| Chemical Abstract Number (CAS #) |
133904
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| Synonyms | Chloramben |
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3-Amino-2,5-dichlorobenzoic acid |
| Analytical Methods |
EPA Method 515.1 |
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EPA Method 555 |
EPA Method 8151 |
| Molecular Formula | C7H5CL2NO2 |
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| Use | HERBICIDE FOR GRASSES & BROADLEAF WEEDS ON SOYBEANS, DRY
BEANS, LIMA BEANS, ASPARAGUS, PUMPKINS, SQUASH, CORN, TOMATOES,
PEPPERS, SWEET POTATOES
PREPLANT INCORPORATED OR PRE-EMERGENCE WEED CONTROL. APPLIED AT
PLANTING OF CORN, DRY BEANS, LIMA BEANS, PEANUTS, PUMPKINS, SEEDLING
ASPARAGUS, SOYBEANS, SQUASH, SUNFLOWERS, ESTABLISHED TOMATOES AND
PEPPERS, CUCUMBERS, CANTALOUPES, SNAPBEANS, AND SWEET POTATOES.
POST EMERGENCE IN SOYBEANS.
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| Consumption Patterns | 98% AS A HERBICIDE FOR GRASSES & BROADLEAF WEEDS ON SOYBEANS;
2% AS A HERBICIDE FOR GRASS & BROADLEAF WEEDS ON OTHER CROPS (DRY
BEANS, LIMA BEANS, SEEDLING ASPARAGUS, PUMPKINS, SQUASH, CORN,
TOMATOES, PEPPERS, & SWEET POTATOES) (1971)
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| Apparent Color | COLORLESS CRYSTALLINE SOLID
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| Odor | ODORLESS
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| Melting Point | 200-201 DEG C
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| Molecular Weight | 206.03
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| Sensitivity Data | MILD TO MODERATE DERMAL IRRITATION.
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| Environmental Impact | Amiben may be released to the environment by ground spray or granular application to
various crops during its use as a herbicide. If released to the air, Amiben may exist in the
particulate or the vapor phase. Particulate phase Amiben may rapidly photodegrade while vapor
phase Amiben will degrade relatively rapidly by reaction with photochemically produced hydroxyl
radicals (estimated half-life of about 15 hrs). The pKa of the Amiben -COOH group is
approximately 3 and the pKa of the Amiben -NH2 group is expected to be <4.6, thereby allowing
adsorption of protonated Amiben at low pHs. If released to water, Amiben should not volatilize,
bioconcentrate in aquatic organisms, or hydrolyze. In surface water exposed to sunlight, Amiben
will photodegrade rapidly (half-life of about 6 hr). In water and soil, Amiben may chemically bind
to soil and sediments with higher adsorption occurring either at a low pH with a low organic
matter content or at a neutral pH with a high organic matter content. Biodegradation in nonsterile
soils may occur via decarboxylation; however, the rate of microbial degradation is expected to
depend on the organic content, temperature, and moisture content. On soil surfaces, some Amiben
may photodegrade. Workers may be exposed to Amiben by dermal contact or inhalation during
the application of Amiben as a herbicide. The general public may be exposed to Amiben through
drinking water or groundwater supplies in which it has been detected.
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| Environmental Fate | LOSS OF CHLORAMBEN BY LEACHING WAS MOST PRONOUNCED FROM A
SANDY SOIL & WAS PROGRESSIVELY LESS AS CLAY & ORGANIC COMPONENTS
INCREASED.
VOLATILITY & SOIL MOVEMENT ARE MORE DEPENDENT ON FORM OF
CHLORAMBEN APPLIED THAN ON SOIL TYPE. ALUMINUM & AMMONIUM
SALTS WERE EASILY LEACHED FROM SEVERAL ARKANSAS SOILS. METHYL &
BUTOXYETHYL ESTERS RESISTED LEACHING, WHILE AMIDE WAS
INTERMEDIATE WITH RESPECT TO LEACHING.
/FROM INVESTIGATIVE STUDIES ONE MIGHT EXPECT THAT CHLORAMBEN
PERSISTENCE MAY BE GREATEST AS THE BUTOXYETHYL ESTER IN DRY SOIL
OF HIGH ORG CONTENT & LEAST FOR SALT IN A MOIST SANDY SOIL WHERE
HIGH RAINFALL WOULD ACCELERATE LEACHING.
ABSORPTION OF CHLORAMBEN TO SOIL PARTICLES SIGNIFICANTLY REDUCED
HERBICIDAL ACTIVITY. IN ONE INSTANCE, UNDER CONTROLLED LAB
CONDITIONS, A MUCK SOIL ABSORBED 29% OF APPLIED CHLORAMBEN,
WHEREAS A SILTY CLAY LOAM ABSORBED ONLY 9%. DESORPTION OF
CHLORAMBEN FROM MUCK SOILS IS SLOW.
VOLATILIZATION MAY BE A SIGNIFICANT PATHWAY FOR LOSS OF
CHLORAMBEN FROM SOIL SURFACE. NO CRITICAL STUDY OF CHLORAMBEN
VOLATILIZATION OR POSSIBLY CODISTILLATION FROM SOIL SURFACE HAS BEEN
MADE
Resultant average persistence at recommended rates (2.24 to 4.5 kg/ha) approximately 6 to 8
weeks.
TERRESTRIAL FATE: Photodecomposition may account for some loss of Amiben on soil
surfaces(1,7). Experimental Koc values of 190(9) and 21(10) for the undissociated form indicate
that Amiben will have high to very high soil mobility and will leach(11). Amiben is expected to
exist as an anion in most soil systems under environmental conditions (pH 5-9) and this form is
expected to demonstrate high soil mobility. Amiben has been shown to chemically bind to
soil with higher adsorption to soil occurring either at a low pH with a low organic matter content
or at a neutral pH with a high organic matter content(2,5,8). Biodegradation in nonsterile soil may
occur(2-6); however, the rate of microbial degradation is expected to depend on the organic
content, temperature, and moisture content(4-6).
AQUATIC FATE: Volatilization from water, bioconcentration in aquatic organisms and
hydrolysis in water are not expected to be important removal processes of Amiben from
environmental water systems. In surface water exposed to sunlight, Amiben will
photodegrade rapidly (0.001 M Amiben half-life of 6 hr) . Amiben may leach through sediments
to groundwater(7-10). However, Amiben may chemically bind to sediments with higher
adsorption occurring either at a low pH with a low organic matter content or at a neutral pH with
a high organic matter content(2,5). Although the available biodegradation studies are not specific
to water(2-6), they suggest that Amiben in water may be susceptible to slow
biodegradation.
A vapor pressure of 1X10-7 mm Hg at 25 deg C can be estimated using the Clausius-Clapeyron
equation and a measured vapor pressure of 0.007 mm Hg at 100 deg C(1,SRC). Based on this
vapor pressure value, Amiben may exist in the particulate or the vapor phase in the ambient
atmosphere . Vapor phase Amiben will degrade relatively rapidly in the atmosphere by reaction
with photochemically produced hydroxyl radicals (estimated half-life of about 15 hrs)(3,SRC).
Particulate phase Amiben may be subject to rapid photodegradation .
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| Drinking Water Impact | GROUNDWATER: Amiben was detected in 1 Wisconsin well at a concentration
exceeding the recommended health advisory of 10 ug/L . According to a Wisconsin
groundwater monitoring study, Amiben was detected in 2% of the wells studied at a maximum
concentration of 50 ug/L . Also, Amiben detection in groundwater was reported in Iowa, but
no concns were given . Amiben was detected in wells from 12 of 91 farms during November
and December, 1984 in Southern Ontario, Canada . In a monitoring survey studying the
occurrence of pesticides in Ontario farm wells, Amiben was detected in 6 of 103 wells in 1986
and in 1 of 76 wells in 1987 .
DRINKING WATER: Amiben has been qualitatively identified in drinking water from Seattle,
WA on November 15, 1976 .
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