| Chemical Abstract Number (CAS #) |
139402
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| Synonyms | Propazine |
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1,3,5-Triazine-2,4-diamine, 6-chloro-N,N'-bis(1-methylethyl)- | 2-Chloro-4,6-bis(isopropylamino)-s-triazine | Gesamil |
| Analytical Method |
EPA Method 619 |
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| Molecular Formula | C9H16ClN5 |
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| Use | SELECTIVE POST-EMERGENCE HERBICIDE FOR CARROTS, CELERY &
FENNEL
IT IS HERBICIDE RECOMMENDED FOR CONTROL OF BROAD-LEAVED & GRASS
WEEDS IN SORGHUM & UMBELLIFEROUS CROPS AT 0.5 TO 3 KG AI/HA.
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| Apparent Color | COLORLESS POWDER
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| Melting Point | 212-214 DEG C
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| Molecular Weight | 230.09
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| Density | 1.162 g/cu cm @ 20 deg C
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| Sensitivity Data | Mildly irritating to skin, eyes, and upper respiratory tract.
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| Environmental Impact | Propazine may be released to the environment via effluents at manufacturing sites and at
points of application where it is employed as a herbicide. The amount of propazine used annually
in the U.S. was estimated in 1985 to be greater than 1.28 million pounds. If released to soil,
propazine will be expected to exhibit degrees of mobility in soil varying from low to moderate and
therefore it may leach to groundwater. Adsorption of propazine to soil has been observed to vary
with pH with maximum adsorption occuring at pH 2.0. Propazine will be subject to slow to
moderate degradation in soil which may be due both slow chemical hydrolysis and slow
biodegradation. The half-lives for degradation (purportedly mainly soil-catalyzed hydrolysis) of
propazine in Hatzenbuhl soil at pH 4.8 and Neuhofen soil at pH 6.5 are 62 and 127 days,
respectively. It has been reported that propazine and other s-triazines can be utilized by certain
soil microorganisms as a source of energy. The persistence of propazine in soil has been reported
to be at least 2-3 years based upon reduced soybean yields observed after treatment with 4 pounds
propazine/acre. A decrease of the amount of inhibition of Italian ryegrass to below 20% inhibition
of growth occurred within 4.5 to 25 weeks an in > 60 weeks at application rates of 0.25 and 1-4
pounds/acre, respectively. Two to fourteen months time has reported as the time required for
decomposition of propazine applied at "normal" application rates in soil; however, it was not
reported whether this refers to total degradation of parent herbicide and active metabolites.
Propazine is not expected to volatilize from near surface soils or surfaces under normal
environmental conditions. If released to water, propazine will not be expected to bioconcentrate
in aquatic organisms, adsorb to sediment and suspended particulate matter, or to volatilize. Slow
biodegradation of propazine may occur in natural water based upon its biodegradation in soil.
Chemical hydrolysis of propazine may be more important environmentally than biodegradation at
low pH and when various catalysts are present. Propazine is fairly resistant to hydrolysis with
reported half-lives for hydrolysis in aqueous buffer solutions at 25 deg C at pH 5, 7, and 9 of 61,
>200, and >200 days, respectively. The product of propazine hydrolysis is
2-hydroxy-4,6-bis(isopropylamino)-1,3,5-triazine. No data were located regarding the direct
photolysis of propazine in sunlit natural waters. However, photolysis may be an important
mechanism of removal from aquatic evironments based upon observed degradation of propazine
in water solutions irradiated with artificial light at wavelengths >290 nm. If released to the
atmosphere, propazine is expected to exist almost entirely in the particulate phase based upon a
reported vapor pressure of 2.9X10-8 mm Hg at 20 deg C. The half-life for vapor-phase reaction
of propazine with photochemically produced hydroxyl radicals has been estimated to be about 2.4
hr. The most probable exposure would be occupational exposure, which may occur through
dermal contact or inhalation at places where propazine is produced or used as a herbicide.
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| Environmental Fate | TERRESTRIAL FATE: Depending upon the region of the USA, soil treated with
propazine may be planted to sorghum, corn, or cotton 12 months following application. Propazine
will persist longer under dry & cold conditions or other conditions not conducive to chemical &
biological degradation.
TERRESTRIAL FATE: If released to soil, propazine will be expected to exhibit degrees of
mobility in soil varying from low to moderate and therefore it may leach to groundwater.
Adsorption of propazine to soil has been observed to vary with pH with maximum adsorption
occurring at pH 2.0 . Propazine will be subject to slow to moderate degradation in soil which
may be due to both slow chemical hydrolysis and slow biodegradation. The half-lives for
degradation (purportedly mainly soil-catalyzed hydrolysis) of propazine in Hatzenbuhl soil at pH
4.8 and Neuhofen soil at pH 6.5 are 62 and 127 days, respectively . It has been reported that
propazine and other s-triazines can be utilized by certain soil microorganisms as a source of
energy . No 14-CO2 release was observed in 16 weeks from a silt loam soil treated with
propazine labeled with 14-C in the triazine ring . The persistence of propazine in soil has been
reported to be at least 2-3 years based upon reduced soybean yields observed after treatment with
4 pounds propazine/acre . A decrease of the amount of inhibition of Italian ryegrass to below
20% inhibition of growth occurred within 4.5 to 25 weeks and in >60 weeks at application rates
of 0.25 and 1-4 pounds/acre, respectively(7). Two to fourteen months time has been reported as
the time required for decomposition of propazine applied at "normal" application rates in soil;
however, it was not reported whether this refers to total degradation of parent herbicide and
active metabolites(6). Propazine is not expected to volatilize from near surface soils or surfaces
under normal environmental conditions.
AQUATIC FATE: If released to water, propazine will not be expected to bioconcentrate in
aquatic organisms, adsorb to sediment and suspended particulate matter, or to volatilize.
Although no information concerning biodegradation in natural waters was located, slow
biodegradation of propazine may occur in water based upon its biodegradation in soil .
Chemical degradation of propazine may be more important environmentally than biodegradation.
Propazine is fairly resistant to hydrolysis with reported half-lives for hydrolysis in aqueous buffer
solutions at 25 deg C at pH 5, 7, and 9 of 61, >200, and >200 days, respectively . The product
of propazine hydrolysis is 2-hydroxy-4,6-bis(isopropylamino)-1,3,5-triazine . The rate of
hydrolysis may be increased by various catalysts based upon the observed increase in rate of
hydrolysis rates for the chemically similar herbicide atrazine in water solutions upon addition of
sterilized soil and humic and fulvic acids .
AQUATIC FATE: No data were located regarding the direct photolysis of propazine in sunlit
natural waters. However, photolysis may be an important removal mechanism from aquatic
environments based upon degradation of propazine observed in water and methanol solutions
irradiated with artificial light at wavelengths >290 nm . The photolysis of propazine has been
reported to be enhanced by the presence of the photosensitizer riboflavin .
ATMOSPHERIC FATE: If released to the atmosphere, propazine is expected to exist almost
entirely in the particulate phase based upon a reported vapor pressure of 2.9X10-8 mm Hg at
20 deg C . The rate constant for the vapor-phase reaction of propazine with photochemically
produced hydroxyl radicals has been estimated to be 157.5 cu cm/molecule-sec at 25 deg C which
corresponds to an atmospheric half-life of about 2.4 hr at an atmospheric concn of 5X10 5
hydroxyl radicals per cu cm .
TERRESTRIAL FATE: THE LONG SOIL PERSISTENCE OF THESE CMPD DOES
CREATE THE PROBLEM OF SOIL CARRY OVER, WHICH CAN DAMAGE
SUCCEEDING CASH CROPS. THEREFORE EXTREME CAUTION MUST BE TAKEN IN
THEIR APPLICATION ON CROPLAND TO AVOID SUCH INJURY TO FOLLOWING
CROPS. TRIAZINES
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| Drinking Water Impact | DRINKING WATER: PROPAZINE DETECTED IN FINISHED WATER IN US.
It has been detected in groundwater samples in 8 states with maximum concentrations of 20 ppb
in surface water and 300 ppb in groundwater.
DRINKING WATER: Propazine has been identified at trace levels (<0.1 ppb) in 3 New Orleans
LA drinking water supplies sampled in 1974 .
GROUNDWATER: Propazine has been found in groundwater from new wells in the Northern
Italy province of Bergamo at a concn range of 0 to 30 parts/trillion .
SURFACE WATER: Propazine has been detected in water samples from 2 of 4 sites on the
Mississippi River sampled in the summer of 1984 . It was detected in water samples at Cairo,
IL, 25 miles below the Ohio River inflow and at the Carrolton Street water intake in New
Orleans, LA at 36 and 84 ng/l, respectively .
EFFL: Propazine was detected at a concn of 100 ppb in a sample of industrial effluent and at 1-7
ppb in the water of the river into which the effluent was discharged . It also was detected at
300, 3,000, and 2 ppm in the sediment of the river near the plant, 1.5 km downstream from the
plant, and near a nearby dam, respectively .
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