triadimenol (Baytan) Chemical Fact Sheet 7/89
EPA Pesticide Fact Sheet for Triadimenol
Name of Chemical: beta-(4-chlorophenoxy)-alpha-(1,l-dimethyl-ethyl)-
Reason for Issuance: New Chemical Registration
Date Issued: July 1989
Fact Sheet Number: 204
1. DESCRIPTION OF CHEMICAL
- Generic Name: beta-(4-chlorophenoxy)-alpha-(1,1-dimethylethyl)-
lH-1,2,4-triazole-1-ethanol and its metabolites c1
ontaining chlorophenoxy and triazole moieties.
- Common Name: triadimenol
- Trade Name: Baytan
- EPA Shaughnessy Codes: 127201
- Chemical Abstracts Service (CAS) Number: 5219-65-3
- Year of Initial Registration: 1989
- Pesticide Type: Fungicide
- U.S. and Foreign Producers: Mobay Corporation
2. USE PATTERNS AND FORMULATIONS
APPLICATION SITES: Seeds of barley, corn, oats, rye, sorghum and wheat
to control seed- and soil-borne diseases and to provide early
season control of foliar diseases.
METHOD OF APPLICATION: Application will be made as a waterbased slurry
through standard slurry or mist type commercial seed treatment
TYPES OF FORMULATION: 25% dry flowable end-use product and 90%
technical powder for formulating use.
APPLICATION RATES: For barley, oats, rye and wheat, apply 0.25-0.5 oz.
ai./100 lbs of seed; for sorghum, apply 0.5 oz. ai./100 lbs of
seed; and for corn, apply 1.0 oz.ai./100 lbs of seed.
USUAL CARRIER: water.
3. SCIENCE FINDINGS
Summary Science Statement
Available acute toxicity studies indicate that triadimenol is in
toxicity category II (warning) based on an acute inhalation toxicity study
Chronic feeding/oncogenicity studies were conducted in both the rat
and mouse. Clinical chemistry findings in the chronic feeding study in the
rat suggests that the target organ for toxicity may be the liver. Although
there was an accompaying small increase in liver weight in the females of
the high dose group, there were no histopathologic changes in the liver in
In the chronic feeding study in mice, the results of blood chemistry,
organ weights and gross and histological examinations, again indicated the
liver as the target organ.
Triadimenol did not induce either genotoxic effects or chromosomal
aberrations in a series of mutagenicity studies. In addition, no strong
structural activity correlation to other carcinogens has been found.
Triadimenol was also found not to be teratogenic in either the rat or
Environmental fate data indicates that triadimenol is stable to
hydrolysis and appears to be stable to photolysis on the soil surface. In
addition, based on low adsorption coefficients, triadimenol will have a low
potential to leach in soil. However, triadimenol may have a moderate
potential to leach in some Western soils.
Additional studies indicate that due to the manufacturing process,
triadimenol should have no adverse effects on non-target organisms provided
waste is disposed of properly. An overview of the toxicity test results
suggests that triadimenol is practically non-toxic to birds, slightly toxic
to fish, and moderately toxic to aquatic invertebrates. It is also unlikely
that this registration would affect endangered species because of its
relatively low use rates, agricultural techniques which involve drill
planting of most small grains and corn, and the low toxicity of triadimenol
to all animals.
4. TOXICOLOGICAL CHARACTERISTICS
Acute oral toxicity in rats:
LD50 689 mg/kg in males
752 mg/kg in females
Toxicity category III
Acute dermal toxicity in rats:
LD50 >5000 mg/kg
Toxicity category III
Acute inhalation toxicity in rats
LC50 >1.56 mg/L
Toxicity category III
Primary eye irritation in rabbit:
Primary dermal irritation in rabbit:
Toxicity category IV
Dermal sensitization in guinea pigs:
core minimum; no effect
Chronic studies: Triadimenol has been evaluated in the following
1. A 2-year feeding/oncogenicity study with rats using dietary
concentrations of 0, 125, 500, and 2000 parts per million (ppm) equivalent
to 0, 6.25, 25.0, and 100 mg/kg bwt/day in males and females. Clinical
chemistry findings suggest that the target organ for toxicity may be the
liver. The levels of SGOT and SGPT enzymes were consistently higher at 2000
ppm in males and females when compared to controls, and some increase in
these two parameters was also observed at 500 ppm. Although there was an
accompanying small increase in liver weight in 2000 ppm females, there were
no accompanying increases in histopathologic changes of the liver in either
sex. There were only marginal effects seen on other clinical chemistry
parameters, and no effect of test compound on clinically observed signs of
toxicity, food consumption, hematologic, or urinalysis parameters. The
systemic NOEL (no-observed effect level) is 125 ppm (6.25 mg/kg/day for
males and females) based on the increase in liver enzymes (SGOT and SGPT).
The systemic LEL (lowest effect level) was 500 ppm (25 mg/kg/day for males
and for females).
2. A 2-year chronic feeding/oncogenicity study in mice using dietary
concentrations of 0, 125, 500, and 2000 ppm (equivalent to doses of 0, 18,
72, and 285 mg/kg/day for males and females). The results of blood
chemistry, organ weights, and gross and histological examinations indicated
the liver to be the target organ. There were time- and dose-related
increases in SAP (serum alkaline phosphatase), SGOT and SGPT activities in
both male and female animals receiving 500 and 2,000 ppm of the test
In addition, increased incidence of enlarged livers, hyperplastic
nodules and increased liver weights in both male and female animals
receiving 2,000 ppm of test material were detected at necropsy. Female
animals receiving 2000 ppm exhibited a significant increase in the
incidences of liver adenomas only, a compound-related oncoqenic effect. In
males, there were no differences in the incidences of these lesions in
treated and control males, and the incidences of liver adenomas were
similar to those observed in historical controls.
Based on this evidence the Agency classified triadimenol as a Category
C (possible human carcinogen) in accordance with the EPA Guidelines for
Carcinogen Risk Assessment (September 24, 1986, 51 FR 33992). This
evaluation was confirmed by the Agency's Scientific Advisory Panel on
December 15, 1987. However, it was also concluded that this evidence of
carcinogenicity did not warrant a low dose extrapolation of risks since the
tumors were only benign, were observed in only one sex, and only at the
highest dose tested. Moreover, the chemical was negative in the genotoxic
Based on blood chemistry findings, the systemic NOEL and the LEL are
125 ppm and 500 ppm respectively (equivalent to 18 and 72 mg/kg/day for
males and females).
3. A 3-month rat feeding study using doses of 0, 150, and 600 ppm
(equivalent to 0, 7.5, and 30 mg/kg bwt/day for males and females)
demonstrated a decrease in body weight, decrease in hematocrit values,
eosinophil count and medium cell hemoglobin and increase in the high dose
group and dose-related increase in liver weight. The NOEL is 150 ppm and
the LEL is 600 ppm.
Non-Rodent Feeding Study
1. A 2-year male and female dog feeding study using doses of 0, 150,
600 and 2400 ppm (equivalent to 0, 3.75, 15, and 60 mg/kg bwt/day for males
and females). The NOEL is 150 ppm based on changes in enzyme levels
(equivalent to 3.75 mg/kg bwt/day for males and females). The LEL is 600
ppm. Although there were significant decreases in mean body weights in
males receiving 150 and 2400 ppm and in females receiving 600 and 2400 ppm,
the biological significance of these changes could not be assessed. There
were noted increases in alkaline phosphatase N-demethylase, and cytochrome
P-450 in males receiving 2400 ppm and significant increases in N-
demethylase in females receiving 600 and 2400 ppm and in cytochrome P-450
in females receiving 2400 ppm when compared to controls.
2. A 6-month dog feeding study using doses of 0, 10, 30, and 100 ppm
(equivalent to 0, 0.25, 0.75, 2.5 mg/kg bwt/day for males and females). The
NOEL was demonstrated at doses up to 100 ppm, the highest dose level
3. A 3-month dog feeding study using doses of 0, 150, 600 and 2400 ppm
(equivalent to 0, 3.75, 15, and 60 mg/kg bwt/day for males and females).
Weight gain in all male groups and in the highest dose female group was
significantly less than the control. Alkaline phosphatase in males and
females showed a dose-related negative trend. There was no gross
pathological changes. Effects at 600 ppm included an increase in serum
cholesterol level in males. Although the NOEL appeared to be less than 150
ppm based on reduced body weight and decreased alkaline phosphatase in
males, the Agency has concluded that effects below 600 ppm in the 2-year
dog study were not biologically significant and the longer-term study
supercedes the 90-day dog study. Therefore, the NOEL remains at 150 ppm.
1. A rabbit teratology study with a NOEL for maternal toxicity of 8
mg/kg. The maternal LEL was 40 mg/kg based on decreased body weight gains
and food consumption. The developmental NOEL and LEL were 40 mg/kg and 200
mg/kg respectively. This study has to be resubmitted with all the findings
statistically analyzed on a per litter and per fetus basis in order to be
upgraded from its current classification as core supplementary.
2. A rat teratology study using dose levels 0, 30, 60, and 120
mg/kg/day was determined to be core supplementary because the NOEL for
developmental toxicity (supernumerary ribs) was not definitively
established. The NOEL and LOEL for maternal toxicity for this study are 30
and 60 mg/kg/day, respectively, based on decreases in maternal body weight,
body weight gain, and food consumption at 60 and 120 mg/kg/day.
Furthermore, increased embryolethality (embryotoxicity) was only observed
at the highest dose level tested (120 mg/kg/day). This study must be
repeated to clearly define a NOEL for developmental toxicity.
The above rat study indicated that triadimenol caused a dose-
dependent, statistically significant increase in the incidence of
rudimentary supernumerary ribs. Although the effect at the low dose level
was not statistically significant, it was considered to be treatment
related because of the dose-related trend.
The biological significance of the manifestation of supernumerary ribs
is subject to scientific debate, especially if the ribs are not fully
developed (rudimentary). Nonetheless, the margin of safety (MOS) for this
effect must be taken into consideration. The MOS is the ratio between the
NOEL for the effect and the acute exposure in mg/kg/day. A NOEL for
developmental toxicity could not be defined in the rat teratology study but
it is unlikely to be far below the threshold (LEL) of 30 mg/kg/day observed
in the current study.
Based on worker exposure information and an estimation of the NOEL at
about 15 mg/kg/day for developmental toxicity (rudimentary supernumerary
ribs in rats) and assuming a maximum dermal penetration of about 10%, a
margin of safety was calculated to be >100 for factory workers involved in
seed treatments using a closed system. Because of possible developmental
toxicity and the lack of a well defined NOEL for this effect, the product
label must include a recommendation for the use of protective clothing by
factory workers involved in the treatment of seeds and for farm workers
handling the treated seed.
A rat multigeneration reproduction study using doses of 0, 20, 100,
and 500 ppm (equivalent to 0, 1, 5, and 25 mg/kg bwt/day for males and
females) indicated that the NOEL and LOEL for both parental and pup
toxicity are 100 and 500 ppm, respectively, based on significant body
weight and organ weight changes. The NOEL for reproductive toxicity is 500
ppm, highest dose level tested.
A reverse mutation assay (AMES), a dominant lethal test in mice, DNA
damage/repair, unscheduled DNA synthesis, in vitro and in vivo (rat)
cytogenic assays, and a forward mutation in mice, all of which were
negative for mutagenic effects.
5. ENVIRONMENTAL FATE
Hydrolysis: STABLE. Triadimenol in sterile aqueous buffer solutions
showed no apparent degradation at either temperature or pH
tested. Recovery was 97% greater after 32 days of
Soil Surface Photolysis: STABLE. Triadimenol appears to be stable to
photolysis on the soil surface. Studies indicate that
triadimenol photodegrades with a half-life of 36 hours in
distilled water and 17 hours in a photo-sensitized
Aerobic Soil Metabolism: STABLE. Studies indicate that triadimenol has
an estimated aerobic half-life of 8 to 9 months.
Triadimenol reached a maximum level of 68% of that applied
at 14C in 71 days and declined slightly to 45.2% by day
238. Consequently, the anaerobic half-life is considerably
greater than 8-9 months.
Adsorption/Desorption: Because of its low adsorption coefficients,
triadimenol is shown to have a low to moderate potential to
bind to soil particles. Studies indicate that the
adsorption coefficient, k, for triadimenol ranged from 2.37
to 5.26. The k values for desorption ranged from 1.49 in a
silty clay soil (0.49 ppm) to 9.12 in a loam soil (9.57
ppm). Consequently, there is no correlation between
adsorption and soil organic matter content. The highest
degree of adsorption was observed with the loam soil,
intermediate in organic matter content.
Environmental fate data requirements have been satisfied with the
exception of a field dissipation study. The company will be required to
submit results of this study by July 1990.
6. ECOLOGICAL CHARACTERISTICS
Studies submitted show that this chemical is practically non-toxic to
birds, slightly toxic to fish and moderately toxic to aquatic
invertebrates. It is unlikely that the seed treatment use of triadimenol
will affect any terrestrial or aquatic animals. Chronic effects are
unlikely due to the low use rates and because the seed treatment use
requires incorporation of seeds into the soil. For the above reasons it is
also unlikely that this use will affect any endangered species.
This chemical has been shown to be environmentally safe, is used at
low rates and has a broad biological spectrum. Triadimenol controls seed-,
soil-, and wind-borne pathogens of wheat, barley, oats, rye, corn and
sorghum. Crops may be grazed 40 days after seeding. The chemical improves
winter survival and drought tolerance of cereals, lowers the inoculum
levels for overwintering foliar diseases and may eliminate the need for
early season foliar sprays.
8. TOLERANCE ASSESSMENT:
Tolerances are established for the fungicide triadimenol and its
butanediol metabolite (calculated as triadimenol) in or on the following
commodities: 2.5 ppm for green forage of barley, oats, rye and wheat; 0.1
ppm for straw of barley, oats, rye and wheat; 0.05 ppm for grains of
barley, oats, rye and wheat, corn fodder, fresh corn (including sweet),
corn forage, corn grain, and green forage of sorghum; and 0.01 ppm for
sorghum grain and sorghum fodder. Tolerances are established for the
fungicide triadimenol and its metabolites containing the chlorophenoxy
moiety (calculated as triadimenol) in or on the following commodities: 0.1
ppm for fat, meat and meat by-products of cattle, goats, hogs, horses, and
sheep; and 1.01 ppm for eggs, milk, and fat, meat and meat by-products of
Where tolerances are established for residues of both 1-(4-
(triadimefon) and triadimenol, including its butanediol metabolite, in or
on the same raw agricultural commodity and its products thereof, the total
amount of such residues shall not yield more residue than that permitted by
the higher of the two tolerances. The nature of the residue is adequately
understood and the Agency concluded that the pesticide is useful for the
purposes for which tolerances are sought and that the establishment of the
tolerances will protect the public health.
9. SUMMARY OF MAJOR DATA GAPS:
The Agency concurs with conditional registration of this chemical for
use as a seed treatment fungicide pending submission of a field dissipation
study by July 1990.
10. CONTACT PERSON AT EPA
Susan T. Lewis,
Acting Product Manager (PM) 21,
Registration Division (H-7505C),
Environmental Protection Agency,
401 M St., SW.,
Washington, DC 20460
Office location and telephone number:
Rm. 227, CM#2,
1921 Jefferson Davis Highway,
Arlington, VA 22202
DISCLAIMER: The information in this Pesticide Fact Sheet is a summary only
and is not to be used to satisfy data requirements for pesticide
registration and reregistration.