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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:
Trade names include Bladex, DW3418, Fortrol, Match, and Payze.
Cyanazine may be used in combination with other herbicides.
Cyanazine is classified by the EPA as a Restricted Use Pesticide
(RUP) because of its teratogenicity and because it has been found
in groundwater. Restricted Use Pesticides may be purchased and
used only by certified applicators. Classified as toxicity class
II - moderately toxic, products containing cyanazine bear the
Signal Word WARNING.
Cyanazine, a triazine, is used as a pre- and post-emergent
herbicide to control annual grasses and broadleaf weeds. It is
used mostly on corn, some on cotton, and less than 1% on grain
sorghum and wheat fallow. Nearly 2.25 million acres of land were
treated with cyanazine in the U.S. The compound is formulated as
a wettable powder, a flowable suspension, or as granules.
compound is formulated as a wettable powder, a flowable
suspension, or as granules.
- Acute toxicity: Cyanazine is moderately
toxic to mammals. The oral LD50 in rats ranges from 182
mg/kg to 332 mg/kg, with females experiencing higher
toxicities (lower LD50). The oral LD50 is 380 mg/kg in
mice and 141 mg/kg in rabbits [3,6,15]. Poisoned animals
have labored breathing and blood in their saliva
[5,6,15]. Cyanazine may also cause inactivity and
depression in laboratory animals. The dermal LD50 in
rabbits treated with technical cyanazine is greater than
2000 mg/kg, and the dermal LD50 in rats is greater than
1200 mg/kg [3,6,15]. Cyanazine is only slightly toxic
through inhalation. It is a mild eye irritant.
- Chronic toxicity: Several long-term
feeding studies in rats and mice at doses up to 225
mg/kg/day showed that cyanazine decreases body weight
gain and increases liver weights .
- Reproductive effects: Cyanazine caused
decreases in maternal body weight gain in rats at doses
of 30 mg/kg/day . It also caused maternal toxicity
and decreased fetal viability in rabbits at doses of 2
mg/kg/day . It appears that reproductive effects are
not likely in humans at expected exposure levels.
- Teratogenic effects: Cyanazine can cause
a variety of birth defects in animals over a wide range
of doses. In a long-term study of rats fed cyanazine,
moderate doses resulted in increased brain weights and
decreased kidney weights in third generation offspring
. Toxic effects on the fetus were also observed in
experiments on rabbits using comparable doses. Female
rats fed cyanazine through a stomach tube during
pregnancy ate less food and their fetuses had incomplete
bone development. At the higher doses, fetuses showed
cleft palates and the absence of, or underdeveloped
eyeballs . Other birth defects observed in animals
include abnormalities in diaphragm development and
changes in the brain. Birth defects have been observed in
the offspring of pregnant rats fed cyanazine during
gestation at doses as low as 1 mg/kg/day.
- Mutagenic effects: Cyanazine is not
- Carcinogenic effects: Cyanazine does not
appear to be carcinogenic. A study evaluated the
carcinogenicity of the compound in mice and found, up to
the maximum dose tested (50 mg/kg/day), no evidence of
cancer in the animals [3,11].
- Organ toxicity: Cyanazine in animals
causes depression of the central nervous system.
- Fate in humans and animals: Low doses of
cyanazine fed to rats, dogs, and cows are rapidly
absorbed from the gastrointestinal tract. In a study on
rats and dogs, much of the cyanazine ingested was
eliminated from animals within 4 days . There is some
tendency for cyanazine to accumulate in the brain, liver,
kidney, muscle, and fat . Cows fed very low amounts
of cyanazine eliminated up to 88% of the cyanazine in
urine and feces within 21 days. The concentration in
cows' milk was very low, at 0.022 ppm .
- Effects on birds: Cyanazine is slightly
to moderately toxic in birds. The oral LD50 in mallards
is greater than 2000 mg/kg, and in bobwhite quail is 400
- Effects on aquatic organisms: Cyanazine
is slightly to moderately toxic to fish and aquatic
invertebrates [15,16]. The LC50 (96-hour) for cyanazine
in harlequin fish is 7.5 mg/L, and 18 mg/L in sheepshead
- Effects on other organisms: Cyanazine is
nontoxic to bees .
- Breakdown in soil and groundwater:
Cyanazine has a low to moderate persistence in soil. It
quickly degrades in many soil types mostly due to the
action of microbes . Cyanazine has a half-life of 2
to 4 weeks in an air-dried sandy clay loam, 7 to 10 weeks
in a sandy loam soil, 10 to 14 weeks in a clay soil, and
9 weeks in a fresh sandy clay soil. It undergoes slight
decomposition by sunlight. The rate of evaporation of
cyanazine from soil is very slow . Cyanazine can be
transported in runoff, sediment, and water, and it can
leach through the soil to the groundwater. Cyanazine has
been found in numerous groundwater samples at very low
concentrations (0.001-0.08 mg/L) . A groundwater
advisory statement on cyanazine product labels is
- Breakdown in water: Cyanazine is stable
to the chemical action of water (hydrolysis) and to the
action of sunlight (photolysis) .
- Breakdown in vegetation: Cyanazine is
absorbed by the roots and is translocated up the plant
into the leaves. It works by inhibiting photosynthesis
- Appearance: Cyanazine is a member of the
s-triazine chemical family. This odorless, white
crystalline solid is incompatible with metals .
- Chemical Name:
- CAS Number: 21725-46-2
- Molecular Weight: 240.70
- Water Solubility: 171 mg/L @ 25 C 
- Solubility in Other Solvents: benzene
v.s.; chloroform v.s.; alcohol v.s.; hexane v.s.; xylene
s.s.; ethanol s.s. 
- Melting Point: 167 C 
- Vapor Pressure: 0.0002 mPa @ 20 C 
- Partition Coefficient: 2.22 
- Adsorption Coefficient: 190 
- ADI: Not Available
- MCL: Not Available
- RfD: Not Available
- PEL: Not Available
- HA: 0.01 mg/L (lifetime) 
- TLV: Not Available
DuPont Agricultural Products
Walker's Mill, Barley Mill Plaza
P.O. Box 80038
Wilmington , DE 19880-0038
- Phone: 800-441-7515
- Emergency: 800-441-3637
References for the information in this PIP can be found in
Reference List Number 8
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