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in 1996. EXTOXNET no longer updates this information, but it may be useful
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EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Diflubenzuron is sold under the trade name Dimilin. Other trade
names inlcude DU112307, ENT-29054, Micromite, and OMS-1804.
Some formulations of diflubenzuron may be classified as
Restricted Use Pesticides (RUPs) in the U.S. RUPs may be
purchased and used only by certified applicators. Diflubenzuron
is classified as toxicity class III - slightly toxic. Products
containing it bear the Signal Word CAUTION.
Diflubenzuron is a benzoylphenyl urea used on forest and field
crops to selectively control insects and parasites. Principal
target insect species are the gypsy moth, forest tent
caterpiller, several evergreen eating moths, and the boll weevil.
It is also used as a larvae control chemical in mushroom
operations and animal houses. Diflubenzuron is a stomach and
contact poison. It acts by inhibiting the production of chitin, a
compound that makes the outer covering of the insect hard and
thus interferes with the formation of the insect's cuticle or
shell. It is available as a suspension concentrate, wettable
powder, or in granules.
Formulation: It is
available as a suspension concentrate, wettable powder, or in
- Acute toxicity: No overt signs of
toxicity were observed in any of the acute studies
conducted . The oral LD50 in rats and mice is greater
than 4640 mg/kg, and the dermal LD50 is greater than
10,000 mg/kg in rats and greater than 4000 mg/kg in
rabbits. It is nonirritating to skin and slightly
irritating to eyes .
- Chronic toxicity: Rats given moderate
amounts of the compound for 2 years had enlarged spleens,
while mice in a similar study had liver and spleen
enlargement at slightly lower levels of exposure. In a
study with cats fed over a wide range of doses for 21
days, all of the females had dose related blood chemistry
changes at low doses and the males exhibited changes at
dose levels that were slightly higher . The changes
were reversible. The chemistry changes were associated
with the formation of methemoglobin, a form of hemoglobin
that is unable to carry oxygen.
- Reproductive effects: Day-old ducks and
turkeys fed moderate amounts of the pesticide in their
diets for 90 days had decreased testosterone levels after
42 days, but this did not occur in chickens and pheasants
in the same study. Combs and wattles, which reflect
hormone activity, showed some abnormalities. Some were
underdeveloped and others more developed compared to
controls. A short-term decrease in testosterone levels
was shown in the sexually immature rats but no clear cut
change was shown in young bull calves . A
three-generation study on rats at low doses showed no
effect on mating performance. It does not appear that
diflubenzuron has a significant effect on reproduction
- Teratogenic effects: Diflubenzuron does
not appear to be teratogenic. Newborn rats and rabbits
did not develop any birth defects after their mothers
were exposed to low levels of diflubenzuron (1 to 4
mg/kg/day) on days 6 to 18 of gestation [16,28].
- Mutagenic effects: Extensive testing on
mamalian cells and on bacterial cells shows that
diflubenzuron is not mutagenic [16,28].
- Carcinogenic effects: Rats fed diets
containing low to moderate amounts of diflubenzuron daily
for 2 years had no increase in the number of new or
abnormal tissue growths or lesions. Mice fed low doses
for 80 weeks showed no significant tumor development.
Other studies on both species at higher levels were also
negative for malignant tumors . Diflubenzuron does
not appear to be carcinogenic.
- Organ toxicity: Animal studies have
shown the liver and spleen to be target organs.
- Fate in humans and animals: Intestinal
absorption in mammals decreases with increasing dose
levels . For example, in rats , the total excretion
in urine and bile decreased from about 50% of the dose at
4 mg/kg to only 4% at 900 mg/kg. Mice showed similar
results. A cow given 10 mg/kg orally, eliminated almost
all of the product over a 4-day period. There were only
minute amounts of the pesticide in the milk. The chemical
is not degraded in the digestive tract, but that which is
absorbed by the gut is completely broken down before
excretion . Rabbits' skin absorbed only very small
amounts, all of which was recovered in the urine.
Chickens excreted almost all of an oral dose in 13 days.
Their eggs had low levels of pesticide residues (0.3 to
0.6 mg/kg) from day 9 to the end of the 9-week study.
Body tissues (non-fatty) do not retain diflubenzuron
- Effects on birds: Diflubenzuron is
practically nontoxic to wild birds. Bobwhite quail and
mallard ducks both have an 8-day dietary LC50 of greater
than 4640 ppm [4,7,8].
- Effects on aquatic organisms:
Diflubenzuron is practically nontoxic to fish and aquatic
invertebrates. The LC50 values (96-hour) for
diflubenzuron in various fish are: bluegill sunfish, 660
mg/L; rainbow trout, 240 mg/L; saltwater minnow, 255
mg/L; and channel catfish, 180 mg/L. In oyster larvae and
juveniles EC50 values were 130 and 250 mg/L, respectively
[4,7,8]. Arthropods are most susceptible in the
premolting stage. For instance, fiddler crabs, exposed
for as little as 1 week at levels up to 0.05 mg/L
exhibited limb regeneration effects . Fish tissue can
show some traces of the metabolites when water is
contaminated with diflubenzuron; however, tissue
concentrations decline steadily with time in clean water.
- Effects on other organisms: The compound
is nontoxic to bees .
- Breakdown in soil and groundwater:
Diflubenzuron has a low persistence in soil. The rate of
degradation in soil is strongly dependent on the particle
size of the diflubenzuron . It is rapidly degraded by
microbial processes. The half-life in soil is 3 to 4 days
. Under field conditions, diflubenzuron has very low
- Breakdown in water: In sterilized water
(no microbes), there appears to be little degradation
under neutral or acidic conditions. However, under field
conditions, it is degraded rapidly. Residues could not be
detected in field water 72 hours after an application of
110 g/hectare. Other studies suggest a half-life of 1 to
3 weeks [4,7,8].
- Breakdown in vegetation: Very little
diflubenzuron is absorbed, metabolized, or translocated
in plants. Residues on crops such as apples have a
half-life of 5 to 10 weeks. The half-life in oak leaf
litter is 6 to 9 months [4,7,8].
- Appearance: Diflubenzuron is a white
crystalline solid .
- Chemical Name:
- CAS Number: 35367-38-5
- Molecular Weight: 310.70
- Water Solubility: 0.14 mg/L @ 20 C,
- Solubility in Other Solvents: DMSO s.;
acetone s.s.; methanol s.
- Melting Point: 210-230 C (technical with
- Vapor Pressure: <0.033 mPa @ 50 C 
- Partition Coefficient: Not Available
- Adsorption Coefficient: 10,000 
- ADI: 0.02 mg/kg/day 
- MCL: Not Available
- RfD: 0.02 mg/kg/day 
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
Uniroyal Chemical Co., Inc.
Middlebury, CT 06749
- Phone: 203-573-2000
- Emergency: 203-723-3670
References for the information in this PIP can be found in
Reference List Number 9
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