EPTC (Eptam) Herbicide Profile 10/83
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 06
DATE ISSUED: OCTOBER 3, 1983
1. DESCRIPTION OF CHEMICAL
- Generic Name: s-ethyl dipropylthiocarbamate (C9H19NOS)
- Common Name: EPTC
- Trade Name: Chemolimpex, Eptam, and Eradicane
- EPA Shaughnessy Code: 041401
- Chemical Abstracts Service (CAS) Registry Number: 759-94-4
- Year of Initial Registration: 1969
- Pesticide Type: Herbicide
- Chemical Family: Thiocarbamate
- U.S. and Foreign Producers: Stauffer Chemical Company
2. USE PATTERNS AND FORMULATIONS
- Application sites: EPTC is a selective thiocarbamate herbicide
which is registered for use in preemergent control of certain annual
grasses, broadleaf weeds and perennial weeds, such as quackgrass,
Bermudagrass, and nutsedge on field, vegetable, orchard, ornamental,
and noncrop sites.
- Types of formulations: EPTC is available in granular and emulsifiable
liquid concentrate formulations.
- Types and methods of application: EPTC must be incorporated in the
soil by disking, applied with subsurface injection equipment, or
metered into irrigation water to obtain proper weed control. The
specific method of application and type of equipment are determined by
site, formulation, and availability of equipment.
- Application rates: 2.0 lbs. a.i./A to 7.0 lbs. a.i./A
- Usual carriers: water and clay
3. SCIENCE FINDINGS
Technical EPTC is a light yellow liquid. At room temperature, EPTC is
a liquid, and it has an amine odor. EPTC boils at approx. 285 degrees C.
The chemical does not present any unusual handling hazards.
- Technical EPTC is potentially a strong eye irritant (Toxicity
Category II). The available data also indicate that technical EPTC
has relatively low acute oral, dermal, and inhalation toxicities,
and low potential for primary dermal irritation.
- Studies on butylate (a close structural relative of EPTC), as well
as studies on EPTC itself, have indicated effects of impaired
clotting function in test animals. Therefore, any additional
studies on EPTC must include a test for clotting function and
hematology in the protocol design to better define the effects on
clotting and clearly establish a no-observed-effect-level (NOEL).
- Acute toxicology studies on EPTC are as follows:
- Oral LD50 in rats: 1,652 mg/kg body weight, Toxicity Category III
- Oral LD50 in mice: 3,160 mg/kg body weight, Toxicity Category III
- Inhalation LC50 in rats: 4.3 mg/l, Toxicity Category III
- Dermal LD50 in rabbits: 2,750 mg/kg body weight, Toxicity
- Primary eye irritation in rabbits: severe eye irritant, Toxicity
- Primary dermal irritation in rabbits: mild skin irritant,
Toxicity Category IV
- Chronic toxicology studies on EPTC are as follows:
- In a 54-week feeding study of EPTC in rats: the NOEL was 20
mg/kg/day; the LEL was 80 mg/kg/day.
- In a 2-year chronic feeding and oncogenicity study of EPTC in
mice: the NOEL was 20 mg/kg/day; the LEL was 80 mg/kg/day, and no
evidence of tumorigenicity was found.
- General metabolism: EPTC studies in male and female rats were
reviewed and satisfied the current data requirements for animal
- Major routes of human exposure:
- Current data does not indicate that the U.S. population is exposed
to EPTC through the dietary or non-dietary routes.
Physiological and Biochemical Behavioral Characteristics
- Foliar absorption: EPTC is absorbed mostly through the plant roots,
with little or no foliar penetration.
- Translocation: EPTC is readily absorbed by roots and translocated
upward to the leaves and stems.
- Mechanism of pesticidal action: EPTC disrupts the growth of
meristematic regions of the leaves and protein synthesis.
- Metabolism and persistence in plants: EPTC is rapidly metabolized
by plants to C02 and common plant constituents (amino acids and
- Adsorption and leaching characteristics in basic soil types: EPTC
is adsorbed onto dry soil. The amount of leaching decreases as clay
and organic matter increase.
- Microbial breakdown: Microbes are the primary factor in the
breakdown of EPTC in soils.
- Loss from photodecomposition and/or volatilization: EPTC is readily
lost from volatilization unless it is immediately incorporated in
the soil at time of application.
- Average persistence at recommended rates: The half-life of EPTC in
moist loam soil at 21 to 27 C is approximately one week.
- Avian oral LD50: > 26,000 ppm
- Avian dietary LC50: > 20,000 ppm
- Fish LC50: 17.0 ppm to 27.0 ppm
- Problems with aquatic organisms are not anticipated, because an
estimated environmental concentration of 0.141 ppm in EPTC runoff is
well below the LC50 for aquatic organisms.
- The low toxicity and placement of EPTC into the soil immediately
prior to or just after planting should reduce exposure and provide
an adequate safety margin.
- Tolerances are established for negligible residues (N) of the
herbicide s-ethyl dipropylthiocarbamate in or on the following raw
Commodity Parts Per Million
Almonds, hulls 0.1(N)
Beans, castor 0.1(N)
Cotton, forage 0.1(N)
Fruits, citrus 0.1(N)
Fruits, small 0.1(N)
Grain crops 0.1(N)
Grasses, forage 0.1(N)
Legumes, forage 0.1(N)
Safflower, seed 0.1(N)
Sunflower, seed 0.1(N)
Vegetables, fruiting 0.1(N)
Vegetables, leafy 0.1(N)
Vegetables, root crop 0.1(N)
Vegetables, seed and pod 0.1(N)
Problems Known to Have Occurred With Use of the Chemical
The Pesticide Incident Monitoring System (PIMS) indicated at least four
cases involving EPTC alone from 1966 to 1979. In these reports,
agricultural workers such as mixers, loaders, and applicators received
medical treatment after the pesticide contacted their eyes. The
exposures were caused by equipment failure or splashing, and resulted in
irritation, swelling, redness, and inflammation of the eyes. No
fatalities were reported. PIMS is a voluntary reporting system and does
not include detailed follow up or validation of reported incidents.
Summary Science Statement
EPTC is potentially a strong eye irritant, but it has low acute
toxicities. Since EPTC is incorporated into the soil immediately or just
after planting, it will not present a hazard to birds and aquatic
organisms. At least two chronic toxicology studies are required to
complete the data base.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Use classification: general use
- Use, formulation, or geographical restrictions: No use, formulation,
or geographical restrictions are required.
- Unique label warning statement: None
- Summary of risk/benefit review: No risk assessments were conducted.
5. SUMMARY OF MAJOR DATA GAPS
- The following toxicological studies are required within four years
after receipt of the guidance package:
- A 1-year or longer dog feeding study
- A rat oncogenicity study
- A teratology study in two species*
- A 2-generation reproduction study**
- The requirement for a subchronic neurotoxicity study is being deferred
until an acute neurotoxicity study has been completed in order to
determine whether the subchronic study is necessary. This study must
be submitted within six months after receipt of the guidance package.
- The following environmental fate data are required within four years
after receipt of the guidance package:
- Hydrolysis test
- Photodegradation test in water
- Metabolism test in anaerobic soil
- Mobility (volatility) test in the lab
- Dissipation study in soil
- Accumulation study in combined rotational crops
*A teratology study (CDL:247780) submitted by Stauffer Chemical Company
is pending review by the Agency.
**A reproduction study (CDL:249077) submitted by Stauffer Chemical
Company is pending review by the Agency.
6. CONTACT PERSON AT EPA
Robert J. Taylor
Product Manager (25)
Registration Division (TS-767C)
401 M Street, S.W.
Washington, DC 20460
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.