| Chemical Abstract Number (CAS #) |
1912249
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| Synonyms | Atrazine |
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2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine |
| Analytical Methods |
EPA Method 505 |
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EPA Method 525 |
EPA Method 619 |
EPA Method 8141A |
| Molecular Formula | C8H14ClN5 |
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| Use | ATRAZINE IS A WIDELY USED SELECTIVE HERBICIDE FOR CONTROL OF
BROADLEAF & GRASSY WEEDS IN CORN, SORGHUM, RANGELAND, SUGARCANE,
MACADAMIA ORCHARDS, PINEAPPLE, & TURF GRASS SOD. IT IS USED ALSO IN
SOME AREAS FOR SELECTIVE WEED CONTROL IN CONIFER REFORESTATION &
CHRISTMAS TREE PLANTATION AS WELL AS FOR NONSELECTIVE CONTROL OF
VEGETATION IN CHEMICAL FALLOW. ATRAZINE ALSO IS USED AS A
NONSELECTIVE HERBICIDE FOR VEGETATION CONTROL IN NONCROP LAND.
Selective pre- & post-emergence herbicide used in asparagus, forestry, grasslands, grass crops,
roses.
Crisazina pre and early postemergence on African oil palm, bananas, citrus groves, coffee, corn,
pineapples, sorghum, sugarcane.
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| Consumption Patterns | 96% AS AN AGRICULTURAL HERBICIDE FOR GRASSES & BROADLEAF
WEEDS (PRINCIPALLY ON CORN, SORGHUM & SUGARCANE); 2% AS A HERBICIDE
IN INDUSTRIAL & COMMERCIAL APPLICATIONS (IN RE-FORESTATION); 2% AS A
HERBICIDE FOR HOME & GARDEN USE (ON TURF) (1972).
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| Apparent Color | WHITE, CRYSTALLINE ; COLORLESS POWDER
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| Odor | Odorless
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| Melting Point | 171-174 DEG C
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| Molecular Weight | 215.68
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| Density | 1.187 g/cu cm @ 20 deg C
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| Environmental Impact | Atrazine may be released into the environment via effluents at manufacturing sites and at
points of application where it is employed as a herbicide. The s- triazine ring of atrazine is fairly
resistant to degradation. 2-Chloro-4- ethyl-amino-6-amino-s-triazine,
2-chloro-4-amino-6-isopropylamino-s-triazine,
2-hydroxy-4-ethylamino-6-isopropyl-amino-s-triazine and 2-hydroxy-4-
ethylamino-6-amino-s-triazine have been identified as microbial transformation products of
atrazine. Chemical degradation of atrazine may be more important environmentally than
biodegradation. Atrazine may hydrolyze fairly rapidly in either acidic or basic environments, yet is
fairly resistent to hydrolysis at neutral pHs. Furthermore the rate of hydrolysis was found to
drastically increase upon small additions of humic materials, indicating atrazine hydrolysis could
be catalyzed. For example, the half-life of atrazine at 25 deg C and pH of 4 was 244 days without
an additive and 1.73 days with the presence of 2% humic acid. At 25 deg C, a 5 mg/l solution of
fulvic acid (naturally occurs in soils and most surface waters) resulted in half-lives of 34.8, 174,
398 and 742 days at pHs of 2.9, 4.5, 6.0 and 7.0, respectively. Hydrolysis of atrazine followed
first order kinetics producing hydroxyatrazine as the transformation product. Photolysis of
atrazine did not occur in alcohols and water at wavelengths > 300 nm. However, at wavelengths
greater than or equal to 290 nm, the photolysis half-life of atrazine at a concn of 10 mg/l in
aqueous solution at 15 deg C was 25 hr as compared to a half-life of 4.9 hr for identical
conditions with an acetone sensitizer added at a concn of 1 ml/100 ml. Atrazine is expected to
maintain a very high to medium mobility class in soils and should not strongly absorb to
sediments. Atrazine is not expected to bioconcentrate or volatilize. However if released to the
atmosphere, vapor phase reactions with photochemically produced hydroxyl radicals in the
atmosphere may be important (estimated half-life of about 2.6 hr). The most probable exposure
would be occupational exposure, which may occur through dermal contact or inhalation at places
where atrazine is produced or used as a herbicide.
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| Environmental Fate | IN LAB MODEL ECOSYSTEM STUDY, WITH (14)C RING-LABELED ATRAZINE
THE ENVIRONMENTAL DEGRADATION PRODUCTS WERE
2-AMINO-4-CHLORO-6-ISOPROPYLAMINO-S-TRIAZINE & 2-AMINO-4-CHLORO
-6-ETHYLAMINO-S-TRIAZINE. THERE WAS ONLY A SLIGHT DEGREE OF
FOOD-CHAIN TRANSFER OF ATRAZINE (ECOLOGICAL MAGNIFICATION 11 TIMES
IN FISH) OR ANY OF ITS DEGRADATION PRODUCTS.
TERRESTRIAL FATE: The s-triazine ring of atrazine is fairly resistant to degradation. For
example after 70 days, less than one percent of the C(14) labeled atrazine treated at 10, 1000 and
20,000 ppm to a Webster soil was recovered as CO2 while only 10-20% was transformed to
2-chloro-4-ethyl-amino-6-amino-s-triazine, 2-chloro-4-amino-6- isopropylamino-s-triazine,
2-hydroxy-4-ethylamino-6-isopropyl-amino-s-triazine and
2-hydroxy-4-ethylamino-6-amino-s-triazine . However 14, 70 and 80% of the radio-labeled
atrazine treated to a Cecil soil at concn of 10, 1000 and 20,000 ppm was recovered intact . The
same transformation products were identified and at all concn less than one percent of the parent
material was metabolized to CO2 . A 50% reduction of 1 ppm atrazine was achieved within 130
days based on CO2 evolution from 5 differing soils incubated at 25 deg C . Only 0.49 and
0.76% of C(14) labeled atrazine evolved as CO2 from a soil/barley plant system treated at concn
of 1 and 6 ppm, respectively, after 7 days, whereas 1.69% of 1 ppm the radiolabeled atrazine
evolved from a soil system planted with maize .
TERRESTRIAL FATE: Chemical degradation of atrazine may be more important
environmentally than biodegradation in soil. Atrazine may hydrolyse in either acidic or basic soils
yet is fairly resistent to hydrolysis at neutral pHs. Furthermore the rate of hydrolysis was found to
drastically increase upon small additions of humic materials, indicating atrazine hydrolysis could
be catalyzed. For example the half-life of atrazine at 25 deg C and pH of 4 was 244 days without
an additive and 1.73 days with the presence of 2% humic acid . At 25 deg C, a 5 mg/l solution
of fulvic acid (naturally occurs in soils) at pHs of 2.9, 4.5, 6.0 and 7.0 resulted in half-lives of
34.8, 174, 398 and 742 days, respectively . Hydrolysis of atrazine followed first order kinetics
producing hydroxyatrazine as the transformation product(1-3). Atrazine has the potential to
photolyse from surface soils. The half-lives for sunlight exposed ring-labeled atrazine at concn of
0.10 ppm under aerobic conditions were 330 and 385 days for two agricultural soils . Atrazine
is expected to maintain a very high to medium mobility class in soils. Volatilization of atrazine is
not expected to be environmentally important.
AQUATIC FATE: The s-triazine ring of atrazine is fairly resistant to microbial attack based upon
a number of soil studies. Chemical degradation of atrazine may be more important
environmentally than biodegradation. Atrazine may hydrolyse fairly rapidly in either acidic or
basic waters, yet is fairly resistent to hydrolysis at neutral pHs. Furthermore the rate of hydrolysis
was found to drastically increase upon small additions of humic materials, indicating atrazine
hydrolysis could be catalyzed. For example the half-life of atrazine at 25 deg C and pH of 4 was
244 days without an additive and 1.73 days with the presence of 2% humic acid . At 25 deg C,
a 5 mg/l solution of fulvic acid (naturally occurs in surface waters) at pHs of 2.9, 4.5, 6.0 and 7.0
resulted in half-lives of 34.8, 174, 398 and 742 days, respectively . Hydrolysis of atrazine
followed first order kinetics producing hydroxyatrazine as the transformation product(1-3).
Alkaline hydrolysis proceeds twice as rapid as acidic hydrolysis .
AQUATIC FATE: Photolysis of atrazine did not occur in methanol, ethanol, butanol and water at
wavelengths > 300 nm . However at wavelengths greater than or equal to 290 nm, the
photolysis half-life of atrazine at a concn of 10 mg/l in aqueous solution at 15 deg C was 25 hr as
compared to a half-life of 4.9 hr for identical conditions with an acetone sensitizer added at a
concn of 1ml/100ml . The half-lives for sunlight exposed ring-labeled atrazine at concn of 0.10
ppm under aerobic conditions were 15 and 20 days for two estuarine sediments and 3-12 days for
estuarine water . Hydroxyatrazine (2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine) was
identified as the major short-term metabolite . Atrazine is not expected to strongly absorb to
sediments and may only moderately partition from the water column. Bioconcentration and
volatilization of atrazine are not expected to be environmentally important.
ATMOSPHERIC FATE: If released to the atmosphere, reactions with photochemically produced
hydroxyl radicals in the atmosphere may be important. The rate constant for the
vapor-phase reaction of atrazine with photochemically produced hydroxyl radicals has been
estimated to be 147.2X10-12 cu cm/molecule-sec at 25 deg C which corresponds to an
atmospheric half-life of about 2.6 hr at an atmospheric concn of 5X10 5 hydroxyl radicals per cu
cm .
TERRESTRIAL FATE: Atrazine was applied to a field planted with corn for 20 yr at rates
ranging 1.40-2.24 kg/ha. Analysis of soil samples taken 6 & 12 mo after the final application
showed the presence of residues of the parent cmpd & its mono dealkylated hydroxy analogs.
Long-term annual applications of atrazine for weed control in corn apparently result in the
persistence of some of its degradation products, mainly hydroxylated analogs, in soil 1 yr after the
final herbicide application. Such residues may enter the food crops planted in atrazine-treated soil
in the year or years following the cessation of a long-term treatment.
TERRESTRIAL FATE: The accumulation of atrazine was studied in 8 corn-planted soils, treated
with 1-2 kg atrazine/ha/yr for about 15 yr. The atrazine residues were 0.012-0.02 ppm. The
atrazine degradation products showed the following residues: deethylatrazine, 0.003-0.014 ppm;
deisopropylatrazine, 0.002-0.004 ppm; deethyldeisopropylatrazine, 0.002-0.04 ppm, and
hydroxyatrazine, about 0.01 ppm. C-Cl bond hydrolysis in atrazine was enhanced by acid soils.
TERRESTRIAL FATE: In the spring, 1973 loamy soil was treated with (14)C ring-labeled
atrazine. In the summer, 1981, soil samples were collected & analyzed. The soil still contained
about 83% from the initial (14)C activity. Only 40% could be extracted from those samples.
Besides traces of atrazine, 6 metabolites were identified which originated from the parent cmpd
through N-dealkylation and hydrolysis.
TERRESTRIAL FATE: In soil, microbial degradation occurs, with half-life of about 6-10 wk.
TERRESTRIAL FATE: THE PERSISTENCE IN SOIL & TRANSPORT OF ATRAZINE IN
SURFACE & SUBSURFACE RUNOFF FROM PLOTS IN COASTAL PLAIN OF THE
SOUTHERN UNITED STATE WERE STUDIED. ATRAZINE PERSISTED IN SOIL
SURFACE (10 CM) FOR MORE THAN 4 MONTHS; HOWEVER, IT COULD NOT BE
DETECTED AT GREATER DEPTHS AFTER 2 MONTHS. IT WAS NOT DETECTED IN
SIGNIFICANT SURFACE RUNOFF AFTER 26 DAYS OR IN SUBSURFACE FLOW.
TERRESTRIAL FATE: DEGRADATION PRODUCTS OF CYPRAZINE & ATRAZINE
WERE MONITORED OVER A 3-YEAR PERIOD IN SOIL (PREDOMINANTLY LOAMY
SANDS & SAND CLAY LOAMS) IN FIELDS USED TO GROW MAIZE. THE LEVEL OF
HYDROXYTRIAZINES IN SOIL SAMPLES RANGED FROM 0.05 TO 0.5 PPM & THEY
WERE THE PREDOMINANT TRIAZINE RESIDUES IN THE FIELDS DURING SPRING &
AUTUMN.
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 | SURFACE WATERS: Atrazine concn ranged from 0.1 to 23.2 ug/l for 13 Ohio streams
flowing into Lake Erie and from 1.0 to 45.7 ug/l for 8 sites in the Sandusky River basin, North
Ohio . For the dissolved fraction, 35% of 107 samples from 10 sites in the Cape Fear river
basin, NC tested positive for atrazine at concn up to 131.0 ug/l with an average of 5.6 ug/l; for
the particle fraction, 22% of 106 samples tested positive at concn up to 5.2 ug/l with an average
of 0.4 ug/l . Atrazine concn averaged 1.6 ng/g and 77% of the Canadian streams tested positive
for atrazine at entry points to the Great Lakes with a maximum atrazine level of 26.0 ng/g .
DRINKING WATER: The 7 day average concn of atrazine in 3 New Orleans LA drinking water
supplies ranged from 4.9 to 5.4 ug/l . Atrazine in Iowa's drinking water supplies from the South
Skunk, Racoon, Desmoines, and Rathburn Rivers, Red Rock Reservoir, 3 municipal wells of
Demoines, Davenport and Iowa City, and 4 raw drinking water wells ranged in concn from
NA-12,000, 120-3300, 50-800, 165-3750, 100-1900, 60-405 and 4-483 ng/l, respectively . The
South Skunk, Racoon, Desmoines, and Rathburn Rivers and Red Rock Reservoir maintained
respective average atrazine concn of 200, 814, 211, 1285 and 921 ng/l .
GROUNDWATER: In corn producing regions of Nebraska, atrazine was found in ground water
at concn ranging from 200 to 800 ng/l . Concn of atrazine in 14 irrigation wells in central
Nebraska ranged from 0.06 to 3.12 ug/l .
Atrazine was applied to plots which were drained by tiles. Water samples were collected &
analyzed. Concn during the first season ranged from 0.000 to 0.68 ug/l. The deethylated
metabolite, 2-chloro-4-isopropylamino-6-amino-s-triazine, was detected at similar concn.
SURFACE WATER: A SURVEY OF AGRICULTURAL WATERSHEDS IN SOUTHERN
ONTARIO, 1975-1977, NEAR LAND DEVOTED TO CORN PRODN TREATED WITH
ATRAZINE @ MEAN RATE OF 1.7 KG/HA, WAS CONDUCTED. STREAMS WERE
GAUGED & WATERS MONITORED. ATRAZINE & ITS METABOLITE
DESETHYLATRAZINE WERE DETECTED IN 80% OF STREAM WATERS @ 1.4 UG/L.
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