2,4-DP (dichlorprop) Herbicide Profile 9/88
Name of Chemical: 2-(2,4-dichlorophenoxy) propionic acid
and amine salts and esters
Reason for Issuance: Registration Standard
Date Issued: September 1988
Fact Sheet Number: 180
1. DESCRIPTION OF CHEMICAL(S)
Generic Name(s): 2-(2,4-dichlorophenoxy)propionic acid
2,4,DP, diethanolamine salt
2,4-DP, dimethylamine salt
2,4-DP, butoxyethyl ester
2,4-DP, isooctyl ester
Common Names(s): 2,4-DP, or dichlorprop, and its amines and esters.
Trade Name(s): 2,4-DP is available under a number of trade names,
most often formulated as an amine salt or ester.
EPA Shaughnessy Codes: 031401 (acid)
031416 (diethanolamine salt)
031419 (dimethylamine salt)
031453 (butoxyethyl ester)
031463 (isooctyl ester)
Chemical Abstracts Service
(CAS) Number: 120-36-5 (acid)
84731-66-8 (diethanolamine salt)
53404-32-3 (dimethylamine salt)
53404-31-2 (butoxyethyl ester)
28631-35-8 (isooctyl ester)
Year of Initial Registration: 1968 (acid).
Pesticide Type: Herbicide; plant growth regulator.
Chemical Family: Chlorinated phenoxy.
U.S. and Foreign Producers: 2,4-DP technical products are manufactured
by a number of companies, both U.S. and
2. USE PATTERNS AND FORMULATIONS
- Registered Uses: Terrestrial Nonfood (golf courses, noncrop and
recreational areas) Aquatic Nonfood (drainage ditchbanks)
Domestic Outdoor (home lawns) Forestry (conifer/pine release
forest plantation site preparation).
- Predominant Uses: Ornamental turf, e.g., golf courses and home lawns
(approximately 57% of total usage) rights-of-way/roadways
(approximately 42% of total usage).
- Formulation Types Registered: Granular; liquid (emulsifiable
concentrate, soluble concentrate, ready-to-use) aerosol spray.
- Methods of Application: Ground equipment and aircraft.
3. SCIENCE FINDINGS
Existing data are inadequate to assess environmental and health
effects for 2,4-DP. Available data indicate that 2,4-DP is not
oncogenic in the rat, but there is a positive trend for mutagenic
effects. There is also some potential for toxicity to aquatic
organisms. Additional chronic toxicological testing is not required
since there are no registered food uses for 2,4-DP.
2,4-DP is generally formulated as an amine salt or ester. The
amine and ester forms may differ in biological activity and
environmental fate from the parent compound. Data are needed on
each amine and ester, as well as the acid, to enable a complete
Concern about possible groundwater contamination exists for the
family of 2,4-D compounds (2,4-D, 2,4-DB and 2,4-DP). Additional
data and a label warning statement are required.
Chemical Characteristics. (2,4-DP acid technical)
Physical State - Crystalline solid; flakes.
Color - White to tan.
Odor - Slight phenolic.
Molecular weight - 235.1.
Empirical formula - C9H8Cl203.
Melting point - 116 - 118 degrees C.
Solubility - Highly soluble in acetone, benzene, carbon tetrachloride,
diesel oil and kerosene; slightly soluble in water.
Vapor pressure - Negligible at 20 degrees C.
Specific gravity - 1.186 at 20 degrees C.
Stability - Stable to melting point.
Toxicological Characteristics. (NOTE: 2,4-DP acid is test material
unless specified otherwise).
- Acute Toxicity - Oral LD50 (mouse): 500 mg/kg (males)
620 mg/kg (females)
(rat): 700 mg/kg (males)
500 mg/kg (females)
Toxicity Category III
- Subchronic Toxicity - Oral studies in rats and dogs were inconclusive.
some kidney and liver effects were noted.
- Chronic Toxicity -
- Chronic Feeding/oncogenicity (rat): LOEL for systemic effects 11
mg/kg (male), 13 mg/kg (female); NOEL 4 mg/kg. No significant
increase in tumor incidence in any organ. Kidney and liver toxicity
and decreased body weight/food efficiency at highest dose level. No
oncogenic effects under conditions of the study.
- Oncogenicity (mouse): LOEL for systemic effects 25 mg/kg; NOEL not
established. No oncogenic effects under conditions of the study,
but study inadequate due to numerous reporting deficiencies.
- Teratology: No acceptable data.
- Reproduction: LOEL for maternal and developmental toxicity (rat)
100 mg/kg; NOEL 50 mg/kg. No reproduction or fertility effects
under conditions of the study, but study inadequate due to numerous
- Mutagenicity: There is a positive trend for mutagenic effects for
both 2,4-DP acid and 2,4-DP butoxyethyl ester. Additional data are
required for each 2,4-DP compound.
- Metabolism: No acceptable data.
Physiological and Behavioral Characteristics.
- Mechanism of Pesticide Action: Phenoxy herbicides (including 2,4-DP)
are hormone weed killers affecting the activity of enzymes,
respiration and cell division.
- No data are available.
- Avian Toxicity: No acute oral studies available. Dietary studies
indicate 2,4-DP butoxyethyl ester is practically nontoxic (LC50
>10,000 ppm) to waterfowl and upland game birds.
- Aquatic Organism Toxicity: Acceptable data indicate 2,4-DP
butoxyethyl ester is highly toxic to fish and freshwater
- Non-Target Insect Toxicity: No data are available.
- Non-Target Plants/Endangered species: Since 2,4-DP is a broadleaf
herbicide a potential hazard exists for non-target plants. Hazard
assessments for endangered species cannot be completed until
additional data are received.
- Tolerance Assessment. There are no registered food or feed uses for
2,4-DP acid or its amines or esters that require the establishment
- Reported Pesticide Incidents. Based on the Pesticide Incident
Monitoring System files covering the period 1966 to 1979, reports
were received concerning off-target movement for unspecified
2,4-D (family) compounds. me incidents involved drift from
aerial (173 reports) and ground (104 reports) application, as
well as volatilization (35 reports) and resulted in damage to
non-target crops and other desirable plants.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Summary of Agency Position. The Agency is requiring additional
toxicological data for 2,4-DP and will further evaluate the
mutagenic and teratogenic potential of 2,4-DP when additional
data are received. Environmental effects will also be evaluated
when data gaps for fish/wildlife and environmental fate are
filled. The Agency will not establish any significant new uses
until Registration Standard data are reviewed.
Unique Label Warning Statements.
1. Environmental Hazards - (butoxyethyl ester).
Manufacturing-use: "This product is toxic to fish."
End-use: "This product is toxic to fish and aquatic invertebrates."
2. Groundwater/Protective Clothing - (end-use products).
"This product can reach groundwater as a result of mixing/loading
or from improper handling. To minimize groundwater contamination
from spills-during-mixing/loading/cleaning of equipment, take
the following steps:"
(Liquid only) - "Mixing and loading: When mixing, loading or
applying this product, wear chemical resistant gloves. Wash
nondisposable gloves thoroughly with soap and water before
removing. The mixing and loading of spray mixtures into the
spray equipment-must be carried out on an impervious pad (i.e.,
concrete slab, plastic sheeting) large enough to catch any
spilled material. If spills occur, contain the spill by using
an absorbent material (e.g., sand, earth or synthetic absorbent).
Dispose of the contaminated absorbent material by placing in a
plastic bag and following disposal instructions on this label.
Triple rinse empty containers and add the rinsate to the mixing
(Granular only) - "Handling: When handling this product, wear
chemical resistant gloves. Wash nondisposable gloves thoroughly
with soap and water before removing. If spills occur, collect
the material and dispose of by following disposal instructions
on this label."
(Liquid and granular) - "Cleaning of equipment: When cleaning
equipment, do not pour the washwater on the ground; spray or
drain over a large area away from wells and other water sources."
5. SUMMARY OF MAJOR DATA GAPS
- The following data are required for 2,4-DP acid. The Agency is also
requiring data on each individual amine and ester of 2,4-DP. Specific
requirements are detailed in the Data Tables, Appendix I of the
Due Date (From Issuance of Standard)
Product Chemistry 6 - 15 months
Toxicology: 9 - 18 months
Ecological Effects: 9 - 12 months
and plant studies
Environmental Fate: 9 - 27 months
6. CONTACT PERSON AT EPA
Mr. Richard Mountfort
Product Manager 23
Registration Division (TS-767C)
Office of Pesticide Programs, EPA
Washington, DC 20460
Telephone: (703) 557-1830
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