E X T O X N E T
Extension Toxicology Network
A Pesticide Information Project of Cooperative Extension Offices of
Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Assessment Program.
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Pesticide
Information
Profile
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Butylate
Publication Date: 9/93
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TRADE OR OTHER NAMES
Genate Plus, Anelda Plus, Aneldazin, Anelirox, Sutan, Sutan 6E,
Butilate, Carbamic Acid, Ethyl N, N-Diisobutylthiocarbamate, R1910,
Stauffer R-1, 910.
REGULATORY STATUS
Butylate belongs to the thiocarbamate chemical class. It is
classified by the U.S. Environmental Protection Agency (EPA) as a
general use herbicide, with applications limited to corn fields.
Products containing butylate must bear the signal word "Caution" (16).
INTRODUCTION
Butylate was initially registered in 1967 as a selective herbicide.
It is registered only for use in corn to control grassy weeds such as
nutgrass and millet grass, as well as some broadleaf weeds. It is
applied to soil immediately before corn is planted, often in combination
with atrazine and/or cyanazine herbicides (11). Butylate acts
selectively on seeds of weeds that are in the germination stage of
development (3). It is absorbed from the soil by shoots of grass
seedlings before they emerge, causing shoot growth to be slowed, and
leaves to become twisted (4). Butylate breaks down relatively quickly
in soil, so there are no carry over problems in treated soil that might
jeopardize later plantings of crops on the same plots (13). The exact
poisoning mechanism of the herbicide in plants is not yet fully
understood (1, 11).
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
The major routes of exposure to butylate are dermal and
respiratory.
Butylate is part of a group of chemicals referred to as
thiocarbamates, known for their tendency to irritate the skin and the
mucous membranes of the respiratory tract. It may cause symptoms of
scratchy throat, sneezing and coughing when large amounts of dusts or
spray are inhaled (7, 20). Slight eye irritation can be caused by
butylate, potentially leading to permanent eye damage (3, 12).
Skin irritation was observed in rabbits topically exposed to 2 g of
technical butylate (85.71% pure) for 24 hours. Application of 21 doses
of 20 and 40 mg/kg/day to the skin of rabbits caused no effects other
than local skin irritation (19). The acute dermal LD50 for butylate is
greater than 4,640 mg/kg in rabbits (13). Butylate caused irritation to
the eyes of rabbits (19).
The amount of a chemical that is lethal to one-half (50%) of
experimental animals fed the material is referred to as its acute oral
lethal dose fifty, or LD50. The oral LD50 for butylate ranges from
1,659 milligrams per kilogram (mg/kg) in male guinea pigs, to 5,431
mg/kg in female rats. The lethal concentration fifty, or LC50, is that
concentration of a chemical in air or water that kills half of the
experimental animals exposed to it for a set time period. Butylate's 2-
hour LC50 is 19 milligrams per liter (mg/l) (3, 19).
CHRONIC TOXICITY
Prolonged or repeated exposure to butylate may cause symptoms
similar to the pesticide's acute effects.
In a study where dogs were fed 11, 23 or 45 mg/kg/day for 16 weeks,
no remarkable effects were observed. In another study, rats fed 180
mg/kg/day for 15 weeks were not adversely affected. Rats fed 8, 16 and
32 mg/kg/day for 13 weeks were not affected (19). There were no changes
in behavior, body weight, nerve or eye function, blood chemistry, nor
organ appearance and weight, in dogs that were fed butylate for 13 weeks
(11). Rats and dogs tolerated daily dietary doses of 40 mg/kg of the
herbicide for 13 weeks (2).
When butylate was fed to rats at doses of 50, 100, 200, or 400
mg/kg/day for two years, body weights were decreased and liver to body
weight ratios increased with all but the lowest dose tested. In rats
fed 20, 80 or 120 mg/kg/day for 2 years, no effects were observed at the
20 mg/kg dose, but kidney and liver lesions formed at the two higher
doses. Butylate fed to rats at 10, 30 and 90 mg/kg/day for 56 weeks
affected blood clotting at all doses. At the two higher doses body
weight and testes/body weight ratios decreased, liver to body weight
ratios increased, and lesions formed on the testes. In a study of dogs
fed 5, 25, or 100 mg/kg/day for 12 months, decreased body weights,
increased liver weights, and increased incidence of liver lesions were
observed at the highest dose (19).
The EPA has established a Lifetime Health Advisory (LHA) level for
butylate in drinking water at 700 micrograms per liter. This means that
the EPA believes that water containing butylate at or below this level
is acceptable for drinking every day over the course of one's lifetime,
and does not pose any health concerns.
Reproductive Effects
No reproductive effects were observed in test animals receiving
doses of up to 24 mg/kg of butylate (11).
In a study of two generations of offspring from rats fed 0, 10, 50
or 200 mg/kg/day for 63 days before mating, decreased body weight was
observed in both generations at the 50 mg/k/day dose. Decreased brain
weights were observed in the first generation of offspring at the 50
mg/kg/day dose. At 200 mg/kg/day, adverse effects on the eyes and
kidneys of the first generation were observed. No effects were observed
at the 10 mg/kg/day dose (19).
Long-term consumption of concentrations well above the Lifetime
Health Advisory level (700 ug/l) of butylate has caused damage to the
testes, liver and kidneys, and to delayed fetal development in test
animals (18).
Teratogenic Effects
No teratogenic effects were observed in mice ingesting 4-24
mg/kg/day of Sutan from the sixth through eighteenth days of
gestation/pregnancy. No teratogenic effects were observed in the
offspring of rats given up to 1,000 mg/kg/day on days 6 through 20 of
gestation or in the offspring of rabbits given doses of up to 500
mg/kg/day on days 6 through 18 of gestation (11, 19).
Mutagenic Effects
Mutation was seen in mice given oral doses of one gram per kilogram
(g/kg) of the herbicide (6). It was not mutagenic in the Ames test,
performed on Salmonella bacteria (8, 19).
Carcinogenic Effects
There was no tumor formation related to doses of up to 320
mg/kg/day of the herbicide in a 24-month study of rats. The EPA has
determined that there is no evidence that butylate produces cancers in
humans or in animals (11, 19).
Organ Toxicity
Liver changes were produced by 180 mg/kg dietary doses in a 56-week
rat study with butylate. Blood clotting was affected by ten mg/kg/day
in the same experiment (11). Several studies have shown that long-term
exposure to high doses of butylate have caused increases in liver
weights in test animals (19).
Fate in Humans and Animals
Butylate is rapidly metabolized and excreted in animals (11).
Within 48 hours after administration of radio-labeled butylate to rats
by gavage, 27.3 to 31.5% of the radioactivity was eliminated through the
urine, 60.9 to 64 % was expired as carbon dioxide, and 3.3 to 4.7% was
excreted in the feces. Only 2.2 to 2.4% of the administered
radioactivity was retained in the body, with most of this located in the
blood, kidneys and liver. The same pattern of rapid elimination was
exhibited in two other studies with rats (19).
ECOLOGICAL EFFECTS
Effects on Birds
Given its low toxicity and low exposure rates, butylate is
considered a minimal hazard to birds by the EPA (11). Technical
butylate has an acute oral LD50 greater than 4,640 mg/kg in mallard
ducks. Its 8-day dietary LC50 in bobwhite quail is estimated at 40,000
parts per million (ppm) (12).
Effects on Aquatic Organisms
Butylate is moderately toxic to fish (3). It has a low to moderate
potential for bioaccumulation in fish (19). With the low exposure rates
expected from registered use and proper disposal practices, there should
not be any risk posed by this material to aquatic invertebrates (11).
The LC50 for a 96-hour exposure to technical Sutan ranges from 4.2 ppm
in rainbow trout, to 6.9 ppm in bluegill sunfish (8).
Effects on Other Animals (Nontarget Species)
Butylate is not harmful to bees if it is used appropriately (3).
The herbicide appears to pose few, if any, acute toxicological hazards
to nontarget wildlife (11).
ENVIRONMENTAL FATE
Reportedly, butylate does not pose very much risk to the
environment because its residues are short-lived (8).
Breakdown of Chemical in Soil and Groundwater
Butylate is one of the pesticide compounds considered by the US EPA
to have the greatest potential for leaching into groundwater (9).
Butylate is only slightly soluble in water (46 micrograms/ml). It
degrades fairly rapidly with a soil half life of 3 to 10 weeks in moist
soils under aerobic conditions. Under anaerobic conditions, butylate
degrades with a half-life of 13 weeks (19). In loamy soil, at 70-80 degrees F,
its half-life is three weeks (13). Soil half-lives of 12 days and 1.5
to 3 weeks have also been reported (13, 17). Butylate does not strongly
adsorb to soil particles (Koc = 126 g/ml) and is considered to be
slightly to highly mobile in soils, depending on the soil type (17, 19).
Leaching is more likely to occur in sandy, dry soils, while leaching is
less likely to occur in soil with higher amounts of organic matter and
clay. A study conducted by the EPA in the United States did not find
butylate in groundwater samples (10). Another study found butylate in 2
out of 152 groundwater samples analyzed (19).
Butylate degrades to sulfoxide in soil (5). Butylate has a
residual activity in soil of approximately four months, when it is
applied at five to six kilograms per hectare (kg/her) (3). It is broken
down primarily by soil organisms (microbes) in a process called
microbial degradation. When applied to dry soil surfaces, very little
butylate is lost through vaporization. However, it can be lost by
vaporization when applied to the surface of wet soils without being
sufficiently incorporated (13). 45 to 50% of butylate applied to a clay
loam soil was recovered as volatilized gas during the three weeks
following application (19).
Breakdown of Chemical in Water
Butylate should not be applied directly to water or wetlands, and
water should not be contaminated by cleaning of butylate application
equipment or disposal of related wastes (11). Very low concentrations
of butylate (maximum of 4.70 micrograms/liter) were found in 91 of 836
surface water samples analyzed (19).
Breakdown of Chemical in Vegetation
Butylate is readily adsorbed by plant leaves, but as it is normally
applied to soil, it does not usually come in contact with foliage. Once
it is applied to the soil, butylate is rapidly taken up by the roots of
corn plants and moved upward throughout the entire plant (13). Butylate
is rapidly metabolized in corn roots and leaves, to carbon dioxide,
fatty acids and certain natural plant constituents (12, 13).
The herbicide is not thought to persist in plants since it
disappeared from the stems and leaves of corn plants seven to 14 days
after treatment. It does not have contact activity, that is, the injury
that it causes is not limited to that part of the plant to which it is
applied (7).
PHYSICAL PROPERTIES AND GUIDELINES
Technical butylate is a clear amber to yellow liquid with an
aromatic odor (1, 14, 16). Precautions should be taken to avoid skin
and eye contact, and inhalation or drift exposure to butylate (3).
Under normal ambient conditions, butylate reportedly has an indefinite
storage life (13). It is noncorrosive, but it is hydrolyzed by strong
acids and bases (3). Thermal decomposition may release toxic oxides of
nitrogen and sulfur (20).
Occupational Exposure Limits:
No occupational exposure limits for butylate have been established
by OSHA, ACGIH or NIOSH (20).
Exposure Guidelines:
| NOEL: | A NOEL of 32 mg/kg/day was set based on a 90-day dietary feeding study of rats.
A NOEL of 40 mg/kg/day was set based on a 90-day dietary study in
dogs (13).
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Physical Properties:
| CAS #: | 2008-41-5 |
| H2O solubility: | 44 ppm in water at 20 degrees C (8); 45 ppm (10) - 0.03% in water at room temperature (3)
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| Solubility in other solvents: | miscible with kerosene, xylene, acetone, ethyl-alcohol and other organic solvents (8, 20) |
| Boiling point: | 160 degrees F (71 degrees C) at 10 mmHg (20) |
| Specific gravity: | 0.9402 at 20 degrees C (20) |
| Vapor pressure: | 13 x 10 to the minus 3 power mm at Hg at 25 degrees C (13) |
| Koc: | 540 (soil-water distribution coefficient divided by the organic carbon content and calculated by log Koc = 3.64-0.55 [log water solubility in ppm] + 1.23) (11) |
| Kd: | 1.4-5.0; 2.5-8.9 (11). Soil-water distribution coefficient or adsorption constant from column leaching or TLC studies. - Soil/field dissipation of ambient pH and temperature from lab studies showed three to ten week half-life (11)
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| Chemical Class/Use: | Thiocarbamate fungicide |
BASIC MANUFACTURER
Zeneca Ag Products
Wilmington, DE 19897
Telephone: (302) 886-1000
Review by Basic Manufacturer:
Comments solicited: November, 1992
Comments received:
REFERENCES
Berg, G. L., ed. 1986. Farm chemicals handbook. Willoughby, OH:
Meister Publishing Company.
Gosselin, R. E., et al. 1984. Clinical toxicology of commercial
products. Fifth edition. Baltimore, MD: Williams and Wilkins.
Hartley, D. and H. Kidd. (eds.) 1983. The agrochemicals handbook.
Nottingham, England: Royal Society of Chemistry.
McEwen, F. L. and G. R. Stephenson. 1979. The use and
significance of pesticides in the environment. NY: John Wiley and
Sons, Inc.
Menzie, C. M. 1980. Metabolism of pesticides. Update III. U.S.
Department of the Interior. Fish and Wildlife Service. Special
Scientific Report. Wildlife No. 232. Washington, DC: U.S. Government
Printing Office.
National Institute for Occupational Safety and Health (NIOSH).
1981-1986. Registry of toxic effects of chemical substances (RTECS).
Cincinnati, OH: NIOSH.
Thomson, W. T. 1986. Herbicides. Agricultural Chemicals, Book
II. Fresno, CA: Thomson Publications.
TOXNET. 1975-1986. National library of medicine's toxicology data
network. Hazardous Substances Data Bank (HSDB). Public Health Service.
National Institute of Health, U. S. Department of Health and Human
Services. Bethesda, MD: NLM.
U. S. Environmental Protection Agency. 1987 (Feb. 4). EPA's
Environmental News.
_____. 1984. Memorandum from Stuart Z. Cohen. List of potential
groundwater contaminants. Office of Pesticides and Toxic Substances.
Washington, DC. Photocopy.
_____. 1984 (Mar.). Chemical fact sheet for butylate. Fact
sheet number 7. Office of Pesticide Programs. Washington, DC.
_____. 1983 (Sept. 30). Guidance for the reregistration of
pesticide products containing butylate as the active ingredient.
Washington, DC.
Weed Science Society of America. 1983. Herbicide handbook.
Fifth edition. Champaign, IL: WSSA, Herbicide Handbook Committee.
Worthing, C. R., ed. 1983. The pesticide manual: a world
compendium. Croyden, England: The British Crop Protection Council.
Hayes, W.J. and E.R. Laws (ed.). 1990. Handbook of Pesticide
Toxicology, Vol. 3, Classes of Pesticides. Academic Press, Inc., New
York.
Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister
Publishing Company, Willoughby, Ohio.
U.S. Department of Agriculture, Soil Conservation Service. 1990
(Nov). SCS/ARS/CES Pesticide Properties Database: Version 2.0
(Summary). USDA - Soil Conservation Service, Syracuse, NY.
U.S. Environmental Protection Agency. 1989 (Jan.). Health
Advisory Summary: Butylate. US EPA, Washington, DC.
U.S. Environmental Protection Agency. 1989 (Feb.). Butylate:
Health Advisory. Office of Drinking Water, US EPA, Washington, DC.
Occupational Health Services, Inc. 1991 (Feb. 21). MSDS for
Butylate. OHS Inc., Secaucus, NJ.
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criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
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