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Flumioxazin. Profile from Hazardous Substances Data Bank.
From Hazardous Substances Data Bank (HSDB)
FLUMIOXAZIN
CASRN: 103361-09-7
For other data, click on the Table of Contents
Human Health Effects:
Probable Routes of Human Exposure:
Occupational exposure to flumioxazin may occur through short- and intermediate-term
dermal and inhalation exposure during mixing, loading, applying and post-application
activities(1).
Emergency Medical Treatment:
Animal Toxicity Studies:
Non-Human Toxicity Excerpts:
Non-irritating to skin; mild eye irritant (rabbits). Non-sensitizing to skin
(guinea pigs).
An N-phenylimide herbicide, S-53482, inhibits protoporphyrinogen oxidase,
an enzyme common to chlorophyll & heme biosynthesis, & produces embryolethality,
teratogenicity [mainly ventricular septal defects (VSD) & wavy ribs], &
growth retardation in rats. In order to elucidate the mechanism of the developmental
toxicity, in particular VSD, effects of the herbicide on rat embryonic blood
cells were investigated histologically at the light & electron microscopic
levels at 6, 12, 24, 36, & 48 hr after oral admin of the chemical to pregnant
rats on day 12 of gestation, the most sensitive day for toxicity. Electron &
light microscopy demonstrated mitochondrial lesions, including abnormal iron
deposits that were probably due to inhibition of heme biosynthesis, in erythroblasts
derived from the yolk sac. Subsequently, degeneration of these erythroblasts
occurred followed by erythrophagocytosis. Histologically hearts from exposed
embryos had a thin ventricular wall, which may reflect a compensatory reaction
to a loss of embryonic blood cells.
Pregnant females were admin 400 mg/kg by gavage on gestation day 11 or 12
or 13 or 14 or 15. Day 12 admin showed: largest incidence of embryonic death,
lowest fetal body weights & greatest incidence of ventricular spetal defects.
Mode of action: Herbicide, absorbed by foliage & germinating seedlings.
Acts, in the presence of light & oxygen, by inducing massive accumulation
of porphyrins, & enhancing peroxidation of membrane lipids, which leads
to irreversible damage of the membrane function & structure of susceptible
plants.
Non-Human Toxicity Values:
LD50 Rat oral >5000 mg/kg
LD50 Rat percutaneous >2000 mg/kg
LC50 Rat inhalation >3930 mg/cu m air/ 4 hr
Metabolism/Pharmacokinetics:
Absorption, Distribution & Excretion:
/In rats after oral dose/ GI tract absorption >90% at 1 mg/kg & up
to 50% at 100 mg/kg. At least 97% recovery in feces & urine 7 days after
dosing. Highest levels of residues (36-49 ppb) in blood cells at low dose &
2800-3000 ppb at high dose (RBC levels > plasma). In addition to untransformed
parent, 7 metabolites identified in urine & feces (38-46% for low dose &
about 71% at high dose).
/Rat/ males dosed with suspension of 50 /Valor/ WDG formulation in water at
0.02, 0.20 or 1.0 mg/rat (0.002, 0.020 or 0.100 sq cm. At 0.02 mg/rat, absorption
ranged from 0.48% at 0.5 hr to 5.46% at 24 hr. At 0.2 mg/rat, absorption ranged
from 0.007% at 0.5 hr to 0.74% at 24 hr. At 1.0 mg/rat, absorption ranged from
0.004% at 0.5 hr to 10.47% at 24 hr. Females dosed with 200 or 800 mg/kg b.w.
Dermal absorption for 200 & 800 mg/kg was 3.9 & 8.0% by 48 hr after
initiation of treatment for 6 hr. Blood levels at 6-24 hr after dermal dosing
with 200 mg/kg were similar to those obtained at 2-6 hr after oral dosing with
1 mg/kg. Blood levels at 6-24 hr after dermal dosing with 800 mg/kg were similar
to those obtained at 2-6 hr after oral dosing with 30 mg/kg.
Mechanism of Action:
Mode of action: Herbicide, absorbed by foliage & germinating seedlings.
Acts, in the presence of light & oxygen, by inducing massive accumulation
of porphyrins, & enhancing peroxidation of membrane lipids, which leads
to irreversible damage of the membrane function & structure of susceptible
plants.
Pharmacology:
Environmental Fate & Exposure:
Environmental Fate/Exposure Summary:
Flumioxazin's production may result in its release to the environment through
various waste streams; it's use as a herbicide will result in its direct release
to the environment. If released to air, a vapor pressure of 2.41X10-6 mm Hg
at 20 deg C indicates flumioxazin will exist in both the vapor and particulate
phases in the ambient atmosphere. Vapor-phase flumioxazin will be degraded in
the atmosphere by reaction with photochemically-produced hydroxyl radicals;
the half-life for this reaction in air is estimated to be 6.8 hours. Particulate-phase
flumioxazin will be removed from the atmosphere by wet and dry deposition. If
released to soil, flumioxazin is expected to have a low potential to leach based
on column leaching studies and a fast degradation rate. Volatilization from
moist soil surfaces is negligible. Flumioxazin degrades rapidly in soil water
via hydrolysis with half-lives of 3.4 to 5.1 days at pH 5.0, 21.4-24.6 hours
at pH 7.0, and 14.6-22.0 minutes at pH 9.0; therefore, aqueous chemical hydrolysis
in moist soils will be an important fate process. Microbial degradation in soil
is also an important fate process; the half-life for aerobic soil metabolism
is 11.9 to 17.5 days, with an average of 14.7 days. The photolysis half-life
on soil is 3.2 to 8.4 days (average 5.8 days). The rapid soil dissipation rate
indicates flumioxazin is not persistent in soil. If released into water, chemical
hydrolysis will be a major degradation process. Flumioxazin has an anaerobic
aquatic metabolism half-life of 0.2 days. Volatilization from water surfaces
is not expected to be an important fate process based upon this compound's estimated
Henry's Law constant. An estimated BCF of 18 suggests the potential for bioconcentration
in aquatic organisms is low. Photodegradation in shallow water can occur (surface
half-life of about 1 day at pH 5). Occupational exposure to flumioxazin may
occur through short and intermediate-term dermal and inhalation exposure during
mixing, loading, applying and post-application activities. (SRC)
Probable Routes of Human Exposure:
Occupational exposure to flumioxazin may occur through short- and intermediate-term
dermal and inhalation exposure during mixing, loading, applying and post-application
activities(1).
Artificial Pollution Sources:
Flumioxazin's production may result in its release to the environment through
various waste streams; it's use as a herbicide(1) will result in its direct
release to the environment(SRC).
Environmental Fate:
TERRESTRIAL FATE: Based on column leaching studies and the short aerobic soil
half-life, the potential for flumioxazin to leach in field agricultural soil
is low(1). In soils that have been treated with flumioxazin, it is generally
not found below 3 inches in depth(2). Volatilization losses from soil surfaces
are negligible(1). Flumioxazin degrades rapidly in soil water via hydrolysis
with half-lives of 3.4 to 5.1 days at pH 5.0, 21.4-24.6 hours at pH 7.0, and
14.6-22.0 minutes at pH 9.0(1); therefore, aqueous hydrolysis in moist soils
will be an important fate process(SRC). Microbial degradation in soil is also
an important fate process(1); the half-life for aerobic soil metabolism is 11.9
to 17.5 days, with an average of 14.7 days(1,2). The photolysis half-life on
soil is 3.2 to 8.4 days (average 5.8 days)(2). The rapid soil dissipation rate
indicates flumioxazin is not persistent in soil(1).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value
of 13000(SRC), determined from a structure estimation method(2), indicates that
flumioxazin is expected to adsorb to suspended solids and sediment(SRC). The
hydrolytic degradation half-life of flumioxazin in soil water is 3.4 to 5.1
days at pH 5.0, 21.4-24.6 hours at pH 7.0, and 14.6-22.0 minutes at pH 9.0(3);
therefore, hydrolysis will be the major degradation process in water(SRC). An
anaerobic aquatic metabolism half-life of 0.2 days has been reported(4). The
photolysis half-life in water at pH 5 is 1 day(4). Volatilization from water
surfaces is expected to be slow(5) based upon an estimated Henry's Law constant
of 6.28X10-7 atm-cu m/mole(SRC), derived from its vapor pressure, 2.41X10-6
mm Hg(6), and water solubility, 1.79 mg/l(4). Using this estimated Henry's Law
constant and an estimation method(5), volatilization half-lives for a model
river and model lake are 1,765 hours and 809 days, respectively(SRC). According
to a classification scheme(7), an estimated BCF of 18(SRC), from a log Kow of
2.55(4) suggests the potential for bioconcentration in aquatic organisms is
low(SRC).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile
organic compounds in the atmosphere(1), flumioxazin, which has a vapor pressure
of 2.41X10-6 mm Hg at 25 deg C (2), will exist in both the vapor and particulate
phases in the ambient atmosphere. Vapor-phase flumioxazin is degraded in the
atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC);
the half-life for this reaction in air is estimated to be 6.8 hours(SRC), calculated
from its rate constant of 5.68X10-11 cu cm/molecule-sec at 25 deg C(SRC) (that
was derived using a structure estimation method(3). Particulate-phase flumioxazin
may be removed from the air by wet and dry deposition(SRC).
Environmental Biodegradation:
Based on laboratory tests, loss of flumioxazin in soil appears to be primarily
by microbial degradation(1); the half-life for aerobic soil metabolism is 11.9
to 17.5 days, with an average of 14.7 days(1,2).
Environmental Abiotic Degradation:
The hydrolytic degradation half-life of flumioxazin in soil water is 3.4 to
5.1 days at pH 5.0, 21.4-24.6 hours at pH 7.0, and 14.6-22.0 minutes at pH 9.0(1).
Similar chemical hydrolysis half-lives of 4.2 days (pH 5), 1 day (pH 7), and
0.01 days (pH 9) are also reported(2). The photolysis half-life in water at
pH 5 is 1 day(2). The photolysis half-life on soil is 3.2 to 8.4 days (average
5.8 days)(1).
The rate constant for the vapor-phase reaction of flumioxazin with photochemically-produced
hydroxyl radicals has been estimated as 5.68X10-11 cu cm/molecule-sec at 25
deg C(SRC) using a structure estimation method(1). This corresponds to an atmospheric
half-life of about 6.8 hours at an atmospheric concentration of 5X10+5 hydroxyl
radicals per cu cm(1).
Environmental Bioconcentration:
An estimated BCF of 18 was calculated for flumioxazin(SRC), using an experimental
log Kow of 2.55(1) and a regression-derived equation(2). According to a classification
scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms
is low(SRC).
Soil Adsorption/Mobility:
Using a structure estimation method based on molecular connectivity indices(1),
the Koc for flumioxazin can be estimated to be 13000(SRC). The Koc can also
be estimated as 581 and 2000(SRC), using a log Kow of 2.55(3) and a water solubility
of 1.79 mg/l at 25 deg C(3) and regression-derived equations(2). According to
a classification scheme(3), these estimated Koc values suggests that flumioxazin
is expected to have low to no mobility in soil.
The mobility (unaged leaching) of flumioxazin is reported as moderately mobile(1);
fluxioxazin is generally not found below 3 inches of soil depth(1). Available
data indicate flumioxazin is relatively unstable and its potential to leach
to groundwater is low(1); however, the potential for degradation products to
leach to groundwater is high(1).
Volatilization from Water/Soil:
The Henry's Law constant for flumioxazin is estimated as 6.28X10-7 atm-cu
m/mole(SRC) derived from its vapor pressure, 2.41X10-6 mm Hg(1), and water solubility,
1.79 mg/l at 25 deg C(1). This estimated Henry's Law constant indicates that
flumioxazin is expected to be volatilize slowly from water surfaces(2). Based
on this estimated Henry's Law constant, the volatilization half-life from a
model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated
as 1765 hours(SRC). The volatilization half-life from a model lake (1 m deep,
flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 809 days(SRC).
Flumioxazin is reported to have negligible volatilization losses from soil(3).
Environmental Standards & Regulations:
FIFRA Requirements:
Tolerances are established for residues of flumioxazin, 2-(7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazin-6-yl)-4,5,6,7-tet
rahydro-1H-isoindole-1,3(2H)-dione, in or on the following raw agricultural
commodities: peanuts; and soybean seed.
Allowable Tolerances:
Tolerances are established for residues of flumioxazin, 2-(7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazin-6-yl)-4,5,6,7-tet
rahydro-1H-isoindole-1,3(2H)-dione, in or on the following raw agricultural
commodities: peanuts: 0.02 ppm; and soybean seed: 0.02 ppm.
Chemical/Physical Properties:
Molecular Formula:
C19-H15-F-N2-O4
Molecular Weight:
354.3
Color/Form:
Light tan powdered solid
Yellow-brown powder
Yellow brown solid (technical); Light brown solid (end-use)
Odor:
Slight (end-use)
Melting Point:
201-204 deg C
Corrosivity:
Formulated products are non-corrosive to containers
Density/Specific Gravity:
1.5136 g/ml @ 20 deg C
Dissociation Constants:
Does not dissociate
Octanol/Water Partition Coefficient:
log Kow = 2.55 @ 20 deg C
pH:
pH= 6.2-6.4 @ 20 deg C (end-use)
Solubilities:
Soluble in common organic solvents
In water, 1.79 mg/l @ 25 deg C
Vapor Pressure:
2.41X10-6 mm Hg @ 25 deg C
Other Chemical/Physical Properties:
Odorless; pH= 7.29 @ 25 deg C /Technical/
Chemical Safety & Handling:
Stability/Shelf Life:
Stable under normal storage conditions.
Occupational Exposure Standards:
Manufacturing/Use Information:
Major Uses:
For Flumioxazin (USEPA/OPP Pesticide Code: 129034) ACTIVE products with label
matches. /SRP: Registered for use in the U.S. but approved pesticide uses may
change periodically and so federal, state and local authorities must be consulted
for currently approved uses./
Preemergence herbicide to effectively control a wide variety of broadleaf
weeds
Manufacturers:
Valent USA Corporation, Walnut Creek, CA 94596
General Manufacturing Information:
Registered for use on soybeans and peanuts. ... One application is allowed
per season.
Formulations/Preparations:
USEPA/OPP Pesticide Code 129034; Trade Names: V-53482.
97.9% technical grade; 51% emulsifiable concentrate end-use product
Wettable powder
Laboratory Methods:
Special References:
Synonyms and Identifiers:
Synonyms:
Pesticide Code 129034
**PEER REVIEWED**
2-(7-fluoro-3,4-dihydro-3-oxo-4-(2-propynyl)-2H-1,4-benzoxazin-6-yl)-4,5,6,7-tet
rahydro-1H-isoindole-1,3(2H)-dione
**PEER REVIEWED**
Sumisoya
**PEER REVIEWED**
Valor WDG herbicide
**PEER REVIEWED**
Formulations/Preparations:
USEPA/OPP Pesticide Code 129034; Trade Names: V-53482.
97.9% technical grade; 51% emulsifiable concentrate end-use product
Wettable powder
Administrative Information:
Hazardous Substances Databank Number: 7012
Last Revision Date: 20020830
Last Review Date: Reviewed by SRP on 5/11/2002
Update History:
Complete Update on 08/30/2002, 39 fields added/edited/deleted.
Record Length: