---

The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

---

E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Bromacil

Trade and Other Names: Trade names include Borea, Bromax 4G, Bromax 4L, Borocil, Cynogan, Hyvar X, Hyvar XL, Isocil, Krovar, Rout, Uragan, Urox B, and Urox HX.

Regulatory Status: Bromacil is classified by the U. S. Environmental Protection Agency (EPA) as a General Use Pesticide (GUP). It is in toxicity class IV - practically nontoxic in dry form, and class II - moderately toxic in the liquid form. Dry formulations containing bromacil bear the Signal Word CAUTION. Because of their irritating effects on skin, eyes, and the respiratory tract, liquid formulations bear the Signal Word WARNING.

Chemical Class: Not Available

Introduction: Bromacil is an herbicide used for brush control on non-cropland areas. It is especially useful against perennial grasses. It is also used for selective weed control in pineapple and citrus crops. It works by interfering with photosynthesis, the process by which plants use sunlight to produce energy. Bromacil is one of a group of compounds called uracils. It is sprayed or spread dry on the soil surface just before, or during, a period of active weed growth. It is available in granular, liquid, water soluble liquid, and wettable powder formulations.

Formulation: It is available in granular, liquid, water soluble liquid, and wettable powder formulations.

Toxicological Effects:

• Acute toxicity: Liquid formulations of bromacil are moderately toxic, while dry formulations are practically non-toxic [8]. The herbicide is irritating to the skin, eyes, and respiratory tract [68]. When 100 mg/kg of the herbicide was fed to dogs, it caused vomiting, watering of the mouth, muscular weakness, excitability, diarrhea, and dilation of the pupils. Rats that were fed single doses of bromacil experienced initial weight loss, paleness, exhaustion, and rapid breathing. Within 4 hours of being given 250 mg/kg, sheep became bloated and walked with stilted gaits [30]. Bromacil caused mild dermal irritation when it was applied to the skin of guinea pigs. The LD50 is greater than 5000 mg/kg in rabbits whose skin is exposed. When bromacil was administered to the eyes of rabbits, there was irritation in the conjunctiva (the mucous membrane lining of the eye), but there was no injury to the cornea [30]. The inhalation LC50 (4-hour) is greater than 4.8 mg/L air for rats [1]. The oral LD50 for bromacil in rats is 5200 mg/kg, and in mice is 3040 mg/kg [1,30].
• Chronic toxicity: Enlarged livers were revealed in autopsies on rats that died after 5 days of repeated doses of bromacil at 1500 mg/kg/day [30]. Sheep that died after being given 250 mg/kg/day of bromacil on 4 successive days showed the following: inflammation of the mucous membrane that lines the stomach and intestines, congestion and enlargement of the liver, weakened appearance of the adrenal glands, bleeding of the heart, and swollen, bleeding lymph nodes [30]. Consumption of bromacil at high levels over a long period of time has been shown to cause damage to the testes, liver, and thyroid of laboratory animals [74]. In another study, female rats fed 62.5 mg/kg/day for 2 years, the highest dose level, exhibited decreased weight gain. No other toxic effects were observed [74]. No evidence of toxicity was detected in dogs fed up to 31.2 mg/kg/day for 2 years [74]. In an 18-month study in which mice were given dietary doses of 12.5, 62.5, or 250 mg/kg/day, changes in the liver and testes were observed at the 62.5 mg/kg/day dosage [74]. Chickens given 500 mg/kg/day bromacil did show a decrease in weight gain [75].
• Reproductive effects: Bromacil did not affect the reproduction of rats fed 12.5 mg/kg/day for three generations [8,74]. This suggests that bromocil does not cause reproductive effects.
• Teratogenic effects: There was no evidence of birth defects in the offspring of rats that were given dietary doses of 12.5 mg/kg/day bromacil, nor in rabbits that were given 7.5 mg/kg/day on days 8 through 16 of pregnancy [74]. However, toxic effects and developmental abnormalities of the musculoskeletal system were seen in the embryos or fetuses of rats which inhaled very high bromacil doses of 38 mg/L for 2 hours daily, during days 7 to 14 of pregnancy [22]. Toxic effects and developmental abnormalities were observed in the fetuses of pregnant rats repeatedly exposed by inhalation to bromacil [8]. These data suggest that humans are unlikely to suffer teratogenic effects from bromacil under normal circumstances.
• Mutagenic effects: Several mutagenic screening tests indicate that bromacil is not mutagenic [74].
• Carcinogenic effects: There is limited evidence that bromacil causes cancer in animals receiving high doses over the course of their lifetimes [74]. There was no evidence of carcinogenicity in rats fed 12.5 mg/kg/day for 2 years of bromacil, but at 62.5 mg/kg/day, there was at slight increase in hyperplasia of the thyroid, and one rat developed benign liver tumors [17,74]. An increased incidence of malignant tumors was observed in the livers of male mice given 250 mg/kg/day of bromacil for 78 weeks. No effect on liver tumor incidence was observed in female mice [74]. Based on these results, it is not possible to determine bromacil's carcinogenic potential.
• Organ toxicity: Animal studies have shown the liver, heart, and lymph nodes to be affected.
• Fate in humans and animals: A number of studies show that uracils, the class of compounds to which bromacil belongs, are absorbed into the body from the gut and excreted primarily in the urine [8,74]. Small amounts of bromacil were detected in the milk of lactating cows that were given 5 mg/kg in their food [30]. No bromacil was found in the urine or feces of these cows [8].

Ecological Effects:

• Effects on birds: The 8-day dietary oral LC50 for bromacil is over 10,000 ppm in mallards and quail [23]. This indicates that it is practically nontoxic to these species.
• Effects on aquatic organisms: Bromacil is slightly to practically nontoxic to fish. The 48-hour LC50 for bromacil in bluegill sunfish is 71 mg/L, in rainbow trout is 56 75 mg/L, and in carp is 164 mg/L [8]. The 96-hour LC50 in fathead minnows is 182 mg/L [8]. It is not toxic to aquatic invertebrates [8].
• Effects on other organisms: Bromacil is not toxic to honeybees [1].

Environmental Fate:

• Breakdown in soil and groundwater: Bromacil binds, or adsorbs, only slightly to soil particles, is soluble in water, and is moderately to highly persistent in soil. Its half-life is about 60 days, but may be as much as 8 months under some conditions [11]. Soil persistence is correlated to the organic content of the soil [8,75]. At 18 months after 22.4 kg of bromacil were sprayed on abandoned field sites, residues of the herbicide were detectable, in decreasing amounts, in loamy sand, silt loam, silty clay loam, and light silty clay loam soils. Organic matter content, cation exchange capacity, total nitrogen, and soluble salt concentrations were significantly correlated with residue persistence [8]. Bromacil is expected to leach quite readily through the soil and contaminate groundwater. The amount of leaching is dependent on the soil type and the amount of rainfall or irrigation water. The potential for bromacil to leach and contaminate groundwater is greatest in sandy soils. In normal soils, it can be expected to leach to a depth of 2 to 3 feet [8]. Tests show that at increased temperatures and long exposures to sunlight, there is very little loss of bromacil from dry soil. It does not readily volatilize, nor does it break down in sunlight [8]. Laboratory studies show that 5 to 30% of bromacil is lost 6 to 9 weeks after application to the soil, as carbon dioxide [8].
• Breakdown in water: Bromacil is estimated to have a 2-month half-life in clean river water, which is low in sediment [76].
• Breakdown in vegetation: In plants, bromacil is taken up rapidly by the roots and slightly absorbed through the leaves [58]. When it is applied at 10 ppm, some types of algae show slowed growth, but most strains are unaffected [75]. Improper application of bromacil will destroy shade trees and other desirable vegetation [76].

Physical Properties:

• Appearance: Bromacil is an odorless, white crystalline solid [1].
• Chemical Name: 5-bromo-6-methyl-3-(1-methylpropyl)-2,4(1H,3H)pyrimidinidione [1]
• CAS Number: 314-40-9
• Molecular Weight: 261.10
• Water Solubility: 815 mg/L @ 25 C [1]
• Solubility in Other Solvents: xylene v.s.; acetone v.s.; acetonitrile v.s.; ethyl alcohol v.s.; sodium hydroxide v.s. [1]
• Melting Point: 158-159 C [1]
• Vapor Pressure: 0.033 mPa @ 25 C [1]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 32 (acid) [11]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: 0.09 mg/L [74]
• TLV: 10 mg/m3 (8-hour) [17]

Basic Manufacturer:

DuPont Agricultural Products
Walker's Mill, Barley Mill Plaza
P.O. Box 80038
Wilmington, DE 19880-0038

• Phone: 800-441-7515
• Emergency: 800-441-3637
  

References:

References for the information in this PIP can be found in Reference List Number 10

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.