United States Office of Pesticides »nd To«ie Subst«ne«
Environmental Protection Office of Pestiode Progr«mi (TS-766CI
Agency Washington. DC 20460
&EPA Pesticide
Fact Sheet
Name of Chemical: PROMETRYN
Reason for Issuance: REGISTRATION STANDARD
Date Issued: MAR 2 0 1987
Fact Sheet Number: 121
Description* of Chemical
Common Name: Prometryn
Chemical Name: 2,4-Bis(isopropylamino)-6-(methylthio) -
s_-triazine
Other Names: Prometryne, Caparol, G-34161,
Gesagard, Primatol Q,
Prometrex
OPP (Shaughnessy) Number: 080805
Chemical Abstracts
Service (CAS) Number: 7287-19-6
Empirical Formula:
Molecular Weight: 241.4
Year of Initial Registration: 1964
Pesticide Type: Herbicide
Chemical Family: Substituted triazine
U.S. and Foreign Producers: Ciba-Geigy Corp.
(United States);
Aceto Chemical Company, Inc.
(U.S.); I.Pi.Ci. (Italy);
Makhteshim-Agan (Israel);
Verolit Chemical Manufacturing
Company, Ltd. (Israel)
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2. Use Patterns and Formulations
Application Sites: Cotton, celery, pigeon peas, corn,
ornamental plants, and forest trees (nursery seed beds)
Percent of crop treated with the Pesticide: (1) Cotton, 9 to
12 percent of total U.S. cotton crop; (2) celery,
95 percent of total U.S. celery crop
Percent of Pesticide Applied to Crop: (1) Cotton,
approximately 97 percent (1,100,000 — 1,500,000 pounds
active ingredient, [ ai]) of total domestic usage of
prometryn; (2) celery, approximately 3 percent (31,000 —
37,000 pounds ai) of total domestic usage of prometryn
Types and Methods of Application: Applied by broadcast or
directed spray (preplant, preemergent, or postemergent)
to crop and weeds using ground equipment or aircraft.
Pests Controlled: Annual broadleaf and grass weeds
Application rates: Rates range from 0.48 to 3.2 lb ai/A.
Types of Formulations: 95%, 97% active ingredient (ai)
manufacturing—use products; 80% ai wettable powder;
44.4% (4 lb ai/gal) emulsifiable concentrate; 45.4%
(4 lb ai/gal) flowable concentrate.
Usual Carriers: Water at 20 to 40 gal/A.
3. Science Findings
Summary Science Statement:
Based on available acute studies (oral, dermal), prometryn
has low acute toxicity and falls within Toxicity Category III,
signal word CAUTION. Data gaps exist for the technical in
acute toxicity, subchronic and chronic toxicity, teratology,
oncogenicity, reproduction. and mutagenicity. Prometryn is
not acutely hazardous to birds. It is slightly toxic to
freshwater invertebrates and moderately toxic to fish. The
chemical may pose a risk to some endangered species. The
environmental fate of prometryn is not adequately understood.
Additional data are required on degradation, mobility,
accumulation, field dissipation, and metabolism. Leaching
studies indicate that prometryn has intermediate mobility in
sandy loam soils and is very mobile in sandy soils. A ground
water monitoring study may be required pending the results
of additional leaching and soil field dissipation studies.
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Primary dermal irritation
(rabbit)
Chemical Characteristics:
Physical state: Powder
Color: White
Odor: Odorless
Melting Point: 118—120 °C
Density: 1.15 + 0.02 g/cm 3 at 20 °C
Solubility: 33 ppm in water at 20 °C
readily soluble in organic solvents
Vapor Pressure: 1.3 x i06 mbar at 20 °C
Dissociation Constant: Kb = 4.11 ± 0.5
Octanol—Water
Partition Coefficient: pT( = 4.1 at 20 °C
Stability: Stable in neutral, slightly acidic or
basic media. Half—life at 25°C of 22.2 days
and 1200 days in 0.1 N MCi and 0.]. N NaOH,
respectively. Stable for a minimum
of 3 years at room temperature.
Toxicological Characteristics
Acute oral toxicity (rat): 1R02 mg/kg (males) and
2076 mg/kg (females);
Toxicity Category III
(97% ai)
Acute dermal toxicity (rabbit): Greater than 2000 mg/kg;
Toxicity Category III
(97% ai)
Nonirritating to
: intact and abraded
skin
Toxicity Category IV
(97% ai)
Chronic effects: The only available studies were done
using formulated products. Data gaps remain for the
technical materials.
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Chronic ceer nq (dog): No observable effect level
(NOEL) = 3.75 mg ai/kg/c3ay
Lowest &ffect level
(LEL) = 37.5 mg ai/kg/day
(80% ai)
Teratology (rabbit): Maternal and fetotoxic
NOEL = 12 mg al/kg/day;
Developmental toxicity
and embryotoxic NOEL
> 72 mg al/kg/day
(Formulated prometryn)
Major Routes of Exposure :
Mixers, loaders and applicators would receive the most
exposure via skin/eye contact and inhalation.
Physiological and Biochemical Behavioral Characteristics :
Foliar and Root Absorption: Absorbed through both roots and
foliage
Translocation: Translocated from roots to leaves
Mechanism of Action: Prometryn interferes with electron
transport in the photosynthetic process.
Metabolism and Persistence in plants and animals: The
nature of the residue of prometryn in plants and animals
is not adequately understood. However, available data
indicate the following: (1) In cotton, prometryn appears
to concentrate in lysigenous glands where it slowly
degrades to hydroxypropazine and other conjugated
metabolites. (2) In the rat, most of the administered
prometryn is excreted within 4R hours in urine and feces.
Environmental Characteristics :
Insufficient data are available to fully characterize
the environmental fate of prometryn. Leaching studies
do indicate, however, that proinetryn has intermediate
mobility in sandy loam soils and has high mobility in
sandy soils. In addition, data indicate that prometryn
has hydrolytic stability and is persistent in the soil.
Degradation, accumulation, metabolism, soil field
dissipation and additional leaching studies are required.
Pending the results of soil field dissipation and
leaching studies, a ground water monitoring study may
also be required.
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Ecological Characteristics :
Avian acute oral toxicity: Greater than 4640 mg/kg
(mallard)
Avian dietary toxicity: 34,512 ppm (adjusted to 100% ai,
mallard)
Aquatic invertebrate acute toxicity: 18.59 ppm
( Daphnia magna )
Fish acute toxicity: 10 ppm
(bluegill sunfish)
Fish acute toxicity: 2.9 ppm
(rainbow trout)
Potential problems related to endangered species: The
use of proinetryn on corn and cotton may pose a hazard
to endangered species. A single application per year
of prometryn should not harm most animal species, due
to its low toxicity, except by destruction or adverse
modification of habitat. There is concern for the
endangered species, Solano grass and valley Elderberry
longhorn beetle following a single application of
prometryn on corn. Both species occur in California.
Proposed labeling has been designed to protect these
species.
If multiple applications per year are used on corn
and/or cotton, then several endangered species may
be exposed to potential harm (due to sufficiently high
application rates and the half-life of prometryn).
proposed endangered species labeling has been designed
to protect these species when there are multiple
applications of prometryn.
The endangered species labeling, as mentioned above,
will be required after the Agency receives concurrence
from the U.S. Fish and Wildlife Service. The Agency
will notify registrants, in a pesticide Registration
Notice, of the final label requirements for endangered
species.
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Tolerance Assessment:
Tolerances have been established for residues of prometryn
in or on the following raw agricultural commodities:
Commodity Tolerance (ppm )
Celery 0.5
Corn, fodder, field 0.25
Corn, fodder, pop 0.25
Corn, fodder, sweetl/ 0.25
Corn, forage, field 0.25
Corn, forage, pop 0.25
Corn, forage, sweet 0.25
Corn, fresh (inc. sweet K+CWHR) 0.25
Corn, grain 0.25
Cotton 2 ! 1.00
Cottonseed 0.25
Pigeon peas 0.25
1/ This entry will be deleted from the tolerance
— expression, since corn fodder, sweet, is not
considered a raw agricultural commodity of sweet
corn.
2/ A feeding restriction is currently in effect for
— cotton forage, thus the entry “cotton 1 ’ (presumably
intended to cover cotton forage) will be deleted.
Dietary Assessment :
The provisional acceptable daily intake (PADI) was based
on a 2—year dog feeding study with a NOEL of
3.75 mg ai/kg/day. Applying an uncertainty factor of
l000,* the PADI was calculated to be 0.004 mg/kg/day.
This is equivalent to a maximum permissible intake (MPI)
of 0.24 mg/kg/day for a 60 kg individual. The theoretical
maximum residue contribution (TMRC) of prometryn in the
daily diet is 0.000205 mg/kg/day based on the existing
tolerances and daily food intake of 1.5 kg, with 5.13
percent of the PADI being utilized.
Established tolerances are based on the parent compound.
Additional metabolism studies are required in order to
identify and quantify all metabolites of toxicological
concern.
* It is not clear whether another species will prove to be more
sensitive to prometryn than the dog, thus an uncertainty
factor of 1000 was used.
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4. Summary of Regulatory Position and Rationale :
Use, Formulation or Geographic Restrictions: No
significant new food or feed uses of prometryn will be
permitted until residue chemistry and chronic toxicology
data are available to assess existing uses.
Unique Label Warning Statements: All end-use products
shall bear the following statements:
a. Feeding/Grazing Restriction
Do not allow livestock to feed or graze on
treated cotton crops.
b. Environmental Precautions
Do not apply directly to water or wetlands
(swamps, bogs, marshes, and potholes). Do
not contaminate water by cleaning of
equipment or disposal of wastes.
5. Summary of Major Data Gaps:
Product Chemistry
All product chemistry data
Residue Chemistry
Metabolism studies (plants, livestock)
Residue analytical method
(plant & animal residues)
Storage stability
Residue studies
Toxicology
Acute inhalation (rat)
Eye irritation (rabbit)
Dermal sensitization (guinea pig)
21—Day dermal (rabbit)
Chronic toxicity (rodent)
oncogenicity (2 species)
Teratology (rat)
Reproduction (rat)
Mutagenicity battery
General metabolism
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Fish and Wildlife
Avian dietary (upland game bird)
Avian reproduction
(upland game bird and waterfowl)
Acute toxicity to estuarine
and marine organisms
Fish early life stage and
aquatic invertebrate life—cycle
Aquatic organism accumulation
Plant Protection
Seed germination/seedling emergence
Vegetative vigor
Aquatic plant growth
Environmental Fate
Hydrolysis
Photodegradation (water, soil, air)
Anaerobic soil metabolism
Leaching, adsorption/desorption
Volatility (lab)
Volatility (field)
Soil dissipation
Soil dissipation, long—term
Accumulation:
Rotational crops (confined)
Rotational crops (field)
Fish
6. Contact Person at EPA :
Robert J. Taylor
U.S. Environmental Protection Agency
Registration Division (Ts—767c)
401 M Street SW.
Washington, DC 20460
(703) 557—1830
Disclaimer: The information presented in this Pesticide Fact
Sheet is for informational purposes only and may not be used
to fulfill data requirements for pesticide registration and
reregistration.
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