Description
Bromacil (CAS 314-40-9) belongs to a class of herbicides
known as uracils, first developed by DuPont in 1962. Its
herbicidal activity is due to inhibition of photosynthesis in
several species of weeds and brush. Since its introduction in
1962, farmers in North and South America and Asia have used
bromacil-containing herbicides for crop protection.
Chemical Properties
white to beige crystalline solid
Chemical Properties
Bromacil is a noncombustible colorless, crystalline
solid, which may be dissolved in a flammable liquid.
Uses
Uracil herbicide applied to soil to control a wide variety of annual and perennial
grasses, broad-leaved weeds and general vegetation on uncropped land. It is also used for
selective weed control in apple, asparagus, cane fruit, hops and citrus crops.
Uses
Bromacil is a nonselective inhibitor of photosynthesis,
absorbed mainly through the root and used for general
weed control on uncropped land at 5–15 kg/ha (2–4 kg/ha
annual maintenance). It is also used for weed control in citrus
plantations and for perennial grass control and annual pineapple
plantations.
Definition
Substitute approved by EPA for some uses of 2,4,5-T.
General Description
Colorless to white odorless crystalline solid. Used as an herbicide. Commercially available as a wettable powder or in liquid formulations.
Reactivity Profile
Bromacil is incompatible with the following: Strong acids (decomposes slowly), oxidizers, heat, sparks, open flames .
Hazard
Possible carcinogen. Thyroid effects.
Flammability and Explosibility
Not classified
Agricultural Uses
Bromacil: Bromacil is used primarily for the control of annual and
perennial grasses and broadleaf weeds, both nonselectively on
noncrop lands and selectively for weed-control in citrus and pineapple
crops. The top five applications in California for which this
is used are oranges, lemons, grapefruit, and right-of-ways and
landscapes. A limit of 0.1 mg/kg of agricultural products is set in
several countries[35]. Not approved for use in EU countries.
Trade name
BOREA®; BOROCIL EXTRA®; α-BROMACIL
80 WP®; BROMAX®; CROPTEX ONYX®;
CYNOGEN®; DuPontTM HERBICIDE 976®; EEREX®;
FENOCIL®; HERBICIDE 976®; HIBOR; HYDON®;
HYVAR®; HYVAR-X®; HYVAR X BROMACIL®;
HYVAR X-L®; HYVAR X WEED KILLER®; HYVAR
X-WS®; ISOCIL®; KROVAR®; NALKIL®; ROUT®;
URAGAN®; URAGON®; UROX®; UROX B WATER
SOLUBLE CONCENTRATE WEED KILLER®; UROX
HX GRANULAR WEED KILLER®; WEED-BROOM®
(mixture of DSMA, Bromacil & 2,4-D)
Potential Exposure
Used for general weed or brush control
in noncrop areas and primarily for the control of annual
and perennial grasses and broadleaf weeds, both nonselectively
on noncrop lands and selectively for weed-control in
a few crops (citrus and pineapple). A limit of 0.1 mg/kg of
agricultural products is set in several countries. Those
exposed will be those involved in manufacture, formulation,
and application.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.
Carcinogenicity
No evidence of carcinogenic
potential was seen in rats or dogs fed up to 1250 ppm
bromacil for 2 years. Bromacil was not oncogenic in
rats fed 50, 250, or 2500 ppm for 2 years. A marginal
increase in the incidence of hepatocellular neoplasms was
seen in mice fed 5000 ppm (but not 250 or 1250 ppm) for 18
months.
Environmental Fate
Soil. Metabolites tentatively identified in soil were 5-bromo-3-(3-hydroxy-1-methyl propyl)-6-methyluracil, 5-bromo-3-sec-butyl-6-hydroxymethyluracil, 5-bromo-3-(2-
hydroxy-1-methylpropyl)-6-methyluracil and carbon dioxide. The presence of uracil prod ucts suggests that bromacil was degraded via hydroxylation of the side chain alkyl groups.
In the laboratory, 25.3% of 14C-bromacil degraded in soil to carbon dioxide after 9 weeks
but mineralization in the field was not observed. The half-life of bromacil in a silt loam
was 5–6 months (Gardiner et al., 1969).
To a neutral sandy loam soil maintained at a soil water holding capacity of 60%, 2.88
ppm of 2-14C-bromacil was applied. After 600 days, 22.1% (0.64 ppm) of the applied
amount was converted to 14CO2 (Wolf and Martin, 1974). The evolution of 14CO2 was
sign
Residual activity in soil is limited to approximately 7 months (Hartley and Kidd, 1987).
In California soils, bromacil was persistent for 30 months (Lange et al., 1968; Weber and
Best, 1972). The reported half-life in soil is 60 days (Alva and Singh, 1991
The average half-life for bromacil in soil incubated in the laboratory under aerobic
conditions was 132 days (Zimdahl et al., 1970). In field soils, the average disappearance
half-life was 349 days (Gardiner et al., 1969; Leistra et al., 1975). Under aerobic conditions,
the mineralization half-lives for bromacil in soil ranged from 151 days to 4.5 years
(Gardiner et al., 1969; Wolf and Martin, 1974).
Groundwater. According to the U.S. EPA (1986) bromacil has a high potential to leach
to groundwater.
Metabolic pathway
The microorganism, a Pseudomonas sp. isolated from
soil by using bromacil as a sole source of carbon and
energy, shows a potential to decontaminate soil
samples fortified with bromacil under laboratory
conditions. The degradation pathways of bromacil by
the Pseudomonas sp. may include 5-bromouracil as
an intermediate which leads to 5-
bromodihydroxyluracil. Ozonization, UV photolysis,
and sensitized sunlight photodegradation of aqueous
bromacil solution lead to photodegradation products.
The ozonization yields three main products which are
identified as 3-sec-butyl-5-acetyl-5-hydroxyhydantoin,
3-sec-butylparabanic acid, and 3-sec-butyl-5,5-
dibromo-6-hydroxyuracil. The main products of
photoirradiation are 3-sec-butyl-6-methyluracil, its
dimeric compound, and 3-sec-butyl-5-acetyl-5-
hydroxyhydantoin.
storage
Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Color Code—Green: Generalstorage may be used. Prior to working with bromacil youshould be trained on its proper handling and storage. Storein tightly closed containers in a cool, well-ventilated areaaway from strong acids, oxidizers, heat, and open flame.
Shipping
UN2811 Toxic solids, organic, n.o.s., Hazard
Class: 6.1; Labels: 6.1—Poisonous materials, Technical
Name Required.
Toxicity evaluation
Bromacil is a nonvolatile, slightly water-soluble compound
with a low octanol–water partition coefficient (Kow) and a pKa
of 9. Although the lithium salt is more soluble in water than
bromacil, its environmental fate is identical, since the extent of
ionization of bromacil, that is, the ratio of unionized bromacil
to its anionic form, will be controlled by the pH and buffering
capacity of the terrestrial or aquatic system to which it is
applied. The physicochemical properties are reflected in the
environmental fate properties. Bromacil is weakly absorbed to
soil and is considered highly mobile. The low Kow indicates that
bromacil will not bioaccumulate. Bromacil is stable in water
over the pH range of 5–9, and photolyzes through both direct
and indirect mechanisms in surface water with a half-life of 4–7 days at pH 9. In soil under aerobic conditions in the laboratory,
bromacil degrades slowly forming several metabolites as
a result of microbial activity. In anaerobic environments, bromacil
may degrade very rapidly through a debromination
reaction. In field dissipation studies, bromacil half-lives of
124–1155 days were observed.
Incompatibilities
Incompatible with strong acids; oxidizers,
heat. Decomposes slowly in strong acids.
Waste Disposal
Bromacil should be incinerated
in a unit operating @ 850° C equipped with gas scrubbing
equipment
