Propachlor (Ramrod, Bexton) Herbicide Profile 2/85
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 44
DATE ISSUED: FEBRUARY 11, 1985
1. DESCRIPTION OF THE CHEMICAL
- Generic Name: 2-chloro-N-isopropylacetanilide (C11H14ClNO)
- Common Name: propachlor
- Trade Names: Ramrod, Bexton, and CP 31393
- EPA Shaughnessy Code: 019101
- Chemical Abstracts Service (CAS) Number: 1918-16-7
- Year of Initial Registration: 1965
- Pesticide Type: Herbicide
- Chemical Family: alpha-chloroacetamide
- U.S. Producer: Monsanto Company
2. USE PATTERNS AND FORMULATIONS
- Application sites: Propachlor is registered for use as a preemergence
herbicide on corn (all types), soybeans (seed only), grain sorghum
(milo), green peas, pumpkins, cotton, and flax. In corn, propachlor
can also be applied as an early postemergence control. Sorghum is the
largest use site for propachlor, accounting for most uses of the wet-
able powder formulation. Corn is the second largest use site for
propachlor, accounting for most uses of the granular formulation.
- Types of formulations: Propachlor is available in granular, wettable
powder, and flowable liquid concentrate formulations.
- Types and methods of applications: Propachlor is applied as a pre-
emergence broadcast spray or banded ground application, and only one
application is allowed per year.
- Application rates: 3.0 to 6.0 lbs. a.i./A on crop sites.
- Usual carriers: Attapulgite/montmorillonite clay and water.
3. SCIENCE FINDINGS
- Propachlor is a light tan solid at room temperature, and its molecular
weight is 211.70. The boiling point is 110 degrees C at 0.3 mm Hg.
Propachlor is soluble in most organic solvents and in water (at 23
degrees C) to 693 ppm.
- Acute toxicology effects of propachlor are as follows:
- Acute oral toxicity in rats: 1.80 g/kg body weight, Toxicity
- Acute dermal toxicity in rabbits: >20.0 g/kg body weight,
Toxicity Category IV.
- Skin irritation in rabbits: slight irritant, Toxicity Category III.
- Eye irritation in rabbits: Corrosivity and corneal opacity not
reversible within seven days, Toxicity Category I.
- Chronic toxicology effects of propachlor are as follows:
- A teratology test in rats has shown that propachlor tested at the
highest dose level (HDT) failed to induce teratogenic, fetotoxic,
or maternal effects. The HDT was 200 mg/kg/day.
- Major routes of human exposure:
- Non-dietary exposure to propachlor by a farmer as an applicator
during mixing, loading, spraying, and flagging is probable.
- Exposure of humans to propachlor through contamination of ground-
water and runoff contamination of surface water after heavy spring
precipitation is probable.
- The dietary exposure (mg/kg/day) to propachlor by the U.S. popula-
tion from treated food crops is possible.
Physiological and Biochemical Behavioral Characteristics
- Absorption characteristics: Propachlor is adsorbed mainly by
germinating seedling shoots, secondarily by roots.
- Translocation: Propachlor is translocated throughout the plant,
mainly in the vegetative tissues.
- Mechanism of pesticidal action: Propachlor is a strong inhibitor of
cell elongation and protein synthesis.
- Metabolism in plants: Metabolized rapidly in plants.
- Adsorption and leaching in basic soil types: Propachlor is absorbed
by soil colloids.
- Microbial breakdown: Microbes are the primary factor in the break-
down of propachlor in soils.
- Loss from photodecomposition and/or volatilization: Low
- Average persistence at recommended rates: Half-life of 4 to 6
weeks; longer in soils high in organic matter.
- Avian acute oral toxicity: 91 mg/kg
- Avian 8-day dietary toxicity (Bobwhite quail): >5,000 ppm
- Avian 8-day dietary toxicity (mallard duck): >5,000 ppm
- 96-hour fish toxicity: >1.40 ppm for bluegill sunfish (moderately
toxic) and 0.17 ppm for rainbow trout (highly toxic).
- 48-hour aquatic invertebrate toxicity: 7.80 ppm (moderately toxic)
for Daphnia magna
- Potential problem for endangered species: The Office of Endangered
Species (USDI) has determined that propachlor use on corn, sorghum,
or soybeans may impact the following endangered species: Slackwater
darter, 11 freshwater mussels, Woundfin, and Salanograss.
- The Agency is unable to complete a full tolerance reassessment of
propachlor because of certain residue chemistry data gaps. The
additional residue data requirements may cause specific tolerances
to be revised in the future.
- The tolerances listed below have not been revised:
Commodities parts per million
Beets sugar, roots 0.2
Beets sugar, tops 1.0
Cattle, fat 0.02
Cattle meat by-products 0.02
Cattle meat 0.02
Corn, forage 1.5
Corn fresh (sweet) (K+CWHR) 0.1
Corn grain 0.1
Flax, seed 3.0
Flax, straw 10.0
Goats fat 0.02
Goats meat by-products 0.02
Goats, meat 0.02
Hogs, fat 0.02
Hogs, meat by-products 0.02
Hogs, meat 0.02
Horses, fat 0.02
Horses meat by-products 0.02
Horses meat 0.02
Peas pods removed 0.2
Peas forage 1.5
Poultry fat 0.02
Poultry meat by-products 0.02
Poultry, meat 0.02
Sheep. fat 0.02
Sheep, meat by-products 0.02
Sheep, meat 0.02
Sorghum, fodder 5.0
Sorghum, forage 5.0
Sorghum, grain (milo) 0.25
- International tolerances: Presently, there are no tolerances for
residues of propachlor in Canada, Mexico, or in the Codex
Problems Known to have Occurred with Use of Chemical
- The Pesticide Incident Monitoring System (PIMS) did not show any
incidents involving uses of propachlor.
Summary Science Statement
- Propachlor is not acutely toxic by the oral and dermal routes of
exposure. However, primary eye irritation data on propachlor show
corrosivity and corneal opacity not reversible within seven days in
rabbits. If propachlor came in contact with the eyes, it could
cause irreversible eye injury to man. Propachlor may also induce
photosensitivity or photosensitization due to the presence of
aniline in its composition.
- Propachlor is highly toxic to coldwater fish, highly to moderately
toxic to warmwater fish, and highly to moderately toxic to fresh-
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Based on the review and evaluation of all available data and other
relevant information on propachlor, the Agency has made the following
- The available data are insufficient to show that any of the risk
criteria listed in 162.11(a) of Title 40 of the U.S. Code of Federal
Regulations have been met or exceeded for the uses of propachlor at
the present time.
- There are no valid long-term chronic toxicity data for propachlor.
Studies indicate that propachlor is structurally similar to
alachlor, which is oncogenic in laboratory rats and mice. Data on
propachlor show that it is corrosive to the eye, with corneal
opacity irreversible after seven days. Further, propachlor has been
shown to be highly toxic to coldwater fish, highly to moderately
toxic to warmwater fish, and highly to moderately toxic to fresh-
water invertebrates. In addition to the extensive subchronic and
chronic toxicity data gaps, there are also residue chemistry and
environmental fate data gaps. Because the existing data are
insufficient to show that any of the risk criteria have been met or
exceeded, the Agency is not initiating a Special Review at this
- The most appropriate regulatory action is to move quickly to fill
the data gaps. Then the Agency will make a determination as to the
future registerability of the affected uses.
- Specific label warning statements:
- Hazard information: DANGER. Corrosive, causes irreversible eye
damage. Harmful if swallowed or absorbed. Do not get in eyes or
on clothing. Wear goggles, face shield, or safety glasses.
- Protective clothing requirements:
- Required clothing and equipment for mixing/loading and applying
- One-piece coveralls which have long sleeves and long pants
constructed of laminated fabric as specified in the USDA/EPA
Guide for Commercial Applicators.
- Goggles, face shield, or safety glasses.
- Liquid-proof hat such as a plastic hard hat with a plastic
- Heavy-duty liquid-proof rubber (neoprene) work gloves.
- Any article worn while handling propachlor must be cleaned before
reusing. Clothing which has been drenched or has otherwise
absorbed concentrated pesticide from any significant spill must be
disposed of in a sanitary landfill, by incineration, or, if
allowed by state and local authorities, by burning. If burned,
stay out of smoke.
- Instead of clothing and equipment specific above, the applicator
can use an enclosed tractor cab which provides a filtered air
supply (as described by Taschenberg and Bourke, 1975).
- Prohibition on aerial application: Do not apply with aerial
- Environmental hazard statements:
- All manufacturing-use products (MUPs) intended for formulation
into end-use products (EUPs) must bear the following statement:
Do not discharge effluent containing this product directly into
lakes, streams, ponds, estuaries, oceans, or public waters
unless this product is specifically identified and addressed in
a National Pollutant Discharge Elimination System (NPDES) permit.
Do not discharge effluent containing this product into sewer
systems without previously notifying the sewage treatment plant
authority. For guidance, contact your State Water Board or
Regional Office of the Environmental Protection Agency.
- The following environmental hazard statement must appear on all
granular EUPs: This pesticide is toxic to fish. Do not apply
directly to water. Runoff from treated areas may be hazardous to
aquatic organisms in neighboring areas. Do not contaminate water
by cleaning of equipment or disposal of wastes. In case of
spills, collect for use or properly dispose of granules.
- The following environmental hazard statement must appear on all
non-granular EUPs: This pesticide is toxic to fish. Do not
apply directly to water. Drift and runoff from treated areas may
be hazardous to aquatic organisms in neighboring areas. Do not
contaminate water by cleaning of equipment or disposal of wastes.
In case of spills, collect for proper disposal.
- Registrants must revise the labeling of MUPs and EUPs as specified
in the Required Labeling section on products released for shipment
as of September 1, 1985.
5. SUMMARY OF MAJOR DATA GAPS
- The following toxicological studies are required:
- An acute inhalation toxicity study in the rat.
- A dermal sensitization study in the rabbit.*
- A 90-day dermal study in the rabbit.
- A 90-day inhalation study in the rat.
- A 90-day feeding study in rodent and non-rodent.
- A chronic toxicity study in rat and in dog is required by February,
- An oncogenicity study in rat and in mouse is required by February,
- A teratology study in the rabbit is required by April, 1985.**
- A 2-generation reproduction study in the rat is required by
- The following mutagenicity data are required by January, 1987:
- In vitro mammalian cell point mutation [L5178Y (TK); or
CHO(HGPRT) or V79(HGPRT)].
- In vitro cytogenetic damage: both chromosomal aberration and
SCE (in CHD cells, or human lymphocytes, or other rodent/human
- In vitro/in vivo primary hepatocyte repair for UDS testing
both in vivo and in vitro exposure of cells to alachlor.
- In vivo cytogenetics test for chromosomal aberrations using
bone marrow preparations of rats.
- Dominant lethal test in rats or mice.
- A domestic animal safety study is required.
NOTE: *A dermal sensitization study in guinea pigs (Acc. 255806,
December, 1984) has been received by the Agency, and it is being
**A teratology study in rabbits (Acc. 255758, November, 1984)
has been received by the Agency, and it is being reviewed.
- The following environmental fate data are required:
- A hydrolysis/degradation study is required by July, 1985.
- A photodegradation study in water is required by July, 1985.
- A photodegradation study on Soil is required by July. 1985.
- An additional metabolism test in aerobic soil is required by July,
- Additional data on mobility of degradates from aged propachlor are
required by April, 1985.
- Soil dissipation data are required by July, 1987.
- An accumulation study in rotational crops (confined).
- A flow-through/accumulation test in fish.
- The following ecological effects data are required: An acute fresh-
water fish toxicity test on a coldwater species may be required
pending review of environmental fate data which will be submitted in
1985, 1986, and 1987.
- The following product chemistry data are required:
- A complete statement of composition.
- A preliminary analysis.
- A certification of limits.
- Analytical methods for enforcement of limits.
- The octanol/water partition coefficient.
- The pH of the TGAI.
- The following residue chemistry data are required:
- 14C ring labeled data with corn and sorghum up to the seed stage.
- 14C ring labeled data on the nature of the residue in ruminants.
- Metabolism data on propachlor in poultry.
- Metabolism data on propachlor in non-ruminants (name/species).
- A radiocarbon study in which samples are analyzed simultaneously by
cold and hot analytical methodology for N-isopropylaniline moiety,
including a comparison of the results. (If other metabolites are
found in or on plants and in animals, then an enforcement method to
determine these residues would be required.)
- Storage stability data on propachlor residues in plant and animal
- Residue data on the metabolites of propachlor in plants.
- Residue data on the metabolites of propachlor in animals.
- Residue data on the metabolites of propachlor in poultry and eggs.
- A cow feeding study on propachlor.
- Geographical representation of residue data are not adequate;
therefore, additional field residue data are required.
- Residue data on corn forage to support the application rate of 6 lb.
a.i./A on soils with an organic matter content of more than 3%.
- Additional residue data for corn fodder using the 20% granular
- Residue data for corn grain using the 20% granular and 42% flowable
- Residue data for sweet corn using the flowable liquid concentrate
- Residue data for the oil and milling fractions from the processing
of treated corn or sorghum grain.
- Residue data in cotton forage are required. (But an acceptable
alternative would be a restriction against the grazing of livestock
on cotton forage.)
- Residue data in flax seed hulls which are fed to livestock.
- Residue data for peas using the flowable liquid concentrate.
- Residue data for pumpkins using the 90-day preharvest or postharvest
- The feeding rate data in the sheep study must be clarified.
DISCLAIMER: THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.