Un -ad States C fic« :>f Pesticic , an To ie S ibftan.t
Emironirenta' Protection O fice of Ptetiad Prograim Cn-766C)
Agency Washington. OC 20460 - -
&EPA Pesticide
Fact Sheet
Name of Chemical: MDNOCARBAMIDE DIHYDROGEN SULFATE
Reason for Issuance: NEW CHEMICAL REGISTRATION
Date Issued: [)EC 3 01987
Fact Sheet Number:
151
1. Description of Chemical:
Chemical Name: Monocarbamide dihydrogen sulfate
Other Name: ttonourea sulfuric acid adduct
Trade Name: ENQUIK
OPP Internal Control Number: 078001
«
Year of Initial Registration: 1987
Pesticide Type: Herbicide/Desiccant
U.S. and Foreign Producers: Union Chemicals Division, Unocal Corp.^
2. Use patterns and formulations:
Application sites: Herbicide uses include; Onions (green & dry bulb),
leeks, shallots, spring onions, garlic, peanuts, peas, lentils,
dry beans, garbanzos and grass seed. Desiccant uses include; dry
beans, peas, lentils, peppermint and potato vines.
Types of formulations: liquid, 81.6% active ingredient
Types and methods of*application: Applied postemergence to crops and weeds
as a contact pesticide. Diluted with water and applied as a spray for
broadcast, directed or shield spray treatments, using ground equipment.
A wetting agent or non-ionic surfactant may be added.
Application rates: 20 to 309 Ibs. a.i./A, depending upon application site
Usual carriers: water
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3. Science findings :
Sulimary science statement:
Acute toxicology data indicate that the chemical .,is extremely
caustic and corrosive. The appropriate toxicity category is I
(DANCER), based on primary eye and skin irritation studies.
Chronic toxicology and environmental fate data requirements are
waived. Avian dietary studies indicate that the formulated product
is practically nontoxic to mallard ducks and bobwhite quail.
Diluted monocarbamide dihydrogen sulfate is less hazardous to wildlife
than the undiluted chemical. Application is restricted to use of
the diluted chemical only. Potential hazard to fish and wildlife
including endangered species is minimized due to label restrictions
against aerial application and limiting use to the following states;
Alabama, Georgia, Idaho, Michigan, Oregon and Washington.
Chemical characteristics:
Physical state: Viscous liquid
Color: Colorless
Odor: Odorless
Density: 13.14 pounds per gallon
Miscibility: Limited miscibility in polar organic solvents.
Not miscible with hydrocarbons and lipids.
Vapor pressure: Negligible up to decomposition temperature of 80°C.
Crystallization point: 2°C
pH: 1 (aqueous solution)
Unusual handling characteristics: Corrosive to nylon, cotton, leather,
aluminum and copper alloy such as
brass. Corrosive to skin and eyes.
Explosively decomposes above 160°F.
Do not mix with nitrogen fertilizers
as explosive mixtures may result.
Toxicology characteristics:
Acute toxicology results:
Acute oral toxicity (rat) 1 ,200 mg/kg (male)
350 mg/kg (female)
Toxicity category II
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Acute dermal toxicity (rabbit): greater than 2 g/kg. Study was
terminated at 48 hours because of extreme caustic action and
dermal necrosis. Toxicity category was not determined.
Primary skin irritation (rabbit): Caustic on intact and abraded skin
at 24 hours. Study was terminated at 24 hours after similar
results were obtained with 1 :4 v/v dilution with water.
Toxicity category I
Primary eye irritation (rabbit): Severe corneal involvement, grade 4
chemosis of conjunctivae at 24 hours. Because of severity of
reaction, study was terminated at 24 hours. Toxicity category I
Acute inhalatioLl toxicity (rat): greater than 10.8 mg/l
Toxicity category III
Additional data not required on acute dermal and primary eye
irritation studies, in accordance with EPA-540/9-82-025,
October 1982, Pesticide Assessm t Guidelines Subdivision
( 81—2(a)(1)) and Subdivision F ( 81-4(d)(2)), respectively.
chronic toxicology results: Additional toxicology studies (including
a three-generation reproduction study) were waived in accordance
with provisions of 40 CFR 162.45 (c). Toxicological concerns
over heavy metal impurities in the sulfuric acid, have been
adequately resolved. Recycled (spent) sulfuric acid will not
be used to manufacture the active ingredient.
Hajor routes of exposure: Mixers, loaders and applicators would
be expected to receive the most exposure via skin contact and
inhalation.
Physiological and biochemical behavioral characteristics:
Mechanism of pesticidal action: Monocarbamide dihydrogen sulfate
is a contact herbicide and desiccant. The chemical disrupts
cell membrane structures in a catalytic non-acid consnmptive
reaction. The rate of activity is dependent upon the amount
of waxy cuticle present on the surface of treated plants.
Plants with a significant wax coating are less susceptible
to damage than others.
Environmental characteristics: The environmental fate of urea and
sulfuric acid are well kno from the literature. Environmental
fate data requirements are waived.
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Ecological characteristics:
Hazards to fish and wildlife:
Avian dietary toxicity (Mallard): greater than 5620 ppm (49% a.i.)
Avian dietary toxicity (Bobwhite): greater than 5620 ppm (49% a.i.)
Simulated avian field study: Results indicate that eye and foot
damage may be pronounced for birds exposed to direct applications
of undiluted monocarbamide dihydrogen sulfate. Application of a
diluted solution caused some but much less damage.
Aviart re-entry field study: Results indicate that birds that can
escape during ground application are unlikely to be harmed if
they enter treated fields after application.
pH study in ephemeral ponds and irrigation water: The study
indicates that under most conditions the acidifying effect
of ENQUIK will be temporary. Ck 1y shallow ponds receiving an
over-spraying of ENQUIK would be affected by a lowering of pH.
Rtential problems related to endangered species: Contamination
of habitat areas is not likely to occur as a result of runoff,
since the chemical, once it reaches the soil, is expected to be
neutralized. Potential hazard may exist for those endangered
species receiving a direct spraying of ENQUIK. However,
geographical restrictions arid a prohibition against aerial
application should minimize any potential hazard to endangered
species.
Tolerance assessments: Honocarbarnide dihydrogen sulfate is exempted
from the requirement of a tolerance when used as a herbicide or
desiccant in or on all raw agricultural caiirnodities (40 CFR 180.1084).
4. Stnmnary of regulatory position and rationale :
Use, formulation, geographical restrictions: Pesticidal use is limited
to the following states; Alabama, Georgia, Idaho, Michigan, Oregon
and Washington. Aerial application is prohibited.
Unique label warning statements:
End-Use Product:
Physical or Chemical Hazards
“ENQUIK is corrosive to nylon, aluminum, and any copper
alloy such as brass. E not use pumps or fittings
containing nylon, mild steel, aluminum, brass,, leather, -
natural rubbe or buna N. Non-nylon plastic and 316—L
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stainless steel are recommended for application equipment.
Diluted ENQUIK is more corrosive to steel than the
concentrate. tk not allow ENQUIK to be heated above
160°F as explosive decomposition may occur. DD not weld
equipment containing ENQUIK.
Do not mix with nitrogen fertilizers as explosive mixtures
may result. IY. not mix with other materials witho..it
specific authorization as hazardous combinations may result.
Clothing: ENQUIK can attack cotton, -nylon, and leather -
clothing. If ENQUIK contacts clothing of this type,
flush with plenty of water to minimize damage. Wear non-
nylon plastic protective clothing.”
Human Hazards
“Corrosive. Causes irreversible eye damage and burns to skin.
Face shields or goggles must be rn. Wear suitable protective
equipment to protect skin, such as synthetic rubber or non-nylon
plastic apron, gloves, pants and boots. Wash after contact with
skin. Shower at the end of the woiMng day. I not wear contaminated
clothing. Avoid spray. Avoid breathing spray mist.”
fl vironmental Hazards
“This product may be harmful to wildlife directly sprayed. Keep out
of lakes, ponds and streams. Ek not apply directly to water or
wetlands. Ex not contaminate water by cleaning of equipment or
disposal of wastes. fl not apply near waters already damaged by
acid pollution or in areas with soils of poor buffering capacity
if important aquatic resources are adjacent.”
5. Siniinary of major data gaps : None
6. Contact person at EPA :
Robert J. Taylor
Product Manager (25), (TS—767C)
Environmental Protection Agency
401 H Street, S.W.
Washington, D.C. 20460
(703) 557—1800
DISC I tER The information presented in this Pesticide Fact Sheet
is for informational purposes only and may not be used to fulfill data
requiraiients for pesticide registration and reregistration.
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