses at maternal doses below 2.5 mg/kg/day. At the middle doses tested (around 15 mg/kg/day) the second-generation offspring experienced a decrease in weight gain. At the highest dose, the females experienced a reduction in body weight and a decrease in fertility [16]. In another study conducted over two generations, the female rats showed decreased ovary weight at the 2.5 mg/kg/day dose [13]. At 90 mg/kg/day reductions in litter size, reduced offspring viability and lower birth weight were observed in second-generation offspring [13]. This evidence suggests it is unlikely that triadimefon will cause reproductive toxicity in humans under normal circumstances.
• Teratogenic effects: The teratogenic potential of triadimefon is relatively low [3]. Doses causing birth defects in rats were high enough to also produce maternal toxicity. Cleft palates were noted in the offspring of female rats fed moderate doses of 75 mg/kg/day for an unspecified time period. In a second study, no teratogenic effects were noted in the offspring of female rats fed 50 mg/kg/day of Bayleton in the form of an emulsion. In another teratogenic study in rats, rib deformities were noted at high maternal doses of 90 mg/kg/day [13]. A study of occupationally-exposed female workers showed that the highest combined dermal and inhalation level of exposure for workers was around 60 ug which corresponds to approximately 0.008 mg/kg/shift for a 70 kg worker, a value considerably lower than the lowest dose that caused teratogenic effects in test animals [47]. Thus, it is unlikely that triadimefon will cause birth defects in humans under normal circumstanes.
• Mutagenic effects: Six separate studies indicate that the Bayleton compound is nonmutagenic. Several other tests were inconclusive [4]. It is unlikely that the compound poses a significant mutagenic risk.
• Carcinogenic effects: In a 2-year dietary study with mice, the highest dose tested (600 mg/kg/day) did not produce significant increases in tumor incidence. Due to high mortality, the reliability of this data is suspect [13]. Another 2-year dietary study in mice showed increased liver cell hypertrophy (which may be related to tumor formation) at doses of greater than 36 mg/kg/day in males and 6 mg/kg/day for females. Increased liver cell adenoma was detected at all levels, but carcinoma was not detected at any level in this study [13]. Based on this evidence, no conclusion can be drawn about the overall carcinogenicity of triadimefon.
• Organ toxicity: Triadimefon has been associated with changes in the liver, decreased kidney weights, and altered urinary bladder structure in laboratory animals exposed to 18 to 60 mg/kg/day. There is evidence that acute effects on the central nervous system may also occur [16].

• Fate in humans and animals: After oral administration of a single dose of triadimefon, most of the compound was eliminated unchanged in the urine and feces within 2 to 3 days. Some breakdown of a small amount of the compound occurred in the liver. The compound has a very short residence time in the blood stream, about 2 1/2 hours [6]. When applied to the skin of rats, 40% of the applied amount was excreted in urine and feces within 8 days. Additional amounts (up to 40%) were recovered unabsorbed from the skin surface and in the cage [13].

Ecological Effects:

• Effects on birds: Triadimefon ranges from slightly toxic to practically nontoxic to birds. For instance, the compound has an LD50 value of greater than 4000 mg/kg in mallard ducks [6]. Japanese quail are less tolerant of the compound (LD50 of 2000 mg/kg) and canaries are even less tolerant (LD50 >1000 mg/kg) [6]. Even the most tolerant species exhibited some compound-related acute toxicity such as diarrhea and regurgitation within 5 minutes of administration of the highest doses. At the lowest dose tested (500 mg/kg) no signs of diarrhea were noted [16].
• Effects on aquatic organisms: The compound is slightly toxic to fish, indicating that they are more susceptible to the presence of the compound than are birds. Bluegill sunfish are the most susceptible, followed closely by goldfish, with 96-hour LC50 values of 11 mg/L and 10 to 50 mg/L, respectively [6]. The compound is only slightly toxic to rainbow trout, with a reported LC50 of 14 mg/L [6].
• Effects on other organisms: The compound is nontoxic to honeybees [6].

Environmental Fate:

• Breakdown in soil and groundwater: Triadimefon has low to moderate persistence in soils. In a sandy loam type of soil, half of the initial amount of the compound was lost within 18 days. In loamy soil the half-life was much shorter (about 6 days), which indicates that breakdown of the compound varies with soil type [16]. Other reported soil half-lives are 14 to 60 days with an average of 26 days [20]. Triadimefon and its residues are moderately mobile and may have potential to leach to groundwater [16].
• Breakdown in water: In water with a pH 3.0, 6.0, or 9.0, almost 95% of the compound remained after 28 weeks. The compound is very stable in water and does not readily undergo hydrolysis [16].
• Breakdown in vegetation: In plants, a breaddown product is triadimenol [6], and translocation and metabolism may vary according to plant species. Triadimenol is of comparable toxicity to triadimefon.

Physical Properties:

• Appearance: Triadimefon consists of colorless crystals [6].
• Chemical Name: 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl) butanone [6]
• CAS Number: 43121-43-3
• Molecular Weight: 293.76
• Water Solubility: 260 mg/L @ 20 C [6]
• Solubility in Other Solvents: m.s. in most organic solvents [1]
• Melting Point: 82.3 C [6]
• Vapor Pressure: <0.1 mPa @ 20 C [6]
• Partition Coefficient: 3.1790 [6]
• Adsorption Coefficient: 300 [20]

Exposure Guidelines:

• ADI: 0.03 mg/kg [22]
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Miles, Inc.
8400 Hawthorn Road
P.O. Box 4913
Kansas City, MO 64120

• Phone: 816-242-2429
• Emergency: 816-242-2582
  

References:

References for the information in this PIP can be found in Reference List Number 8

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.