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Agency W thington. OC 20460
Pesticide
Fact Sheet
Name of Chemical: Dalapon
Reason for Issuance: Registration Standard
Date Issued: July 31, 1987
Fact Sheet Number:
DESCRIPTION OF CHEMICAL
Daiapon (free acid)
Chemical Name: 2,2-dichloropropionic acid
CAS Registry No.: 75-99-0
Shaughnessy No.: 28901
Daiapon Sodium Salt
Chemical Name: sodium 2,2-dichloropropionate
CAS Registry No.: 127-20-8
Shaughnessy No.: 28902
Daiapon Magnesium Salt
Chemical Name: magnesium 2,2-dichloropropionate
CAS Registry No.: N/A
Shaughnessy No.: 28903
Year of Initial Registration: 1969
Trade Names: 2,2-dichloropropanoic acid, sodium and magnesium
2,2-dichloropropanoate, Basfapon, Basfapon B, Basfapon N,
Daiapon 85, dalapon magnesium, Dalapon-Na, dalapon sodium,
Ded-Weed, Devipon, Dowpon M, DM Dalapon, DPA (JMAF), Gramevin,
magnesium dalapon, magnesium salt of dalapon, proprop,
Radapon, Revenge, sodium dalapon, and sodium salt of dalapon.
Pesticide Type: Herbicide
U.S. and Foreign Producers: Dow Chemical Company; BASF
Aktiengesellschaft; Crystal Chemical Inter-America; SDS
Biotech Corp.; Sintesul; and Vertec Chemical Corp..*
USE PATTERNS AND FORMULATIONS
Application Sites: Terrestrial, food crops (root and tuber
and legume vegetables; citrus, pome, stone and small fruits;
tree nuts; cereal grains, coffee beans; sugarcane; birds-
foot trefoil); terrestrial, nonfood crops (fallowland;
pastureland; rangeland; noncrop areas; ornamental grasses,
shrubs and trees); aquatic, food crop (taro paddy banks);
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aquatic nonfood sites (drainage ditches; industrial waste
disposal systems, irrigation ditchbanks); forestry (forest
seedlings).
Predominant Uses: Primarily an industrial/noncrop herbicide
(70 percent); agricultural use (30 percent) primarily
on sugarcane and potatoes.
Types and Methods of Application: Conventional aerial or ground
equipment as fall or spring preplant, preemergence, or post-
emergence application, depending on the crop or site situation.
Application Rates: 0.075 lb active ingredient (ai) per 5,000
square feet to 25.5 lb ai per acre (A) for industrial/non—
crop use; 0.12-17 lb ai/A for food uses.
Types of Formulations: Wettable powder, soluble concentrate!
solid, impregnated materials, granular and technical.
Usual Carriers: Water
SCIENCE FINDINGS
Summary Science Statement: Available data are insufficient to
assess the toxicological effects of dalapon. Only one accept-
able oncogenicity study is available and complete evaluation
of this study is not possible without historical control data.’
This study did show an increased incidence of benign lung tumors.
There are no acceptable environmental fate studies. Prelim-
inary data, however, do indicate there may be a potential for
groundwater contamination.
There are insufficient data available to fully assess ecologi-
cal effects from the use of dalapon. However, there is a
threat to endangered plants based on the use pattern of dalapon.
Chemical Characteristics: Product chemistry data are unacceptable,
except dissociation constant as noted below, and are required.
Dissociation constant
(magnesium salt) = pka = 1.84 at 0.05M
Toxicology Characteristics: While published registrant data indi-
cate low toxicity, the Agency has only limited toxicological
data on dalapon as discussed below:
In an acceptable two-year oncogenicity study, mice were fed
doses of 0. 2, 60 and 200 mg/kg/day. All doses (2, 60 and 200
mg/kg/day) showed a doubling of the incidence of benign lung
tumors in the male mice compared with controls. Hi8torical
control data are needed to allow final evaluation of the study
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A supplerrentary study is available on the teratogenic
potential of dalapon in the rat. No teratogenic response
was reported. However, a NOEL for fetal and maternal
toxicity was not determined.
Physiological and Behavioral Characteristics:
Foliar Absorption: Dalapon is absorbed by roots and
leaves but is easily washed off the foliage.
Translocation: Dalapon translocates readily throughout
the plant and accumulates in young tissue; it is not
degraded in plants.
Mechanism of Pesticide Action: The mode of action of dalapon
involves interference of meristematic activity in root
tips and apical meristems, reduction of wax formation
on leaf surfaces, and alteration of cell membranes.
Environmental Characteristics: There are no acceptable studies
to assess the environmental fate of dalapo,n. Supplementary
data do indicate that there may be a potential for groundwater
contamination because dalapon appears to be highly soluble
in water, to leach readily and to be moderately persistent.
Dalapon has been designated as one of the pesticides for
analysis in the National Pesticides in Well Water Survey.
Ecological Characteristics:
Avian Dietary Toxicity - Japanese quail = > 5000 ppm
Ring-necked
pheasant = > 5000 ppm
Mallard duck = > 5000 ppm
Freshwater Fish Toxicity - Bluegill = 105 ppm
Aquatic Invertebrates Toxicity - Daphnia pulex = 11 ppm
Potential Problems Related to Endangered Species: The Office
of Endangered Species has issued a jeopardy opinion which
indicates that several plant species could be in jeopardy
if herbicides are used within or adjacent to their habitat.
This opinion applies to dalapon’s registered forçst uses.
Tolerance Assessment: Tolerances have been established for
residues of dalapon in a variety of raw agricultural com-
modities and meat byproducts (40 CFR 180.150(a)(b)) and in
processed food (21 CFR 193.105) and feed (21 CFR 561.110).
The toxicology data for dalapon are insufficient to deter-
mine an Acceptable Daily Intake (ADI). Prior to reevalu-
ation of dalapon, an ADI of 0.08 mg/kg/day was considered
appropriate based on a NOEL of 8 mg/kg/day from a 2-year
rat study and an uncertainty factor of 100. This study
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has since been determined to be unacceptable. However,
unt .1 such time as data are available and an ADI can be
established, the rat study will be used to determine a
provisional ADI (PADI). Because of the study’s deficien-
cies, an uncertainly factor of 1000 was used to arrive at
a PADI of 0.008 mg/kg/day. Comparing the percent of crop
treated to the PADI results in a Theoretical Maximum Resi-
due Contribution (TMRC) for the U.S. population of 0.00036
mg/kg/day. The TMRC occupies 4.5 percent of the PADI.
Pesticide Incident Monitoring System (PIMS): PIMS files contain
22 incident reports involving dalapon, nine of which involved
dalapon in combination with other Ingredients. Twelve were
related to agricultural use. Equipmeat failure occurred in
four of the incidents. Fifteen of the incidents involved
exposure to humans; while medical treatment was administered
in 14 of these incidents, none required hospitalization.
SUMMARY OF REGULATORY POSITION AND RATIONALE
Summary of Agency Position: The Agency is requiring regis-
trants of dalapon to submit additional data as identified
in the Registration Standard and summarized in the follow-
ing section. The Agency will not establish any new food
use or register any significant new uses until adequate
data are available to fully assess dalapon.
Unique Warning Statements Required on Labels: Unique labeling
is not imposed in the Registration Standard. Endangered
species labeling, however, is required for forest uses.
This labeling is addressed in Pesticide Registration
Notice (PR) 87-4 dated May 1, 1987.
SUMMARY OF MAJOR DATA GAPS
Due Date (From
Data Issuance of Standard )
Product Chemistry 6-12 months
Residue Chemistry 15-18 months
Environmental Fate 9-39 months
Toxicology 9-50 months
Ecological Effects 9-12 months
CONTACT PERSON AT EPA : Robert J. Taylor
Office of Pesticide Programs, EPA
Registration Division (TS--767C)
401 H Street SW.
Washington, DC 20460
Phone: (703) 557-1800
DISCLAIMER: The information presented in this Fact Sheet is
for information purposes only and may not be used to fulfill
data requirements for pesticide registration and reregistration.
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