United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-738-F-98-002
November 1998
R.E.D. FACTS
Pesticide
Reregistration
DCPA
All pesticides sold or distributed in the United States must be registered
by EPA, based on scientific studies showing that they can be used without
posing unreasonable risks to people or the environment. Because of advances
in scientific knowledge, the law requires that pesticides which were first
registered before November 1, 1984, be reregistered to ensure that they meet
today's more stringent standards.
In evaluating pesticides for reregi strati on, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human health
and environmental effects of each pesticide. The Agency develops any
mitigation measures or regulatory controls needed to effectively reduce each
pesticide's risks. EPA then reregisters pesticides that can be used without
posing unreasonable risks to human health or the environment.
When a pesticide is eligible for reregi strati on, EPA explains the basis for
its decision in a Reregistration Eligibility Decision (RED) document. This fact
sheet summarizes the information in the RED document for reregi strati on case
0270, DCPA.
Use Profile
DCPA is a pre-emergent herbicide used to control annual grasses and
broadleaf weeds on ornamental turf and plants, strawberries, seeded and
transplanted vegetables, cotton, and field beans.
Formulations include an emulsifiable concentrate, a flowable concentrate,
granular, soluble concentrate/liquid and wettable powder.
DCPA may be applied at planting, transplant, post-emergence, or post-
transplant as a soil treatment. It also may be applied as a foliar broadcast
treatment or at layby. It can be applied with either ground or aerial equipment.
Use practice limitations prohibit applying DCPA directly to water or
wetlands (swamps, bogs, marshes, and potholes) or through any type of
irrigation system. They prohibit discharging effluent containing DCPA into
sewage systems without notifying the sewage treatment plant authority
(POTW) and prohibit discharging effluent containing DCPA into lakes,
streams, ponds, estuaries, oceans, or public water (NPDES license restriction).
They prohibit feeding clippings, treated foliage, treated screenings or hay to
livestock. They also prohibit grazing livestock in treated areas, feeding or
grazing forage, silage or fodder grown in treated fields to livestock, grazing
treated areas feeding crop refuse to livestock, or using clippings from treated
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Regulatory
History
area for feed or forage. For terrestrial uses, use practice limitations prohibit
applying DCPA directly to water or to areas where surface water is present or
to intertidal areas below the mean high water mark. DCPA also must be left
out of lakes, streams, and ponds. For ground water restrictions, see RED.
DCPA was first registered as a pesticide in the U.S. in 1958 as a
selective preemergence herbicide for weed control on turf grasses. The DCPA
technical products were subject to a June, 1987 Data Call-In Notice (DCI)
requiring analysis for polyhalogenated dibenzo-p-dioxins/dibenzofurans
(referred to as dioxin/furans). EPA issued a Registration Standard for DCPA
in June 1988 (NTIS# 540/RS-88-084). DCI's were issued in September 1992
and October 1995 requiring DCPA occupational exposure monitoring data.
Currently, there are 66 products registered.
Human Health
Assessment
Toxicity
DCPA technical is classified under Toxicity Category IV (practically
non-toxic) for acute-oral toxicity and dermal irritation and Toxicity Category
III (slightly toxic) for dermal LD50, inhalation LC50, and eye irritation.
DCPA is not a dermal sensitizer.
DCPA has been classified as a Group C, possible human carcinogen,
based on increased incidence of thyroid tumors in both sexes of the rat
(although only at an excessive dose in the female), and liver tumors in female
rats and mice, at doses which were not excessive.
Dietary Exposure
People may be exposed to residues of DCPA through the diet.
Tolerances or maximum residue limits have been established for residues of
DCPA in many food and feed crops (see 40 CFR 180.185). EPA has
reassessed the DCPA tolerances and found that some are acceptable, others
must be revoked because refinements in crop groups must be replaced with
new tolerances for the new crop groupings. Acute dietary risk assessments
were not necessary since there were no acute toxicological endpoints of
concern for DCPA or its impurities. Chronic and carcinogenic dietary risks
were assessed, however, due to exposure to DCPA, HCB, and dioxin/furans.
Chronic risk estimates for the U.S. population and all subgroups were well
below 100% of the RfD for DCPA, HCB, and dioxin/furans. Based on these
estimates, the Agency concludes that DCPA use does not pose a significant
chronic dietary risk.
Carcinogenic risk estimate for exposure to DCPA, HCB, and
dioxin/furans through food were 3.5 x 10"7, and 7 x 10"8, respectively. All of
these risk estimates are within the range (zero to 1 x 10"6) generally considered
to be negligible by the Agency. Thus, the Agency concludes that DCPA use
does not pose a significant excess lifetime cancer risk.
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The Agency assessed both chronic (non-cancer) and carcinogenic risk
due to exposure to DCPA and its metabolites through contaminated ground
and surface water. The Agency used annual contamination averages from five
geographic regions as potential drinking water exposure values. The highest
annual average was 50 ppb in New York from a turf study. Although this
represents approximately 71% of the HA, it only corresponds to 11% of RfD.
Even if part of this population were to the maximum 3% of the RfD from other
dietary sources, the chronic dietary risk would still be considered minimal.
Individual excess lifetime cancer risk from the New York turf site was
1.7 x 10"6. The next highest risk estimate is based on data fro Suffolk County,
New York. The risk estimate from that site is 9.7 xlO"7. DCPA's registrant
has voluntarily withdrawn from selling the product in Suffolk, New York.
Exposure values from all other sites resulted in risks below the Agency's
cancer benchmark of 1 x 10"6.
Based on these estimates, the Agency concludes that DCPA and its
metabolites do not currently pose a significant cancer or chronic non-cancer
risk from non-turf uses to the overall U.S. population from exposure through
contaminated drinking water.
Occupational and Residential Exposure
DCPA is currently registered for commercial and residential use. Risk
assessments were performed to assess the individual excess lifetime cancer risk
from DCPA and HCB resulting from occupational and residential exposure to
DCPA. The Agency will not generally allow non-dietary risks to exceed 10"4,
except in cases where EPA has determined that benefits exceed the risks.
Risk was estimated for occupational exposures to both DCPA and HCB.
The highest risk for both commercial applicators and private applicators is
associated with the use of the wettable powder formulation. For the
commercial applicator, the highest risk for DCPA was estimated to be 7.5 x 10"
5 and for HCB (in DCPA) to be 1.9 x 10'4. The Agency is requiring
mixer/loader/applicators using DCPA wettable powders to wear a dust-mist
respirator fitted with a TC-21 filter to mitigate this risk. Wearing a dust-mist
respirator reduces the risks to 4.0 x 10"5 and 1.3 x 10"4 for DCPA and HCB
respectively.
For the private applicator, the highest risk for DCPA was estimated to be
1.6 X ID'6 and for HCB (in DCPA) to be 4.6 X 10'6.
Risks to children playing on a treated lawn were assessed for exposure to
DCPA and HCB. The risks from DCPA and HCB to children playing on an
irrigated lawn are 5.6 x 10"7 and 3.9 x 10"7, respectively. The risks from
DCPA and HCB to children playing on non-irrigated lawns are 2.0 x 10"6 and
2.7 x 10"6, respectively. The Agency is conducting a risk/benefit assessment to
determine whether the turf use is eligible for reregi strati on. However, in the
interim, the Agency is requiring that residential lawns be watered after DCPA
product use and that reentry not occur until sprays have dried, in an effort to
mitigate risks to children.
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Risk from exposure to DCPA and HCB through worker reentry into a
cucumber field was assessed. Harvesting cucumbers immediately after
application resulted in risk estimates of 1.8 x 10"4 for DCPA and 3.2 x 10"4 for
HCB. Delayed reentry periods only minimally reduced risk estimates.
However, the Agency believes that the worker exposures are overestimates.
These scenarios were based solely on a foliar dissipation study, not on dermal
exposure studies. DCPA's registrant is a member of a task force which will
address dermal exposure for hand labor tasks required by various crops, such
as cucumber harvesting. The risk assessment will be refined when the task
force submits it dermal exposure data.
Human Risk Assessment
DCPA and its metabolites generally are of low acute and chronic
toxicity. DCPA has been classified as a Group C, possible human carcinogen.
Many food crop uses are registered, however, dietary exposure to DCPA
residues in foods is at a low level, as is the cancer risk posed to the general
population.
Of greater concern is the risk posed to DCPA handlers, particularly
mixers/loaders/applicators, and field workers who come into contact with
treated areas following application of this pesticide. Exposure and risk to
workers will be mitigated by the use of Personal Protective Equipment
required by the Worker Protection Standard. Because the pesticide is a
possible human carcinogen, the Agency is requiring mixer/loader/applicators
using DCPA wettable powder to wear a dust-mist respirator fitted with a TC-
21 filter to mitigate this risk.
Environmental
Assessment
Environmental Fate
Biodegradation is the primary dissipation process for DCPA. Under
laboratory conditions, the half-life is approximately 15-30 days, but longer
half-lives have been reported in the field. Parent DCPA is not especially
persistent or mobile. Tetrachloroterephthalic acid (TPA or di-acid) is the only
significant DCPA metabolite, with monomethyl tetrachloroterephthalic acid
(mono-acid) as a minor metabolite. TPA is unusually mobile and persistent in
the field. Data suggest that TPA will leach to groundwater wherever DCPA is
used, regardless of soil properties.
Volatilization from soil is also a major dissipation route for parent
DCPA. Volatilization appears to be the source of DCPA residues on crops to
which it has not been applied. The maximum distance that DCPA may move
following volatilization is not known, but drift has been reported in the
published literature. Under warm conditions in fields with high soil moisture
levels, volatilization may be the major dissipation route for DCPA. More
typically volatilization probably accounts for 20-40 percent of DCPA loss. For
TPA leaching is the major dissipation route.
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Ecological Effects
DCPA is practically nontoxic to birds on both an acute and a subacute
dietary basis. New avian reproduction studies are required to determine its
chronic toxicity to birds. DCPA is practically nontoxic to small mammals and
bees, is probably no more than slightly toxic to fish, and is slightly toxic to
practically nontoxic to aquatic invertebrates. DCPA is moderately to highly
toxic to nontarget estuarine and marine organisms. Seedling emergence and
vegetative vigor studies (tier II) are required to assess toxicity of DCPA to
nontarget, offsite plants.
Ecological Effects Risk Assessment
Ecological effects risk assessments indicate that non-turf uses of DCPA,
labeled and used as specified in the RED, will not pose unreasonable risks to
birds, insects, fish and estuarine species, or nontarget plants. However, the
Agency is requiring additional data in the areas of avian toxicity and
reproduction, vegetative vigor, and seedling emergence to confirm these
conclusions. The Agency has concerns regarding chronic risks to mammalian
species and acute risks to mollusk species as a result of DCPA use on turf.
Once the benefits assessment on turf has been completed, the Agency will
determine whether this use is eligible for reregi strati on.
Risk Mitigation EPA is requiring the following risk mitigation measures for DCPA:
Residential Risk Mitigation - Interim risk reduction measures are being
implemented to reduce exposure to children playing on treated lawns. Labels
will require that residential lawns be watered after DCPA product use and that
reentry not occur until sprays have dried.
Groundwater Contamination Risk Mitigation - The registrant has
voluntarily agreed to limit manufacture of DCPA technical grade active
ingredient for use within the United States to current production levels. This
will help insure that groundwater contamination rates do not significantly
increase in the future. Additionally, DCPA labels must bear a groundwater
advisory statement.
Occupational Risk Mitigation - In addition to the personal protective
equipment, reentry intervals and application restrictions required by the
Worker Protection Standard, the Agency is requiring mixer/loader/applicators
using DCPA wettable powders to a wear dust-mist respirator fitted with a TC-
21 filter. This will reduce risks from exposure to both DCPA and HCB.
Ecological Risk Mitigation - To minimize potential harm to endangered
mammals and mollusks from exposure to DCPA the Agency is developing an
Endangered Species Protection Program. This program is intended to
implement mitigation measures that will eliminate adverse impacts to
endangered species from pesticides.
Spray Drift Risk Mitigation - To reduce the possibility of risk to non-
target animals and plants and surface water contamination from spray drift, the
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Agency is requiring label precautions, as well as, application restrictions and
prohibitions intended to reduce spray drift potential. A surface water advisory
statement is also required on DCPA labels.
Additional Data
Required
EPA is requiring the following additional generic studies for DCPA to
confirm its regulatory assessments and conclusions: Avian Reproduction (qual
and duck); Seed Germination and Seedling Emergence; Vegetative Vigor;
Nature of Residue, livestock; and Storage Stability.
The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs), and revised labeling for reregi strati on.
Product Labeling All DCPA end-use products must comply with EPA's current pesticide
Changes Required product labeling requirements and with the following. For a comprehensive list
of labeling requirements, please see chapter V of the DCPA RED document.
Products Intended Primarily for Occupational Use (WPS and nonWPS)
Minimum (Baseline) PPE/Engineering Control Requirements
The minimum (baseline) PPE for some occupational uses of DCPA.
These minimum (baseline) PPE as established by EPA are listed below. PPE
for all formulations not listed below will be based on the toxicity of the end-use
products as assessed during product reregi strati on.
For liquid concentrate formulations:
Mixers and loaders must wear:
—Long-sleeve shirt and long pants,
—Socks plus shoes,
-Chemical-resistant gloves*.
For wettable powder formulations:
Mixers, loaders, and applicators must wear:
-Long-sleeve shirt and long pants,
—Socks plus shoes,
—Chemical-resistant gloves*.
—a dust mist respirator with a TC-21C filter
For applications using a shaker can or backpack sprayer:
Applicators must wear:
-Long-sleeve shirt and long pants,
—Socks plus shoes,
-Chemical-resistant gloves*.
* For the glove statement, use the statement established for DCPA
through the instructions in Supplement Three of PR Notice 93-7.
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Products Intended Primarily for Homeowner Use
Minimum (baseline) PPE Requirements
EPA is not establishing active-ingredient-based minimum (baseline)
handler PPE for DCPA end-use products that are intended primarily for
homeowner use.
Products Intended Primarily for Occupational Use
WPS Uses
Restricted-entry interval:
A 12-hour restricted-entry interval (REI) is required for uses within the
scope of the WPS on all DCPA end-use products.
Early-entry personal protective equipment (PPE):
The PPE required for early entry is:
— coveralls,
— chemical-resistant gloves, and
— shoes plus socks.
NonWPS uses
Entry restrictions:
For liquid applications:
"Do not enter or allow others to enter the treated area until sprays have
dried."
For granular applications:
"Do not enter or allow others to enter the treated area until dusts have
settled. If soil incorporation is required following the application, do not
enter or allow others to enter the treated area (except those persons
involved in the incorporation) until the incorporation is complete. If the
incorporation is accomplished by watering-in, do not enter or allow
others to enter the treated area until the surface is dry following the
watering-in."
Products Intended Primarily for Homeowner Use
Entry Restrictions for Home Use Products
For liquid and granular formulations:
"This product must be watered in following application. Do not allow
persons or pets to enter the treated area until the grass is dry following
watering-in."
Placement in labeling: Place the appropriate entry restrictions in the
Directions for Use, under the heading "Entry Restrictions."
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Other Labeling Requirements for End-Use Products
Products Intended Primarily for Occupational Use
The Agency is requiring the following labeling statements to be located
on all end-use products containing DCPA that are intended primarily for
occupational use:
Application Restrictions:
"Do not apply this product in a way that will contact
workers or other persons, either directly or through drift.
Only protected handlers may be in the area during
application."
User Safety Requirements:
(Registrants: select this if coveralls are required for pesticide
handlers on the end-use product label:}
"Discard clothing or other absorbent materials that have been
drenched or heavily contaminated with this product's concentrate.
Do not reuse them."
(Registrants: select this always:}
"Follow manufacturer's instructions for cleaning/maintaining
PPE. If no such instructions for washables, use detergent
and hot water. Keep and wash PPE separately from other
laundry."
User Safety Recommendations:
"Users should wash hands before eating, drinking, chewing gum,
using tobacco, or using the toilet."
"Users should remove clothing immediately if pesticide gets inside.
Then wash thoroughly and put on clean clothing."
"Users should remove PPE immediately after handling this
product. As soon as possible, wash thoroughly and change into clean
clothing."
Engineering Controls:
"When handlers use closed systems, or enclosed cabs or
aircraft in a manner that meets the requirements listed in the
Worker Protection Standard (WPS) for agricultural
pesticides (40 CFR 170.240(d)(4-6), the handler PPE
requirements may be reduced or modified as specified in the
WPS."
Soil Incorporation Statement:
Registrants must add the following statement to their labeling in the
"Agricultural Use Requirements" box immediately following the restricted
entry interval:
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Regulatory
Conclusion
"Exception: if the product is soil-incorporated, the Worker
Protection Standard, under certain circumstances, allows workers
to enter the treated area if there will be no contact with anything
that has been treated."
Products Intended Primarily for Home Use
Application Restrictions
"Do not apply this product in a way that will contact
any person or pet, either directly or through drift.
Keep people and pets out of the area during
application."
User Safety Recommendations
"Users should wash hands before eating, drinking,
chewing gum, using tobacco, or using the toilet."
"Users should remove clothing immediately if pesticide
gets inside. Then wash thoroughly and put on clean
clothing."
(Registrants: select this only if gloves and/or protective eyewear
are required for homeowner users:}
"Users should remove protective clothing and
equipment immediately after handling this product.
Wash the outside of gloves before removing. Keep and
wash protective clothing and equipment separately
from other laundry."
ADDITIONAL LABELING REQUIREMENTS
The use directions for DCPA on beans prohibit grazing in treated areas
and the feeding of treated plant material or refuse to livestock. Under current
Agency policy, label restrictions prohibiting the feeding of bean forage and
straw/hay to livestock are inappropriate. The registrant must delete
restrictions prohibiting the feeding of bean forage and hay/straw to livestock
from all labels. However, the registrant may restrict the uses of DCPA on
beans to those varieties that are used for human consumption only.
When end-use product DCIs are developed (e.g., at issuance of the
RED), EPA should require that all end-use product labels (e.g., multiple active
ingredient labels, SANS, and products subject to the generic data exemption)
be amended such that they are consistent with the basic producer labels.
The use of currently registered products containing DCPA, except those
registered for turf use, will not pose unreasonable risks or adverse effects to
humans or the environment when used in accordance with approved labeling.
Therefore, all uses, except use on turf, of these products are eligible for
reregi strati on.
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Eligible DCPA products will be reregistered once the required product-
specific data, revised Confidential Statements of Formula, and revised labeling
are received and accepted by EPA.
For More EPA is requesting public comments on the Reregistration Eligibility
Information Decision (RED) document for DCPA during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
Electronic copies of the RED and this fact sheet are available on our
website at www.epa.gov/REDs.
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone 513-
489-8190, fax 513-489-8695.
Following the comment period, the DCPA RED document also will be
available from the National Technical Information Service (NTIS), 5285 Port
Royal Road, Springfield, VA 22161, telephone 703-605-6000.
For more information about EPA's pesticide reregi strati on program, the
DCPA RED, or reregi strati on of individual products containing DCPA, please
contact the Special Review and Reregistration Division (7508C), OPP, US
EPA, Washington, DC 20460, telephone 703-308-8000.
For information about the health effects of pesticides, or for assistance in
recognizing and managing pesticide poisoning symptoms, please contact the
National Pesticides Telecommunications Network (NPTN). Call toll-free 1-
800-858-7378, between 9:30 am and 7:30 pm Eastern Standard Time, Monday
through Friday.
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